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Biomedical subjects

R B Miller

Publications and source records attributed to R B Miller.

At least 19 recordsLinked to original sources
PubMed1992

Measurement of the cytotoxic effects of different strains of Mycoplasma equigenitalium on the equine uterine tube using a calmodulin assay.

The cytopathic effects induced by five strains of Mycoplasma equigenitalium for cells of equine uterine tube explants were tested by measuring changes in cellular and extracellular concentrations of calmodulin (CaM). Calmodulin concentrations in samples of total homogenate (TH) and total homogenate supernates (THS) of the infected equine uterine tube explants were significantly lower than respective measurements on noninfected controls. In tissue culture medium fractions (TCM) of some infected explants, CaM concentrations were significantly higher than noninfected controls (p > 0.95). The results suggest that M. equigenitalium colonization on ciliated cells of the equine uterine tube can affect the permeability of the cell membrane leading to leakage or release of CaM during cell breakdown. Measurement of CaM concentrations in samples of TH revealed significant differences in the cytotoxic effects induced by different strains of M. equigenitalium on the equine uterine tube (EUT). The data suggests that some strains of M. equigenitalium may have a role in reproductive failure in the mare. In addition comparisons of the means of the concentrations of CaM in samples of TH or THS in EUT explants from four mares in the follicular and four in the luteal phase of the estrous cycle were found to be not significantly different.

Animals↗
PubMed1991

Determination of serum cholinesterase activity by liquid chromatography with electrochemical detection.

A sensitive enzymatic assay to measure cholinesterase activity in serum using liquid chromatography with electrochemical detection has been devised and used to examine cholinesterase inhibition in mice treated with diisopropyl phosphorofluoridate. Acetylcholine was used as substrate, and a postcolumn reactor containing immobilized choline oxidase converted the enzymatic product, choline, and the internal standard, ethylhomocholine, into the electrochemically active H2O2. The postcolumn reactor also contained acetylcholinesterase to allow the indirect detection of the substrate. Assay optimization included investigations of substrate concentration, buffer pH and ionic strength, enzyme concentration, incubation time, and reaction termination method. The optimized procedure is applicable to samples with activities of 0.11 to 269 mmol/ml/h. Intrasample coefficient of variation for mouse serum samples was 1.7% (n = 12), while intersample coefficient of variation was 8.0% (n = 5). The mean +/- SE serum cholinesterase activity found for controls and mice treated with diisopropyl phosphofluoridate (6.3 mg/kg, ip, 24 h prior) was 158.7 +/- 5.7 mumol/ml/h and 36.6 +/- 3.1 mumol/ml/h, respectively (P less than 0.001).

Acetylcholinesterase↗
PubMed1991

A validated high-performance liquid chromatographic method for the determination of atenolol in whole blood.

A validated reversed-phase high-performance liquid chromatographic (HPLC) procedure employing fluorescence detection for the analysis of atenolol (Tenormin) in human whole blood is reported. The method is rapid and coupled with standard HPLC procedures leads to a sensitive, accurate and reproducible assay. The retention times of atenolol and internal standard, bamethan, are 4.4 and 6.3 min, respectively. The peak height ratio versus plasma concentration is linear over the range of 20.0-800 ng ml-1, with a detection limit below 10 ng ml-1. The mean absolute recovery of atenolol using the described assay is 90%. The inter- and intra-day accuracy and precision are within 8% of the actual values for all concentrations investigated. Furthermore, this procedure was applied to the analysis of whole blood samples from healthy subjects receiving a single 100 mg oral dose of Tenormin.

Atenolol↗
PubMed1991

High-performance liquid chromatographic assay for the derivatized enantiomers of propranolol and 4-hydroxypropranolol in human plasma.

A stereospecific method for the analysis of propranolol and 4-hydroxypropranolol in human plasma employing fluorescence detection has been developed using the homochiral derivatizing agent 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (TAGIT). The use of fluorescence detection provided enhanced sensitivity and cleaner chromatograms for the analysis of plasma samples, when compared to UV detection. Furthermore, parameters such as TAGIT concentration, vortex time and reaction time were examined to optimize conditions for maximum derivatization recoveries. The analyses of S(-)- and R(+)-propranolol from plasma were linear over the concentration range of 2.0-200 ng ml-1, while S(-)- and R(+)-4-hydroxypropranolol were linear from 5.0 to 200 ng ml-1.

Chromatography, High Pressure Liquid↗
PubMed1991

Endometrial biopsy in Holstein-Friesian dairy cows. I. Technique, histological criteria and results.

Endometrial biopsies were taken for histological assessment from 97 cows which calved in a commercial dairy herd between April and August 1984. Sixty-two cows were biopsied at both day 26 and 40 postpartum, 23 cows at only day 26, and 12 at day 40 only. Subjective and quantitative histological criteria were assessed. Ninety-five percent of biopsies were adequate for at least subjective assessment. The distribution of criteria within each horn-day category, as well as combined readings by day and by gravid or nongravid horn were computed and significant differences noted. There was more severe inflammation and more segmented cells at day 26 than 40 postpartum, and in the gravid compared to the nongravid horn. The distribution patterns for the criteria examined provide an overview of histological characteristics in this group of postpartum cows.

Animals↗
PubMed1991

Endometrial biopsy in Holstein-Friesian dairy cows. II. Correlations between histological criteria.

Endometrial biopsies were taken for histological assessment from 97 cows which calved in a commercial dairy herd between April and August 1984. The main objectives of this study were to analyze the interrelationships among histological criteria and to identify a shortlist of histological parameters to be included in subsequent analysis of associations with results of bacteriological culture, clinical findings and reproductive performance. Epithelial height and segmented cell counts were highly correlated within biopsy, between horns and between days. Subjective assessment of inflammation in the epithelium and/or stratum compactum generally identified biopsies which had any inflammation present. Cows which had inflammation in a biopsy from day 26 were likely to show inflammatory changes at day 40. Quantitative and subjective assessments of gland number, dilation and fibrosis were highly correlated. There was a positive association between the number of cross sections and the diameter of glands, and both of these criteria were negatively correlated with fibrosis and inflammatory changes. There may be different functional significance of the same histological finding at a different number of days postpartum.

Animals↗
PubMed1991

Endometrial biopsy in Holstein-Friesian dairy cows. III. Bacteriological analysis and correlations with histological findings.

This study examines the results of bacterial culture from 159 endometrial biopsy samples from 97 commercial dairy cows and correlations between bacteriological and histological findings. Bacteria were isolated from approximately 80% of biopsies taken at day 26 and day 40 postpartum. Eleven percent of biopsies were positive for both aerobic and anaerobic culture. Streptococci, Escherichia coli and Actinomyces pyogenes were the most common isolates. Isolation of A. pyogenes from a biopsy at day 26 was positively correlated with isolation of anaerobic bacteria and segmented cell inflammation in the same biopsy, and with subsequent isolation of A. pyogenes at day 40. There was a strong association between isolation of A. pyogenes and anaerobes at day 26 with increased uterine lesions at day 40. Isolation of alpha hemolytic streptococci (AHS) was negatively correlated with isolation of A. pyogenes and with inflammation. Actinomyces pyogenes and AHS showed opposite associations with mononuclear cell inflammation and lymphocytic foci.

Actinomyces↗
PubMed1990

Thiol-based inhibitors of mammalian collagenase. Substituted amide and peptide derivatives of the leucine analogue, 2-[(R,S)-mercaptomethyl]-4-methylpentanoic acid.

To define the inhibitory requirements of mammalian collagenase, several N-substituted amide and peptide derivatives of the mercaptomethyl analogue of leucine, 2-[(R,S)mercaptomethyl]-4-methylpentanoic acid (H psi[SCH2]-DL-leucine), were synthesized and tested as inhibitors of pig synovial collagenase with soluble type I collagen as substrate. H psi[SCH2]-DL-leucine (IC50 = 320 microM) was about 10 times more potent than the beta-mercaptomethyl compound, N-acetylcysteine. The amide of H psi[SCH2]-DL-leucine was six times more potent than the parent thiol acid. Aliphatic N-substituted amides were less potent than the unsubstituted amide, whereas the N-benzyl amide was slightly more potent. Dipeptides, particularly those with an aromatic group at P2', were up to 20-fold more potent, while tripeptides with an aromatic L-amino acid at P2' and Ala-NH2 at P3' were up to 2200 times more potent than H psi[SCH2]-DL-leucine. The resolved diastereomers of H psi[SCH2]-DL-Leu-Phe-Ala-NH2 inhibited by 50% at 0.3 and 0.04 microM, respectively. The most potent inhibitor synthesized, an isomer of H psi[SCH2]-DL-Leu-L-3-(2'-naphthyl)alanyl-Ala-NH2, exhibited an IC50 of 0.014 microM, a value about 300 times less than similar thiol-based analogues of the P'-cleavage sequence of type I collagen, H psi[SCH2]-DL-Leu-Ala-Gly-Gln-. These structure-function studies establish within the present series of compounds that the most effective inhibitors of mammalian collagenase are not closely related to the P2'-P3' elements of the cleavage site of the natural substrate but rather have an aromatic group at the P2' position and Ala-NH2 at the P3' position.

Amides↗
PubMed1990

Common sulfoglycolipid receptor for mycoplasmas involved in animal and human infertility.

Sulfoglycolipids are ubiquitous components of the male germ cell membrane. Sulfogalactoglycerolipid (SGG) is restricted to mammalian cells and has recently been implicated in sperm/egg interactions. Mycoplasma infections have been implicated in infertility in a variety of species, including humans. Four such species-specific mycoplasmas, Ureaplasma urealyticum and Mycoplasma hominis (humans), Mycoplasma pulmonis (rodents), and Ureaplasma diversum (cattle) are not shown to specifically recognize SGG and the sphingolipid counterpart, sulfogalactosyl ceramide. This glycolipid receptor binding may relate to the reproductive pathogenesis of these organisms.

Animals↗
PubMed1989

A competitive enzyme-linked immunosorbent assay (ELISA) to detect retronecine and monocrotaline in vitro.

Antibodies to the nonesterified pyrrolizidine nucleus, retronecine (155 mol.wt), were produced in rabbits and detected using an avidin-biotin antibody ELISA. A competitive ELISA for the detection of retronecine and the cyclic diester monocrotaline was also developed using the antiserum produced against the hapten conjugate, retronecine-bovine serum albumin. Retronecine was obtained by hydrolysis of monocrotaline, succinylated and directly coupled to bovine serum albumin or ovalbumin. Antibodies to the pyrrolizidine nucleus, retronecine, can be detected within 5 min after the addition of substrate using the avidin-biotin ELISA. Competitive inhibition of antibodies to retronecine is obtained by the addition of known amounts (0-11.42 micrograms/microliters) of either the homologous antigen, retronecine, or the heterologous antigen, monocrotaline, however, retronecine acts as the better competitor.

Animals↗
PubMed1989

On transplanting human fetal tissue: presumptive duties and the task of casuistry.

The procurement of fetal tissue for transplantation may promise great benefit to those suffering from various pathologies, e.g., neural disorders, diabetes, renal problems, and radiation sickness. However, debates about the use of fetal tissue have proceeded without much attention to ethical theory and application. Two broad moral questions are addressed here, the first formal, the second substantive: Is there a framework from other moral paradigms to assist in ethical debates about the transplantation of fetal tissue? Does the use of fetal tissue entail cooperation in abortion? To answer these questions I develop a theoretical framework by combining the paradigm of just-war reasoning with canons governing the use of cadaverous tissue. The kinds of safeguards provided by this paradigm allow fetal tissue to be procured without the taint of association with abortion. Central to solving the problem of cooperation is the distinction between intending and foreseeing a moral misdeed. Fetal researchers may foresee fetal death in elective abortions without intending such deaths to occur. Thus, even those who object unequivocally to elective abortion may condone the procurement of fetal tissue, if sufficient reason exists.

Aborted Fetus↗
PubMed1989

Estradiol-induced blockade of ovulation in the cow: effects on luteinizing hormone release and follicular fluid steroids.

Administration of 10 mg estradiol valerate (EV) to nonlactating Holstein cows on Days 16 of the estrous cycle prevented ovulation in 7 of 8 cows for 14 days post-injection. In these 7 cows, the timing of luteolysis and the luteinizing hormone (LH) surge was variable but within the normal range. At 14 days post-treatment, each of these cows had a large (greater than 10 mm) follicle, with 558 +/- 98 ng/ml estradiol-17 beta, 120 +/- 31 ng/ml testosterone, and 31 +/- 2 ng/ml progesterone in follicular fluid (means +/- SE). A second group of animals was then either treated with EV as before (n = 22), or not injected (control, n = 17) and ovariectomized on either Day 17, Day 18.5, Day 20, or Day 21.5 (24, 60, 96, or 132 h post-EV). Treatment with EV did not influence the timing of luteolysis, but surges of LH occurred earlier (59 +/- 8 h post-EV vs. 100 +/- 11 h in controls). The interval from luteolysis to LH peak was reduced from 44 +/- 6 h (controls) to 6.9 +/- 1.5 h (treated). Histologically, the largest follicle in controls tended to be atretic before luteolysis, but nonatretic afterwards, whereas the largest follicle in treated animals always tended to be atretic. Nonatretic follicles contained high concentrations of estradiol (408 +/- 59 ng/ml) and moderate amounts of testosterone (107 +/- 33 ng/ml) and progesterone (101 +/- 21 ng/ml), whereas atretic follicles contained low concentrations of estradiol (8 +/- 4 ng/ml) and testosterone (12 +/- 4 ng/ml), and either low (56 +/- 24 ng/ml) or very high (602 +/- 344 ng/ml) concentrations of progesterone. This study suggests that EV prevents ovulation by inducing atresia of the potential preovulatory follicle, which is replaced by a healthy large follicle by 14 days post-treatment.

Animals↗
PubMed1989

Protein A gold identification of ureaplasmas on the bovine zona pellucida.

The object of this study was to develop a prefixation protein A gold labelling technique for Ureaplasma diversum and to apply this to bovine embryos. Sixteen hour cultures of Ureaplasma diversum strain 2312 were incubated with either specific antiserum or nonimmune serum, followed by exposure to protein A gold and negative staining. The ureaplasmas which were incubated with specific antiserum were labelled with gold particles while those ureaplasmas which were incubated with nonimmune serum were not labelled. Twenty-three unhatched, day 7 bovine embryos were then incubated in either embryo culture medium (ECM) alone, ECM with sterile ureaplasma broth added or ECM with 1.7 X 10(6) colony forming units of Ureaplasma diversum strain 2312 per embryo. After 16 hours, the embryos were washed twice and incubated with either specific antiserum or nonimmune serum. The embryos were then incubated with medium containing protein A gold and examined by electron microscopy. No ureaplasmas were identified on the zona pellucida of the control embryos. Ureaplasmas were identified on the outer surface of the zona pellucida of 13 of the 17 embryos which had been exposed to the organism. Of these, the embryos which were incubated with specific antiserum had labelled ureaplasmas while the embryos which were incubated with nonimmune serum had unlabelled ureaplasmas on the zona pellucida. It was concluded that the protein A gold method was a suitable technique for the identification of ureaplasmas in EM preparations. The presence of ureaplasmas on the outer surface of the bovine zona pellucida following in vitro exposure to the organism was confirmed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗