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Biomedical subjects

M Kelley

Publications and source records attributed to M Kelley.

At least 109 records · Page 6Linked to original sources
PubMed1990

A test of the tridimensional personality theory: association with diagnosis and platelet imipramine binding in obsessive-compulsive disorder.

We administered the Tridimensional Personality Questionnaire (TPQ) to a sample of 25 individuals with obsessive-compulsive disorder (OCD) and 35 normal controls. As predicted, OCD cases scored much higher on the harm avoidance dimension than normal controls. Findings for the novelty seeking and reward dependence dimensions were less dramatic, although compatible with the underlying theory. Despite a theoretical link between the harm avoidance dimension and serotonin-mediated neuropathways, we failed to find an association between this dimension and platelet imipramine binding in either OCD cases or controls.

Arousal↗
PubMed1990

Effects of cytochrome P-450 monooxygenase inducers on mouse hepatic microsomal metabolism of testosterone and alkoxyresorufins.

The effects of treatment with phenobarbital, 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP), pregnenolone-16 alpha-carbonitrile (PCN), 3-methylcholanthrene (3-MC) and isosafrole on the hepatic microsomal formation of nine monohydroxy metabolites of testosterone and the O-dealkylation of the ethyl and pentyl ethers of resourfin were evaluated in adult male C57BL/6J and DBA/2NCR mice. In both strains, phenobarbital, TCPOBOP and PCN induced testosterone 2 beta-, 6 beta-, 15 beta- and 16 beta-hydroxylases up to 5-fold, while phenobarbital and TCPOBOP increased the rate of dealkylation of pentoxyresorufin by approximately 30-fold. However, phenobarbital and TCPOBOP did not exhibit identical patterns of induction for the testosterone oxidation reactions. Hepatic microsomes from C57BL/6J mice treated with TCPOBOP displayed a depression in 6 alpha-testosterone hydroxylase activity, which was also observed in PCN-treated animals, whereas phenobarbital-treated mice exhibited an elevation in this monooxygenase activity. A dose of TCPOBOP (0.5 mumol/kg) previously demonstrated to represent an ED50 for mouse aminopyrine N-demethylase activity was also found to approximate the ED50 for pentoxyresorufin O-dealkylase activity in the C57BL/6J mouse. Isosafrole or 3-MC treatment had little effect on testosterone metabolism or pentoxyresorufin O-dealkylase activity in either strain, while 3-MC induced ethoxyresorufin O-deethylase activity in C57BL/6J but not DBA/2NCR mice. This study confirms that TCPOBOP is a potent cytochrome P-450 inducer which most closely resembles phenobarbital in its mode of action. However, TCPOBOP and phenobarbital do not evoke identical modulations of cytochrome P-450-dependent monooxygenases in mice.

Animals↗
PubMed1990

The effects of ions on the conjugation of xenobiotics by the aralkyl-CoA and arylacetyl-CoA N-acyltransferases from bovine liver mitochondria.

The aralkyl-CoA:glycine N-acyltransferase and the arylacetyl-CoA:amino acid of N-acyltransferase were purified from bovine liver mitochondria and their response to a variety of ions investigated. The activity of the aralkyl transferase was inhibited by divalent cations with all substrates investigated. For benzoyl-coenzyme A (CoA), K+ was a competitive inhibitor, competing for binding at the benzoyl-CoA binding site. With salicylyl-CoA, K+ did increase the dissociation constant (KD) for acyl-CoA but it was not a competitive inhibitor and in addition, K+ increased the Michaelis constant for glycine (Kglym) tenfold. The data suggest that the increase in Kglym is due to bound K+ forcing reorientation of salicylyl-CoA at the active site so that it impinges on the glycine binding site. Inorganic anions and cations did not affect the extent of product inhibition by hippuric acid with either acyl-CoA and this was because they affected the binding of acyl-CoA and hippuric acid to the same extent. Ions did, however, greatly reduce the extent of product inhibition by CoA. This is critical because under approximate in vivo conditions (2.5 mM CoA), the salt-free enzyme would be almost completely inhibited by CoA. The arylacetyl transferase was activated by inorganic ions when assayed at saturating substrate concentrations. However, at physiologic concentrations of glycine certain salts were modestly inhibitory. The inhibitory effect of KCl was characterized by a large decrease in the affinity of the enzyme for phenylacetyl-CoA, suggesting that the arylacetyl-CoA region of the active site contained an inhibitory ion binding site. At low (physiologic) concentrations of substrate, the arylacetyl transferase was extensively inhibited by CoA and this inhibition was greatly reduced by ions. The 3'-phosphate group on CoA was found to be important for binding to the salt-free enzyme but in the presence of ions its importance was diminished. In the absence of inorganic ions the affinity of the enzyme for phenylacetyl-CoA and naphthylacetyl-CoA was so high that it could not be measured. In the presence of KCl the KD values for phenylacetyl-CoA and naphthylacetyl-CoA were similar, but the Km for glycine was extremely high for 1-naphthylacetyl-CoA conjugation, which accounts for its slow rate of metabolism. Conjugation with glutamine had a high Michaelis constant for glutamine (KGlum) and a low maximum velocity (Vmax) which accounts for the absence of glutamine conjugation in vivo.

Acetyltransferases↗
PubMed1990

Cytokine effects on the down regulation of cytolytic T cell responses in vitro.

Lymphocytes from mouse and men can be stimulated by a variety of cellular signals including concanavalin A and the interferons to generate cells capable of non-specific down regulation of the generation of immune responses. The studies reported here extend this finding to show that such regulatory cells are also generated during the course of a mixed lymphocyte response and following stimulation of the CD3 component of the T cell receptor with anti-CD3 antibody. Regulatory activity was assessed by the addition of putative regulatory cells to mixed lymphocyte cultures and measuring the generation of cytolytic T cell activity in these cultures. The action of such non-specific regulatory cells was blocked by antiserum to the N-terminal sequence of soluble immune response suppressor (SIRS). In addition, generation of the regulatory cell population was inhibited by antiserum to the 55 kd subunit of the IL-2 receptor. A survey of cytokines showed that while IL-2 was able to stimulate the generation of non-specific regulatory cell activity, IL-1,3,6,7, and 10 as well as TNF alpha and TGF beta were unable to generate such activity. IL-2 was unable to generate non-specific suppressive activity in the presence of anti-IL-2 receptor antibody. The regulatory activity of cells generated by IL-2 was inhibited by the anti-SIRS antiserum.

Animals↗
PubMed1990

Hypotensive responses to common daily activities in institutionalized elderly. A potential risk for recurrent falls.

Transient hypotension may be one of many factors contributing to the high prevalence of falls among elderly people. To determine the frequency and magnitude of hypotensive responses to common daily activities, and their potential relationship to falls in the elderly, we examined blood pressure (BP) and heart rate during a standardized series of activities in 38 institutionalized recurrent fallers (age, 87 +/- 6 years), 20 institutionalized nonfallers (age, 85 +/- 5 years), and 10 healthy young control subjects (age, 24 +/- 3 years). The coefficient of variation for systolic BP during all activities was higher in elderly subjects (fallers, 14% +/- 5%; nonfallers, 12% +/- 3%) than in young control subjects (8% +/- 1%). In contrast, the coefficient of variation for heart rate during all activities was higher in young subjects than in the elderly subjects. Elderly subjects had marked BP reduction following meals and nitroglycerin, which was significantly greater in fallers than in nonfallers, independent of the cause of the fall. Thus, institutionalized elderly have marked BP variability and hypotensive responses to meals and nitroglycerin. A decline in BP during common preload-reducing stresses may predispose some elderly people to falls.

Accidental Falls↗
PubMed1989

Corticotropin-releasing factor immunoreactive neurons persist throughout the brain in Alzheimer's disease.

Corticotropin-releasing factor (CRF) immunoreactivity was examined in the hippocampal formation, cerebellum and hypothalamus of normal aged and Alzheimer's disease (AD) brains. Immunoreactive non-pyramidal neurons were located in the polymorphic layer of the dentate gyrus and CA fields. A plexus of CRF terminals was seen in the supragranular layer of the dentate gyrus. In AD, occasional senile plaques contained CRF-immunoreactive fiber terminals but the pattern of staining was otherwise unchanged aside from a suggestion of increased staining intensity. Similarly, the pattern of immunoreactive cerebellar climbing fibers and paraventricular hypothalamic neurons was preserved in AD brains aside from increased perikaryal staining intensity in the hypothalamus.

Aged↗
PubMed1989

Radiation enhancement of lung nodule formation in mice is not potentiated by treatment with a perfluorochemical emulsion and carbogen.

The ability of intravenously-injected mouse mammary tumor cells to form lung tumors is increased by irradiation of the thorax 24 h previously. We examined the effects of treatment with a perfluorochemical emulsion (Fluosol-DA, 20%) plus carbogen before and during irradiation on the radiation-induced enhancement of lung nodule formation. We found no evidence that treatment with Fluosol plus carbogen altered the development of tumor nodules in irradiated mouse lungs.

Animals↗
PubMed1989

Direct observation of microtubules with the scanning tunneling microscope.

To observe surface topography of microtubules, we have applied scanning tunneling microscopy (STM), which can image metal and semiconductive surfaces with atomic resolution. Isolated microtubules fixed in 0.1% glutaraldehyde in reassembly buffer containing 0.8 M glycerol were imaged in air on a graphite substrate. The presence of microtubules in solution was verified by electron microscopy. At atmospheric pressure and room temperature, STM probing of both freeze-dried and hydrated microtubules reveals structures approximately 25 nm in width, consisting of longitudinal filaments about 4 nm in width. These structures match electron microscopy images of microtubules and their component protofilaments. Microtubules imaged by STM frequently appear buckled and semiflattened. Top-view shaded scans show what appear to be individual tubulin subunits within protofilaments. We believe these results represent the first direct STM observation of protein assemblies in which components can be identified. Although the microtubule image resolution described here is no better than that presently obtainable by other techniques (e.g., electron microscopy with freeze-drying, shadowing, and/or negative staining), it is significant that suitably prepared biomolecules may be sufficiently conductive and stable for STM imaging, which is ultimately capable of atomic resolution. Further development of STM technology, computer-enhanced image processing, and elucidation of optimal STM sample preparation indicate that STM and related applications will offer unique opportunities for the study of biomolecular surfaces.

Animals↗
PubMed1988

OKT4+ T cell abnormality in patients with active systemic lupus erythematosus: HLA-DR antigen expressions.

The objective of this study was to define immunologic T cell abnormality characteristic of active systemic lupus erythematosus (SLE). Eight of nine patients who had severe clinical and laboratory manifestations of active SLE had a characteristically marked increase in OKT4+ and a decrease in OKT8+ T cells. Using OKIa1 and OKDR monoclonal antibody, we found that, in circulating blood of all patients with active SLE, an increased percentage of Ia+ and DR+ T cells is present compared to inactive SLE. Five of these active SLE patients had Tac+ antigens, an interleukin 2 receptor on OKT4+ and OKT8+ T cell subsets in resting blood. The present study demonstrates that Ia+ and DR+ antigens are selectively expressed on the majority of OKT4+ T cell subsets of all patients with active SLE, whereas Ia+ and DR+ antigens are expressed almost equally on both OKT4+ and OKT8+ T cell subsets in inactive SLE. The elevated percentage of Ia+, DR+, OKT4+ T cells in active SLE was accompanied by a highly depressed proliferative response to T cell mitogens, phytohemagglutinin and concanavalin A. However, OKT8+ T cell subsets in active SLE possessed a normal proliferative response to these T cell mitogens. We conclude that this abnormality of activated OKT4+ T cells bearing HLA-DR antigens may play a role in the development of active SLE.

Adult↗
PubMed1988

Preclinical studies of a perfluorochemical emulsion as an adjunct to radiotherapy.

Tumor growth and tumor cell survival endpoints were used to examine the effects of a perfluorochemical emulsion, Fluosol-DA, 20%, and carbogen (95% O2/5% CO2) on EMT6 mouse mammary tumors in BALB/c mice. These studies defined the effects of the Fluosol dose on the hematocrit and fluorocrit of the mice and on the radiation response of the tumors. The effect of varying the duration of carbogen breathing before irradiation was examined; times of 5-60 min gave similar enhancements of tumor radiosensitivity. Potentiating effects were not observed when the tumors were irradiated 1-3 days after Fluosol injection, probably reflecting the observed clearance of the perfluorochemicals from the circulating blood. Fluosol injected 30 min-2 days before irradiation did not alter the radiation response of tumors in air-breathing or N2-asphyxiated mice. Together, these studies provided additional support for the hypothesis that the potentiation of tumor radiation response observed after treatment with Fluosol plus carbogen results from changes in O2 delivery to the hypoxic tumor cells by oxygenated perfluorochemical particles. This confirms the conclusion drawn on the basis of the observed changes in the tumor cell survival curve. Studies of tumor cell survival, tumor cell yield, tumor growth, and artificial lung metastasis formation revealed no effects of Fluosol treatment (without irradiation) on tumor progression or metastasis. Studies examining the effects of Fluosol plus carbogen on the growth of tumors irradiated with 5 Gy showed that the changes in tumor radiosensitivity observed using cell survival endpoints also occurred in tumors left in situ after irradiation with a radiation dose similar to those used in some clinical trials.

Animals↗
PubMed1988

Organ-specific effects of long term feeding of 2,3,7,8-tetrachlorodibenzo-p-dioxin and 1,2,3,7,8-pentachlorodibenzo-p-dioxin on I-compounds in hepatic and renal DNA of female Sprague-Dawley rats.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent hepatocarcinogen, and 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PCDD) on liver and kidney DNA of female Sprague-Dawley rats were investigated by 32P-post-labeling assay. The compounds were administered by gavage [1 microgram/kg/week in corn oil (5 ml/kg)] to the animals for up to 6 months. No exposure-related 32P-labeled spots indicative of TCDD or PCDD covalent DNA adducts were noted on the chromatograms of kidney or liver DNA nucleotides from the rats exposed to the toxins for 2 and 6 months. Corn-oil treated control animals exhibited the characteristic tissue- and age-specific patterns of 32P-labeled I-spots in liver and kidney DNA which are associated with specific DNA modifications of unknown origin and function. Treatment with either TCDD or PCDD resulted in a substantial reduction of the levels of I-compounds in liver, a target organ for TCDD carcinogenesis. After 6 months of exposure to TCDD the reductions in the amounts of individual hepatic I-compounds ranged from 37 to 77% and decreased levels were also observed after 2 months of treatment. It was apparent that PCDD was not as effective as TCDD in reducing hepatic I-compound levels and this corresponded with the lower aryl hydrocarbon receptor binding activity of the former compound. In contrast, TCDD and PCDD did not cause any significant decrease of I-compounds in the kidney which is not a site of TCDD-mediated carcinogenicity in female Sprague-Dawley rats. Whether I-compound deficiency contributes to TCDD-mediated hepatocarcinogenesis (e.g. by facilitating DNA replication) needs to be investigated.

Aging↗
PubMed1988

Interactions between a viral protease and cystatins.

The interactions of two cystatins with a viral cysteine protease were studied using several types of assays. Complex formation between the protease and inhibitor was directly demonstrated using a gel retardation assay. It was also shown that the formation of enzyme inhibitor complexes could occur after first binding either the enzyme or the inhibitor to filter paper, and ultimately decorating the complex with antibody and radio-labelled protein A or by preparing one of the protein ligands with an internal radiolabel. The procedure can be adapted to provide a method for screening expression libraries for protease or inhibitor genes. The inhibition of a cysteine protease by a cystatin was shown not to directly involve binding to the active site thiol of the enzyme, but rather to be the result of a steric block in the active site region which prevents large affinity labels and protein substrates from reaching the active site.

Animals↗
PubMed1987

Effects of ovariectomy and estradiol benzoate on high affinity choline uptake, ACh synthesis, and release from rat cerebral cortical synaptosomes.

Several presynaptic processes were studied in cerebral cortical synaptosomes prepared from intact adult female rats or from ovariectomized animals that received 3 subcutaneous injections of either estradiol benzoate (10 micrograms/kg) or vehicle. Injections were given 1/day, every other day, and animals were sacrificed 1 h after the last injection. High affinity choline uptake and coupled acetylcholine (ACh) synthesis were reduced by ovariectomy, and restored to control levels by the estradiol benzoate injections. In contrast, low affinity choline uptake and depolarization-induced [3H]ACh release were unaffected by either ovariectomy or estradiol benzoate injections. These results suggest that changes in estradiol levels may alter the high affinity transport process regulating ACh synthesis in this tissue.

Acetylcholine↗
PubMed1987

The effects of organochlorine pesticides as inducers of testosterone and benzo[a]pyrene hydroxylases.

p,p'-DDE, phenobarbital, dieldrin heptachlor, chlordane and toxaphene induced rat liver microsomes exhibited increased formation of the 4,5-dihydrodiol, 3,6-quinone, 9- and 3-hydroxymetabolites of benzo[a]pyrene and the latter three compounds also induced an increase in the rate of formation of the 9,10-dihydrodiol metabolite. Lindane was inactive as an inducer of benzo[a]pyrene hydroxylase. With the exception of lindane, all the organochlorine pesticides and PB induced testosterone 16 alpha- and 16 beta-hydroxylases; in contrast lindane induced testosterone 6 alpha-, 7 alpha- and 6 beta-hydroxylases and PB also induced testosterone 15 beta-hydroxylase and androstenedione formation. Using a battery of monooxygenase enzyme assays it was evident that there were significant differences between PB and several organochlorine pesticides as inducers of rat hepatic cytochrome P-450-dependent monooxygenases.

Aminopyrine N-Demethylase↗
PubMed1987

Co-induction of cytochrome P-450 isozymes in rat liver by 2,4,5,2',4',5'-hexachlorobiphenyl or 3-methoxy-4-aminoazobenzene.

A multitude of xenobiotics have been demonstrated to co-induce either cytochromes P-450c and P-450d or cytochromes P-450b and P-450e in rat hepatic microsomes. Recently, the compounds 2,4,5,2',4',5'-hexachlorobiphenyl (HCB) and 3-methoxy-4-aminoazobenzene (3-MeO-AAB) have been suggested as selective inducers of cytochrome P-450b (Eur. J. Biochem. 151:67 (1985)) and P-450d (Biochem. Biophys. Res. Commun. 133:1072 (1985)), respectively. Since the identification of inducers with such unique characteristics would have implications with regard to the mechanism of induction of all four isozymes, we have examined the induction of cytochromes P-450b and P-450e by HCB and cytochromes P-450c and P-450d by 3-MeO-AAB in liver microsomes from adult male rats. Immunoblot analysis with monoclonal antibodies directed against cytochromes P-450b and P-450e indicate that HCB induces both isozymic species at the three dosage levels examined (10, 90, and 180 mg/kg). Similarly, 3-MeO-AAB does not appear to represent a unique inducer. Immunoblots of hepatic microsomes from animals treated with three different dosage regimens of 3-MeO-AAB demonstrate that, even at the lowest dosage level (50 mg/kg), both cytochromes P-450c and P-450d are induced. Moreover, immunoinhibition of 7-ethoxyresorufin O-deethylase (EROD) activity by monospecific antibody against either cytochrome P-450c or P-450d confirms this result. 3-MeO-AAB increases this enzyme activity 10-fold; approximately one-third of this induced activity is inhibited with monospecific anti-P-450c, while two-thirds is inhibited with monospecific anti-P-450d. This study also demonstrates that hepatic EROD activity is not an accurate estimate of cytochrome P-450c content since the majority of this enzyme activity in control and 3-MeO-AAB-treated rats is inhibited with monospecific anti-P-450d but not with monospecific anti-P-450c.

Animals↗