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Biomedical subjects

D Paul

Publications and source records attributed to D Paul.

At least 127 records · Page 7Linked to original sources
PubMed1990

Ethylnitrosourea-induced mutations in vivo involving the Dolichos biflorus agglutinin receptor in mouse intestinal epithelium.

A mutagenesis assay system is introduced based on the induction of mutations in somatic cells of mouse small intestine using ethylnitrosourea (ENU). F1 mice heterozygous for the Dolichos biflorus agglutinin (DBA) locus (Dlb-1a/Dlb-1b) encoding the DBA cell surface receptor, were treated in utero on either day 7, day 9 or day 11 post coitum. Mutant intestinal cell populations of adult mice were visualised in whole-mount preparations by the absence of histochemical staining using peroxidase-labelled Dolichos biflorus agglutinin. Loss of staining is attributed to mutagenesis of the Dlb-1b allele in the heterozygote. This system allows one to evaluate mammalian mutagenesis in vivo at a single locus. Mutant cell populations appeared as discrete groups of 'striped' villi, each stripe comprising cells derived from unstained crypt stem cells (cf. Schmidt et al., 1985a). A spontaneous mutation level was noted in untreated controls which was found to differ significantly from that recorded in mice treated with the mutagen (P less than 0.01). The mutation scores were highly consistent among mice and a small number of animals (i.e., 16) were sufficient to detect mutagenic effects of ENU. Thus, the advantages which accrue from the assay are (1) the ability to detect small clones of mutant cell populations in the intestine (i.e., cells derived from a single mutated crypt); (2) a small number of tested mice are required to generate a conclusive result, especially when compared to the mammalian spot test (Fahrig, 1978).

Analysis of Variance↗
PubMed1990

Proglumide selectively potentiates supraspinal mu 1 opioid analgesia in mice.

The cholecystokinin antagonist proglumide potentiates morphine analgesia. To understand more fully the opiate receptor subtypes involved with this effect, we investigated the effect of proglumide on spinal and supraspinal mu and spinal delta analgesia in mice. Proglumide alone had no effect on tailflick latencies, but increased, in a dose-dependent manner, tailflick latencies in morphine-tolerant mice. Proglumide also potentiated morphine analgesia in naive mice in a dose-dependent manner, with a maximal effect at 5-10 mg/kg. Proglumide both shifted the dose-response curve for morphine analgesia to the left and prolonged morphine's duration of action. Proglumide increased the sensitivity of supraspinal mu 1 receptor mechanisms of analgesia without influencing spinal mechanisms. Proglumide administered subcutaneously potentiated the analgesic actions of intracerebroventricular [D-Ala2,MePhe4,Gly(ol)5]enkephalin (DAGO; (mu 1), but not intrathecal DAGO (mu 2) or [D-Pen2,D-Pen5]enkephalin (DPDPE; delta). The selective mu 1 receptor antagonist naloxonazine blocked proglumide-enhanced morphine analgesia.

Animals↗
PubMed1990

Associative factors in tolerance to analgesia produced by electrical stimulation in the brainstem.

Tolerance to the analgesic effects of electrical stimulation of the periaqueductal gray was confirmed, and it was demonstrated that this effect was mediated by environmental conditional stimuli (CSs). First, tolerance was extinguished after repeated presentation of CSs in the absence of brain stimulation. Second, environment-specific tolerance was demonstrated. Analgesia was reinstated after brain stimulation in a different test environment. Omission of brain stimulation in the stimulation environment failed to reveal a hyperalgesic response in tolerant Ss. Brain-stimulation analgesia should be beneficial for analyzing neural mechanisms underlying conditioned tolerance to analgesia.

Animals↗
PubMed1990

Productive human immunodeficiency virus infection levels correlate with AIDS-related manifestations in the patient.

Mononuclear cells were obtained from 71 human immunodeficiency virus type 1 (HIV-1) seropositive subjects presenting and first visit either as asymptomatic or with minor symptoms and with CD4 lymphocytes greater than 550 per mm3 (group A, 35 patients) or as patients with AIDS, AIDS-related illnesses, or CD4 lymphocytes less than 400 per mm3 (group B, 36 patients). After 1-5 years of follow-up, 13 patients of group A had essentially retained their initial status (asymptomatics); the 22 others had suffered clinical or immunological deterioration (progressors). Frozen cells were thawed and submitted to lethal gamma-irradiation in vitro (4500 rads; 1 rad = 0.01 Gy) before they were cultured with normal phytohemagglutinin-stimulated lymphocytes to determine radiation-resistant HIV expression ex vivo (R-HEV). HIV antigenemia correlated with R-HEV values in 142 samples (r = 0.92, P less than 0.001) but was a less sensitive predictor of disease than R-HEV. R-HEV was detected in all specimens from patients with major AIDS-related illnesses or HIV-associated CD4 lymphopenia. In 77% of the progressors from group A, R-HEV detection preceded the onset of AIDS-associated disease or CD4 lymphopenia by 1 year (average). Conversely, R-HEV was low or was not detected in 36 sequential specimens from the 13 patients who remained asymptomatic over the following 2-5 years. Thus, persistently low HIV expression in vivo predicted a nondiseased state, whereas higher HIV expression levels seemed necessary for disease to occur. These data indicate that R-HEV is related to productive HIV infection in vivo, the latter acting as a determinant of AIDS-related illnesses. In view of this, measurement of HIV expression levels in the patient should be useful in antiviral efficacy trials.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Chemical modification of cellulosic membranes and their blood compatibility.

Blood compatibility is determined by interactions at the blood-material interface that depend on the material surface chemical structure. Through selective modifications of the chemically reactive hydroxyl groups of cellulose, the aim was to improve the biocompatibility of cellulose membranes. The number of potentially reactive hydroxyl groups on the cellulose membrane surface were reduced through isocyanate cross-links or through the introduction of hydrophilic, hydrophobic, or ionic functionalities by graft copolymerization. To assess blood compatibility, levels of C3a desArg were determined in plasma after membrane contact. Using the electrophoretic mobility test, the release of cytokines were measured after in-vitro incubation of mononuclear cells with membranes. Adsorption of 131J-human fibrinogen was additionally investigated. With respect to the biocompatibility parameters selected, the modified cellulose membranes show improved in-vitro blood compatibility in comparison to unmodified cellulose membranes.

Biocompatible Materials↗
PubMed1990

Naloxone benzoylhydrazone (NalBzoH) analgesia.

Naloxone benzoylhydrazone (NalBzoH) is a novel mixed agonist/antagonist. Against mu agonists, NalBzoH is a potent antagonist with a prolonged duration of action corresponding to its extremely slow rate of dissociation from mu receptors in binding assays. In the present studies, NalBzoH also antagonized mu analgesia, reversing both mu 1 and mu 2 analgesia independently elicited by intracerebroventricular or intrathecal [D-Ala2,MePhe4,-Gly(ol)5]enkephalin injections. It also antagonized kappa 1 analgesia elicited by U50,488H, and delta analgesia produced by intrathecal [D-Pen2,D-Pen5]enkephalin. Yet, at higher doses, NalBzoH alone produced analgesia in the tail-flick, hot plate and writhing assays. Neither the mu-selective antagonist beta-funaltrexamine, the delta-selective antagonist naltrindole, nor the kappa 1-selective antagonist norbinaltorphimine reversed NalBzoH analgesia in the tail-flick test. Analgesia observed with systemically administered NalBzoH was reversed easily by the antagonist WIN44,441 when it was given intracerebroventricularly, but not intrathecally. These observations confirm the opioid nature of NalBzoH analgesia and imply a supraspinal mechanism of action. In contrast, intrathecal, but not intracerebroventricular WIN44,441 reversed analgesia from systemic U50,488H quite potently. Thus, NalBzoH antagonizes mu, delta and kappa 1 actions while retaining its ability to elicit analgesia through a novel and distinct supraspinal kappa 3 system.

Analgesia↗
PubMed1989

Mediation of anorexia by human recombinant tumor necrosis factor through a peripheral action in the rat.

Human recombinant tumor necrosis factor (TNF) produces significant anorexia in the rat which persists for up to 24 h after a single dose (5 micrograms/325 g rat). Dose-response studies indicate similar potencies for TNF following central or peripheral administration. Brain 125I-TNF levels were more than 100-fold greater after intracerebroventricular than i.v. injection, whereas blood levels of radioactivity were quite similar following both routes of administration. Gel filtration chromatography and precipitation by trichloroacetic acid showed that the radioactive label which exited the central nervous system was associated with intact TNF. The rapid effusion of 125I-TNF from the central nervous system resulted in detection of similar levels of the cytokine in a number of important target tissues (skin, muscle, fat) relative to that detected after peripheral administration. After i.v. or intracerebroventricular administration, blood levels of TNF declined rapidly to nearly undetectable levels over 4 h. However, the anorexia induced by TNF was sustained, and feeding remained depressed between 6 and 24 h postadministration. These observations suggest that TNF produces its anorectic effects at peripheral sites, possibly through mediators.

Animals↗
PubMed1989

Reduction in opioid and non-opioid forms of swim analgesia by 5-HT2 receptor antagonists.

Acute exposure to continuous (CCWS) or intermittent (ICWS) cold-water swims elicits non-opioid and opioid forms of analgesia respectively. Intrathecal administration of methysergide blocks ICWS, but not CCWS analgesia. The present study evaluated the role of serotonin (5-HT) receptor subtypes in the mediation of CCWS and ICWS analgesia on the tail-flick and jump tests following administration of methysergide, a non-specific 5-HT antagonist and pirenpirone and ketanserin, two 5-HT2 receptor subtype antagonists. Systemic methysergide was more effective in reducing CCWS analgesia (50-58%, 0.1-1.0 mg/kg) than ICWS analgesia (21%, 5 mg/kg) on both pain tests. Systemic pirenpirone (0.04-0.2 mg/kg) and ketanserin (1-5 mg/kg) were also more effective in reducing CCWS analgesia (43-57%) on both tests than ICWS analgesia (pirenpirone: 0.4 mg/kg, 34%; ketanserin: 5 mg/kg, 21%) on the tail-flick test. Indeed, both 5-HT2 receptor antagonists potentiated ICWS analgesia on the jump test. While serotonin antagonist effects upon hypothermia could not account for CCWS analgesia effects, similar potentiations in ICWS analgesia and hypothermia were observed following pirenpirone and ketanserin. Finally, both 5-HT2 receptor antagonists differentially reduced CCWS hypothermia and potentiated ICWS hypothermia. These data suggest differential serotonergic modulation of the two forms of swim analgesia with opioid-mediated ICWS analgesia acting through spinal 5-HT1 receptors and non-opioid-mediated CCWS analgesia acting through supraspinal 5-HT2 receptors.

Analgesia↗
PubMed1989

Different mu receptor subtypes mediate spinal and supraspinal analgesia in mice.

To examine the relative roles of mu 1- and mu 2-receptors in spinal and supraspinal analgesia, we assessed the effects of naloxonazine, naloxone, beta-funaltrexamine (beta-FNA), and ICI-154,129 on tail-flick analgesia produced by intrathecal or intracerebroventricular injections of the highly mu-selective agonist, [D-Ala2,Me-Phe4,Gly(ol)5]enkephalin (DAGO; mu 1 and mu 2), [D-Ser2,Leu5]enkephalin-Thr6 (DSLET; mu 1 and delta), and the selective delta-receptor agonist [D-Pen2,D-Pen5]enkephalin (DPDPE) in mice. Both DAGO and DSLET supraspinal analgesia were mediated through mu 1-receptors. Naloxonazine shifted the supraspinal DAGO dose-response curve 4-fold to the right without changing the curve for spinal DAGO. Likewise, naloxonazine pretreatment shifted supraspinal DSLET analgesia 10-fold, whereas spinal DSLET analgesia was not affected. DPDPE analgesia was not antagonized spinally or supraspinally by naloxonazine pretreatment. These findings suggest that DAGO produces analgesia spinally and supraspinally through different sets of mu-receptors. Moreover, at least two distinct receptor subtypes mediated spinal analgesia. First, naloxone inhibited spinal DAGO analgesia more potently than DPDPE analgesia. Second, the irreversible mu-antagonist, beta-FNA, blocks spinal DAGO analgesia. Since spinal DAGO was insensitive to naloxonazine, ruling out a mu 1 mechanism, these results indicate a role for mu 2-receptors. Spinal DAGO analgesia also developed tolerance to morphine far more slowly than supraspinal DAGO analgesia even though mu-receptors mediate both, as indicated by their sensitivity towards beta-FNA. Finally, the delta-antagonist ICI-154,129 is a more potent inhibitor of spinal DPDPE analgesia than spinal DAGO analgesia. Thus, delta-receptors mediate spinal DPDPE analgesia.

Analgesia↗
PubMed1989

Chronic opioid antagonist treatment increases mu and delta receptor mediated spinal opioid analgesia.

Chronic systemic treatment with the opioid antagonist, naltrexone, increased the analgesic potency of intrathecally administered opioid agonists at spinal mu and delta receptors, but not at kappa receptors. These results indicate that, contrary to a previous report, opioid receptors in the spinal cord display up-regulation and supersensitivity and are no different in this regard from supraspinal receptors.

Analgesia↗
PubMed1989

Establishment and partial characterization of SV40 virus-immortalized hepatocyte lines of normal and lethal mutant mice carrying a deletion on chromosome 7.

Deletions in chromosome 7 of the mouse have been shown to cause failure of expression of various hepatocyte-specific genes in newborn deletion homozygotes, including the gene encoding tyrosine amino transferase (TAT) (EC 2.6.1.5) (Gluecksohn-Waelsch, 1979). Primary liver cultures of newborn albino deletion mutant mice (c14CoS/c14CoS) and of phenotypically normal mice (c14CoS/cch or cch/cch) were infected with SV40 virus and multiplying hepatocytes selected in arginine-deficient medium containing epidermal growth factor (EGF), insulin, and hydrocortisone (HC). Resulting normal (NMH-ch) and mutant (NMH-m14) hepatocyte lines expressing integrated viral transforming sequences did not senesce, they multiplied autonomously of EGF in medium with insulin plus HC, and they retained hepatocyte-specific functions. Both lines synthesized arginine and contained albumin and alpha-fetoprotein (AFP) mRNAs. TAT-specific mRNA was detected in normal but not in mutant hepatocyte lines. A fragment of the mouse tyrosinase gene, known to map at the albino locus (c) within the region deleted in the c14CoS mutant, hybridized with a 2.5 kb EcoRI fragment of normal NMH-ch DNA, whereas this fragment was undetectable in mutant NMH-m14 DNA. These immortalized hepatocyte lines reflect important properties of normal and mutant liver tissues from which they were derived. The deletion mutant mouse cell lines may be useful for complementation studies involving sequences corresponding to the deletions that encode regulatory gene(s) involved in the control of inducible expression of certain hepatocyte-specific genes such as TAT.

Animals↗
PubMed1989

Proliferation of fetal rat hepatocytes in response to growth factors and hormones in primary culture.

Fetal rat hepatocytes (day 19 of gestation) multiply in primary culture in arginine-free, hydrocortisone-containing chemically defined medium MX-82 supplemented either with epidermal growth factor (EGF) or insulin or both. In contrast, hepatocytes did not multiply under similar culture conditions using Dulbecco's minimum essential medium (DMEM). Cells underwent two divisions within 10 days in cultures maintained in MX-82 medium without a medium change, and cells grew to increased final cell densities when the medium was renewed every third day. When the medium MX-82 was enriched by the addition of lipids, intermediary metabolites, and trace metals (medium MX-83), cells grew to higher densities. In the absence of the growth factors, cells became quiescent and subsequently could be induced to synthesize DNA in response to EGF. With the increasing numbers of cells per dish, the growth response of the hepatocytes diminished. Levels of hepatocyte-specific albumin and alpha-fetoprotein mRNAs at day 0 were similar to those observed at day 10 in primary fetal rat hepatocyte cultures and were maintained at higher levels in medium MX-83 than in medium MX-82.

Animals↗
PubMed1989

Intrasplenic hepatocyte transplantation: evaluation of DNA synthesis and proliferation in auxiliary transplanted cells.

The value of isolated hepatocyte transplantation as a temporary support in acute hepatic failure remains controversial regarding the functional capacities of freshly isolated and transplanted hepatocytes. To evaluate the survival rate of intrasplenically transplanted liver cells and their response to a proliferation stimulus like partial hepatectomy, 3H-thymidine incorporation into hepatic and auxiliary transplanted hepatocyte DNA was determined. The survival rate of intrasplenically transplanted hepatocytes was evaluated by analyses of m-albumin-RNA within the splenic tissue and compared to the morphological findings. The histological results show a marked decrease (greater than x 100) of intrasplenically transplanted hepatocytes within 1 week after injection. The amount of surviving cells then remained constant for 3 months without any signs of proliferation. After partial hepatectomy a stimulation of hepatic regeneration was observed in the remaining liver tissue but not in auxiliary transplanted hepatocytes. M-albumin-RNA determination of auxiliary transplanted hepatocytes revealed a decrease of m-albumin-RNA concentration of greater than 100 times within 24 h after transplantation indicating early cell necrosis of the transplanted cells. Since intrasplenically transplanted hepatocytes underwent an early cell necrosis without any evidence for a directly postoperatively inducible cell proliferation, it is concluded that a sufficient metabolic support in acute hepatic failure cannot be taken into consideration.

Albumins↗
PubMed1989

Differential development of acute tolerance to analgesia, respiratory depression, gastrointestinal transit and hormone release in a morphine infusion model.

To determine whether the differences in development of acute tolerance to several morphine actions correlate with the mu receptor subtype mediating them, we have examined the appearance of acute tolerance to analgesia, respiratory depression, gastrointestinal transit, and hormone release in an intravenous morphine infusion model. Analgesia, a naloxonazine-sensitive mu1 action, peaked at 2 hr after initiation of the infusions. The log dose-response relationship of the infusion rate to peak tailflick latency was linear from 10 to 50 micrograms/kg/min. By 8 hr, the tailflick latencies declined nearly to baseline levels, implying the rapid development of tolerance. Tolerance to morphine-induced prolactin release, another mu1 action, also developed rapidly over 8 hr. In contrast two mu2 actions, respiratory depression measured with arterial blood gas, determinations and gastrointestinal transit, showed no significant tolerance over a similar 8 hr infusion. We also observed no tolerance to morphine-induced growth hormone release, a non-mu1 action, over the same period. Thus, these results demonstrate that mu1 actions develop tolerance in an infusion model far more rapidly than a number of naloxonazine-insensitive (non-mu1) ones and may help explain differences in the rate of tolerance development to morphine actions.

Analgesia↗
PubMed1989

Human immunodeficiency virus type 1 antigenemia in children.

Human immunodeficiency virus type 1 (HIV-1) core antigen was assayed in the plasma of children at risk for infection with HIV to determine its usefulness in the diagnosis of infection and to correlate it with the clinical stage of disease. Antigen was detected in the plasma of all children less than 15 months of age with acquired immunodeficiency syndrome (AIDS). Two thirds of children with AIDS-related illnesses and half of children with asymptomatic infection had antigen. Although 53% of plasma specimens originating from HIV-infected children younger than 6 months of age contained antigen, only 25% of plasma specimens from children younger than 6 months who had no symptoms and none of the 10 specimens from HIV-infected newborn infants contained antigen. Half of the specimens containing core antigen also contained anticore antibody. Quantitative mean antigen levels were more likely to be elevated in children with AIDS (516 pg/ml) than in children with AIDS-related illnesses (295 pg/ml) or in those who had no symptoms (70 pg/ml). Antigen levels tended to increase over time in children with advancing clinical illness, but they tended to decrease over time after a diagnosis of AIDS was made. Antigen was detected in the plasma of 4 of 14 children without symptoms who subsequently reverted to an HIV seronegative state. We conclude that the detection of core antigen occurs with high frequency in children, even young infants, with symptomatic HIV infection. Plasma core antigen was less frequent in children without symptoms and was not detected in 10 infected children when they were tested at birth.

AIDS-Related Complex↗
PubMed1989

Structure-activity relationships in differential nerve block at high and low frequency stimulation.

We have examined the in vitro sensitivities of A, B and C fibres in rabbit vagus nerves to local anaesthetic block with a range of local anaesthetic drugs. The nerves were maintained at 37 degrees C and pH 7.4 using an electrolyte solution equilibrated with 5% carbon dioxide. A fibres were the most, and C fibres the least, sensitive to block at low frequency stimulation (0.0167 Hz). Equipotent concentrations of the various drugs blocked C fibres at approximately the same rate. Rate of A fibre block was related to physicochemical properties of individual drugs. Low pKa and high lipid solubility favoured block of A fibres before C, whereas the reverse was true for high pKa and low solubility. Absolute potency was related to lipid solubility, but each type of local anaesthetic drug in clinical use has a different inherent potency. With stimulation at high frequencies (20 and 40 Hz), C fibres were more sensitive to use-dependent block than A fibres; this effect was more marked with drugs containing an amide than an ester linkage. Molecular size and lipid solubility may inter-react to govern the ability to produce use dependent block. Agents which contain an amide linking group, have a high pKa and are of low lipid solubility, may be used to produce differential C fibre block.

Action Potentials↗