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Biomedical subjects

L S Harris

Publications and source records attributed to L S Harris.

At least 37 records · Page 2Linked to original sources
PubMed1995

The effect of methadone on the immune status of B6C3F1 mice.

Previously, morphine has been shown to elevate corticosterone via the hypothalamic-pituitary-adrenal axis and to suppress the immune system. The present investigation sought to determine if the mu-opiate receptor agonist methadone incurred a similar immune suppression in B6C3F1 mice. Serum methadone and corticosterone levels peaked 1 hr following a single subcutaneous injection of 20 mg/kg methadone HCl. Indeed, the rise in corticosterone levels paralleled that of methadone. After a single injection with 20 mg/kg methadone a pharmacokinetic analysis revealed a serum half-life of approximately 2 hr. Following five injections of methadone over a 24-hr period (every 6 hr), methadone levels were elevated as would be expected; however, corticosterone levels did not become elevated. This suggests that the ability of methadone to elevate corticosterone becomes uncoupled following repeated dosing, indicative of either a tolerance or an increased catabolic mechanism. Moreover, dosing every 6 hr for 5 days induced an increase in the catabolism of methadone itself. Therefore, all assays were begun 1 hr after subcutaneous administration of methadone HCl, a time at which both methadone and corticosterone serum levels were elevated. The primary IgM antibody response to sheep red blood cells (sRBC) was suppressed when splenocytes were immunized in vitro. In contrast, animals immunized with sRBC and assayed for the primary IgM antibody response 4 days later were not suppressed. The activity of the resident macrophages of the liver and spleen as measured by the uptake of 51Cr-sRBC was suppressed in a dose-dependent manner. Previously, it has been demonstrated that morphine suppresses hepatic and splenic phagocytic activity through an opiate receptor-mediated pathway that involves the release of corticosterone. It would appear that methadone plays a similar role in the suppression of hepatic and splenic phagocytosis.

Animals↗
PubMed1994

Antipodal alpha-N-(methyl through decyl)-N-normetazocines (5,9 alpha-dimethyl-2'-hydroxy-6,7-benzomorphans): in vitro and in vivo properties.

The enantiomeric (-)- and (+)-N-(methyl through decyl) normetazocines (5,9 alpha-dimethyl-2'-hydroxy-6,7-benzomorphans) were synthesized and their in vitro and in vivo activities determined. Increasingly bulky enantiomeric N-alkyl homologs were prepared until their interaction with the sigma 1 receptor decreased and their insolubility became a hindrance to their evaluation in vivo and/or in vitro. The (-)-methyl, -pentyl, -hexyl, and -heptyl homologs were essentially as potent as, or more potent than, morphine in the tail-flick, phenylquinone, and hot-plate assays for antinociceptive activity; the (-)-propyl homolog had narcotic antagonist activity between that of nalorphine and naloxone in the tail-flick vs morphine assay, and it also displayed antagonist properties in the single-dose suppression assay in the rhesus monkey. The antinociceptively potent (-)-heptyl homolog did not substitute for morphine in monkeys but did show morphine-like properties in a primary physical-dependence study in continuously infused rats. All five potent compounds showed high affinity for the mu opioid receptor from both rat and monkey preparations and the kappa opioid receptor (< 0.05 microM), and all except the (-)-methyl homolog interacted reasonably well at the delta receptor (K(i) < 0.1 microM). The (-)-propyl compound was equipotent (K(i) 1.5-2.0 nM) at mu and kappa receptors. The pattern of interaction of the (-)-enantiomeric homologs with mu receptors from rat and monkey preparations was similar, but not identical. The enantioselectivity of the homologs for mu receptors was greater in the rat than in the monkey preparation for all but the N-H and butyl compounds, and the enantioselectivity of the lower homologs (methyl through butyl) for the mu (monkey) receptor was greater than for the kappa or delta receptors. However, bulkier homologs (hexyl through decyl) displayed higher enantioselectivity at kappa or delta receptors than at the mu (monkey) receptor. The (+)-butyl through (+)-octyl homologs were essentially equipotent with, or more potent than, (+)-pentazocine at the sigma receptor. Only the (+)-H and (+)-methyl homologs had high affinity (< 0.05 microM) at PCP binding sites.

Amino Acid Sequence↗
PubMed1994

Immunotoxicological profile of morphine sulfate in B6C3F1 female mice.

This study was undertaken to investigate a number of immune parameters which may be compromised with exposure to morphine sulfate. Mice were implanted subcutaneously with 8-, 25-, or 75-mg morphine sulfate pellets. Placebo pellets of identical makeup to the 75-mg morphine pellet (without morphine of course) were used as a control. Twenty-four hours after implantation of a 75-mg morphine pellet, blood levels reached a peak of 1610 ng/ml. Corticosterone increased in parallel with morphine and reached a peak level of 966 ng/ml 24 hr after implantation. The dose response of morphine to increase corticosterone, however, was flat. The weight of the lymphoid organs, spleen and thymus, and the liver were significantly reduced in the morphine-treated groups. Morphine treatment was associated with an increase in serum albumin, SGPT, BUN, and alkaline phosphatase indicative of hepatic damage. In contrast to increased serum proteins, the C3 component of complement was reduced in a dose-dependent manner. Leukocyte number in the peripheral blood was significantly reduced, while erythrocyte number and hematocrit were both increased. The number of B cells and T cells was decreased in morphine-treated animals. However, the percentage of T cells relative to B cells was increased. The primary IgM antibody response to the T-dependent antigen, sheep red blood cells, was decreased. Natural killer cell activity was reduced in response to morphine, as was the phagocytic capacity of Kupffer cells. Host-resistance models of Listeria monocytogenes or Streptococcus pneumoniae showed an increased resistance following administration of morphine. This increased host resistance, however, was not due to an increase in antimicrobial action of sera obtained from mice treated with morphine. The majority of morphine's effects on the immune system exhibited a flat dose response, suggesting that these effects may be mediated secondarily through corticosterone.

Animals↗
PubMed1994

Evaluation of the abuse liability of aminorex.

Aminorex is a cyclic phenylisopropylamine that has been marketed as an anorectic. Despite obvious pharmacological similarities to the amphetamines, little is known about its liability for abuse. In the present study, one group of rhesus monkeys (n = 3) was prepared with intravenous catheters and allowed to self-administer either methohexital or saline in daily experimental sessions. When methohexital and saline self-administration were stable and clearly different, various doses of aminorex (0.001-0.1 mg/kg/injection) were made available for self-administration. Aminorex maintained self-administration above that maintained by saline and slightly lower than that maintained by methohexital in all monkeys. The discriminative stimulus effects of aminorex were evaluated in rhesus monkeys trained to discriminate d-amphetamine (n = 3) or pentobarbital (n = 4) from saline. Aminorex substituted completely for d-amphetamine as a discriminative stimulus but engendered little or no pentobarbital-appropriate responding. Aminorex stimulated locomotor activity in mice and exacerbated the withdrawal syndrome in rats that were dependent upon pentobarbital. These findings indicate that aminorex is a psychomotor stimulant that would be predicted to have significant d-amphetamine-like abuse liability in humans.

Aminorex↗
PubMed1993

Cytomorphology of familial hemophagocytic syndrome.

Familial hemophagocytic syndrome (FHS) is a rare, fatal disorder of childhood demonstrating failure to thrive, fever, hepatosplenomegaly (HSM), recurrent infections, pancytopenia, and histologically, the infiltration of reticuloendothelial organs by benign-appearing histiocytes demonstrating hemophagocytosis. We report two fatal cases of FHS including a 3 year-old female who underwent fine-needle aspiration (FNA) biopsy of the liver in the initial workup of the disease (case 1) and an 8 month-old boy with ascites and HSM having peritoneal fluid cytology submitted as the first specimen for morphologic examination (case 2). In case 1, the FNA cytologic findings included benign hepatocytes and scattered mature and reactive lymphocytes and histiocytes. The histiocytes demonstrated fine to coarse cytoplasmic vacuoles and erythrophagocytosis. The diagnosis was confirmed at autopsy which revealed extensive lymphohistiocytic infiltrates in various organs including the central nervous system. In case 2, the peritoneal fluid cytology specimen contained numerous atypical and degenerating mononuclear lymphoreticular cells which were dispersed as a single cell suspension admixed with infrequent mesothelial elements; hemophagocytosis was not appreciated. Subsequent liver biopsy revealed portal tracts and sinusoids infiltrated by benign but atypical histiocytes with hemophagocytosis. Bone marrow examination and then autopsy confirmed the diagnosis of FHS. A panel of immunocytochemical studies was performed in the first case which was an aid in confirming the diagnosis of FHS and ultrastructural examination of the second case revealed well-developed erythrophagocytosis. Both patients had siblings who died of FHS. Although not diagnostic, cytomorphology may suggest FHS.

Ascitic Fluid↗
PubMed1993

Hepatic and splenic phagocytosis in female B6C3F1 mice implanted with morphine sulfate pellets.

Morphine sulfate has previously been shown to produce a dose-dependent decrease in hepatic phagocytosis when administered as 8-, 25- and 75-mg pellets implanted subcutaneously. This study was undertaken to determine the time course of suppression of hepatic and splenic phagocytosis after subcutaneous implantation of morphine sulfate pellets. Mice were implanted with either 75 mg of morphine sulfate or placebo pellets. The uptake of chromated sheep red blood cells by the liver and spleen was taken as an index of phagocytosis by resident Kupffer cells or macrophages, respectively. The results indicate that maximum suppression of hepatic phagocytosis by 67% occurred 18 hr after implantation of 75 mg of morphine sulfate. Hepatic phagocytic capacity returned to control levels within 48 hr of implantation. The initial time course of suppression of splenic phagocytosis by 41% was similar to that of the liver (maximum at 12 hr). However, splenic phagocytic capacity returned toward placebo levels over a longer period of time reaching control after 4 days after implantation. The opiate receptor antagonist, naltrexone (30-mg pellet), completely blocked the ability of morphine to suppress either hepatic or splenic phagocytosis. Corticosterone is known to increase in parallel with plasma morphine levels presumably through a hypothalamic-pituitary-adrenal axis. The glucocorticoid receptor antagonist RU 486 was used to block the actions of corticosterone and investigate its possible role in morphine sulfate-induced suppression of phagocytosis. RU 486 (200 mg/kg) completely blocked morphine sulfate's ability to suppress splenic phagocytosis. In contrast, RU 486 only partially blocked morphine-induced suppression of hepatic phagocytosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The acoustic startle response as a measure of behavioral dependence in rats.

A series of experiments was conducted to assess the sensitivity of the acoustic startle response to chronic morphine administration and naloxone-precipitated withdrawal. Rats were implanted with two subcutaneous pellets containing either 75 mg each of morphine or containing only placebo. In experiment 1, withdrawal induced by 0.05-0.2 mg/kg naloxone dose-dependently decreased the magnitude of the startle response. Physical dependence was confirmed by a naloxone-induced acute weight loss seen in morphine-implanted rats, but naloxone had no effect on startle or body weight in non-dependent animals. In experiment 2, a modified procedure with fewer trials per session and fewer test days was employed. Naloxone (0.2 mg/kg) given 4-5 days after implantation induced large startle-response decreases in morphine-dependent rats while having no effect in placebo-implanted rats. Post-naloxone saline tests revealed no significant differences in startle between morphine and placebo groups. Startle scores were significantly higher in morphine-implanted rats than in placebo rats during a saline test given 3 days following pellet implantation. In a separate group of animals, however, acute IP injections of morphine from 0.3-10 mg/kg had no significant effect on startle amplitude. The effect of repeated pairings of withdrawal with the startle environment was assessed in experiment 3. Morphine-dependent rats startled significantly less if naloxone injections were given before the startle session than if they were administered 4 h later. Conditioned withdrawal effects, expressed during a final test session when all rats received saline, were observed for the body-weight measure but not for the startle response.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1992

Sudden death associated with aortitis and fibrosclerosing disease of the conduction system.

Aortitis is known to complicate a number of autoimmune diseases and syphilis. In most patients with autoimmune disease, arthritis is the initial presentation followed by aortic insufficiency. We report two cases of ostensibly healthy, middle-aged men in whom the initial manifestation of aortitis was sudden death. In each patient, there was extension of inflammation from the aorta into the atrioventricular node. These cases emphasize the importance of examining the conducting system in cases of sudden death associated with aortitis and no grossly evident cause of death. To our knowledge, this is the first report of aortitis presenting as sudden death.

Aortitis↗
PubMed1991

Postmortem magnetic resonance images of the injured brain: effective evidence in the courtroom.

Magnetic resonance images (MRI) of the whole, formalin-fixed brain produce details of pathologic changes deep within brain substance not apparent on external examination. Photographs of these radiographic images present pathologic features in a black-and-white, 2-dimensional format which has proven particularly effective in court before judge and jury. This pathologist has noted acceptance of such photographs in explaining to jurors the details of his testimony in selected cases where brain trauma resulted in a wrongful death. Penetrating missile wounds and blunt impact injuries are particularly well documented by this method.

Brain↗