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Biomedical subjects

N Hanna

Publications and source records attributed to N Hanna.

At least 73 records · Page 4Linked to original sources
PubMed1989

Structural analysis of the human immunodeficiency virus-binding domain of CD4. Epitope mapping with site-directed mutants and anti-idiotypes.

The CD4 molecule, a differentiation marker expressed primarily by T lymphocytes, plays an important role in lymphocyte activation. CD4 is also the receptor for HIV. A number of recent studies have localized the high affinity binding site of the HIV envelope glycoprotein, gp120, to the NH2-terminal (V1) domain of CD4, a region with sequence and predicted structural homology with Ig kappa chain V domains (V kappa). In this report, we show that V1 bears structural similarities with V kappa regions through detailed epitope mapping of 26 CD4 mAbs. The binding sites of these mAbs were initially defined relative to one another by crossblocking analysis and were then localized to specific domains of CD4 in blocking studies with truncated, soluble CD4 proteins. The epitopes within the V1 domain were mapped in detail with a panel of 17 substitution mutants, and the specificities of several mAbs that appear to recognize very similar epitopes were examined in crossblocking studies with anti-idiotype antibodies. The location of the epitopes is consistent with a V kappa-like structure of V1. Most of the epitopes lie within regions of predicted exposed loops. A number of these epitopes span discontinuous residues in the linear sequence that lies in close proximity in an Ig fold. Alignment of CD4 V1 with the Ig V kappa chains places these epitopes within stretches corresponding to the complimentarity-determining regions. This epitope analysis is relevant for a vaccine strategy for HIV based on anti-idiotype antibodies to CD4 mAbs and for studies with CD4 antibodies on the role of CD4 in T lymphocyte activation.

Amino Acid Sequence↗
PubMed1989

Synergistic antitumor effects of topoisomerase inhibitors and natural cell-mediated cytotoxicity.

The mechanism of augmentation of tumor cell killing by immune effector cells and chemotherapeutic drugs was studied. The effect of treating tumor cells with various antineoplastic drugs on their sensitivity to murine natural cell-mediated cytotoxicity in vitro was investigated. Pretreatment with actinomycin D at nontoxic concentrations rendered L929 and WEHI-164 tumor cells more susceptible to killing by mouse spleen lymphocytes in a dose-dependent manner. Similarly, enhancement of L929 tumor cell killing by natural cell-mediated cytotoxicity was observed following treatment of the target cells with the topoisomerase II inhibitors, Adriamycin, amsacrine, bisantrene, etoposide, and teniposide, as well as with topoisomerase I inhibitor, camptothecin. In contrast, drugs which induce their cytotoxic effects by mechanisms that do not involve topoisomerase inhibition such as bleomycin, vinblastine, vincristine, and mitomycin C failed to exhibit synergism with natural cell-mediated cytotoxicity. However, moderate synergy was consistently observed with cis-platinum. The effector cells responsible for the cytotoxicity in the present system are natural cytotoxic cells since they kill WEHI-164 but not YAC cells, are resistant to treatment with anti-asialo-GM1 antibody, and their activity is abolished by anti-tumor necrosis factor antibodies. Indeed, tumor necrosis factor-mediated cytotoxicity of WEHI-164 or L929 was enhanced by treatment of the target cells with topoisomerase II inhibitors. Moreover, WEHI-164 cells selected for tumor necrosis factor resistance were resistant to natural cell-mediated cytotoxicity, and no synergy could be observed with topoisomerase inhibitors.

Animals↗
PubMed1989

Inhibition of inflammatory cell infiltration by bicyclic imidazoles, SK&F 86002 and SK&F 104493.

The mode of action of the dual inhibitors of eicosanoid metabolism, SK&F 86002 and SK&F 104493 was evaluated on inflammatory cell infiltration induced in mice by carrageenan, monosodium urate crystals, and arachidonic acid. The results were compared to those seen with standard antiinflammatory compounds. Inflammatory cell infiltration was inhibited by SK&F 86002. SK&F 104493, colchicine, and phenidone but not naproxen. In vivo, PMN infiltration induced by LTB4 was inhibited by colchicine but not by SK&F 86002, SK&F 104493, or phenidone treatment. Similarly, in vitro chemotaxis to LTB4 was not inhibited by SK&F 86002. The 5-lipoxygenase inhibitors, SK&F 86002, SK&F 104493, and phenidone inhibited LTB4 production in vivo as well as inflammatory cell infiltration induced by arachidonic acid. The data are consistent with the suggestion that the bicyclic imidazoles inhibit PMN infiltration by virtue of inhibition of LTB4 production.

Animals↗
PubMed1989

Effects of prostaglandins and cAMP levels on monocyte IL-1 production.

The effects of prostaglandin E2 (PGE2), as well as other cAMP-elevating agents, on the in vitro production of interleukin-1 (IL-1) by human monocytes (HM) were examined. Exposure to E. coli lipopolysacharide (LPS) resulted in a dose- and time-dependent increase of IL-1 activity in monocytes culture supernatants. Maximal levels of secreted IL-1 in response to 10 ng LPS/ml were obtained at 18 h. PGE1, PGE2, cholera toxin (CT) and the phosphodiesterase inhibitor, isobutylmethylxanthin (IBMX), when added with LPS, resulted in a dose-dependent increase in cellular cAMP and in secreted IL-1. Maximal levels of secreted IL-1 were 2.5-5.0-fold over LPS alone. When CT or PGE2 was added with IBMX a further increase was observed. These agents exhibited marginal effect on cell-associated IL-1. Maximum cAMP levels was achieved at 10 min in response to either PGE1 or PGE2 and returned to near basal levels after 18 h. While PGE1 elevated cAMP to a larger extent than PGE2 (58- vs. 30-fold) the latter resulted in a higher levels of secreted IL-1. Elevated cAMP persisted throughout the entire culture period in response to CT (4-6-fold) or IBMX (7-fold). Thus, we conclude that in adherent HM, IL-1 production is potentiated and not inhibited by prostaglandins or agents that elevate cellular cAMP.

1-Methyl-3-isobutylxanthine↗
PubMed1989

Inhibitory effect of SK&F 86002 on monocyte IL-1 production.

The effects of several anti-inflammatory and anti-arthritic drugs on the in vitro production of interleukin-1 by human monocytes were examined. SK&F 86002-A2 was shown to be a potent inhibitor of IL-1 production with a 50% inhibitory concentration (IC50) of 1.3 +/- 0.5 microM. Standard compounds which inhibit the cyclooxygenase (CO) or CO and 5-lipoxygenase (5LO) pathways of arachidonic acid metabolism did not inhibit IL-1 production at nontoxic concentrations. Analysis of SK&F 86002 analogs also showed no clear correlation between 5LO and IL-1 synthesis inhibitory activity. The precise mechanism of action is not known except that it is post-transcriptional. Thus, SK&F 86002 may serve as a useful reagent in the understanding of the synthetic, processing and/or secretory pathways of interleukin-1, and may provide important insight into the treatment of disease states where aberrant IL-1 production is implicated.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

The pharmacology of arachidonic acid-induced rat PMN leukocyte infiltration.

Arachidonic Acid (AA) injected into a hindpaw of Lewis rats produces high levels of tissue myeloperoxidase (MPO), a biochemical marker for PMN leukocytes. Treatment with a corticosteroid (prednisolone) or dual 5-LO/CO inhibitors of AA metabolism (phenidone, SKF 86002) produced dose-related inhibition of AA-induced elevations in paw tissue MPO levels. In contrast, administration of high pharmacologic doses of selective cyclooxygenase inhibitors (indomethacin, ibuprofen, naproxen), anti-histamine/serotonin agents (cyproheptadine, chlorpheniramine) or an anti-arthritic gold compound (auranofin) produced only slight or moderate effects. Thus, AA-induced hindpaw inflammation is a useful method for determining pharmacologic effects of 5-LO/CO inhibitors on PMN leukocyte infiltration in vivo.

Animals↗
PubMed1989

Fetal cardiac output in the isoimmunized pregnancy: a pulsed Doppler-echocardiographic study of patients undergoing intravascular intrauterine transfusion.

The mechanism of development of hydrops fetalis in severe isoimmunization has been subject to speculation. We performed pulsed Doppler assessment of cardiac output in 13 severely isoimmunized fetuses before and after intravascular transfusion and compared the results with 37 control fetuses between 20 and 34 weeks' gestation. The cardiac index of the anemic fetuses was significantly greater than that of the control group. A significant (right ventricle, p less than 0.01; left ventricle, p less than 0.02) increase in indexed output was noted from both ventricles and in the combined ventricular output (mean +/- SEM 644 +/- 35.3 ml/kg/min in control fetuses versus 879 +/- 86.0 ml/kg/min in anemic fetuses, p less than 0.006). An increase in cardiac output was also noted when anemic fetuses were compared with gestational age-specific norms. We conclude that severely anemic fetuses of isoimmunized pregnancies tend to have significantly higher cardiac output than do unaffected fetuses and that this high output state may play a part in the development of hydrops fetalis.

Blood Transfusion, Intrauterine↗
PubMed1989

Percutaneous epidural catheterization for intractable pain in terminal cancer patients.

We examined the effects of long-term percutaneous epidural catheterization for pain relief in nine terminally ill gynecologic cancer patients. All patients were free of side-effects such as respiratory depression, nausea, vomiting, urinary retention, or pruritus. Analgesia was excellent in six patients. Puncture-site skin inflammation occurred in four patients. Catheter dislodgement occurred in three patients. Although percutaneous epidural catheters were well tolerated in a few patients for an extended period of time, the frequency of catheter problems demonstrate that other methods such as catheter tunneling or implantable systems should be considered for long-term epidural administration of narcotics. This method appears to be most effective in patients suffering from pain due to nerve root involvement.

Analgesia, Epidural↗
PubMed1989

Inhibition of animal models of autoimmune disease and the induction of non-specific suppressor cells by SK&F 105685 and related azaspiranes.

SK&F 105685 (N,N-dimethyl-8,8-dipropyl-2-azaspiro[4.5]decane-2-propanamine+ ++ dihydrochloride), administered orally to adjuvant arthritic (AA) rats inhibited immune-mediated hindpaw inflammation with an ED50 of 20 mg/kg/day. Both prophylactic and therapeutic administration were effective in this model. In addition, SK&F 105685 inhibited skin wheal responses to purified protein derivative (PPD) of tuberculin in AA rats and the development of hindleg paralysis associated with experimental allergic encephalomyelitis (EAE). Spleens of normal rats treated with SK&F 105685 were found to contain a population(s) of suppressor cells (SC) which inhibited the response of normal cells to Concanavalin A (Con A) in co-culture assays. The association between SC induction and anti-arthritic activity was determined by evaluating a series of chemically related azaspiranes in the AA rat model and for SC induction in normal rats. A statistically significant correlation was demonstrated (r = 0.79, P less than 0.001), indicating that SC induction may be responsible for the therapeutic activity of these compounds.

Adjuvants, Immunologic↗
PubMed1989

Evaluation of the Phadebact ETEC-LT test for the heat-labile enterotoxin of Escherichia coli.

The Phadebact ETEC-LT is a rapid method of identifying enterotoxigenic Escherichia coli (ETEC), producing the heat-labile enterotoxin (LT). It uses staphylococcal coagglutination as a means of identifying the LT released from ETEC. In this investigation both known strains of ETEC from a variety of sources as well as strains from patients were tested. Good agreement was found between the Phadebact ETEC-LT test and established tests for LT. The test was found easy to use in the clinical laboratory environment, and revealed that LT producing ETEC may be more common causes of diarrhoea in Australia than had been anticipated.

Agglutination Tests↗
PubMed1989

Protective effect of SK&F 86002, a novel dual inhibitor of arachidonic acid metabolism, in murine models of endotoxin shock: inhibition of tumor necrosis factor as a possible mechanism of action.

The effect of a new, structurally novel, dual inhibitor of arachidonic acid (AA) metabolism, SK&F 86002, was studied in two murine models of endotoxin shock. The first model was the injection of C57BL/6 mice with lipopolysaccharide (LPS) in combination with D-galactosamine (D-gal), which resulted in death within 6-48 hr. Treatment of these mice with SK&F 86002 (100 mg/kg, p.o.) 30 min to 2 hr prior to the administration of D-gal and LPS protected the animals from mortality. Protection was also provided by treatment with the corticosteroid dexamethasone, whereas only partial protection was afforded by the dual inhibitor of AA metabolism phenidone and the cyclooxygenase inhibitors naproxen and indomethacin. In a similar dosing protocol, SK&F 86002 also protected mice in a second endotoxin shock model in which mice sensitized with Proprionibacterium acnes received LPS 10 days later. Moreover, partial protection was obtained when SK&F 86002 was administered therapeutically after LPS injection. The administration of SK&F 86002 to P. acnes/LPS-treated mice decreased serum levels of tumor necrosis factor (TNF), which was not observed following naproxen or indomethacin treatment. Consistent with the role of TNF in this model of endotoxin shock was the observation that treatment with antibodies against TNF also prevented or reduced mortality.

Animals↗
PubMed1989

Absence of a lyso-PAF relationship with PAF (platelet activating factor) in monosodium urate crystal-induced inflammatory exudates.

Monosodium urate crystal (MSU)-induced inflammation was evaluated for increased vascular permeability and platelet activating factor (PAF) production. Intraperitoneal injection of MSU crystals increased vascular permeability and lyso-PAF, as shown by acetylation and bioassay, but PAF was not detected. Intraperitoneal administration of PAF elicited dye-extravasation, which was abolished by the PAF antagonist WEB-2086, but this compound had no significant effect upon MSU-induced dye extravasation. Thus, the presence of lyso-PAF did not reflect in situ production of PAF. Lyso-PAF extracted from normal serum in amounts equivalent to that extravasated could account for the lyso-PAF observed. Thin-layer chromatographic analysis of acetylated extracts from plasma and peritoneal washouts showed identical Rf values to the PAF standard. We conclude that lyso-PAF in the exudate was associated with extravasated plasma proteins rather than a reflection of in situ production of PAF.

Animals↗
PubMed1988

Effect of inhibitors of eicosanoid metabolism in murine collagen-induced arthritis.

The dual inhibitors of arachidonic acid metabolism, Smith Kline & French (SK&F) 86002, SK&F 104351, and phenidone; the corticosteroid, dexamethasone; and the selective cyclooxygenase inhibitors, ibuprofen, indomethacin, naproxen, and piroxicam were evaluated for their antiarthritic potency in the murine, collagen-induced arthritis model. The ability of these compounds to alter the severity of arthritic lesions and to reduce serum levels of the acute-phase reactant, serum amyloid P component (SAP) were monitored. Serum concentrations of SAP were found to correlate strongly (r = 0.985) with disease severity at day 35 postimmunization. Treatment with SK&F 86002, SK&F 104351, phenidone, or dexamethasone significantly reduced disease severity, as judged by clinical score (55%, 72%, 41%, and 45% inhibition, respectively) and SAP levels (62%, 94%, 52%, and 94% inhibition, respectively) in arthritic mice. This profile of activity was not shared by the selective cyclooxygenase inhibitors, which did not uniformly inhibit disease activity by both parameters. The results suggest that dual inhibitors of 5-lipoxygenase and cyclooxygenase may prove more effective than selective cyclooxygenase inhibitors as anti-arthritic agents.

Animals↗
PubMed1988

Inhibition of monocyte IL-1 production by the anti-inflammatory compound, SK&F 86002.

The effects of several anti-inflammatory/anti-arthritic drugs on the in vitro production of interleukin-1 (IL-1) by human monocytes were examined. SK&F 86002, a novel dihydroimidazo thiazoline which inhibits both 5-lipoxygenase- and cyclooxygenase-mediated arachidonate metabolism was shown to be a potent inhibitor of IL-1 production by LPS-stimulated human monocytes. The inhibition was dose-dependent (IC50 = 1.30 +/- 1 microM), reversible and was independent of the concentration or type of stimulus used. The compound also inhibited cell-associated IL-1 activity. The compound did not exert general inhibitory effects on such parameters as adherence, cytotoxic function and protein synthesis of the monocytes. Other cyclooxygenase and/or 5-lipoxygenase inhibitors of arachidonic acid metabolism tested, with the exception of nordihydroguaiaretic acid, were inactive in inhibiting monocyte IL-1 production suggesting that the inhibition of IL-1 production by 86002 may be dissociated from its inhibition of the fatty acid oxygenases. The inhibition of IL-1 production by SK&F 86002 adds another facet of drug action contributing to its spectrum of anti-inflammatory activities.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1988

CD3-associated heterodimeric polypeptides on suppressor hybridomas define biologically active inhibitory cells.

We have investigated the relationship between CD3 expression and the suppressor T-cell function. We have isolated stable clonal cell lines of the F12.23 suppressor T-cell hybridoma that are either CD3+ or CD3-. These lines were subjected to functional assays including inhibition of in vivo hapten-specific delayed-type hypersensitivity responses, in vitro hapten-specific interleukin 2 responses, as well as hapten-specific cytotoxic T-lymphocyte assays. In all assays, the functional suppressor phenotype absolutely correlated with CD3 surface expression. Furthermore, we have immunoprecipitated heterodimeric proteins that share molecular features with some receptor polypeptides previously described. CD3 polypeptides found on the surface of suppressor T cells are phosphorylated after phorbol ester stimulation. Collectively these studies unambiguously define the suppressive supernatant function as a product of CD3+ receptor-bearing T cells.

Animals↗
PubMed1988

An emulsion formulation of amphotericin B improves the therapeutic index when treating systemic murine candidiasis.

Incorporating amphotericin B into liposomes was reported to decrease amphotericin B toxicity without a concomitant loss of antifungal efficacy. We formulated an alternative emulsion-based delivery system for amphotericin B and compared it with Fungizone. The maximal tolerated dose (MTD) in mice was 1 mg of Fungizone/kg; however, the MTD was greater than 9 mg of the Intralipid emulsion formulation/kg. The emulsion formulation and Fungizone were equipotent for treating systemic candidiasis in mice. Amphotericin B nephrotoxicity, as manifested by polyuria that was resistant to antidiuretic hormone, was markedly diminished when amphotericin B was administered as an emulsion to rats. Loss of potassium from human red blood cells was also reduced by formulating this agent within emulsions. The emulsion formulation extended the survival time of mice that had established Candida albicans infections, when compared with the Fungizone treatment. The efficacy and reduced toxicity of the amphotericin B emulsion are findings suggesting that the emulsion formulation is preferable to Fungizone.

Amphotericin B↗
PubMed1988

Sexual transmission of human papillomaviruses in heterosexual and male homosexual couples, studied by DNA hybridisation.

The prevalence of human papillomavirus (HPV) 6, 11, 16, and 18 in 36 heterosexual couples and seven male homosexual couples with genital warts was investigated for evidence of sexual transmission of genital HPV. The prevalence of virus type and number of copies of viral genome equivalents/cell in the lesions were assessed, and the factors influencing transmission analysed. Our results show that HPV 6 and, to a lesser extent, HPV 11 were the types most readily transmitted, and that transmission appears to depend on the copy number and the duration and frequency of exposure.

DNA, Viral↗