Biomedical subjects
Publications and source records attributed to H Merz.
HIV infection can be transferred by blood, blood products and organ transplantation. In traumatic surgery allogeneic bone transplantation is commonly used for reconstruction in severe bone injuries. This technique has been abandoned since the appearance of reports of infections with HIV. In an experimental in vitro study we showed that ozone treatment cannot inactivate HIV in bone for transplantation.
P40 is a cytokine that was originally identified in the mouse as a T cell growth factor, but whose spectrum of potential targets was recently shown to include mast cells as well as megakaryoblastic leukemic cells. Given these multiple activities, it was proposed that the protein be renamed IL-9. The analysis of P40 genomic clones reported here shows that the human and mouse P40 genes consist of 5 exons spread over approximately 4 kb of DNA and organized in a similar fashion in both species. The two genes exhibit a high degree of identity in the coding sequence and in the 5' untranslated regions, which contain, among other consensus motifs, a conserved sequence for the binding of AP-1. Expression of human P40 was studied in PBMC. Treatment of the cells with PMA and a calcium ionophore induced strong expression of a 0.7-kb P40 mRNA. No message was detected in unstimulated cells or in cells stimulated with LPS or Staphylococcus aureus, indicating that P40 expression is not constitutive and suggesting that the gene is not easily activated in B lymphocytes and in monocytes. By contrast, T cell mitogens such as PHA or anti-CD3 antibodies induced a substantial P40 expression that was further enhanced in the presence of PMA. Cell fractionation experiments indicated that, under these conditions, the protein is preferentially induced in CD4+ T cells. The induction of P40 by anti-CD3 antibodies suggests that P40 production is part of the normal T cell response to antigenic stimulation.
An expression vector (pU3R-III/2-5AS) of human 2',5'-oligoadenylate (2-5A) synthetase was constructed in which a cDNA encoding an active form of the enzyme was located 3' to a 3'-long terminal repeat (LTR) of human immunodeficiency virus type 1 (HIV-1). The LTR-directed expression of this hybrid DNA could be activated in trans by the HIV tat gene product. This vector was used for transfection of HeLa-T4+ cells, which are permissive to HIV infection, as well as of normal HeLa cells. HIV replication after infection of the CD4-receptor-bearing HeLa-T4+ cells with HIV-1 was found to be strongly reduced when drug-selected cells cotransfected with pU3R-III/2-5AS and a hygromycin B resistance gene containing plasmid were used. In nontransfected cultures or after transfection with the selectable marker plasmid only, about 60% p17- and p24-positive cells were found 5 days after infection. However, after stable transfection with pU3R-III/2-5AS the number of positive cells was decreased to about 2%. The reverse transcriptase (RT) activity, as a measure for virus production, was markedly decreased in the culture fluids of pU3R-III/2-5AS transfected cells compared with the mock-transfected controls. In parallel experiments it was established that Tat-mediated trans-activation of HIV-1 LTR-directed 2-5A synthetase expression resulted in a great increase in both 2-5A synthetase mRNA level and activity as well as in cellular 2-5A content. Similar results were found in HeLa-T4+ cells and in HeLa cells (without CD4 receptor) cotransfected with pU3R-III/2-5AS and a tat gene containing plasmid or after introduction of purified Tat protein into the pU3R-III/2-5AS transfected cells by using a modified scrape loading procedure. These results indicate that HIV-trans-activated 2-5A synthetase can selectively inhibit HIV replication in vitro, and might be a promising gene therapeutical approach.
2',3'-Dideoxy-3'-fluorothymidine (FddThd), 2',3'-didehydro-2',3'- dideoxythymidine (ddeThd), and 3'-fluoro-5-methyl-deoxycytidine (FddMeCyt) are, in their triphosphate forms, selective inhibitors of human immunodeficiency virus type 1 reverse transcriptase. We report that 0.3 microM FddThd, FddMeCyt, or ddeThd as well as 3'-chloro-5-methyl-deoxycytidine (ClddMeCyt) or 3'-amino-5-methyl-deoxycytidine (AddMeCyt) almost completely blocked production of hepatitis B virus (HBV) particles by HBV DNA-transfected cell line 2.2.15 in vitro. Only at an at least 10-fold-higher concentration was a cytotoxic effect observed. These results indicate that FddThd, FddMeCyt, ClddMeCyt, AddMeCyt, and ddeThd are potent anti-HBV agents in vitro.
During differentiation and maturation well defined genetic rearrangements of B- and T-cell receptors are followed by a stepwise expression of defined phenotypic properties. Transformational events on such defined steps of cell differentiation result in different types of malignant lymphomas, some of which have these events during early steps of cell differentiation but show further maturation or activation. This is shown for the plasmacytoma but may also be true for Hodgkins disease or large cell anaplastic lymphoma. Inducing signals for maturation, differentiation, and activation are given by cytokines. The loss of a regular function of these cytokines may result in para- or autocrine growth signals in malignant lymphomas.
Explore the source record for details and available documents.
During the photocycle of bacteriorhodopsin (BR) the chromophore, a retinal Schiff base, is deprotonated. Simultaneously an asp residue is protonated. These results suggest that this deprotonation occurs via a Schiff base - asp hydrogen bond. Therefore, we studied carboxylic acid - retinal Schiff base model systems in CCl4 using IR spectroscopy. The IR spectra show that double minimum proton potentials are present in the OH ... N in equilibrium with O- ... HN+ H-bonds formed and that the proton can easily be shifted in these bonds by local electrical fields. The thermodynamic data of H-bond formation and proton transfer within these H-bonds are determined. On the basis of these data a hypothesis is developed with regard to the molecular mechanism of the deprotonation of the Schiff base of BR.
2,9 alpha-Dimethyl-5-(m-hydroxyphenyl)morphan (3a) has been synthesized from 5-(m-methoxyphenyl)-2-methyl-9-oxomorphan (4) and resolved into its enantiomers (+)-3a and (-)-3a. The assigned alpha-orientation of the 9-methyl group was derived from studies of induced NMR shifts using Eu(fod)3-d27. Compound (+)-3a has inappreciable agonist (antinociceptive) activity in mice, and (-)-3a shows codeine-like potency in the hot-plate and writhing tests only. The 9-demethyl homologues, (+)-1 and (-)-1, are strong agonists, about as potent as morphine in these tests as well as in the tail-flick assay. The racemic compound 3a and (+)-3a, but not (-)-3a, exhibit low-potency, narcotic-antagonist activity in mice (tail-flick test, vs. morphine). All three, however, precipitate abstinence in nonwithdrawn, morphine-dependent rhesus monkeys. Monkey studies with the 9-demethyl homologues confirmed earlier results showing that (+)-1, suppressing abstinence in withdrawn animals, has high physical dependence capacity, while (-)-1 has none. Instead, (-)-1 precipitates abstinence in nonwithdrawn animals. Studies in rats and isolated organs (guinea pig ileum and mouse vas deferens) and receptor-binding assays confirm the quite different opioid-action profiles of (+)-1 and (-)-1, which thus might interact with different opioid receptors. Catalytic hydrogenation of the methiodide (7) of 5 gave, instead of the expected epimer of 3a, ring-opened compound 8.
For various opioid agonists (n = 35) an unsatisfactory correlation between analgesic activity in vivo (mouse) and receptor binding affinity (rat brain) in vitro was obtained. Excellent correlations were observed, however, after separation of the opioid agonists into two groups with mu- and kappa-receptor selectivity, respectively. The correlation of the analgesic potency with the affinity to the opioid kappa-receptor was very high for the group of kappa-agonists, while it was low for the group of mu-agonists. The slopes of the regression lines were near unity and parallel. The shift from the less potent mu-agonists to the more potent kappa-agonists was about one order of magnitude indicating that analgesia of kappa-agonists is mediated by both mu- and kappa-receptors.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The quaternary opiate antagonists naloxone methylbromide (MB) and naltrexone MB do not cross the blood-brain barrier, and may be used to differentiate peripheral from central nervous system effects of the opioid peptides. When administered intravenously to the conscious, chronically instrumented dog, naloxone MB transiently reduces mean systemic arterial pressure and increases heart rate in a dose-dependent manner over the concentration range from 0.1 to 1.0 mg/kg. The [Leu5]enkephalin response is completely inhibited at naloxone MB doses as low as 0.25 mg/kg, but this inhibition has terminated by 30 min after dosing. Naltrexone MB displays a similar spectrum of activity. This inhibition of the intravenous [Leu5]enkephalin response by the quaternary opiate antagonists indicates that the [Leu5]enkephalin response occurs by activation of peripheral receptor sites. The decrease in mean pressure induced by these antagonists coupled with the inhibition of the [Leu5]enkephalin response suggests that peripheral enkephalins may play a role in blood pressure regulation.
The benozomorphan derivative (-)-2-[2-(p-bromoacetamidophenyl)ethyl]-5,9 alpha-dimethyl-2'-hydroxy-6,7-benzomorphan (BAB), capable of reacting with nucleophilic groups, acts on neuroblastoma X glioma hybrid cells as a potent, irreversible opiate agonist. Its potency in inhibiting the increase in cellular cyclic AMP, evoked by prostaglandin E1, is comparable to that of Leu-enkephalin. This also applies to its capacity to compete with [3H]D-Ala2-Met-enkephalinamide ([3H]DAEA) in binding on cell membrane preparations. The comparatively lower potency of (-)-2-[2-(p-acetamidophenyl)-ethyl]-5,9 alpha-dimethly-2'-hydroxy-5,7-benzomorphan (AB), which differs from BAB in the substitution of the bromoacetamido group by an acetamido group, is of the same order of magnitude as that of morphine. The covalent interaction of BAB with the opiate receptors is deduced from the observations that (1) it is not possible to wash away this compound from the receptors, (2) the potency of BAB in inhibiting the specific binding of [3H]DAEA increases with prolonged preincubation time, and (3) AB behaves as a reversible agonist.
Mr 2033 CL is a very potent non-morphine-like opioid analgesic as shown in different test models and animal species. On a weight for weight basis, it is about 20 times more potent than morphine. The analgesic effects of Mr 2033 CL are supposed to be different from those of morphine and bremazocine because of individual sensitivity against selective antagonists like naloxone and Mr 2266 CL. Mr 2033 CL does not induce the Straub tail phenomenon and increased circling movements in mice, catatonia in rats, and stupor in rabbits which are characteristic for mu agonists. Moreover, Mr 2033 CL does not have a morphine-like abuse potential in rats, dogs and rhesus monkeys. CNS-depressive effects were observed in different species. Respiratory depression and inhibition of intestinal transit seem to be of minor degree. In contrast to morphine, Mr 2033 CL provokes diuresis in rats. Binding studies in rats as well as dependence studies in rats and rhesus monkeys characterize Mr 2033 CL as a predominant kappa agonist with morphine antagonistic properties.
Naltrexone methylbromide and naloxone methylbromide, quaternary derivatives of naltrexone and naloxone respectively, are assumed to act peripherally. Both compounds reversed the intestinal stimulating effect of morphine in the dog. Naltrexone methylbromide 5 mg/kg s.c. blocked morphine-induced intestinal spike potentials for 50 min while intravenous doses caused antagonism for only 25 min. The antagonism by the s.c. route approximated that produced by naltrexone 0.2 mg/kg s.c. In morphine-dependent dogs, naltrexone methylbromide did not appear to antagonize morphine centrally in doses ranging from 0.25 to 50 mg/kg s.c. since it did not induce behavioral signs of narcotic withdrawal. Similarly, i.v. naloxone methylbromide was also able to reverse morphine-induced intestinal spike potential in dogs but the protection lasted only 25 min. In rats, naltrexone methylbromide 10 and 30 mg/kg i.p. neither reversed morphine block of PGF2 alpha-induced diarrhea nor antinociception. This suggests a lack of CNS narcotic antagonism in both test. In mice, naltrexone methylbromide, 60-720 mg/kg orally and 3-140 mg/kg i.p. failed to block morphine inhibition of prostaglandin F2 alpha-induced diarrhea. Paradoxically, in this species, 30 mg/kg s.c. of naltrexone methylbromide appeared to cross the blood-brain barrier since this dose reversed morphine-induced antinociception. In conclusion, naltrexone methylbromide effectively antagonizes the acute gut stimulating effect, but not the chronic behavioral effect of morphine administration in dogs. Based upon the antinociception test, naltrexone methylbromide does not cross the blood-brain barrier in rats but may in mice. Morphine inhibits prostaglandin F2 alpha-induced diarrhea by a central mechanism in rodents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.