Shakir S K S Sarhan (original) (raw)
Papers by Shakir S K S Sarhan
Peptides, 1997
Several lines of evidence have shown that neurotensin can modulate dopamine neurotransmission. It... more Several lines of evidence have shown that neurotensin can modulate dopamine neurotransmission. It has been suggested that neurotensin has potential antipsychotic activity because it reduces dopaminergic activity preferentially in the nucleus accumbens. In the present study, the effects of neurotensin and NT1 (N ␣ Me-Arg-Lys-Pro-Trp-TIe-Leu or Eisai hexapeptide), a metabolically stable and systemically active neurotensin agonist, were examined in several models of antipsychotic activity and side effect liability in mice; analgesic and hypothermic effects of both compounds also were determined. Up to high doses, neurotensin (5.0 and 10.0 g, ICV) and NT1 (10.0 and 20.0 mg/kg, IP) did not produce catalepsy. A much lower dose of neurotensin (0.03 g, ICV) significantly reduced amphetamine-and phencyclidine-stimulated locomotor activity; NT1 also diminished amphetamine-and phencyclidine-stimulated locomotion with ED 50 values of 0.3 and 0.4 mg/kg, IP, respectively. Neurotensin (0.01-0.3 g, ICV) and NT1 (0.1-1.0 mg/kg, SC) also produced dose-dependent analgesia in the paw pressure test and decreased body temperature; these effects were insensitive to pretreatment with naloxone (10.0 mg/kg, IP). Together, the results support the hypothesis that neurotensin agonists have antipsychotic and analgesic activity. Moreover, the data suggest that such compounds may not produce extrapyramidal side effects.
European Journal of Pharmacology, 2003
The neuroprotective activity of ACEA 1021 (5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione;... more The neuroprotective activity of ACEA 1021 (5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione; licostinel), a selective antagonist at the strychnine-insensitive glycine site associated with the NMDA receptor complex, has been investigated in various models of focal cerebral ischemia. In isoflurane-anaesthesised Wistar rats with permanent ipsilateral carotid artery ligation and transient middle cerebral artery occlusion (duration of occlusion, 2 h) followed by reperfusion (24 h), intravenous administration of ACEA 1021 (bolus: 10 mg/kg, 15 min after the onset of middle cerebral artery occlusion; infusion: 7 mg/kg/h for 6 h beginning 30 min after occlusion of the artery) produced a 32% reduction in infarct volume. Similarly, in Sprague-Dawley rats with transient middle cerebral artery occlusion (2 h) followed by 24 h of reperfusion, identical treatment with ACEA 1021 decreased infarct size by 39%. Magnetic resonance imaging (MRI) confirmed these effects in the transient model, in that infarct volume observed using apparent diffusion coefficient (ADC) maps was significantly smaller after 24 h in the ACEA 1021-treated rats compared with Tris-treated controls. Furthermore, the increase in perfusion signal intensity after reperfusion was more pronounced in the ACEA 1021-treated rats than in controls. In Fisher 344 rats with permanent occlusion of the middle cerebral artery, ACEA 1021 induced a dose-related decrease in infarct volume, which was associated with an improvement in neurological outcome as measured by the rope suspension procedure. Administration of the same dose regimen, as above, in Fisher rats with permanent middle cerebral artery occlusion reduced infarct volume by 68%. This dose was as effective when administration was delayed for 2 h. In mice with permanent middle cerebral artery occlusion, ACEA 1021 (5 mg/kg, i.v., 5 min after occlusion; 30 mg/kg, s.c., 1 and 4 h post-middle cerebral artery occlusion) decreased infarct size by 42%. The consistent anti-ischemic effects of ACEA 1021 make it a valuable compound for exploratory stroke research.
International Journal of Developmental Neuroscience, 1988
Xells dissociated from cerebral hemispheres of 8-day-old chick embryos were seeded on poly-L-lysi... more Xells dissociated from cerebral hemispheres of 8-day-old chick embryos were seeded on poly-L-lysine coated Petri dishes in serum-containing medium. After 24 hr the culture medium was switched to a serum-free, chemically defined medium. These cultures contain mainly neuronal cells until day 14, characterized by the presence of acetylcholinesterase activity and neurotilament proteins. After 2 weeks glial cells progressively contaminated the neuronal culture. Cultures were maintained for a period of 4 weeks. From day 6 on numerous synapses with clear vesicles were observed. The activity of choline acetyltransferase remained low throughout the culture period, while GABA levels increased in parallel with synaptogenesis. Our observations indicate that chick cerebral hemisphere neuronal cultures grown in serum-free, chemically defined medium contain GABAergic neurons that undergo maturation.
Journal of Biochemistry, Jul 1, 1979
... Nikolaus SEILER,* Thomas SCHMXDT-GLENEWINKEL,** and Shakir SARHAN* Centre de Recherche Merre... more ... Nikolaus SEILER,* Thomas SCHMXDT-GLENEWINKEL,** and Shakir SARHAN* Centre de Recherche Merrell International, 16 rue d'Ankara, 67084 Strasbourg Cedex, France, and "Department of Biobehavioral ... 20, 699-708 5. Seiler, N. & Eichentopf, B. (1975) Biochem. ...
Cancer Research, Aug 15, 1990
The combination of inhibitors of ornithine decarboxylase and polyamine oxidase and of antibiotics... more The combination of inhibitors of ornithine decarboxylase and polyamine oxidase and of antibiotics suitable for the (partial) decontamination of the gastrointestinal tract with a polyamine-deficient diet reduced the growth rate of Lewis lung carcinoma by more than 80%. The formation of lung métastases was prevented by 70 to 100%, depending on the treatment. The reduction of tumor growth was accompanied by a decrease of tissue polyamine concentrations, a reduced rate of tumor cell prolifer ation, and protein synthesis. The comparison of the ornithine decarbox ylase inhibitors Eflornithine [D,L-2-(difluoromethyl)ornithine] and ( /:')-2-(fluoromethyl)dehydroornithine ethylester confirmed the greater in vivo potency of the latter compound. Our method of growth inhibition by systematic polyamine deprivation is not tumor specific, but presumably generally applicable to rapid growth.
Anticancer Research, 1991
It has previously been shown that systematic polyamine deprivation results in the almost complete... more It has previously been shown that systematic polyamine deprivation results in the almost complete inhibition of the growth of several solid tumors. The same polyamine deficient diet (containing antibiotics for the decontamination of the gastrointestinal tract, the ornithine decarboxylase inhibitor 2-(difluoromethyl)ornithine, and the polyamine oxidase inhibitor N1, N4-bis-(2,3-butadienyl)putrescine; "drug-containing polyamine deficient chow", DC-PDC) was applied for the first time to the treatment of rats with an intracranial tumor. Rats received intracortical grafts of C6 rat glioblastoma cells, and the length of their survival was determined. Treatment with DC-PDC, starting four days after tumor cell inoculation, significantly prolonged the median survival of the glioblastoma-bearing rats. The results underline the general growth inhibitory effect of systematic polyamine deprivation. Since the effect of polyamine restriction on tumor growth is reversible, combinations with cytotoxic drugs have to be found which exploit the changed functions of polyamine deficient tumor cells.
Neurochemistry International, 1983
Journal of chromatography. B, Biomedical applications, Jan 18, 1994
Orotic acid was separated from other urinary constituents by ion-pair formation with tetrabutylam... more Orotic acid was separated from other urinary constituents by ion-pair formation with tetrabutylammonium, and isocratic elution from a reversed-phase column. Absorbance at 280 nm was recorded for quantitation. Owing to the better column characteristics the separations are somewhat faster, and the sensitivity of the method is higher than those of analogous methods using anion-exchange columns. The method was used for the determination of orotic acid in human urine, in urine of rats with portacaval shunts and in small (30 microliters) urine samples from sparse fur mice. Shunted rats excreted ca. 100% more orotic acid per 24 h than sham-operated controls, in spite of their considerably lower body weight. Excessive orotic acid in urine indicates a conditional deficiency of ornithine. Sparse fur mice are congenitally hyperammonemic because of a defective hepatic ornithine carbamoyltransferase. Determination of orotic acid in the urine is a suitable method to identify those animals among l...
General pharmacology, 1984
Administration of muscimol to mice in subcutaneous doses between 0.34 and 1.25 mg/kg produced par... more Administration of muscimol to mice in subcutaneous doses between 0.34 and 1.25 mg/kg produced partial protection against 3-mercaptopropionic acid (MPA)-induced seizures. Glycine at a dose of 750 mg/kg (10 mmol/kg) protected 20% of the animals 45 min after its administration. Combined treatment with the two compounds gave a near to complete protection against MPA-induced seizures. These observations suggest that the concomitant enhancement of glycinergic and GABAergic activities amplify the anticonvulsant effect of these neuronal systems against seizures induced by impairment of GABA-mediated transmission.
General pharmacology, 1985
THPO, a GABA uptake inhibitor, when given in doses of up to 4 mmol/kg (i.p.) to mice, had only a ... more THPO, a GABA uptake inhibitor, when given in doses of up to 4 mmol/kg (i.p.) to mice, had only a marginal protective effect against seizures induced 1 hr later by 3-mercaptopropionic acid (MPA). THPO (4 mmol/kg), when given in combination with 10 mmol/kg of glycine, protected 60% of the mice from MPA-induced convulsions. The combination of THPO and glycine delayed the onset of metrazol-induced clonic convulsions and protected 30% of the animals from seizures, although neither glycine or THPO alone had a significant anticonvulsant effect against metrazol induced seizures. In agreement with earlier findings, the results presented in this work seem to indicate that the synergistic anticonvulsant effects of glycine and GABAergic agents are independent of their mode of action: the effects of GABA agonists (muscimol) GABA-T inhibitors (vinylGABA), or an inhibitor of glial GABA uptake (THPO) are similarly amplified by glycine.
General pharmacology, 1989
1. The anticonvulsant properties of L-proline, of proline derivatives (trans-4-hydroxy-L-proline,... more 1. The anticonvulsant properties of L-proline, of proline derivatives (trans-4-hydroxy-L-proline, cis-4-hydroxy-D-proline, 3,4-dehydro-D,L-proline) and of D- and L-pipecolic acid were studied alone and in combination with vigabatrin (R/S-4-aminohex-5-enoic acid). 3-Mercaptopropionic acid and pentylenetetrazol-induced convulsions in mice were used as animal models of epilepsy. 2. Proline and proline derivatives are weak anticonvulsants if given alone in doses up to 10 mmol/kg, however, they are capable of potentiating the anticonvulsant effects of vigabatrin, in a manner similar to that reported previously for glycine, and some glycine derivatives. Among the compounds tested, trans-4-hydroxy-L-proline was the most potent anticonvulsant in combination with the indirect GABA agonist vigabatrin. 3. A potential explanation for the synergistic anticonvulsant effect of the combination of the GABA agonist and proline is the presumed role of proline as inhibitory neurotransmitter, and/or its...
Cancer research, Jan 15, 1990
The combination of inhibitors of ornithine decarboxylase and polyamine oxidase and of antibiotics... more The combination of inhibitors of ornithine decarboxylase and polyamine oxidase and of antibiotics suitable for the (partial) decontamination of the gastrointestinal tract with a polyamine-deficient diet reduced the growth rate of Lewis lung carcinoma by more than 80%. The formation of lung metastases was prevented by 70 to 100%, depending on the treatment. The reduction of tumor growth was accompanied by a decrease of tissue polyamine concentrations, a reduced rate of tumor cell proliferation, and protein synthesis. The comparison of the ornithine decarboxylase inhibitors Eflornithine [D,L-2-(difluoromethyl)ornithine] and (E)-2-(fluoromethyl)dehydroornithine ethylester confirmed the greater in vivo potency of the latter compound. Our method of growth inhibition by systematic polyamine deprivation is not tumor specific, but presumably generally applicable to rapid growth.
Journal of chromatography, Jan 11, 1979
The thin-layer electrophoretic separation at pH 4.8 of brain extracts and a procedure for fluores... more The thin-layer electrophoretic separation at pH 4.8 of brain extracts and a procedure for fluorescent staining of the plates with fluorescamine are described for the rapid routine determination of 4-aminobutyric acid (GABA), glutamic acid and aspartic acid in brain extracts and in particulate fractions of brain tissue. Automated sample application, electrophoretic separation using two chambers, and quantitation by in situ fluorescence scanning allows the assay of 280 samples within three working days. The method is reproducible (S.D. less than 8% of the mean) within the range of 0.2--2 nmole per spot. The staining procedure can be applied to a variety of related analytical problems. The method has proved useful for the determination of the specific radioactivities of GABA, glutamic acid and aspartic acid in metabolic studies.
Biological Chemistry Hoppe-Seyler, 1989
Putrescine, spermidine and spermine were determined in the nuclear fraction of rat liver which wa... more Putrescine, spermidine and spermine were determined in the nuclear fraction of rat liver which was obtained by density gradient centrifugation in non-aqueous media, i.e. under conditions which avoid migration of water-soluble compounds. Calculations of the distribution of the polyamines between nuclear and extranuclear compartments were based on the assumption that the DNA is concentrated in the nuclei. No significant losses of the polyamines occurred during fractionation. From the polyamine determination in tissue and nuclear fraction it appeared that 16-17% of the liver spermidine and spermine, and about 8% of the putrescine content was localized in the nuclei. The spermidine/spermine-ratios in nuclei and whole tissue were not significantly different. Pretreatment of the animals with inhibitors of ornithine decarboxylase caused a decrease of putrescine exclusively in the extranuclear compartments, in agreement with a higher proportion of the inhibitors in the cytoplasm. Since the nuclear volume of rat liver corresponds to about 5% of total liver volume, the concentration of spermidine and spermine is higher in the nucleus than in extranuclear compartments. Published histochemical localizations of the polyamines suggested very low polyamine concentrations in the nuclei of non-dividing liver and HeLa cells, but dramatic polyamine accumulations in metaphase and anaphase nuclei. These results are in disagreement with previously reported autoradiographic data, subcellular localizations based on density gradient centrifugations, and with our present results. Since subcellular localization is a key issue in all attempts to clarify cellular functions of the polyamines the careful revision of the techniques involved in subcellular polyamine localizations seems imperative.
Peptides, 1997
SARHAN, S., J. M. HITCHCOCK, C. A. GRAUFFEL AND J. G. WETTSTEIN. Comparative antipsychotic profil... more SARHAN, S., J. M. HITCHCOCK, C. A. GRAUFFEL AND J. G. WETTSTEIN. Comparative antipsychotic profiles of neurotensin and a related systemically active peptide agonist. PEPTIDES 18(8) [1223][1224][1225][1226][1227] 1997.-Several lines of evidence have shown that neurotensin can modulate dopamine neurotransmission. It has been suggested that neurotensin has potential antipsychotic activity because it reduces dopaminergic activity preferentially in the nucleus accumbens. In the present study, the effects of neurotensin and NT1 (N ␣ Me-Arg-Lys-Pro-Trp-TIe-Leu or Eisai hexapeptide), a metabolically stable and systemically active neurotensin agonist, were examined in several models of antipsychotic activity and side effect liability in mice; analgesic and hypothermic effects of both compounds also were determined. Up to high doses, neurotensin (5.0 and 10.0 g, ICV) and NT1 (10.0 and 20.0 mg/kg, IP) did not produce catalepsy. A much lower dose of neurotensin (0.03 g, ICV) significantly reduced amphetamine-and phencyclidine-stimulated locomotor activity; NT1 also diminished amphetamine-and phencyclidine-stimulated locomotion with ED 50 values of 0.3 and 0.4 mg/kg, IP, respectively. Neurotensin (0.01-0.3 g, ICV) and NT1 (0.1-1.0 mg/kg, SC) also produced dose-dependent analgesia in the paw pressure test and decreased body temperature; these effects were insensitive to pretreatment with naloxone (10.0 mg/kg, IP). Together, the results support the hypothesis that neurotensin agonists have antipsychotic and analgesic activity. Moreover, the data suggest that such compounds may not produce extrapyramidal side effects. © 1997 Elsevier Science Inc.
Neuroscience Letters, Aug 28, 2003
The glycine site, N-methyl-D-aspartate antagonist 5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalin... more The glycine site, N-methyl-D-aspartate antagonist 5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione (ACEA1021) was previously tested only in models of transient stroke with pre-treatment paradigms. We therefore tested whether it would protect in two models of permanent stroke in two rat strains with delayed treatment. Intravenous ACEA1021 reduced cerebral infarction by 62% (15 min treatment delay) and 42% (2 h treatment delay), relative to vehicle-injected rats, when subjected to a modified Tamura and permanent intraluminal filament model of stroke, respectively. In comparison, intravenous nicotinamide (500 mg/kg), which was tested in separate animal cohorts, had no significant effect on infarction. These data show that ACEA1021 protects against permanent focal cerebral ischemia, even with a 2 h post-treatment delay. Characterization of the therapeutic window with longer outcome times including infarction and neurobehavioral endpoints is needed. q
Neuroscience, 1991
Six-day-old neuronal cultures derived from 14-day-old embryonic rat cerebral hemispheres were hig... more Six-day-old neuronal cultures derived from 14-day-old embryonic rat cerebral hemispheres were highly enriched in GABAergic neurons, as was demonstrated by immunocytochemistry using an anti-glutamate decarboxylase antiserum. They contained about 64% glutamate decarboxylase-positive neurons. About 8% of these neurons proliferated, as shown by a combination of glutamate decarboxylase immunocytochemistry and [3H]thymidine incorporation into cell nuclei. The proliferative activity of GABAergic precursor cells and changes in the cellular concentrations of the non-essential amino acids, including GABA under the effect of basic fibroblast growth factor were studied. When basic fibroblast growth factor was added to the cultures 4 h after seeding, the proliferation of the GABAergic neurons was stimulated about threefold. Under this culture condition, the concentration per cell of all amino acids increased, except those of GABA and fl-alanine. When basic fibroblast growth factor was added to cultures only on day four, the proliferation of the neuronal cells was no more enhanced. Under this condition of treatment, the concentrations of all non-essential amino acids, including those of GABA and fl-alanine were enhanced. Under both basic fibroblast growth factor treatments the concentration of GABA per GABAergic cell was increased. In contrast, the specific activity of glutamate decarboxylase was not stimulated under these conditions. We hypothesize that under the effect of basic fibroblast growth factor the capabilities of the cells to store GABA are improved.
Neurochemical Research, 1983
The anticonvulsive effects of GABA, taurine, and glycine were investigated on several chemically-... more The anticonvulsive effects of GABA, taurine, and glycine were investigated on several chemically-induced and genetic seizure models. Intravenous injections of either GABA, taurine, or glycine provided protection against 3-mercaptopropionic acid (MPA)-indticed convulsions in adult Swiss mice. GABA was partially effective against isonicotinic acid hydrazide and was without effect against bicucullineinduced convulsions. Prolonged administration ofglycine prevented MPA-induced convulsions but not electrically induced seizures or seizures induced by strychnine or metrazol. Intragastric glycine protected young audiogenic seizure-susceptible DBA/2 mice against all three phases of sound-induced convulsions (wild running, clonic and tonic seizure), but GABA and taurine provided little or no protection. With increase of glycine, the cerebral levels of glutamine and serine also increased, but that of gtutamic acid decreased. The endogenous glutamic and glycine levels were slightly higher in the brains of the audiogenic seizure-susceptible DBA/2 mice than in that of the resistant BALB/Cy strain.
Neurochemical Research, 1980
Peptides, 1997
Several lines of evidence have shown that neurotensin can modulate dopamine neurotransmission. It... more Several lines of evidence have shown that neurotensin can modulate dopamine neurotransmission. It has been suggested that neurotensin has potential antipsychotic activity because it reduces dopaminergic activity preferentially in the nucleus accumbens. In the present study, the effects of neurotensin and NT1 (N ␣ Me-Arg-Lys-Pro-Trp-TIe-Leu or Eisai hexapeptide), a metabolically stable and systemically active neurotensin agonist, were examined in several models of antipsychotic activity and side effect liability in mice; analgesic and hypothermic effects of both compounds also were determined. Up to high doses, neurotensin (5.0 and 10.0 g, ICV) and NT1 (10.0 and 20.0 mg/kg, IP) did not produce catalepsy. A much lower dose of neurotensin (0.03 g, ICV) significantly reduced amphetamine-and phencyclidine-stimulated locomotor activity; NT1 also diminished amphetamine-and phencyclidine-stimulated locomotion with ED 50 values of 0.3 and 0.4 mg/kg, IP, respectively. Neurotensin (0.01-0.3 g, ICV) and NT1 (0.1-1.0 mg/kg, SC) also produced dose-dependent analgesia in the paw pressure test and decreased body temperature; these effects were insensitive to pretreatment with naloxone (10.0 mg/kg, IP). Together, the results support the hypothesis that neurotensin agonists have antipsychotic and analgesic activity. Moreover, the data suggest that such compounds may not produce extrapyramidal side effects.
European Journal of Pharmacology, 2003
The neuroprotective activity of ACEA 1021 (5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione;... more The neuroprotective activity of ACEA 1021 (5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione; licostinel), a selective antagonist at the strychnine-insensitive glycine site associated with the NMDA receptor complex, has been investigated in various models of focal cerebral ischemia. In isoflurane-anaesthesised Wistar rats with permanent ipsilateral carotid artery ligation and transient middle cerebral artery occlusion (duration of occlusion, 2 h) followed by reperfusion (24 h), intravenous administration of ACEA 1021 (bolus: 10 mg/kg, 15 min after the onset of middle cerebral artery occlusion; infusion: 7 mg/kg/h for 6 h beginning 30 min after occlusion of the artery) produced a 32% reduction in infarct volume. Similarly, in Sprague-Dawley rats with transient middle cerebral artery occlusion (2 h) followed by 24 h of reperfusion, identical treatment with ACEA 1021 decreased infarct size by 39%. Magnetic resonance imaging (MRI) confirmed these effects in the transient model, in that infarct volume observed using apparent diffusion coefficient (ADC) maps was significantly smaller after 24 h in the ACEA 1021-treated rats compared with Tris-treated controls. Furthermore, the increase in perfusion signal intensity after reperfusion was more pronounced in the ACEA 1021-treated rats than in controls. In Fisher 344 rats with permanent occlusion of the middle cerebral artery, ACEA 1021 induced a dose-related decrease in infarct volume, which was associated with an improvement in neurological outcome as measured by the rope suspension procedure. Administration of the same dose regimen, as above, in Fisher rats with permanent middle cerebral artery occlusion reduced infarct volume by 68%. This dose was as effective when administration was delayed for 2 h. In mice with permanent middle cerebral artery occlusion, ACEA 1021 (5 mg/kg, i.v., 5 min after occlusion; 30 mg/kg, s.c., 1 and 4 h post-middle cerebral artery occlusion) decreased infarct size by 42%. The consistent anti-ischemic effects of ACEA 1021 make it a valuable compound for exploratory stroke research.
International Journal of Developmental Neuroscience, 1988
Xells dissociated from cerebral hemispheres of 8-day-old chick embryos were seeded on poly-L-lysi... more Xells dissociated from cerebral hemispheres of 8-day-old chick embryos were seeded on poly-L-lysine coated Petri dishes in serum-containing medium. After 24 hr the culture medium was switched to a serum-free, chemically defined medium. These cultures contain mainly neuronal cells until day 14, characterized by the presence of acetylcholinesterase activity and neurotilament proteins. After 2 weeks glial cells progressively contaminated the neuronal culture. Cultures were maintained for a period of 4 weeks. From day 6 on numerous synapses with clear vesicles were observed. The activity of choline acetyltransferase remained low throughout the culture period, while GABA levels increased in parallel with synaptogenesis. Our observations indicate that chick cerebral hemisphere neuronal cultures grown in serum-free, chemically defined medium contain GABAergic neurons that undergo maturation.
Journal of Biochemistry, Jul 1, 1979
... Nikolaus SEILER,* Thomas SCHMXDT-GLENEWINKEL,** and Shakir SARHAN* Centre de Recherche Merre... more ... Nikolaus SEILER,* Thomas SCHMXDT-GLENEWINKEL,** and Shakir SARHAN* Centre de Recherche Merrell International, 16 rue d'Ankara, 67084 Strasbourg Cedex, France, and "Department of Biobehavioral ... 20, 699-708 5. Seiler, N. & Eichentopf, B. (1975) Biochem. ...
Cancer Research, Aug 15, 1990
The combination of inhibitors of ornithine decarboxylase and polyamine oxidase and of antibiotics... more The combination of inhibitors of ornithine decarboxylase and polyamine oxidase and of antibiotics suitable for the (partial) decontamination of the gastrointestinal tract with a polyamine-deficient diet reduced the growth rate of Lewis lung carcinoma by more than 80%. The formation of lung métastases was prevented by 70 to 100%, depending on the treatment. The reduction of tumor growth was accompanied by a decrease of tissue polyamine concentrations, a reduced rate of tumor cell prolifer ation, and protein synthesis. The comparison of the ornithine decarbox ylase inhibitors Eflornithine [D,L-2-(difluoromethyl)ornithine] and ( /:')-2-(fluoromethyl)dehydroornithine ethylester confirmed the greater in vivo potency of the latter compound. Our method of growth inhibition by systematic polyamine deprivation is not tumor specific, but presumably generally applicable to rapid growth.
Anticancer Research, 1991
It has previously been shown that systematic polyamine deprivation results in the almost complete... more It has previously been shown that systematic polyamine deprivation results in the almost complete inhibition of the growth of several solid tumors. The same polyamine deficient diet (containing antibiotics for the decontamination of the gastrointestinal tract, the ornithine decarboxylase inhibitor 2-(difluoromethyl)ornithine, and the polyamine oxidase inhibitor N1, N4-bis-(2,3-butadienyl)putrescine; "drug-containing polyamine deficient chow", DC-PDC) was applied for the first time to the treatment of rats with an intracranial tumor. Rats received intracortical grafts of C6 rat glioblastoma cells, and the length of their survival was determined. Treatment with DC-PDC, starting four days after tumor cell inoculation, significantly prolonged the median survival of the glioblastoma-bearing rats. The results underline the general growth inhibitory effect of systematic polyamine deprivation. Since the effect of polyamine restriction on tumor growth is reversible, combinations with cytotoxic drugs have to be found which exploit the changed functions of polyamine deficient tumor cells.
Neurochemistry International, 1983
Journal of chromatography. B, Biomedical applications, Jan 18, 1994
Orotic acid was separated from other urinary constituents by ion-pair formation with tetrabutylam... more Orotic acid was separated from other urinary constituents by ion-pair formation with tetrabutylammonium, and isocratic elution from a reversed-phase column. Absorbance at 280 nm was recorded for quantitation. Owing to the better column characteristics the separations are somewhat faster, and the sensitivity of the method is higher than those of analogous methods using anion-exchange columns. The method was used for the determination of orotic acid in human urine, in urine of rats with portacaval shunts and in small (30 microliters) urine samples from sparse fur mice. Shunted rats excreted ca. 100% more orotic acid per 24 h than sham-operated controls, in spite of their considerably lower body weight. Excessive orotic acid in urine indicates a conditional deficiency of ornithine. Sparse fur mice are congenitally hyperammonemic because of a defective hepatic ornithine carbamoyltransferase. Determination of orotic acid in the urine is a suitable method to identify those animals among l...
General pharmacology, 1984
Administration of muscimol to mice in subcutaneous doses between 0.34 and 1.25 mg/kg produced par... more Administration of muscimol to mice in subcutaneous doses between 0.34 and 1.25 mg/kg produced partial protection against 3-mercaptopropionic acid (MPA)-induced seizures. Glycine at a dose of 750 mg/kg (10 mmol/kg) protected 20% of the animals 45 min after its administration. Combined treatment with the two compounds gave a near to complete protection against MPA-induced seizures. These observations suggest that the concomitant enhancement of glycinergic and GABAergic activities amplify the anticonvulsant effect of these neuronal systems against seizures induced by impairment of GABA-mediated transmission.
General pharmacology, 1985
THPO, a GABA uptake inhibitor, when given in doses of up to 4 mmol/kg (i.p.) to mice, had only a ... more THPO, a GABA uptake inhibitor, when given in doses of up to 4 mmol/kg (i.p.) to mice, had only a marginal protective effect against seizures induced 1 hr later by 3-mercaptopropionic acid (MPA). THPO (4 mmol/kg), when given in combination with 10 mmol/kg of glycine, protected 60% of the mice from MPA-induced convulsions. The combination of THPO and glycine delayed the onset of metrazol-induced clonic convulsions and protected 30% of the animals from seizures, although neither glycine or THPO alone had a significant anticonvulsant effect against metrazol induced seizures. In agreement with earlier findings, the results presented in this work seem to indicate that the synergistic anticonvulsant effects of glycine and GABAergic agents are independent of their mode of action: the effects of GABA agonists (muscimol) GABA-T inhibitors (vinylGABA), or an inhibitor of glial GABA uptake (THPO) are similarly amplified by glycine.
General pharmacology, 1989
1. The anticonvulsant properties of L-proline, of proline derivatives (trans-4-hydroxy-L-proline,... more 1. The anticonvulsant properties of L-proline, of proline derivatives (trans-4-hydroxy-L-proline, cis-4-hydroxy-D-proline, 3,4-dehydro-D,L-proline) and of D- and L-pipecolic acid were studied alone and in combination with vigabatrin (R/S-4-aminohex-5-enoic acid). 3-Mercaptopropionic acid and pentylenetetrazol-induced convulsions in mice were used as animal models of epilepsy. 2. Proline and proline derivatives are weak anticonvulsants if given alone in doses up to 10 mmol/kg, however, they are capable of potentiating the anticonvulsant effects of vigabatrin, in a manner similar to that reported previously for glycine, and some glycine derivatives. Among the compounds tested, trans-4-hydroxy-L-proline was the most potent anticonvulsant in combination with the indirect GABA agonist vigabatrin. 3. A potential explanation for the synergistic anticonvulsant effect of the combination of the GABA agonist and proline is the presumed role of proline as inhibitory neurotransmitter, and/or its...
Cancer research, Jan 15, 1990
The combination of inhibitors of ornithine decarboxylase and polyamine oxidase and of antibiotics... more The combination of inhibitors of ornithine decarboxylase and polyamine oxidase and of antibiotics suitable for the (partial) decontamination of the gastrointestinal tract with a polyamine-deficient diet reduced the growth rate of Lewis lung carcinoma by more than 80%. The formation of lung metastases was prevented by 70 to 100%, depending on the treatment. The reduction of tumor growth was accompanied by a decrease of tissue polyamine concentrations, a reduced rate of tumor cell proliferation, and protein synthesis. The comparison of the ornithine decarboxylase inhibitors Eflornithine [D,L-2-(difluoromethyl)ornithine] and (E)-2-(fluoromethyl)dehydroornithine ethylester confirmed the greater in vivo potency of the latter compound. Our method of growth inhibition by systematic polyamine deprivation is not tumor specific, but presumably generally applicable to rapid growth.
Journal of chromatography, Jan 11, 1979
The thin-layer electrophoretic separation at pH 4.8 of brain extracts and a procedure for fluores... more The thin-layer electrophoretic separation at pH 4.8 of brain extracts and a procedure for fluorescent staining of the plates with fluorescamine are described for the rapid routine determination of 4-aminobutyric acid (GABA), glutamic acid and aspartic acid in brain extracts and in particulate fractions of brain tissue. Automated sample application, electrophoretic separation using two chambers, and quantitation by in situ fluorescence scanning allows the assay of 280 samples within three working days. The method is reproducible (S.D. less than 8% of the mean) within the range of 0.2--2 nmole per spot. The staining procedure can be applied to a variety of related analytical problems. The method has proved useful for the determination of the specific radioactivities of GABA, glutamic acid and aspartic acid in metabolic studies.
Biological Chemistry Hoppe-Seyler, 1989
Putrescine, spermidine and spermine were determined in the nuclear fraction of rat liver which wa... more Putrescine, spermidine and spermine were determined in the nuclear fraction of rat liver which was obtained by density gradient centrifugation in non-aqueous media, i.e. under conditions which avoid migration of water-soluble compounds. Calculations of the distribution of the polyamines between nuclear and extranuclear compartments were based on the assumption that the DNA is concentrated in the nuclei. No significant losses of the polyamines occurred during fractionation. From the polyamine determination in tissue and nuclear fraction it appeared that 16-17% of the liver spermidine and spermine, and about 8% of the putrescine content was localized in the nuclei. The spermidine/spermine-ratios in nuclei and whole tissue were not significantly different. Pretreatment of the animals with inhibitors of ornithine decarboxylase caused a decrease of putrescine exclusively in the extranuclear compartments, in agreement with a higher proportion of the inhibitors in the cytoplasm. Since the nuclear volume of rat liver corresponds to about 5% of total liver volume, the concentration of spermidine and spermine is higher in the nucleus than in extranuclear compartments. Published histochemical localizations of the polyamines suggested very low polyamine concentrations in the nuclei of non-dividing liver and HeLa cells, but dramatic polyamine accumulations in metaphase and anaphase nuclei. These results are in disagreement with previously reported autoradiographic data, subcellular localizations based on density gradient centrifugations, and with our present results. Since subcellular localization is a key issue in all attempts to clarify cellular functions of the polyamines the careful revision of the techniques involved in subcellular polyamine localizations seems imperative.
Peptides, 1997
SARHAN, S., J. M. HITCHCOCK, C. A. GRAUFFEL AND J. G. WETTSTEIN. Comparative antipsychotic profil... more SARHAN, S., J. M. HITCHCOCK, C. A. GRAUFFEL AND J. G. WETTSTEIN. Comparative antipsychotic profiles of neurotensin and a related systemically active peptide agonist. PEPTIDES 18(8) [1223][1224][1225][1226][1227] 1997.-Several lines of evidence have shown that neurotensin can modulate dopamine neurotransmission. It has been suggested that neurotensin has potential antipsychotic activity because it reduces dopaminergic activity preferentially in the nucleus accumbens. In the present study, the effects of neurotensin and NT1 (N ␣ Me-Arg-Lys-Pro-Trp-TIe-Leu or Eisai hexapeptide), a metabolically stable and systemically active neurotensin agonist, were examined in several models of antipsychotic activity and side effect liability in mice; analgesic and hypothermic effects of both compounds also were determined. Up to high doses, neurotensin (5.0 and 10.0 g, ICV) and NT1 (10.0 and 20.0 mg/kg, IP) did not produce catalepsy. A much lower dose of neurotensin (0.03 g, ICV) significantly reduced amphetamine-and phencyclidine-stimulated locomotor activity; NT1 also diminished amphetamine-and phencyclidine-stimulated locomotion with ED 50 values of 0.3 and 0.4 mg/kg, IP, respectively. Neurotensin (0.01-0.3 g, ICV) and NT1 (0.1-1.0 mg/kg, SC) also produced dose-dependent analgesia in the paw pressure test and decreased body temperature; these effects were insensitive to pretreatment with naloxone (10.0 mg/kg, IP). Together, the results support the hypothesis that neurotensin agonists have antipsychotic and analgesic activity. Moreover, the data suggest that such compounds may not produce extrapyramidal side effects. © 1997 Elsevier Science Inc.
Neuroscience Letters, Aug 28, 2003
The glycine site, N-methyl-D-aspartate antagonist 5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalin... more The glycine site, N-methyl-D-aspartate antagonist 5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione (ACEA1021) was previously tested only in models of transient stroke with pre-treatment paradigms. We therefore tested whether it would protect in two models of permanent stroke in two rat strains with delayed treatment. Intravenous ACEA1021 reduced cerebral infarction by 62% (15 min treatment delay) and 42% (2 h treatment delay), relative to vehicle-injected rats, when subjected to a modified Tamura and permanent intraluminal filament model of stroke, respectively. In comparison, intravenous nicotinamide (500 mg/kg), which was tested in separate animal cohorts, had no significant effect on infarction. These data show that ACEA1021 protects against permanent focal cerebral ischemia, even with a 2 h post-treatment delay. Characterization of the therapeutic window with longer outcome times including infarction and neurobehavioral endpoints is needed. q
Neuroscience, 1991
Six-day-old neuronal cultures derived from 14-day-old embryonic rat cerebral hemispheres were hig... more Six-day-old neuronal cultures derived from 14-day-old embryonic rat cerebral hemispheres were highly enriched in GABAergic neurons, as was demonstrated by immunocytochemistry using an anti-glutamate decarboxylase antiserum. They contained about 64% glutamate decarboxylase-positive neurons. About 8% of these neurons proliferated, as shown by a combination of glutamate decarboxylase immunocytochemistry and [3H]thymidine incorporation into cell nuclei. The proliferative activity of GABAergic precursor cells and changes in the cellular concentrations of the non-essential amino acids, including GABA under the effect of basic fibroblast growth factor were studied. When basic fibroblast growth factor was added to the cultures 4 h after seeding, the proliferation of the GABAergic neurons was stimulated about threefold. Under this culture condition, the concentration per cell of all amino acids increased, except those of GABA and fl-alanine. When basic fibroblast growth factor was added to cultures only on day four, the proliferation of the neuronal cells was no more enhanced. Under this condition of treatment, the concentrations of all non-essential amino acids, including those of GABA and fl-alanine were enhanced. Under both basic fibroblast growth factor treatments the concentration of GABA per GABAergic cell was increased. In contrast, the specific activity of glutamate decarboxylase was not stimulated under these conditions. We hypothesize that under the effect of basic fibroblast growth factor the capabilities of the cells to store GABA are improved.
Neurochemical Research, 1983
The anticonvulsive effects of GABA, taurine, and glycine were investigated on several chemically-... more The anticonvulsive effects of GABA, taurine, and glycine were investigated on several chemically-induced and genetic seizure models. Intravenous injections of either GABA, taurine, or glycine provided protection against 3-mercaptopropionic acid (MPA)-indticed convulsions in adult Swiss mice. GABA was partially effective against isonicotinic acid hydrazide and was without effect against bicucullineinduced convulsions. Prolonged administration ofglycine prevented MPA-induced convulsions but not electrically induced seizures or seizures induced by strychnine or metrazol. Intragastric glycine protected young audiogenic seizure-susceptible DBA/2 mice against all three phases of sound-induced convulsions (wild running, clonic and tonic seizure), but GABA and taurine provided little or no protection. With increase of glycine, the cerebral levels of glutamine and serine also increased, but that of gtutamic acid decreased. The endogenous glutamic and glycine levels were slightly higher in the brains of the audiogenic seizure-susceptible DBA/2 mice than in that of the resistant BALB/Cy strain.
Neurochemical Research, 1980