Synthesis of anticonvulsive AMPA antagonists: 4-oxo-10-substituted-imidaz.

The overstimulation of excitatory amino acid receptors such as the glutamate AMPA receptor has been implicated in the physiopathogenesis of epilepsy as well as in acute and chronic neurodegenerative disorders. An original series of readily water soluble 4-oxo-10-substituted-imidazo[1,2-a]indeno[1,2-e]pyrazin-2-carboxylic acid derivatives was synthesized. The most potent derivative 6a exhibited nanomolar binding affinity (IC50 = 35nM) and antagonist activity (IC50 = 6nM) at ionotropic AMPA receptor. This compound also demonstrated potent anticonvulsant properties in MES in mice and rats with long durations of action with ED50 values in the 1-3 mg/kg dose range following ip and iv administration.

Bioisosteres of 9-carboxymethyl-4-oxo-imidazo[1,2-a]indeno-[1,2-e]pyrazin-2-carboxylic acid derivatives. Progress towards selective, potent in vivo AMPA antagonists with longer durations of action.

A novel series of 2- and 9-disubstituted heterocyclic-fused 4-oxo-indeno[1,2-e]pyrazin derivatives was synthesized. One of them, the 9-(1H-tetrazol-5-ylmethyl)-4-oxo-5,10-dihydroimidazo[1,2-a]indeno[1,2-e]pyrazin-2-yl phosphonic acid 4i exhibited a strong and a selective binding affinity for the AMPA receptor (IC50 = 13 nM) and demonstrated potent antagonist activity (IC50 = 6nM) at the ionotropic AMPA receptor. This compound also displayed good anticonvulsant properties against electrically-induced convulsions after ip and iv administration with ED50 values between 0.8 and 1 mg/kg. Furthermore, a strong increase in potency was observed when given iv 3 h before test (ED50 = 3.5 instead of 25.6 mg/kg for the corresponding 9-carboxymethyl-2-carboxylic acid analogue). These data confirmed that there is an advantage in replacing the classical carboxy substituents by their bioisosteres such as tetrazole or phosphonic acid groups.

Isolation-rearing of rats produces deficits as adults in the serotonergic innervation of hippocampus.

Isolation-rearing of rats causes a variety of behavioral changes, including anxiety, learning deficits and sensory changes related to schizophrenia. Similar changes are seen following loss of serotonin during development. Thus, the effects of isolation-rearing on behavior may be due to changes in serotonin. Sprague-Dawley rats were raised in groups of four (social animals) or in isolation, from postnatal day 22 until postnatal day 64. The hippocampi were examined immunochemically for changes in serotonin. Our findings show that serotonin terminals are lost throughout the CA regions of hippocampus, where there is also an associated loss of dendrites, but not in the molecular layer of the dentate gyrus. Thus, some of the brain and behavioral changes seen in isolation-reared animals could be due to loss of serotonin.

8-Methylureido-10-amino-10-methyl-imidazo[1,2-a]indeno[1,2-e] pyrazine-4-ones: highly in vivo potent and selective AMPA receptor antagonists.

Water soluble 8-methylureido-10-amino-10-methyl-imidazo[1,2-a]indeno[1,2-e]pyraz ine-4-one 4 represents a novel class of highly potent and selective AMPA receptors antagonists with in vivo activity. The dextrorotatory isomer (+)-4 was found to display the highest affinity with an IC50 of 10 nM. It also exhibited very good anticonvulsant effects after i.p., s.c. and i.v. administration in mice subjected to electrical convulsions (MES) and i.p. in audiogenic seizure-e in DBA/2 mice (ED50's < or = 10 mg/kg).

Changes in hippocampal morphology following chronic treatment with the synthetic cannabinoid WIN 55,212-2.

Learning and memory are often correlated with cellular changes within the hippocampus, and drugs or environmental factors which affect learning and memory will thus often induce observable morphological changes in this structure. Like tetrahydrocannabinol (THC) itself, many synthetic cannabinoids such as the CB-1 receptor agonist WIN 55,212-2 will induce learning and memory changes. In the current study, we investigate whether or not these changes could be related to structural changes within the hippocampus. Adult male Sprague-Dawley rats were injected twice daily (12:00 and 0:00 h) subcutaneously with WIN 55,212-2 (2.0 mg/kg) in DMSO or DMSO for 21 days. On day 22, animals were perfused and stained immunochemically for the dendritic marker MAP-2, or with cresyl violet. Morphometric analysis showed dendritic rearrangement with increased staining of MAP-2 in CA3 and the lower blade of the dentate gyrus. However, a loss of staining was observed in CA1. Counting of cresyl violet stained sections showed an apparent increase in granule cell number in the lower blade of the dentate gyrus. This work shows the potential for cannabinoids to influence hippocampal morphology. The pattern of changes may be similar to that seen after ischemic or toxic damage, but may be opposite to changes seen in stress.

Indeno[1,2-b]pyrazin-2,3-diones: a new class of antagonists at the glycine site of the NMDA receptor with potent in vivo activity.

Indeno¿1,2-bpyrazin-2,3-diones have been identified as a novel series of potent ligands on the glycine site of the NMDA receptor. To improve their in vivo activities, an acetic acid-type side chain was introduced to the 5-position, giving water-soluble compounds when formulated as the sodium salt (>10 mg/mL). Introduction of a chlorine atom in the 8-position led to a dramatic improvement of anticonvulsant activity and this was surprising since this change did not improve binding affinity. A plausible explanation is a reduced recognition by a Na(+),K(+)-ATPase active transport system responsible for the excretion of these compounds from the brain and kidney. This promising new chemical series led to the optically active isomer (-)-10i (RPR 118723), a glycine/NMDA antagonist with nanomolar binding affinity and in vivo activity in animal model of convulsions and electrophysiology at doses in the range of 2-3 mg/kg following iv administration.

4,10-Dihydro-4-oxo-4H-imidazo[1,2-a]indeno[1,2-e]pyrazin-2-carboxylic acid derivatives: highly potent and selective AMPA receptors antagonists with in vivo activity.

A novel series of 2-substituted-4,5-dihydro-4-oxo-4H-imidazo[1,2-a]indeno[1,2-e]pyrazine derivatives was synthesised. One of them, 4e-a highly water soluble compound exhibited a nanomolar affinity and demonstrated competitive antagonist properties at the ionotropic AMPA receptors. This compound also displayed potent anticonvulsant properties against electrically or sound-induced convulsions in mice after systemic administration, thus suggesting adequate brain penetration.

8-Methylureido-4,5-dihydro-4-oxo-10H-imidazo[1,2-a]indeno[1,2-e]pyrazines: highly potent in vivo AMPA antagonists.

A novel series of readily water soluble 8-methylureido-4,5-dihydro-4-oxo-10H-imidazo[1,2-a]indeno[1,2-e]++ +pyrazines were synthesized. The -10-yl acetic acid ((+)-3) and -10-carboxylidene (4) derivatives exhibit potent affinities (IC50=4 and 19 nM, respectively) and antagonist properties (IC50 = 2 and 3 nM, respectively) at the ionotropic AMPA receptor. These compounds also display anticonvulsant properties against both electrically and sound-induced convulsions in mice after ip, sc and iv administration with ED50 values between 0.9 and 11 mg/kg, thus suggesting adequate brain penetration.

Synthesis and potent anticonvulsant activities of 4-oxo-imidazo[1,2-a]inden.

The over-stimulation of excitatory amino acid receptors such as the glutamate AMPA receptor has been suggested to be associated with neurodegenerative disorders. Here we describe an original series of readily water soluble 4-oxo-imidazo[1,2-a] indeno[1,2-e]pyrazin-8- and -9-carboxylic (acetic) acid derivatives. One of these compounds, 4f, exhibited nanomolar binding affinity, potent competitive antagonism at the ionotropic AMPA receptor and a long duration of anticonvulsant activity after administration by parenteral route in vivo.

Spiro-imidazo[1,2-a]indeno[1,2-e]pyrazine-4-one derivatives are mixed AMPA and NMDA glycine-site antagonists active in vivo.

Original spiro-imidazo[1,2-a]indeno[1,2-e]pyrazine-4-one derivatives were synthesised and led to the identification of 3e which showed good affinities for both the AMPA and the NMDA glycine-site receptors, and displayed good anticonvulsant effects after i.p. and i.v. administrations in the electroshock-induced convulsion assay in mice. The corresponding dextrorotatory isomer (+)-3e was notably more potent than the levorotatory isomer (-)-3e in in vitro and in vivo assays.

Serotonin depletion during synaptogenesis leads to decreased synaptic density and learning deficits in the adult rat: a possible model of neurodevelopmental disorders with cognitive deficits.

Studies in the past have revealed serotonin to play a role in regulating the development and maturation of the mammalian brain, largely through the release of the astroglial protein S-100beta. S-100beta plays a role in neurite extension, microtubule and dendritic stabilization and regulation of the growth associated protein GAP-43, all of which are key elements in the production of synapses. Depletion of serotonin, and thus of S-100beta, during synaptogenesis should lead to a loss of synapses and the behaviors dependent on those synapses. The current study was undertaken to test this hypothesis. In order to assess the influence of serotonin we have looked at the synaptic density in the adult after depletion, by using immunodensitometry of synaptic markers (synaptophysin and MAP-2) and by studying behaviors thought to be highly dependent on synaptic plasticity and density. Male Sprague-Dawley rats were depleted of serotonin on postnatal days (PND) 10-20 by treating with the tryptophan hydroxylase inhibitor parachlorophenylalanine (PCPA; 100 mg/kg, s.c.). On PND's 30 and 62, animals were perfused for immunodensitometry. Littermates were used for behavioral testing. At PND 55-62, the animals were tested in an interchangeable maze with olfactory cues and in an eight-arm radial maze. Our results show a loss of both synaptic markers in the hippocampus on PND 30. At PND 62, the only remaining loss was of the dendritic marker MAP-2. The animals had deficits in both behaviors tested, suggestive of spacial learning deficits and of the failure to extinguish learned behaviors or to re-learn in a new set. Our findings show the long-term consequences of interfering with the role of serotonin in brain development on the morphology and function of the adult brain. These findings may have implications for human diseases, including schizophrenia, thought to be related to neurodevelopmental insults such as malnutrition, hypoxia, viruses or in utero drug exposure. Moreover, they provide further insights into the functioning of serotonin and S-100beta in development and aging.

Role of the 5-HT1A receptor in development of the neonatal rat brain: preliminary behavioral studies.

Serotonin exerts an influence on the prenatal development of rat brain. However, later developmental times may be more applicable to the understanding of the role of serotonin in human developmental disorders. Therefore, the current study was undertaken to gain preliminary information on the postnatal effects of serotonin on rat brain development. As the 5-HT1A receptor has been shown to be involved in much of the developmental functions of serotonin, an agonist for this receptor, 8-hydroxy-DPAT (8-OH-DPAT), was used. Neonatal rat pups at three ages (postnatal days, PNDs) 3-10, 10-17 or 17-24) were injected daily with 1 mg/kg 8-OH-DPAT and evaluated for behavioral consequences. The youngest group showed accelerated incisor eruption and eye-opening, a possible consequence of 5-HT1A receptor interactions with epidermal growth factor (EGF). Behaviorally, the animals were more anxious. Animals treated from PND 10-17, showed no change in craniofacial development but showed greater behavioral maturity in measures of spontaneous alternation and activity in the open field. The oldest animals (PND 17-24) showed no behavioral alterations, suggesting that this time length is beyond the critical period for serotonin's influence in brain development.

Transgenic mice overexpressing the neurotrophic factor S-100 beta show neuronal cytoskeletal and behavioral signs of altered aging processes: implications for Alzheimer's disease and Down's syndrome.

S-100 beta is a neurotrophic factor released by astroglial cells and localized to chromosome 21, within the region which is considered obligate for Down's syndrome (DS). S-100 beta is increased in the postmortem brains of both DS and Alzheimer's disease. Transgenic mice, produced by insertion of the human gene for S-100 beta, were examined for dendritic development at two ages, using an antibody against microtubule associated protein-2 (MAP-2). At the earliest stages, the density of dendrites within the hippocampus of transgenic animals exceeded that of controls. Also, MAP-2 immunostaining was evident in the region of the cell body. By 1 year of age, the transgenic animals had significant loss of dendrites compared to controls and the number of cells showing cell body staining was further increased. These pathological changes could be indicative of the presence of neurofibrillary tangles and cytoskeletal collapse. Behaviorally, younger transgenic animals could not perform in a learning task as well as controls. Together, these findings suggest that increased S-100 beta in brain may lead to accelerated development, followed by increased aging. The pathological changes may prove useful as an animal model of Down's syndrome and Alzheimer's disease.

Serotonin depletion in the adult rat causes loss of the dendritic marker MAP-2. A new animal model of schizophrenia?

Many trophic factors are now thought to also function in maintenance of the adult brain. We hypothesized that since serotonin plays a role in synaptogenesis, it may also function in maintenance of synapses in the adult. Adult rats were depleted of serotonin with the tryptophan hydroxylase inhibitor p-chlorophenylalanine (PCPA) for 10 days. Fourteen days after the final treatment, immunodensitometry showed a significant decrease in the synaptic marker, MAP-2. Our results are discussed in respect to the recent finding of decreased MAP-2 staining in postmortem schizophrenic brains.

A 5-HT3 receptor antagonist fails to prevent cisplatin-induced toxicity in immature rat spinal cord.

The use of high doses of cisplatin in treating cancers has been limited by two major adverse effects--emesis and peripheral neuropathies. The emesis has become largely controlled by the introduction of a new class of drugs--the 5-HT3 receptor antagonists. The current study was undertaken to determine if these drugs would also prevent cisplatin-induced neuropathy. We have used a developing rat as an animal model and determined the effects of cisplatin on morphology (loss of spinal cord calcitonin gene-related peptide (CGRP)-containing neurons) and behavior (gait abnormalities and pain perception). Rat pups from the age of 5 days were treated twice weekly for 4 weeks with cisplatin (1 mg/kg), the 5-HT3 antagonist MDL 72222 (3 mg/kg) or both. The animals were tested for pain perception (using tail-flick latencies) at 17 and 21 days of age and for a gait abnormality at 24 days of age. At 34 days of age, the animals were perfused and the lumbar region of the spinal cords stained immunocytochemically for CGRP. Our results show that cisplatin treatment resulted in a dramatic loss of CGRP neurons in the dorsal horn of the spinal cord and a corresponding increase in the animals' threshold for pain. In addition, the animals showed a pronounced gait abnormality, characterized by 'toeing-in'. Treatment with MDL 72222 not only failed to protect against the loss of CGRP neurons but also worsened the gait abnormalities seen after cisplatin treatment alone. These studies confirm and extend the list of morphological and functional adverse effects of cisplatin treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Vertical transmission of hepatitis A resulting in an outbreak in a neonatal intensive care unit.

Vertical transmission of hepatitis A virus (HAV) has not been reported. From 25 October to 15 November 1989, 10 cases of symptomatic HAV infection occurred among neonatal intensive care unit (NICU) staff. Testing of other NICU staff and patients identified 4 infected infants. Hepatitis A among staff was associated with caring for 1 of these infants, infant A (relative risk [RR], undefined; P = .05). Risk of illness was greater for staff who did not routinely wash their hands after treating infant A for apnea and bradycardia (RR = 4.9; P = .02). Staff, infants, visitors, and transfused blood products could not be implicated as a source of infant A's infection. Infant A's mother, however, was diagnosed with hepatitis A 10 days after premature labor and delivery. Evidence suggests that infant A was infected by his mother before or during birth. HAV then spread within the NICU because of breaks in infection control precautions. To prevent future outbreaks, NICU staff should adhere rigorously to body substance isolation measures.

[Cements for fixed prostheses. Traction resistance force]. / Cementi per fissazione protesica. Forza di resistenza alla trazione.

The cementation is a basic step in the fixed prosthesis rehabilitation. Therefore, it is very important to know the main chemical, physical and biological properties of luting cements. The tensile strength of some dental cements for fixed cast restorations has been studied. Results obtained showed that glass ionomer and zinc oxide-eugenol with Eba are better than the other dental cements. The difference between the data obtained showed to be statistically significant.