Ergotism related to concurrent administration of ergotamine tartrate and indinavir.
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Adult↗
Biomedical subjects
F Sala
Publications and source records attributed to F Sala.
A residue in the middle of the M2-M3 loop of the beta4 subunit specifically affects gating of neuronal nicotinic receptors.
An aspartate residue in the M2-M3 loop of neuronal nicotinic receptor alpha7 subunits is a major determinant of the channel functional response. This residue is conserved in most beta4 subunits, e.g. human and rat, but not in others, e.g. bovine. We have used these differences to examine the mechanism by which this residue alters the functional properties of alpha3beta4 receptors. Having ruled out an effect on the macroscopic binding ability of the agonist, the level of receptor expression, or the single channel conductance, the results suggest that receptors lacking that residue have a deficient coupling between binding and gating.
Animals↗
[Treatment of iliac artery stenosis and obliteration by transluminal angioplasty].
PURPOSE: Percutaneous transluminal angioplasty (PTA) has an established and valuable role in the treatment of iliac stenoses and occlusions. The use of stents may improve the results of PTA. The aim of this study is to report our surgical experience of iliac angioplasty over the past 5 years. PATIENTS AND METHODS: From January 1993 to October 1997, 201 iliac PTA were performed in 175 patients, at the level of the common iliac artery (n = 111) and external iliac artery (n = 90). In 26 cases, two iliac lesions were treated simultaneously. There were 188 stenoses and 13 chronic occlusions. During PTA, 55 stents were used, because of unsatisfactory results (dissection, residual stenosis) or in case of total occlusion, in the common iliac artery in 35 cases and in the external iliac artery in 20 cases. In 15 cases (8.6%), a femoro-popliteal bypass was associated to the iliac PTA, because of multilevel occlusive disease. RESULTS: There were no early deaths. There were seven initial failures. The initial success rate was 96%. The clinical follow-up has been achieved in 163 patients, (range: 3 to 48 months, mean: 28 months). The primary patency rates were 84%, 79% and 63% respectively at 1, 2, and 4 years. The secondary patency rates were 87%, 85% and 73% respectively at 1, 2, and 4 years.
Adult↗
Assessment and surgical management of posterior fossa epidermoid tumors: report of 28 cases.
OBJECTIVE: The management of a series of 28 patients operated on for posterior fossa epidermoids is reviewed, emphasizing the need for long-term follow-up. We discuss the rationale for a comprehensive classification system that may allow the comparison of results from homogeneous series. METHODS: We grouped the tumors to differentiate the surgical management according to various tumor sites and the degree of extension. Twenty patients harbored tumors located in the cerebellopontine angle, five patients harbored tumors in the fourth ventricle, and three patients harbored tumors in the posterior fossa basal. In 17 patients, extensions of tumors outside the posterior fossa included the following regions: the suprasellar/ chiasmatic (n = 5), the parasellar/temporobasal (n = 5), and the mesencephalic/pineal (n = 7). Tumor extension was also defined by the number of regions involved. Pre- and postoperative magnetic resonance imaging and computed tomographic findings collected in 17 and 28 patients, respectively, were carefully evaluated. RESULTS: Clinical features and surgical approaches varied according to location and growth pattern. Fifty-seven percent of the tumors were completely removed. A higher total removal rate was achieved in patients with tumors confined to the primary location. One patient (3%) died in the perioperative period. Approximately half of the patients presented with transient mild focal deficit impairments resulting from the manipulation of the nervous structure over a wide area. There was a higher rate of surgical complications with fourth ventricle and mesencephalic extended cerebellopontine angle tumors. The mean follow-up period was 8.6 years. Thirty percent of the patients with subtotal removal experienced symptomatic recurrences after 8.1 years, whereas all patients with total removal were still asymptomatic. The recurrence-free survival rate was 95% at 13 years for patients with total removal compared with 65% for patients with subtotal removal. Problems of identification of tumor regrowth are discussed. CONCLUSION: By assessing posterior fossa epidermoids, we determined that location and extension play a major role in the prognosis. Our data suggest that more aggressive surgery is called for at first operation, and that a second operation should be planned when regrowth becomes symptomatic and/or tends to extend outside its original site.
Adolescent↗
Surgical treatment of quadrigeminal plate lipoma presenting with seizures and behavioural disorders.
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Brain Neoplasms↗
Prognostic factors in childhood intracranial ependymomas: the role of age and tumor location.
Despite several clinical reports on intracranial ependymomas in children, the factors which affect prognosis, and the possibility that certain combinations of factors might limit survival, are still a matter of debate. Between 1976 and 1996 we operated on 35 children with intracranial ependymomas. Postoperative irradiation was given to 27 patients, with associated chemotherapy in 6 cases. Mean follow-up was 62 months. In 12 patients a 5-year follow-up was possible. In October 1996, 18 patients (51.4%) were still alive, the longest disease-free follow-up being 20 years, and the shortest 8 months. We analyzed the prognostic relevance of eight factors. For each factor, different subgroups were distinguished and compared as follows: age at diagnosis (<4 vs. >/=4 years), sex, tumor location (supratentorial vs. infratentorial), tumor size (<4 vs. 4-7 vs. >7 cm), surgical removal (total vs. subtotal), histology (low-grade vs. anaplastic), morphology (solid vs. cystic), adjuvant therapies (treatment vs. no treatment). Two-way contingency tables were made to identify associations between variables. The only significant association was between age and tumor location (p = 0.022): in children under 4, tumors were almost invariably located in the posterior fossa (9 out of 10 cases) with a clear preference for the lateral recess (8 cases). Other correlations were not significant. Kaplan-Meier survival curves were compared to assess the prognostic relevance of each factor. Survival was significantly lower for children under 4, for those with posterior fossa tumors, and for patients with residual tumor (p < 0.05). A multivariate analysis compared variables which significantly affected survival, revealing that age is the most important factor affecting prognosis (p < 0.05), while tumor location and surgical removal do not add any significance to the effect of age on survival. We conclude that age has the strongest prognostic relevance in childhood intracranial ependymomas, while the effect of tumor location on survival may be related to the high incidence of lateral recess ependymomas in younger children.
Age Distribution↗
Intracranial myxoid chondrosarcoma with early intradural growth.
Chondrosarcomas are extremely rare intracranial cartilaginous tumors of which the myxoid variant is the least reported in the literature. They develop extradurally and generally infiltrate the dura only in advanced stages or at recurrence. We describe the case of a 55-year-old woman with a posterior cranial fossa myxoid chondrosarcoma which had a primarily intradural extension.
Chondrosarcoma↗
[Carotid angioplasty: review of the literature].
PURPOSE: In order to assess the current knowledge of carotid angioplasty and stenting, we reviewed the pertinent literature distinguishing two types of reports on angioplasty for atherosclerotic stenosis of the internal carotid artery: case reports and series with less than 10 cases, and series reporting more than 10 cases. METHODS: Each series was examined individually followed by a general analysis. RESULTS: The 11 largest series in the literature included a total of 912 patients. The rate of transient ischemic attacks ranged from 6 to 14.8%. Stroke rate varied from 1.5 to 9.1%. Restenosis was reported in 4 to 16% of cases. CONCLUSION: Based on the data available in the literature, we cannot recommend carotid angioplasty. Carotid endarterectomy is recognised as safe and is generally considered to be the gold standard. In order to assess carotid angioplasty and stenting accurately, prospective randomized studies comparing surgery and angioplasty are necessary.
Angioplasty↗
Role of the putative transmembrane segment M3 in gating of neuronal nicotinic receptors.
The involvement of some structural domains in the gating of the neuronal nicotinic acetylcholine receptor (AChR) was studied by expressing functional alpha7/alpha3 chimeric subunits in Xenopus oocytes. Substitution of the M3 transmembrane segment in the alpha7 subunit modifies the kinetic properties of the chimeric AChRs as follows: (a) a 6-fold reduction in the maximal current evoked by nicotinic agonists, (b) a 10-fold decrease in the macroscopic desensitization rate, (c) an increase of almost 1 order of magnitude in the apparent affinity for acetylcholine and nicotine, and (d) a decrease in the affinity for alpha-bungarotoxin. Computer simulations showed that the first three effects could be accounted for by a simple kinetic model in which chimeric AChRs presented a smaller ratio of the gating rates, beta/alpha, and a slightly slower desensitization rate. It is concluded that the M3 domain influences the gating of neuronal AChRs.
Amino Acid Sequence↗
Neuronal nicotinic acetylcholine receptors on bovine chromaffin cells: cloning, expression, and genomic organization of receptor subunits.
Neuronal nicotinic acetylcholine receptors from bovine adrenomedullary chromaffin cells play a primary role in triggering catecholamine secretion. In the present study, their constituent subunits were characterized. In addition to the alpha 3 subunit, which we have previously cloned, the presence of alpha 5 and beta 4 but not of beta 2 subunits was detected by reverse transcription-PCR analysis of mRNA from adrenal medulla. In situ hybridization indicated that alpha 3, alpha 5, and beta 4 subunits are coexpressed in all chromaffin cells. The primary structure of alpha 5 and beta 4 subunits was determined and functional receptors were obtained upon coinjection of subunit cRNAs into Xenopus oocytes. In contrast to other beta 4-containing nicotinic receptors, the ones formed by the bovine beta 4 subunit are insensitive to the agonist cytisine. Finally, we characterized the intergenic region of alpha 3 and alpha 5 subunits, which together with the beta 4 subunit, form a gene cluster in rats and chickens. RNase assays and the existence of overlapping cDNAs indicate that, in the bovine genome, the alpha 3 and alpha 5 genes overlap at their 3' ends. This fact is probably due to inefficient transcription termination, as a result of weak polyadenylation signals.
Animals↗
Acetylcholine receptor subunit homomer formation requires compatibility between amino acid residues of the M1 and M2 transmembrane segments.
The neuronal nicotinic acetylcholine receptor (nAChR) subunits alpha3 and alpha7 have different assembly behavior when expressed in heterologous expression systems: alpha3 subunits require other subunits to assemble functional nAChRs, whereas alpha7 subunits can produce homomeric nAChRs. A previous analysis of alpha7/alpha3 chimeric constructs identified a domain comprising the first putative membrane-spanning segment, M1, as essential to homomeric assembly. The present study dissected further this domain, identifying three amino acid residues, which are located at the most intracellular third of the M1 transmembrane segment, as important in the assembly of homomers. Moreover, formation of homooligomeric complexes seems to require a compatible accommodation between this region and certain residues of the second transmembrane segment, M2. Thus, compatibility between defined domains of the M1 and M2 transmembrane segments appears as a determinant factor governing homomer association of nAChR subunits.
Amino Acid Sequence↗
A single residue in the M2-M3 loop is a major determinant of coupling between binding and gating in neuronal nicotinic receptors.
Binding of agonists to nicotinic acetylcholine receptors generates a sequence of changes that activate a cation-selective conductance. By measuring electrophysiological responses in chimeric alpha7/alpha3 receptors expressed in Xenopus oocytes, we have showed the involvement of the M2-M3 loop in coupling agonist binding to the channel gate. An aspartate residue therein, Asp-266 in the alpha7 subunit, was identified by site-directed mutagenesis as crucial, since mutants at this position exhibited very poor functional responses to three different nicotinic agonists. We have extended this investigation to another neuronal nicotinic receptor (alpha3/beta4), and found that a homologous residue in the beta4 subunit, Asp-268, played a similar role in coupling. These findings are consistent with a hypothesis that the aspartate residue in the M2-M3 loop, which is conserved in all homomer-forming alpha-type subunits and all neuronal beta-type subunits that combine to form functional receptors, is a major determinant of information transmission from binding site to channel gate in all neuronal nicotinic receptors.
Amino Acid Sequence↗
Evidence for genomic changes in transgenic rice (Oryza sativa L.) recovered from protoplasts.
The occurrence of genomic modifications in transgenic rice plants recovered from protoplasts and their transmission to the self-pollination progeny has been verified with the random amplified polymorphic DNA (RAPD) approach. The plant was the Indica-type rice (Oryza sativa L.) cultivar Chinsurah Boro II. The analysed material was: (1) microspore-derived embryogenic rice cells grown in suspension culture, (2) transgenic plants recovered from protoplasts produced from the cultured cells and (3) the self-pollination progeny (two successive generations) of the transgenic plants. DNA purified from samples of these materials was PCR-amplified with different random oligonucleotide primers and the amplification products were analysed by agarose gel electrophoresis. Band polymorphism was scored and used in band-sharing analyses to produce a similarity matrix. Relationships among the analysed genomes were expressed in a dendrogram. The extensive DNA changes evidenced in cultured cells demonstrate the occurrence of somaclonal variation in the material used to produce protoplasts for gene transfer. Quantitatively reduced DNA changes were also found in the resulting transgenic plants and in their self-pollination progenies. While confirming the stability of the foreign gene in transgenic plants, this work gives molecular evidence for the occurrence of stable genomic changes in transgenic plants and points to in vitro cell culture as the causative agent. RAPDs are shown to be a convenient tool to detect and estimate the phenomenon at the molecular level. The methodology is also proposed as a fast tool to select those transgenic individuals that retain the most balanced genomic structure and to control the result of back-crosses planned to restore the original genome.
DNA, Plant↗
Inhibition of nicotinic receptor-mediated responses in bovine chromaffin cells by diltiazem.
1. The effects of diltiazem on various functional parameters were studied in bovine cultured adrenal chromaffin cells stimulated with the nicotinic receptor agonist dimethylphenylpiperazinium (DMPP) or with depolarizing Krebs-HEPES solutions containing high K+ concentrations. 2. The release of [3H]-noradrenaline induced by DMPP (100 microM for 5 min) was gradually and fully inhibited by increasing concentrations of diltiazem (IC50 = 1.3 microM). In contrast, the highest concentration of diltiazem used (10 microM) inhibited the response to high K+ (59 mM for 5 min) by only 25%. 3. 45Ca2+ uptake into cells stimulated with DMPP (100 microM for 1 min) was also blocked by diltiazem in a concentration-dependent manner (IC50 = 0.4 microM). Again, diltiazem blocked the K(+)-evoked 45Ca2+ uptake (70 mM K+ for 1 min) only by 20%. In contrast, the N-P-Q-type Ca2+ channel blocker omega-conotoxin MVIIC depressed the K+ signal by 70%. In the presence of this toxin, diltiazem exhibited an additional small inhibitory effect, indicating that the compound was acting on L-type Ca2+ channels. 4. Whole-cell Ba2+ currents through Ca2+ channels in voltage-clamped chromaffin cells were inhibited by 3-10 microM diltiazem by 20-25%. The inhibition was readily reversed upon washout of the drug. 5. The whole-cell currents elicited by 100 microM DMPP (IDMPP) were inhibited in a concentration-dependent and reversible manner by diltiazem. Maximal effects were found at 10 microM, which reduced the peak IDMPP by 70%. The area of each curve represented by total current (QDMPP) was reduced more than the peak current. At 10 microM, the inhibition amounted to 80%; the IC50 for QDMPP inhibition was 0.73 microM, a figure close to the IC50 for 45Ca2+ uptake (0.4 microM) and [3H]-noradrenaline release (1.3 microM). The blocking effects of diltiazem developed very quickly and did not exhibit use-dependence; thus the drug blocked the channel in its closed state. The blocking effects of 1 microM diltiazem on IDMPP were similar at different holding potentials (inhibition by around 30% at -100, -80 or -50 mV). Diltiazem did not affect the current flow through voltage-dependent Na+ channels. 6. These data are compatible with the idea that diltiazem has little effect on Ca2+ entry through voltage-dependent Ca2+ channels in bovine chromaffin cells. Neither, does diltiazem affect INa. Rather, diltiazem acts directly on the neuronal nicotinic receptor ion channel and blocks ion fluxes, cell depolarization and the subsequent Ca2+ entry and catecholamine release. This novel effect of diltiazem might have clinical relevance since it might reduce the sympathoadrenal drive to the heart and blood vessels, thus contributing to the well established antihypertensive and cardioprotective effects of the drug.
Animals↗
Comparative toxicology of two enantiomers of the peripherally acting non-narcotic antitussive drug moguisteine.
Moguisteine (R,S(+/-)-2-(2-methoxyphenoxy)-methyl-3-ethoxycarbonylacetyl-1,3-t hiazolidine, CAS 119637-67-1), a new peripheral non-narcotic antitussive drug, is a racemate composed of an equimolar mixture of R(+) and S(-) enantiomers (BBR 2221 and BBR 2222, respectively). Since in some cases the use of only one enantiomer instead of a racemate may increase the efficacy and/or the tolerability of a compound, moguisteine enantiomers were submitted to toxicological evaluation. Given in a single oral (gavage) or intraperitoneal administration to mice and rats, both moguisteine enantiomers show very low general toxicity. Administered by gavage to rats and dogs for four consecutive weeks, BBR 221 and BBR 2222 are tolerated at up to the dose of 240 mg/kg/day in both sexes with no appreciable toxic changes. Finally, the mutagenicity tests show that both enantiomers are devoid of any mutagenic potential both in vitro and in vivo. Considering the overall results of the toxicological studies and comparing them with the data obtained from the previously performed studies with the racemate moguisteine, it can be affirmed that no differences can be identified between the two enantiomers and the racemate moguisteine. These findings justify the development of moguisteine as a racemate since neither enantiomer should offer any advantage over the racemate.
Administration, Oral↗
alpha-Bungarotoxin-sensitive nicotinic receptors on bovine chromaffin cells: molecular cloning, functional expression and alternative splicing of the alpha 7 subunit.
Chromaffin cells from the bovine adrenal medulla express alpha-bungarotoxin-sensitive acetylcholine receptors whose subunit composition is unknown. Northern blot analysis showed that the alpha 7 subunit, a main component of these alpha-bungarotoxin-sensitive acetylcholine receptors in avian and rat brain, is expressed in chromaffin cells. The cDNA of this bovine alpha 7 subunit was cloned by polymerase chain reaction amplification of adrenal medulla RNA for detailed characterization of structure and function. The protein-coding region revealed 92% amino acid sequence identity to rat alpha 7 and 89% to chicken alpha 7 subunits. The alpha-bungarotoxin affinity of alpha 7 homomers expressed in Xenopus oocytes was similar to that observed previously with native chromaffin alpha-bungarotoxin-sensitive acetylcholine receptors. Cross-linking and sucrose gradient experiments suggested that, like the muscular and neuronal acetylcholine receptors; the alpha 7 receptor has a pentameric structure. Upon activation with nicotinic agonists the alpha 7 receptor exhibited rapidly desensitizing cation currents that were blocked by nicotinic antagonists and showed inward rectification. The amplification of adrenal medulla RNA by reverse transcription-polymerase chain reaction methods revealed an alternatively spliced isoform of the bovine alpha 7 subunit, where the exon that codes for the M2 transmembrane segment was skipped during mRNA processing. Oocyte expression of this isoform does not yield functional channels. However, this alternative mRNA exhibits dose-dependent inhibition of alpha 7 homomer expression when coinjected with the undeleted isoform.
Alternative Splicing↗
Presence of a chloroplast DNA sequence in an autonomous circular DNA molecule in cultured rice cells (Oryza sativa L).
Sequence analysis of twelve DNA fragments, which had previously been found to be extensively amplified in suspension-cultured rice cells, revealed that two of them, isolated on plasmids designated pE10 and pE11, have sequences identical to distinct regions of chloroplast DNA (ct-DNA). Both sequences are part of an extrachromosomal circular DNA molecule (ECD). The molecular structure of the ECD was investigated by a combination of restriction analysis, standard and pulsed-field gel electrophoresis, hybridization with ct-DNA probes and amplification by the polymerase chain reaction in the presence of oligonucleotide primers homologous to selected regions of rice ct-DNA. The results showed that a continuous and unrearranged stretch of ct-DNA from the long single-copy region, of at least 28 kbp in length, is present in the ECD. It was estimated that the number of copies of the ECD in cultured cells was almost equivalent to that of ct-DNA molecules in rice leaves, while the ratio of ECD to ct-DNA molecules in the cultured cells was approximately 200:1.
Cells, Cultured↗
Role of two acetylcholine receptor subunit domains in homomer formation and intersubunit recognition, as revealed by alpha 3 and alpha 7 subunit chimeras.
Differential expression of subunit genes from the nicotinic acetylcholine receptor (AChR) superfamily yields distinct receptor subtypes. As each AChR subtype has a specific subunit composition and many subunit combinations appear not to be expressed, each subunit must contain some information leading to proper assembly. The neuronal AChR subunits alpha 3 and alpha 7 are expressed in bovine chromaffin cells, probably as constituents of two different AChR subtypes. These subunits have different assembly behavior when expressed in heterologous expression systems: alpha 7 subunits are able to produce homomeric AChRs, whereas alpha 3 subunits require other "structural" subunits for functional expression of AChRs. This feature allows the dissection of the requirements for subunit interactions during AChR formation. Analysis of alpha 7/alpha 3 chimeric constructs identified two regions essential to homomeric assembly and intersubunit recognition: an N-terminal extracellular region, controlling the initial association between subunits, and a second domain within a region comprising the first putative transmembrane segment, M1, and the cytoplasmic loop coupling it to the pore-forming segment, M2, involved in the subsequent interaction and stabilization of the oligomeric complex.
Amino Acid Sequence↗