Loss of dopamine uptake sites and dopamine D2 receptors in striatonigral degeneration

To explore the mechanisms underlying L-dopa response, we studied, by postmortem autoradiography, selective makers of dopamine presynaptic terminals, [3H]WIN 35428, and dopamine D2 receptors, [3H]nemonapride, in the putamen of four Parkinson's disease (PD) and one striatonigral degeneration (SND) neuropathologically confirmed brains as compared with six matched control brains. Dopamine uptake transporter was dramatically decreased (> 90%) both in PD and SND striatum. Dopamine D2 receptors were preserved in PD, but clearly reduced (> 76%) in the SND putamen. These data confirm that L-dopa response is closely associated with the preservation of striatal dopamine D2 receptors.

Apoptosis induction and inhibition of H-ras overexpression by novel trans-[PtCl2(isopropylamine)(amine')] complexes

Hitherto, it has been generally accepted as a paradigm of the biochemical pharmacology of platinum antitumor drugs that a cis configuration of the leaving groups is necessary for antitumor activity of platinum compounds. However, it has been recently observed that certain trans-platinum complexes have both in vitro and in vivo antitumor activity. We previously reported the synthesis, characterization and cytotoxic activity against ras-transformed cells of several trans-[PtCl2LL'] complexes where L and L' are asymmetric aliphatic amines (L = dimethylamine and butylamine, L' = isopropylamine). The results reported in this paper show that the compounds trans-[PtCl2(isopropylamine)(dimethylamine)] and trans-[PtCl2(isopropylamine)(butylamine)] kill Pam 212-ras cisplatin resistant cells through apoptosis induction. Moreover, Western blot data show that both compounds inhibit overexpression of H-ras oncogene in Pam 212-ras cells. Altogether, these data indicate that, in contrast with cis-DDP, the apoptotic activity of these novel trans-Pt(II) compounds in ras-transformed cells is associated with their ability to abolish ras-overexpression.

Phylogeographic patterns of mtDNA reflecting the colonization of the Canary Islands

Although the Canary Islands were settled by humans, possibly of Berber origin, as late as 2500 years ago, the precise course and numbers of early migrations to the archipelago remain controversial. We have therefore analysed mtDNA variation (HVS-I as well as selected RFLP sites) in 300 individuals from the seven Canary Islands. The distribution and variation across the islands in a specific mtDNA clade of Northwest African ancestry suggest that there was one dominant initial settlement process that affected all the islands, from east to west. This indicates that a certain genetic affinity of present-day Canary Islanders to Northwest African Berbers mainly stems from the autochthonous population rather than slaves captured on the neighbouring African coast. The slave trade after the European conquest left measurable, though minor, traces in the mtDNA pool of the Canary Islands, which in its majority testifies to the European immigration.

Mitochondrial DNA analysis of northwest African populations reveals genetic exchanges with European, near-eastern, and sub-Saharan populations

Genetic studies have emphasized the contrast between North African and sub-Saharan populations, but the particular affinities of the North African mtDNA pool to that of Europe, the Near East, and sub-Saharan Africa have not previously been investigated. We have analysed 268 mtDNA control-region sequences from various Northwest African populations including several Senegalese groups and compared these with the mtDNA database. We have identified a few mitochondrial motifs that are geographically specific and likely predate the distribution and diversification of modern language families in North and West Africa. A certain mtDNA motif (16172C, 16219G), previously found in Algerian Berbers at high frequency, is apparently omnipresent in Northwest Africa and may reflect regional continuity of more than 20,000 years. The majority of the maternal ancestors of the Berbers must have come from Europe and the Near East since the Neolithic. The Mauritanians and West-Saharans, in contrast, bear substantial though not dominant mtDNA affinity with sub-Saharans.

Molecular diagnosis of alkaptonuria mutation by analysis of homogentisate 1,2 dioxygenase mRNA from urine and blood

Alkaptonuria (AKU) is caused by lack of homogentisate 1, 2 dioxygenase (HGO) activity. From the complete sequence of a human HGO cDNA, primers were designed in order to obtain reverse transcription-polymerase chain reaction products from tissues with ectopic transcription amenable to diagnostic analysis. A search for mutations in HGO cDNA was performed in an AKU family using urine and blood samples. The results show complete cosegregation (Z = 6.32; theta = 0) between a C-->T transition at position 817 of the human HGO cDNA and AKU. This mutation predicts a Pro-->Ser replacement at amino acid 230, and generates an EcoRV site.

Population genetic structure and colonization sequence of Drosophila subobscura in the Canaries and Madeira Atlantic Islands as inferred by autosomal, sex-linked and mtDNA traits

The genetic structure in Atlantic Islands and continental populations of Drosophila subobscura has been studied using autosomal and sex-linked allozymes and mitochondrial DNA (mtDNA) haplotypes. From the data it is deduced that whereas the Canary islands have long been isolated, the neighboring island of Madeira has been subjected to continuous migration from the mainland. In addition, sex-linked allozymes and mtDNA data show a large divergence between the geologically younger western islands of the Canarian Archipelago and the older central ones, finding strong founder effects in the former. Divergence rates of sex-linked and mitochondrial genes relative to autosomic loci several times higher than expected under neutrality have been explained by differential migration between sexes. The Canarian Archipelago colonization fits in well with a stepping-stone model of a directional east-west migration that parallels the geological origin of these Islands.

Sub-Saharan influence on the Canary Islands population deduced from G6PD gene sequence analysis

In a screening of glucose-6-phosphate dehydrogenase (G6PD) A variants in the Canary Islands and northwest African populations by electrophoresis and posterior gene sequencing, the common A+ 376G and A- 202A/376G and the rare A- 376G/968C mutations were found. In addition, three new silent C-->T transitions have been detected at nucleotides 759 (exon 7), 1338 (exon 11), and 1573 (exon 13). Canary Island and North African samples share sub-Saharan haplotypes with Equatorial Guineans. The slave trade seems the most probable origin of the African haplotypes found in the Canary Islands.

Genetic relationship between the Canary Islanders and their African and Spanish ancestors inferred from mitochondrial DNA sequences

Nucleotide sequences of the hypervariable segment I of the control region of the mtDNA were determined in 101 individuals: 54 Canary Islanders, 18 North African Berbers, 18 Spanish mainlanders and 11 sub-Saharan Guineans. In spite of the fact that only members of the Fang tribe were analysed, nucleotide diversity in Guineans (theta x 100 = 2.33) is one of the highest found in African populations. Estimates of genetic contribution to the Canarians from their putative parental populations based on mtDNA (43.25 +/- 1.38% Berbers, 35.54 +/- 0.55% Spanish, 21.21 +/- 1.92% Guineans) showed an important North African substrate. These mtDNA results, when compared with data based on nuclear markers, point to a strong male female asymmetry, 75% of the Spanish nuclear contribution was due to males and practically all the Berber and Guinean was due to females. These results are in agreement with the way that the Canary Islands were conquered. Pairwise difference distributions in Guineans and Berbers are compatible with the model of populations in expansion. Departures from a Poisson distribution for the Canarians and Spanish can be explained by admixture and the way of sampling respectively.

Autoradiographic demonstration of increased alpha 2-adrenoceptor agonist binding sites in the hippocampus and frontal cortex of depressed suicide victims

To examine directly in the brain the status of alpha 2-adrenoceptors in major depression, the specific binding of the agonist [3H]UK 14304 was measured by quantitative receptor autoradiography in the hippocampus and frontal cortex of suicide victims (n = 17) with a retrospective diagnosis of depression (n = 7) or other psychiatric disorders (n = 10) as well as of matched control subjects (n = 9). In suicide victims, a significant increase in the number of alpha 2-adrenoceptors was found in the CA1 field (40%) and dentate gyrus (20%) of the hippocampus and in the external layers I (33%) and II (31%) of the frontal cortex, compared with that in matched controls. In depressed suicide victims, the increase in alpha 2-adrenoceptors in the CA1 field (57%) was significantly greater (24%, p < 0.05) than that observed in the group of suicide victims with other diagnoses (26%). In the same depressed suicide victims, the increase in cortical alpha 2-adrenoceptors was restricted to layer I (34%) and it was equivalent to that found in layer I (33%) of suicide victims with other diagnoses. The results indicate that suicide is associated with increases in the high-affinity state of brain alpha 2-adrenoceptors adrenoceptors and that there is a pronounced localized increase of this inhibitory receptor in the hippocampus of depressed suicide victims.

Human enzyme polymorphism in the Canary Islands. VI. Northwest African influence

The genetic polymorphism of eight red cell enzymes was analyzed in population samples from the Northwest African Continent and from the South of Spain in order to study their genetic relationships with the Canarian population. The Moroccan, Berber and Spanish populations, although geographically more distant from the Canary Islands than the Saharan and Mauritanian ones, are genetically more closely related to the Canarian population. The glucose-6-phosphate dehydrogenase Gc allele earlier found only in the Canary Islands was detected in the Berber sample. The Spanish, Berber and African Black contributions to the Canarian hybrid population was estimated to 70, 20 and 10%, respectively.

Changes in aminergic receptors in a PSP postmortem brain: correlation with pathological findings

The state of different aminergic receptors was assessed, by quantitative autoradiography in tissue sections, in several representative brain regions from a typical progressive supranuclear palsy (PSP) patient and from 9 matched brains. The densities of muscarinic receptors were within control limits in most of the brain areas of this PSP brain. Serotonin1 receptors were clearly reduced only in areas with very relevant neuropathological damage, such as locus niger and globus pallidus. The density of D1 dopamine receptors in the caudate-putamen and frontal cortex of the patient was within control limits. By contrast, nigral D1 and striatal D2 dopamine receptors were dramatically reduced in the patient as compared to controls. Finally, alpha 2-adrenoceptors were clearly reduced in all the examined areas of this PSP patient as compared to control group. Both the potential role of these receptor changes in the pathophysiology of the clinical features of PSP and their correlation with the neuropathological findings of this PSP patient are discussed.

Autoradiographic demonstration of loss of alpha 2-adrenoceptors in progressive supranuclear palsy: preliminary report

We assessed, by quantitative autoradiography in tissue sections, the density of alpha 2-adrenoceptors in several representative brain regions from a typical progressive supranuclear palsy (PSP) patient and in 9 matched brains. The full agonist 3H-bromoxidine was used as a ligand. The density of alpha 2-receptors was dramatically reduced in all the examined brain areas of this PSP patient as compared to the control group. The locus ceruleus degeneration observed here is the most plausible explanation for this loss of alpha 2-receptors. Our data show that abnormalities in the noradrenergic system may justify some clinical features of the PSP clinical picture, this supporting the idea of further study of the clinical effects of noradrenergic drugs in PSP.

Latitudinal differences in sex chromosome inversions, sex linked allozymes, and mitochondrial DNA variation in Drosophila subobscura

Mitochondrial DNA, sex linked allozymes, and chromosome A gene arrangement data, from eight European natural populations of Drosophila subobscura, were analyzed to determine the existence of latitudinal clines. Strong north-south correlations with latitude were found for gene arrangements and for the Hbdh and 6Pgdh allozymes. Gametic associations between the A2 gene arrangement, the Hbdh96 and the 6Pgdh96 alleles, point out some kind of epistatic interaction. At mtDNA level, the Hae III, A variant did not show a previously found north-south clinal variation.

Human enzyme polymorphism in the Canary Islands. V. Western Islands

Autochthonous human samples of the three westernmost islands of the Canarian Archipelago, La Palma, Gomera, and Hierro, have been analyzed for eight red cell polymorphic enzymes. Only a small intra and inter-insular differentiation exists among these three islands. However, a marked heterogeneity is found when all seven islands of the Archipelago are compared by Nei's genetic distances [1972]. Nevertheless, there is no correlation between genetic and geographic distances. Historical factors could explain the frequency similarities of some distant islands. The rare variant GD*A+Negroid allele, and the endemic GD*Gc allele, previously found in other islands, have also been detected in this survey.

Modification of muscarinic acetylcholine receptors in the rat brain following chronic immobilization stress: an autoradiographic study

The modifications of rat brain muscarinic acetylcholine receptors induced by chronic immobilization stress lasting 10 min/daily or 2 h/daily for 3, 7 or 21 days were analyzed by quantitative in vitro autoradiography. [3H]N-Methylscopolamine ([3H]NMS) was used as ligand. Chronic immobilization stress for 10 min/day did not produce any significant change in the properties of [3H]NMS binding sites throughout the rat brain. In contrast, 2 h/day immobilization caused a significant increase in the maximal number of muscarinic receptors (Bmax) in several brain areas such as the cortical layers, the CA1 field of the hippocampus and caudate-putamen, among others. Affinity values (Kd) were not modified. These results suggest that chronic immobilization stress induces supersensitivity of muscarinic receptors in certain cholinergic pathways in rat brain, the pattern of response being different to that previously found for acute stress.

Dopamine D1 and D2 receptors in progressive supranuclear palsy: an autoradiographic study

Dopamine D1 and D2 receptors were studied in brain tissue sections from a typical patient with progressive supranuclear palsy and in 7 age-matched brains. The density of D1 receptors in the caudate-putamen and frontal cortex of the patient was within control limits. By contrast, the density of nigral D1 receptors and striatal D2 receptors was dramatically reduced in the patient as compared to the control brains. This work shows again that the loss of striatal D2 receptors is the most plausible explanation for the poor response to dopaminergic drugs in patients with progressive supranuclear palsy. While the loss of nigral D1 receptors can be explained by the loss of nigral neurons, it seems that neurons bearing striatal D1 receptors are spared in progressive supranuclear palsy. The clinical effects of selective D1 agonists are worth testing in this devastating disorder.

Quantitative light microscopic autoradiographic localization of alpha 2-adrenoceptors in the human brain

In the present work the anatomical distribution of alpha 2-adrenoceptors in the human central nervous system was studied in detail by quantitative autoradiography using the selective alpha 2 agonist [3H]bromoxidine ([3H]UK-14304) as a ligand. Only postmortem tissues from subjects free of neurological disorders were used in this study. Very high or high densities of alpha 2-adrenoceptors were found along layers I and III in non-visual neocortex, layers III and IVc of the visual cortex, CA1 field--stratum lacunosum-moleculare--and dentate gyrus--stratum granularis--at the hippocampal formation, nucleus arcuatus at the hypothalamus, locus ceruleus, nucleus dorsalis of vagus and at the stratum granularis of the cerebellar cortex. Relevant densities of alpha 2-adrenoceptors were also observed along the remaining layers of neocortex, nuclei centralis, medialis and corticalis at the amygdala, anterior thalamic group and rotundocellularis nuclei, paraventricular and ventromedial hypothalamic nuclei, substantia innominata, superior colliculus--stratum zonale--and lateral periaqueductal area at the midbrain, nucleus tractus solitarii and dorsal horn--substantia gelatinosa--of the spinal cord. [3H]Bromoxidine specific binding was very low or negligible in the remaining brain areas. Although a general parallelism between the distribution of these receptors could be observed for the rat and human brain, dramatic species differences in the level of alpha 2-receptors were found in several brain areas, such as thalamus, amygdala or cerebellar cortex. In general, the distribution of alpha 2-adrenoceptors in the human brain found here was parallel to that described for the noradrenergic presynaptic terminals in the mammalian central nervous system, lending some weight to the proposed predominant presynaptic localization of these receptors. The relevance of the anatomical distribution of alpha 2-adrenoceptors in the human brain for a better knowledge of the neurochemistry of neuropsychiatric disorders is discussed.

Affinity changes in muscarinic acetylcholine receptors in the rat brain following acute immobilization stress: an autoradiographic study

The modifications in rat brain muscarinic acetylcholine receptors induced by acute immobilization stress lasting 10 min or 2 h were analyzed by quantitative in vitro autoradiography. [3H]N-Methylscopolamine ([3H]NMS) was used as a ligand. Immobilization stress for 10 min did not produce any significant change in the properties of [3H]NMS binding sites throughout the brain. In contrast, 2 h immobilization caused a significant increase in receptor affinity (Kd) without modification in the maximal number of receptors (Bmax) in several brain areas such as the caudate-putamen, cortical layers and CA1 field of the hippocampus, among others. These results, found even in animals killed immediately after the end of the immobilization sessions, suggest that immobilization stress induces supersensitivity of muscarinic receptors in certain cholinergic pathways in rat brain.

Regionally specific age-dependent decline in alpha 2-adrenoceptors: an autoradiographic study in human brain

The effect of sex, postmortem delay and aging on alpha 2-adrenoceptor binding was studied in tissue sections from several representative regions of the human brain from 21 subjects using [3H]UK-14304 as a ligand. Sex and postmortem delay did not influence the density of alpha 2-receptors. Aging resulted in clear decreases in most forebrain areas examined (n. basalis greater than basal ganglia greater than hypothalamus greater than fronto-temporal cortex greater than hippocampus greater than visual cortex), whereas alpha 2-receptors did not significantly change with age in the amygdala and several infratentorial areas. We conclude that age-related, regionally specific decreases in the density of alpha 2-receptors occur in the human brain. The implications of these findings for age-dependent noradrenergic degeneration are discussed.

Human enzyme polymorphism in the Canary Islands. IV. Eastern islands

The genetic polymorphism of eight red cell enzymes was analyzed in four population samples from the two easternmost islands of the Canary Archipelago. No heterogeneity was detected within the islands, but differences between them were of the same magnitude as those found between the islands and the Spanish mainland. The presence of the African G6PD-A+ and the rare G6PD-Gc alleles seems to be a characteristic of all Canarian populations studied.

Autoradiographic localization of alpha 2-adrenoceptors in chick brain

alpha 2-Adrenoceptors were localized in the chick brain by 'in vitro' receptor autoradiography using [3H]UK 14304 as a ligand. High or very high densities of binding sites were found in the hyperstriatum, tuberculum olfactorium, hypothalamic nuclei, tectum opticum and some medullary nuclei. Comparatively, intermediate densities were observed over the thalamic nuclei and locus ceruleus, among others. Low densities of alpha 2-adrenoceptors were detected in the paleostriatum, hippocampus and cerebellum. Our data indicate that alpha 2-adrenoceptors in the chick brain present similar properties and homologous anatomical distribution to those reported in mammalian brain.

Mitochondrial DNA evolution in the obscura species subgroup of Drosophila

Mitochondrial DNA (mtDNA) restriction site maps for nine species of the Drosophila obscura subgroup and for Drosophila melanogaster were established. Taking into account all restriction enzymes (12) and strains (45) analyzed, a total of 105 different sites were detected, which corresponds to a sample of 3.49% of the mtDNA genome. Based on nucleotide divergences, two phylogenetic trees were constructed assuming either constant or variable rates of evolution. Both methods led to the same relationships. Five differentiated clusters were found for the obscura subgroup species, one Nearctic, represented by Drosophila pseudoobscura, and four Palearctic, two grouping the related triads of species Drosophila subobscura, Drosophila madeirensis, Drosophila obscura, Drosophila subsilvestris, and two more represented by one species each, Drosophila bifasciata, and Drosophila tristis. The different Palearctic clusters are as distant between themselves as with the Nearctic one. For the related species D. subobscura, D. madeirensis, and D. guanche, the pair D. subobscura-D. madeirensis is the closest one. The relationships found by nucleotide divergence were confirmed by differences in mitochondrial genome size, with related species sharing similar genome lengths and differing from the distant ones. The total mtDNA size range for the obscura subgroup species was from 15.5 kb for D. pseudoobscura to 17.1 for D. tristis.

Characterization of [3H]hemicholinium-3 binding sites in human brain membranes: a marker for presynaptic cholinergic nerve terminals

We report here on the binding properties of [3H]hemicholinium-3, a selective inhibitor of the high-affinity choline uptake process, to human brain membranes. Under the assay conditions described, the binding of [3H]hemicholinium-3 exhibited a dependency of physiological conditions on pH, temperature, and NaCl concentrations. Striatal binding proved to be specific, to a single site, saturable, and reversible, with an apparent KD of 10 nM and a Bmax of 82 fmol/mg of protein. [3H]Hemicholinium-3 specific binding exhibited a pharmacological profile and an ionic dependency suggestive of physiologically relevant interactions and comparable with those reported for the high-affinity choline uptake. Moreover, specific [3H]hemicholinium-3 binding exhibited an uneven regional distribution: striatum much greater than nucleus basalis greater than spinal cord much greater than midbrain = cerebellum greater than or equal to hippocampus greater than neocortex = anterior thalamus greater than posterior thalamus much much greater than white matter. This distribution closely corresponds to the reported activity of both enzymatic cholinergic presynaptic markers and high-affinity choline uptake in mammalian brain. There are no significant differences between these results and those previously found in the rat brain using this radioligand. Our results demonstrate, for the first time, the presence of [3H]hemicholinium-3 binding sites in human brain and strongly support the proposal that this radioligand binds to the carrier site mediating the high-affinity choline uptake process on cholinergic neurons. Thus, [3H]hemicholinium-3 binding may be used in postmortem human brain as a selective and quantifiable marker of the presynaptic cholinergic terminals.