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2.
Lipids ; 51(10): 1171-1191, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27590240

RESUMO

Omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) are essential components of the diet of all vertebrates. The major dietary source of n-3 LC-PUFA for humans has been fish and seafood but, paradoxically, farmed fish are also reliant on marine fisheries for fish meal and fish oil (FO), traditionally major ingredients of aquafeeds. Currently, the only sustainable alternatives to FO are vegetable oils, which are rich in C18 PUFA, but devoid of the eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) abundant in FO. Two new n-3 LC-PUFA sources obtained from genetically modified (GM) Camelina sativa containing either EPA alone (ECO) or EPA and DHA (DCO) were compared to FO and wild-type camelina oil (WCO) in juvenile sea bream. Neither ECO nor DCO had any detrimental effects on fish performance, although final weight of ECO-fed fish (117 g) was slightly lower than that of FO- and DCO-fed fish (130 and 127 g, respectively). Inclusion of the GM-derived oils enhanced the n-3 LC-PUFA content in fish tissues compared to WCO, although limited biosynthesis was observed indicating accumulation of dietary fatty acids. The expression of genes involved in several lipid metabolic processes, as well as fish health and immune response, in both liver and anterior intestine were altered in fish fed the GM-derived oils. This showed a similar pattern to that observed in WCO-fed fish reflecting the hybrid fatty acid profile of the new oils. Overall the data indicated that the GM-derived oils could be suitable alternatives to dietary FO in sea bream.


Assuntos
Brassicaceae/genética , Ácidos Graxos Ômega-3/análise , Óleos de Peixe/análise , Plantas Geneticamente Modificadas/química , Dourada/fisiologia , Ração Animal/análise , Animais , Encéfalo/metabolismo , Brassicaceae/química , Gorduras na Dieta , Ácidos Graxos Ômega-3/farmacologia , Óleos de Peixe/farmacologia , Pesqueiros , Regulação da Expressão Gênica/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Metabolismo dos Lipídeos , Fígado/metabolismo , Especificidade de Órgãos
3.
Aquaculture ; 444: 1-12, 2015 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-26146421

RESUMO

Currently, one alternative for dietary fish oil (FO) in aquafeeds is vegetable oils (VO) that are devoid of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFAs). Entirely new sources of n-3 LC-PUFA such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids through de novo production are a potential solution to fill the gap between supply and demand of these important nutrients. Camelina sativa was metabolically engineered to produce a seed oil (ECO) with > 20% EPA and its potential to substitute for FO in Atlantic salmon feeds was tested. Fish were fed with one of the three experimental diets containing FO, wild-type camelina oil (WCO) or ECO as the sole lipid sources for 7 weeks. Inclusion of ECO did not affect any of the performance parameters studied and enhanced apparent digestibility of individual n-6 and n-3 PUFA compared to dietary WCO. High levels of EPA were maintained in brain, liver and intestine (pyloric caeca), and levels of DPA and DHA were increased in liver and intestine of fish fed ECO compared to fish fed WCO likely due to increased LC-PUFA biosynthesis based on up-regulation of the genes. Fish fed ECO showed slight lipid accumulation within hepatocytes similar to that with WCO, although not significantly different to fish fed FO. The regulation of a small number of genes could be attributed to the specific effect of ECO (311 features) with metabolism being the most affected category. The EPA oil from transgenic Camelina (ECO) could be used as a substitute for FO, however it is a hybrid oil containing both FO (EPA) and VO (18:2n-6) fatty acid signatures that resulted in similarly mixed metabolic and physiological responses.

4.
Sci Rep ; 5: 8104, 2015 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-25632018

RESUMO

For humans a daily intake of up to 500 mg omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) is recommended, amounting to an annual requirement of 1.25 million metric tonnes (mt) for a population of 7 billion people. The annual global supply of n-3 LC-PUFA cannot meet this level of requirement and so there is a large gap between supply and demand. The dietary source of n-3 LC-PUFA, fish and seafood, is increasingly provided by aquaculture but using fish oil in feeds to supply n-3 LC-PUFA is unsustainable. Therefore, new sources of n-3 LC-PUFA are required to supply the demand from aquaculture and direct human consumption. One approach is metabolically engineering oilseed crops to synthesize n-3 LC-PUFA in seeds. Transgenic Camelina sativa expressing algal genes was used to produce an oil containing n-3 LC-PUFA to replace fish oil in salmon feeds. The oil had no detrimental effects on fish performance, metabolic responses or the nutritional quality of the fillets of the farmed fish.


Assuntos
Ácido Eicosapentaenoico/farmacologia , Óleos de Peixe/farmacologia , Valor Nutritivo , Óleos de Plantas/farmacologia , Salmo salar/crescimento & desenvolvimento , Ração Animal , Animais , Brassicaceae/química , Brassicaceae/genética , Ceco/efeitos dos fármacos , Ceco/metabolismo , DNA/metabolismo , Dieta , Ácidos Docosa-Hexaenoicos/metabolismo , Ácido Eicosapentaenoico/administração & dosagem , Perfilação da Expressão Gênica , Fígado/efeitos dos fármacos , Fígado/metabolismo , Músculos/efeitos dos fármacos , Músculos/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Plantas Geneticamente Modificadas , Reprodutibilidade dos Testes , Sementes/efeitos dos fármacos , Sementes/metabolismo , Análise de Sobrevida , Transcriptoma/genética
5.
J Thromb Haemost ; 11(4): 724-30, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23332144

RESUMO

BACKGROUND: Factor XI (FXI) deficiency is one of the most frequent inherited disorders in Ashkenazi Jews (AJ). Two predominant founder mutations termed type II (p.Glu117Stop) and type III (p.Phe283Leu) account for most cases. OBJECTIVES: To present clinical aspects of a third FXI mutation, type I (c.1716 + 1G>A), which is also prevalent in AJ and to discern a possible founder effect. METHODS: Bleeding manifestations, FXI levels and origin of members of 13 unrelated families harboring the type I mutation were determined. In addition, eight intragenic and five extragenic polymorphisms were analyzed in patients with a type I mutation, in 16 unrelated type II homozygotes, in 23 unrelated type III homozygotes and in Ashkenazi Jewish controls. Analysis of these polymorphisms enabled haplotype analysis and estimation of the age of the type I mutation. RESULTS: Four of 16 type I heterozygotes (25%) and 6 of 12 (50%) compound heterozygotes for type I mutation (I/II and I/III), or a type I homozygote had bleeding manifestations. Haplotype analysis disclosed that like type II and type III mutations, the type I is also an ancestral mutation. An age estimate revealed that the type I mutation occurred approximately 600 years ago. The geographic distribution of affected families suggested that there was a distinct origin of the type I mutation in Eastern Europe. CONCLUSIONS: The rather rare type I mutation in the FXI gene is a third founder mutation in AJ.


Assuntos
Deficiência do Fator XI/genética , Fator XI/genética , Judeus/genética , Mutação , Fator XI/metabolismo , Feminino , Efeito Fundador , Humanos , Masculino , Linhagem
6.
Eur J Neurol ; 20(6): 891-8, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23305304

RESUMO

BACKGROUND AND PURPOSE: Polymorphic paraoxonase (PON1) variants can variably prevent low- and high-density lipoprotein oxidation, but their role in provoking atherosclerosis remained unclear. We addressed this issue by profiling PON1 polymorphisms and enzymatic activities, and assessing atherosclerosis and cerebral arteriosclerosis severity in post-stroke patients. METHODS: Carotid artery intima-media-thickness (IMT), cerebral white matter lesions (WML), serum PON1 -108C/T, Q192R and L55M polymorphisms, and PON and acetylcholinesterase (AChE) enzyme activities were determined in 237 patients. RESULTS: Genetic variation at the PON1 locus showed a strong influence on PON1 activity in ischaemic stroke patients, but lacked direct influence on IMT. Stroke patients with PON1 QQ192 or MM55 genotypes demonstrated lower PON and arylesterase activities at both Day 1 and 12 months post-stroke than patients with either RQ/RR192 or LM/LL55 genotypes (P < 0.001). Furthermore, patients with carotid atherosclerosis and/or cerebral arteriosclerosis expressed as IMT, carotid plaques and WML had lower 12 months PON1 activity than patients without (P = 0.02, P = 0.027 and P = 0.001, respectively), and PON and AChE hydrolysis rates were more tightly correlated in patients carrying the PON1 192R compared with the 192QQ allele, in a gene dose-dependent manner (P < 0.001). CONCLUSION: Our findings show inverse PON1 activity-carotid atherosclerosis and -cerebral arteriosclerosis association in stroke patients: the lower the PON1 activity the more progressed is the atherosclerotic process and the weaker is the association with AChE activity. Extending previous PON1 genetic studies in stroke populations, our study emphasizes the PON1 activity as a potential anti-atherogenic element and proposes involvement of cholinesterase activities in its effects.


Assuntos
Acetilcolinesterase/metabolismo , Arildialquilfosfatase/genética , Doenças das Artérias Carótidas/genética , Arteriosclerose Intracraniana/genética , Polimorfismo Genético/genética , Acidente Vascular Cerebral/genética , Idoso , Idoso de 80 Anos ou mais , Arildialquilfosfatase/metabolismo , Doenças das Artérias Carótidas/enzimologia , Doenças das Artérias Carótidas/epidemiologia , Estudos de Coortes , Ativação Enzimática/fisiologia , Humanos , Arteriosclerose Intracraniana/enzimologia , Arteriosclerose Intracraniana/epidemiologia , Pessoa de Meia-Idade , Acidente Vascular Cerebral/enzimologia , Acidente Vascular Cerebral/epidemiologia
8.
Eur J Neurol ; 14(3): 315-20, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17355554

RESUMO

C-reactive protein (CRP) increases following an acute stroke/transient ischemic attack (TIA), but the increment level varies among patients. We analyzed CRP concentrations during an acute stroke/TIA in relation to the CRP gene -717A>G polymorphism. Six months following an acute ischemic stroke/TIA, basal concentrations of CRP were measured in 507 controls and 219 patients and were found to be unassociated with the CRP -717A>G polymorphism. However, during the acute phase of stroke/TIA, individuals with the AG/GG genotype had significantly elevated CRP concentrations as opposed to those with the AA genotype (2.02 +/- 1.59 vs. 1.73 +/- 1.69 mg/l, P = 0.027). In addition, significant 3.22-fold increments in CRP concentrations was noted in individuals carrying the -717G allele when comparing the acute phase with the basal state of each patient and averaging the results. CRP -717A>G polymorphism is associated with triggered CRP concentrations during acute stroke/TIA. These findings might shed more light on the mechanisms of CRP elevation in acute ischemic stroke/TIA.


Assuntos
Proteína C-Reativa/genética , Proteína C-Reativa/metabolismo , Predisposição Genética para Doença/genética , Ataque Isquêmico Transitório/genética , Polimorfismo Genético/genética , Acidente Vascular Cerebral/genética , Doença Aguda , Idoso , Proteína C-Reativa/análise , Análise Mutacional de DNA , Feminino , Frequência do Gene , Marcadores Genéticos/genética , Genótipo , Humanos , Ataque Isquêmico Transitório/sangue , Ataque Isquêmico Transitório/fisiopatologia , Masculino , Pessoa de Meia-Idade , Mutação/genética , Acidente Vascular Cerebral/sangue , Acidente Vascular Cerebral/fisiopatologia , Regulação para Cima/genética
13.
Blood ; 94(6): 2039-47, 1999 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-10477733

RESUMO

alphaIIbb3 integrin is a heterodimeric receptor facilitating platelet aggregation. Both genes are on chromosome 17q21.32. Intergenic distance between them has been reported to be 125 to 260 kilobasepairs (kb) by pulsed-field gel electrophoresis (PFGE) genomic analysis, suggesting that they may be regulated coordinately during megakaryopoiesis. In contrast, other studies suggest these genes are greater than 2.0 megabasepairs (mb) apart. Because of the potential biological implications of having these two megakaryocytic-specific genes contiguous, we attempted to resolve this discrepancy. Taking advantage of large kindreds with mutations in either alphaIIb or beta3, we have developed a genetic linkage map between the thyroid receptor hormone-1 gene (THRA1) and beta3 as follows: cen-THRA1-BRCA1-D17S579/alphaIIb-beta3-qte r, with a distance of 1.3 centiMorgans (cM) between alphaIIb and beta3 and the two genes being oriented in the same direction. PFGE genomic and YAC clone analysis showed that the beta3 gene is distal and >/=365 kb upstream of alphaIIb. Additional restriction mapping shows alphaIIb is linked to the erythrocyte band 3 (EPB3) gene, and beta3 to the homeobox HOX2b gene. Analysis of alphaIIb(+)-BAC and P1 clones confirm that the EPB3 gene is approximately 110 kb downstream of the alphaIIb gene. Sequencing the region surrounding the human alphaIIb locus showed the Granulin gene approximately 18 kb downstream to alphaIIb, and the KIAA0553 gene approximately 5.7 kb upstream. This organization is conserved in the murine sequence. These studies show that alphaIIb and beta3 are not closely linked, with alphaIIb flanked by nonmegakaryocytic genes, and imply that they are unlikely to share common regulatory domains during megakaryopoiesis.


Assuntos
Antígenos CD/genética , Árabes/genética , Cromossomos Humanos Par 17 , Judeus/genética , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Glicoproteínas da Membrana de Plaquetas/genética , Proteína 1 de Troca de Ânion do Eritrócito/genética , Mapeamento Cromossômico , Cromossomos Artificiais de Levedura , Éxons , Feminino , Ligação Genética , Marcadores Genéticos , Humanos , Integrina beta3 , Íntrons , Iraque/etnologia , Israel , Masculino , Linhagem , Mapeamento por Restrição
14.
Am J Hum Genet ; 64(4): 1071-5, 1999 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10090892

RESUMO

The type II and type III mutations at the FXI locus, which cause coagulation factor XI deficiency, have high frequencies in Jewish populations. The type III mutation is largely restricted to Ashkenazi Jews, but the type II mutation is observed at high frequency in both Ashkenazi and Iraqi Jews, suggesting the possibility that the mutation appeared before the separation of these communities. Here we report estimates of the ages of the type II and type III mutations, based on the observed distribution of allelic variants at a flanking microsatellite marker (D4S171). The results are consistent with a recent origin for the type III mutation but suggest that the type II mutation appeared >120 generations ago. This finding demonstrates that the high frequency of the type II mutation among Jews is independent of the demographic upheavals among Ashkenazi Jews in the 16th and 17th centuries.


Assuntos
Deficiência do Fator XI/epidemiologia , Deficiência do Fator XI/genética , Frequência do Gene/genética , Judeus/genética , Mutação/genética , Alelos , Cromossomos Humanos/genética , Variação Genética/genética , Humanos , Incidência , Iraque , Desequilíbrio de Ligação/genética , Cadeias de Markov , Repetições de Microssatélites/genética , Modelos Genéticos , Recombinação Genética/genética , Fatores de Tempo
15.
Clin Chem Lab Med ; 36(8): 645-8, 1998 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9806478

RESUMO

Approximately ten percent of patients with malignant melanoma have family histories of the disease, suggesting a genetic predisposition. Germline mutations in tumour suppressor p16 gene have been implicated as disease causing mutations in some of the melanoma families. The frequency of families with p16 germline mutations among melanoma prone families varies from eight to fifty percent. The range of the variability is influenced apparently by the number of melanoma affected individuals within the family, as well as by other, yet unidentified factors. Ethnic background is known to determine both the frequency and the nature of germline alterations. Recently, specific mutations in tumour suppressor genes involved in breast cancer and in colon cancer were found at elevated frequency among Ashkenazi Jews. This report describes results of a screening for p16 germline alterations in a collection of Israeli melanoma families. We have analyzed genomic DNA from thirty one Ashkenazi and non-Ashkenazi Jewish melanoma families, as well as from thirty melanoma patients without an apparent family history of the disease. The entire coding region of the p16 gene was screened by single strand conformation polymorphism analysis and direct DNA sequencing. We have detected a number of carriers with the Ala148 Thr polymorphism at the end of the second exon and several instances of 500(G=>C) substitution at the 3' untranslated portion of the gene.


Assuntos
Genes p16 , Mutação em Linhagem Germinativa , Melanoma/genética , Feminino , Testes Genéticos , Humanos , Israel/etnologia , Masculino , Melanoma/etnologia , Linhagem
16.
Br J Haematol ; 102(2): 582-7, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9695977

RESUMO

Glanzmann thrombasthenia is an autosomal recessive bleeding disorder caused by mutations in the genes encoding platelet GPIIb or GPIIIa. Both genes map to chromosome 17q21 and polymorphisms within this chromosomal region have been identified. In the current study, prenatal diagnosis was performed for a family that already had one affected child, patient 1, who had a compound heterozygous mutation in GPIIb. At the time of prenatal diagnosis, the maternal GPIIb mutation had been identified but the paternal GPIIb mutation was unknown. By sequence analysis, the fetus was identified as a carrier of the mother's mutation. To determine the probability of the fetus inheriting the father's mutation, haplotype analysis of DNA samples from the fetus, mother, father and affected child were performed using polymorphic markers on chromosome 17q12-q21. These markers included polymorphisms within the thyroid hormone receptor alpha1 gene (THRA1), the breast cancer gene (BRCA1), GPIIb, GPIIIa, and an anonymous marker D17S579. Heterozygosity within the THRA1, BRCA1 and GPIIIa polymorphic markers predicted that the fetus carried the father's normal allele. Based on genetic linkage studies, no recombination was identified with any of the informative markers, and from the map distance between GPIIb and BRCA1 the accuracy of diagnosis was predicted to be >98%. The father's mutation was subsequently identified and direct sequence analysis of fetal DNA confirmed that the fetus did not inherit the fathers' mutant allele.


Assuntos
Proteína BRCA1/análise , Cromossomos Humanos Par 17/genética , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Diagnóstico Pré-Natal/métodos , Receptores dos Hormônios Tireóideos/metabolismo , Trombastenia/diagnóstico , Pré-Escolar , Mapeamento Cromossômico , Marcadores Genéticos , Haplótipos , Humanos , Masculino , Linhagem , Reação em Cadeia da Polimerase , Polimorfismo Genético , Polimorfismo de Fragmento de Restrição
17.
Blood ; 90(7): 2654-9, 1997 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-9326232

RESUMO

Previous studies showed that factor XI (FXI) deficiency commonly observed in Ashkenazi Jews is caused by two similarly frequent mutations, type II (Glu117stop) and type III (Phe283Leu) with allele frequencies of 0.0217 and 0.0254, respectively. In Iraqi Jews, who represent the ancient gene pool of Jews, only the type II mutation was observed with an allele frequency of 0.0167. In this study we sought founder effects for each mutation by examination of four FXI gene polymorphisms enabling haplotype analysis in affected Jewish patients of Ashkenazi, Iraqi, and other origins and in Arab patients. Initial population surveys of 387 Middle Eastern Jews (excluding Iraqi Jews), 560 North African/Sephardic Jews, and 382 Arabs revealed allele frequencies for the type II mutation of 0.0026, 0.0027, and 0.0065, respectively. In contrast, the type III mutation was not detected in any of these populations. All 60 independent chromosomes bearing the type III mutation were solely observed in Ashkenazi Jewish patients and were characterized by a relatively rare haplotype. All 103 independent chromosomes bearing the type II mutation in patients of Ashkenazi, Iraqi, Yemenite, Syrian, and Moroccan Jewish origin and of Arab origin were characterized by another distinct haplotype that was rare among normal Ashkenazi Jewish, Iraqi Jewish, and Arab chromosomes. These findings constitute the first example of a mutation common to Ashkenazi Jews, non-Ashkenazi Jews, and Arabs and are consistent with the origin of type II mutation in a founder before the divergence of the major segments of Jews. Our findings also indicate that the type III mutation arose more recently in an Ashkenazi Jewish individual.


Assuntos
Deficiência do Fator XI/etnologia , Fator XI/genética , Frequência do Gene , Judeus/genética , África do Norte/etnologia , Árabes/genética , Cromossomos Humanos Par 4/genética , Análise Mutacional de DNA , Europa (Continente)/etnologia , Deficiência do Fator XI/classificação , Deficiência do Fator XI/genética , Grécia/etnologia , Haplótipos/genética , Humanos , Iraque/etnologia , Oriente Médio/etnologia , Linhagem , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Espanha/etnologia , Iêmen/etnologia
18.
Obstet Gynecol ; 89(2): 221-6, 1997 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9015024

RESUMO

OBJECTIVE: To quantify the roles of suspected sociodemographic, anthropometric, behavioral, and pathologic determinants in the etiology of abruptio placentae. METHODS: We performed a hospital-based cohort study of 36,875 nonreferred births between January 1978 and March 1989. Gestational age was based on menstrual dates confirmed (within 7 days) by early ultrasound. RESULTS: Parity, maternal education, pre-pregnancy weight, and the rate of net gestational weight gain did not have significant independent associations with abruption. Significant determinants included the following: severe small for gestational-age (SGA) birth (odds ratio [OR] 3.99; 95% confidence interval [CI] 2.75, 5.77), chorioamnionitis (OR 2.50; 95% CI 1.58, 3.98), prolonged rupture of membranes (OR 2.38; 95% CI 1.55, 3.65), preeclampsia (OR 2.05; 95% CI 1.39, 3.04), pregnancy-induced hypertension without albuminuria (OR 1.57; 95% CI 1.00, 2.46), pre-pregnancy hypertension (OR 1.77; 95% CI 1.05, 2.99), maternal age at least 35 years (OR 1.50; 95% CI 1.14, 2.01), unmarried status (OR 1.50; 95% CI 1.13, 1.98), cigarette smoking (OR 1.40; 95% CI 1.00, 1.97 for ten to 19 cigarettes per day and OR 1.13; 95% CI 0.81, 1.59 for at least 20 cigarettes per day), and male fetal gender (OR 1.38; 95% CI 1.12, 1.70). Removal of SGA from the regression model resulted in little change in the magnitude of the other associations. CONCLUSIONS: Severe fetal growth restriction, prolonged rupture of membranes, chorioamnionitis, hypertension (before pregnancy and pregnancy-induced), cigarette smoking, advanced maternal age, unmarried status, and male fetal gender are significant etiologic determinants of placental abruption. Non-SGA determinants appear to operate largely independently of their effects on fetal growth.


Assuntos
Descolamento Prematuro da Placenta/etiologia , Adulto , Antropometria , Estudos de Coortes , Intervalos de Confiança , Feminino , Humanos , Recém-Nascido , Recém-Nascido Pequeno para a Idade Gestacional , Modelos Logísticos , Masculino , Razão de Chances , Gravidez , Assunção de Riscos , Fatores Socioeconômicos
19.
J Neurophysiol ; 77(2): 874-95, 1997 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9065856

RESUMO

We adapted the saccadic gain (saccadic amplitude/target step amplitude) by requiring monkeys to track a small spot that stepped to one side by 5, 10, or 15 degrees and then, during the initial targeting saccade, jumped either forward or backward by a fixed percentage of the initial step. Saccadic gain increased or decreased, respectively, as a function of the number of adapting saccades made in that direction. The relation between gain and the number of adapting saccades was fit with an exponential function, yielding an asymptotic gain and a rate constant (the number of saccades to achieve 63% of the total change in gain). Backward intrasaccadic target jumps of 15, 30, and 50% of the initial target step reduced the asymptotic gain by an average of 12.2, 23.1, and 36.4%, respectively, with average rate constants of 163, 368, and 827 saccades, respectively. During 50% backward jumps, some saccades, especially those to larger target steps, became slower and lasted longer. Forward intrasaccadic jumps of 30% increased the asymptotic gain by 23.3% (average rate constant of 1,178 saccades). After we had caused adaptation, we induced recovery of gain toward normal by requiring the animal to track target steps without intrasaccadic jumps. Recovery following forward adaptation required about one third fewer saccades than the preceding gain increase. Recovery following backward adaptation required about the same average number of saccades as the preceding gain decrease. The first saccades of recovery were slightly less adapted than the last saccades of adaptation, suggesting that a small part of adaptation might have been strategic. After 50% backward jumps had reduced saccadic gain, the hypometric primary saccades during recovery were followed by hypometric corrective saccades, suggesting that they too had been adapted. When saccades of only one size underwent gain reduction, saccades to target steps of other amplitudes showed much less adaptation. Also, saccades in the direction opposite to that adapted were not adapted. Gain reductions endured if an adapted animal was placed in complete darkness for 20 h. These data indicate that saccadic gain adaptation is relatively specific to the adapted step and does not produce parametric changes of all saccades. Furthermore, adaptation is not a strategy, but involves enduring neuronal reorganization in the brain. We suggest that this paradigm engages mechanisms that determine saccadic gain in real life and therefore offers a reversible means to study their neuronal substrate.


Assuntos
Adaptação Fisiológica/fisiologia , Retroalimentação/fisiologia , Movimento/fisiologia , Movimentos Sacádicos/fisiologia , Animais , Macaca mulatta , Masculino
20.
Hum Mutat ; 10(2): 155-9, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9259198

RESUMO

The multiple endocrine neoplasia type 2 (MEN2) syndromes and Hirschsprung's disease (HSCR) are inherited neurocristopathies characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, parathyroid disease, and gastrointestinal neuromatosis. Mutations in the RET proto-oncogene are the underlying cause of the MEN2 syndromes and some cases of HSCR. In this report, we show that Cys 618 Arg mutation cosegregates with familial MTC and HSCR in two Moroccan Jewish families in which no involvement of pheochromocytoma or parathyroidism was observed. A single haplotype shared by chromosomes bearing the Cys 618 Arg mutation in both families strongly suggests a founder effect for this mutation. We have observed in our and in several other previously reported families, an excess of maternal over paternal mutated RET alleles in offsprings affected by HSCR. We suggest that parental imprinting may play a role in the ethiology of HSCR caused by mutations in the RET protooncogene.


Assuntos
Carcinoma Medular/genética , Proteínas de Drosophila , Doença de Hirschsprung/genética , Mutação , Proteínas Proto-Oncogênicas/genética , Receptores Proteína Tirosina Quinases/genética , Neoplasias da Glândula Tireoide/genética , Arginina/genética , Desoxirribonucleases de Sítio Específico do Tipo II/genética , Feminino , Impressão Genômica , Haplótipos , Humanos , Lactente , Judeus , Masculino , Marrocos/etnologia , Neoplasia Endócrina Múltipla/genética , Linhagem , Polimorfismo Conformacional de Fita Simples , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas c-ret , Razão de Masculinidade
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