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1.
Nat Commun ; 13(1): 364, 2022 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-35042881

RESUMO

The near-Earth asteroid (162173) Ryugu, the target of Hayabusa2 space mission, was observed via both orbiter and the lander instruments. The infrared radiometer on the MASCOT lander (MARA) is the only instrument providing spectrally resolved mid-infrared (MIR) data, which is crucial for establishing a link between the asteroid material and meteorites found on Earth. Earlier studies revealed that the single boulder investigated by the lander belongs to the most common type found on Ryugu. Here we show the spectral variation of Ryugu's emissivity using the complete set of in-situ MIR data and compare it to those of various carbonaceous chondritic meteorites, revealing similarities to the most aqueously altered ones, as well as to asteroid (101955) Bennu. The results show that Ryugu experienced strong aqueous alteration prior to any dehydration.

2.
Eur J Neurol ; 28(1): 1-2, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32986259

Assuntos
Deglutição , Humanos
3.
Science ; 365(6455): 817-820, 2019 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-31439797

RESUMO

The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu's surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.

4.
Eur J Neurol ; 25(9): 1182-1188, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29782693

RESUMO

BACKGROUND AND PURPOSE: The aim of this pooled patient-level data analysis was to test if multidomain interventions, addressing several modifiable vascular risk factors simultaneously, are more effective than usual post-stroke care for the prevention of cognitive decline after stroke. METHODS: This pooled patient-level data analysis included two randomized controlled trials using a multidomain approach to target vascular risk factors in stroke patients and cognition as primary outcome. Changes from baseline to 12 months in the trail making test (TMT)-A, TMT-B and 10-words test were analysed using stepwise backward linear mixed models with study as random factor. Two analyses were based on the intention-to-treat (ITT) principle using different imputation approaches and one was based on complete cases. RESULTS: Data from 322 patients (157 assigned to multidomain intervention and 165 to standard care) were analysed. Differences between randomization groups for TMT-A scores were found in one ITT model (P = 0.014) and approached significance in the second ITT model (P = 0.087) and for complete cases (P = 0.091). No significant intervention effects were found for any of the other cognitive variables. CONCLUSION: We found indications that multidomain interventions compared with standard care can improve the scores in TMT-A at 1 year after stroke but not those for TMT-B or the 10-words test. These results have to be interpreted with caution due to the small number of patients.


Assuntos
Disfunção Cognitiva/etiologia , Disfunção Cognitiva/prevenção & controle , Acidente Vascular Cerebral/complicações , Idoso , Disfunção Cognitiva/psicologia , Terapia Combinada , Feminino , Humanos , Análise de Intenção de Tratamento , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Fatores de Risco , Acidente Vascular Cerebral/psicologia , Reabilitação do Acidente Vascular Cerebral/métodos , Teste de Sequência Alfanumérica , Resultado do Tratamento
6.
Eur J Neurol ; 21(1): 5-10, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24112436

RESUMO

BACKGROUND AND PURPOSE: Diabetes is a predictor for poor outcome after thrombolysis in stroke patients, and early post-stroke glycaemia is associated with higher rates of post-thrombolytic symptomatic intracerebral haemorrhages (SICHs). Diabetic stroke patients may nevertheless profit from thrombolysis. Here, we compared outcome data of matched thrombolysed and non-thrombolysed diabetic and non-diabetic stroke patients from a national database. METHODS: The outcomes of 1079 matched quadruples, each consisting of a thrombolysed diabetic, a non-thrombolysed diabetic, a thrombolysed non-diabetic and a non-thrombolysed non-diabetic case (a total of 4316 cases), enrolled in the Austrian Stroke Unit Registry (2004-2013), were compared. Patients were matched according to sex, age, stroke severity, pre-stroke disability and prior stroke. RESULTS: A regression model with improvement as depending variable found no effect of diabetes (P = 0.158) or the interaction diabetes × thrombolysis (P = 0.507), whereas the effect of thrombolysis itself was highly significant (P < 0.001). Functional outcome (modified Rankin Scale) was significantly better in thrombolysed than in non-thrombolysed diabetic patients at discharge from the stroke-unit (P < 0.001) and 3 months later (P = 0.006). No significant differences were found in the number of SICHs after thrombolytic treatment between diabetic (4.9%) and non-diabetic strokes (3.5%). Both groups had a higher risk of SICH compared with the non-thrombolysed groups (diabetics 2.6%, non-diabetics 2.5%). Due to lack of documentation, the effect of admission blood glucose on SICH was not investigated. CONCLUSIONS: Data from this nationwide survey show that diabetic stroke patients receive a substantial benefit from thrombolysis, and therefore diabetic strokes should not be excluded from thrombolytic treatment.


Assuntos
Diabetes Mellitus , Acidente Vascular Cerebral/terapia , Terapia Trombolítica , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Sistema de Registros
7.
Eur J Neurol ; 20(1): 35-49, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22672523

RESUMO

BACKGROUND AND PURPOSE: Despite a high prevalence of post-stroke cognitive impairment, therapeutic possibilities are still limited. Stroke and dementia share the same cluster of modifiable risk factors. Thus, lifestyle interventions and strict adherence to medication may not only decrease the risk of recurrent stroke but also the risk of post-stroke cognitive decline. METHODS: We performed a systematic literature search for randomized clinical trials (RCTs) targeting modifiable risk factors for the prevention of cognitive decline following stroke. RESULTS: We identified 25 non-pharmacological interventions and eight multiple risk factor interventions in stroke patients using cognition as outcome measure. None of the published trials investigated interventions aimed at the prevention of post-stroke cognitive decline. However, a number of ongoing trials aim at risk factor reduction and include measures on cognition. CONCLUSION: Evidence for risk factor modification for the prevention of cognitive decline after stroke is scarce and comes mainly from observational studies. There is a need for more RCTs targeting the prevention of post-stroke dementia using lifestyle interventions and a multiple risk factor approach.


Assuntos
Transtornos Cognitivos , Estilo de Vida , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/terapia , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/prevenção & controle , Transtornos Cognitivos/psicologia , Bases de Dados Factuais/estatística & dados numéricos , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto
8.
Science ; 336(6082): 687-90, 2012 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-22582254

RESUMO

Vesta's surface is characterized by abundant impact craters, some with preserved ejecta blankets, large troughs extending around the equatorial region, enigmatic dark material, and widespread mass wasting, but as yet an absence of volcanic features. Abundant steep slopes indicate that impact-generated surface regolith is underlain by bedrock. Dawn observations confirm the large impact basin (Rheasilvia) at Vesta's south pole and reveal evidence for an earlier, underlying large basin (Veneneia). Vesta's geology displays morphological features characteristic of the Moon and terrestrial planets as well as those of other asteroids, underscoring Vesta's unique role as a transitional solar system body.

10.
J Neurol Neurosurg Psychiatry ; 79(3): 246-52, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17578857

RESUMO

Alien hand syndrome (AHS) is rare, but important due to its disabling impact on everyday life. The determining characteristic of AHS is intermanual conflict, a type of inhibitory motor behaviour that occurs against willed action. Its components have previously been described as single case reports, but not as a systematic study. This review includes eight chronic cases, all of which are due to infarcts of the anterior cerebral artery. Clinical investigation included testing of motor behaviour related to everyday activities, such as tying shoelaces, lighting a candle and other bimanual tasks. Video-analysis showed that conflicting behaviour occurs in two distinct forms. One consists of interfering, rudimentary, hesitant and repetitive movements of the (alien) hand, often initiated by movements of the other hand. In some instances, disturbance of ongoing action is seen as spacious, ballistic-like extensions of the whole arm. This was most prevalent in three of the eight cases. In one patient, it was also seen as conflict with both feet (eg, when putting on slippers) or as a conflict of intentions (eg, when planning to enter a room). The other form consisted of massive groping and grasping behaviour as the most dominant features, such as a "tug of war between hands", and was seen in five patients. Avoidance behaviour included sitting on the affected arm, holding it under the table or keeping objects out of reach. Enforcement of such strategies was used for rehabilitation and--although beneficial in the training sessions--carried over very little to everyday life. All cases had two distinct brain lesions, one in the genu or anterior rostrum of the corpus callosum and one in the contralateral frontomedial cortical and subcortical region. Chronic AHS is the only clinical syndrome that shows complex inhibitory motor behaviour in a more or less pure form because it has become detached from the control of motor planning and execution. It can best be understood as sequences of complex inhibitory motor programmes that have become isolated from normal motor planning, which usually suppresses them via the contralateral cortico-subcortical prefrontal circuits and the corpus callosum. Thus, the mirror world of complex motor inhibition becomes clinically visible in such patients.


Assuntos
Apraxia Ideomotora/diagnóstico , Apraxia Ideomotora/etiologia , Mãos/fisiopatologia , Transtornos dos Movimentos/etiologia , Transtornos da Percepção/etiologia , Acidente Vascular Cerebral/complicações , Adulto , Idoso , Doença Crônica , Feminino , Lateralidade Funcional , Humanos , Masculino , Pessoa de Meia-Idade , Transtornos dos Movimentos/diagnóstico , Estudos Prospectivos , Acidente Vascular Cerebral/diagnóstico , Síndrome , Gravação em Vídeo
11.
Eur J Neurol ; 13(9): 1002-8, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16930368

RESUMO

Neurological patient populations are usually described by diagnosis or in terms of functional disability measures but rarely by their clinical syndromes. A point-prevalence study was conducted assessing 349 neurological inpatients to determine the frequency and co-occurrence of disabling neurological syndromes, considering a wider spectrum including pain, emotional, neuropsychological, vegetative and sensorimotor syndromes. Of the study patients, 61% (n = 224) had sensorimotor syndromes, 53% (n = 185) had neuropsychological disorders, 40% (n = 139) of the patients suffered from pain, emotional disorders were found in 36% (n = 122) and vegetative disorders in 33% (n = 113). Although frequency varied by neurological diagnosis, these disabling conditions were found across all inpatient groups of diagnosis. Similarly, disorders outside the motor domains grouped according to their Barthel Index showed a striking frequency in patients considered as activities of daily living independent, reflecting a wider spectrum of disability that functional measures are not able to capture. Of the study population, 68% (n = 237) suffered from co-occurring disorders from different categories (pain, emotional, neuropsychological, vegetative and sensorimotor syndromes). There is a high prevalence and co-occurrence of disabling syndromes in neurological inpatients. These proportions reflect the neurological workload in a patient population and should be considered in future rehabilitation research and allocation of resources.


Assuntos
Avaliação da Deficiência , Pessoas com Deficiência , Hospitais , Doenças do Sistema Nervoso/epidemiologia , Doenças do Sistema Nervoso/fisiopatologia , Atividades Cotidianas , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doenças do Sistema Nervoso/classificação
12.
Nature ; 435(7038): 66-9, 2005 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-15875014

RESUMO

The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed. By contrast, Saturn's regular satellites (with prograde, low-inclination, circular orbits) probably accreted within the sub-nebula in which Saturn itself formed. Here we report imaging spectroscopy of Phoebe resulting from the Cassini-Huygens spacecraft encounter on 11 June 2004. We mapped ferrous-iron-bearing minerals, bound water, trapped CO2, probable phyllosilicates, organics, nitriles and cyanide compounds. Detection of these compounds on Phoebe makes it one of the most compositionally diverse objects yet observed in our Solar System. It is likely that Phoebe's surface contains primitive materials from the outer Solar System, indicating a surface of cometary origin.

13.
Eur J Neurol ; 11(11): 742-8, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15525295

RESUMO

Previous studies have shown a peak occurrence of ischemic stroke in the morning but no consistent finding has been attributed to this. Focused on lacunar strokes we performed a prospective study with a detailed diagnostic protocol including parameters of recent infection, indicators of sleep apnea and cerebral vasoreactivity (CVR), aimed at defining differences in risk profiles between diurnal and nocturnal strokes. Consecutively we included 33 nocturnal and 54 diurnal strokes. Baseline characteristics, known risk factors, stroke severity and topology were not different between groups. The mean low-density lipoprotein (LDL) cholesterol level was significantly higher amongst patients with nocturnal strokes (133.3 +/- 35.2 mg/dl vs. 115.5 +/- 39.8 mg/dl; P = 0.04), as well as the proportion of patients with any dyslipidemia (94% vs. 77.8%; P = 0.047). Twenty-four-hour blood pressure recordings showed a reduced nocturnal decrease of blood pressure in subjects with strokes that occurred between 10 pm and 6 am in comparison with those whose strokes occurred between 6 am and 2 pm (5.0 +/- 7.3% vs. 11.0 +/- 6.7%; P = 0.049). No significant differences were found for parameters of recent infection (including seroreactivity against Chlamydia pneumoniae and cytomegalovirus), CVR, indicators of sleep apnea and the degree of white matter disease assessed by magnetic resonance tomography. Dyslipidemia, especially elevated LDL cholesterol is more prevalent in nocturnal lacunar strokes especially when combined with a reduced nocturnal dipping of blood pressure. This risk factor profile can be regarded as an additional target for stroke prevention.


Assuntos
Pressão Sanguínea/fisiologia , LDL-Colesterol/sangue , Hiperlipidemias/sangue , Hiperlipidemias/fisiopatologia , Acidente Vascular Cerebral/sangue , Acidente Vascular Cerebral/fisiopatologia , Idoso , Monitorização Ambulatorial da Pressão Arterial , Encéfalo/diagnóstico por imagem , Infarto Cerebral/diagnóstico por imagem , Ritmo Circadiano/fisiologia , Eletrocardiografia , Feminino , Humanos , Hipertensão/fisiopatologia , Lipídeos/sangue , Masculino , Fatores de Risco , Acidente Vascular Cerebral/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Ultrassonografia Doppler Transcraniana
14.
Eur Surg Res ; 34(1-2): 61-7, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11867903

RESUMO

BACKGROUND: Sepsis is still a major cause of death despite well-developed therapeutical strategies such as antibiotics and supportive medication. The aim of this study was to characterize the long-term effects of a two-hit porcine sepsis model with a hemorrhagic shock as 'first hit' followed by a Pseudomonas aeruginosa infusion as 'second hit'. MATERIALS AND METHODS: Twelve juvenile healthy pigs were anesthetized and hemodynamically monitored. The two-hit group (n = 6) underwent a hemorrhagic shock with a 50% reduction of the mean arterial pressure and/or cardiac index for 45 min, followed by resuscitation, while the control group (n = 6) received no pretreatment. All chronically catheterized conscious pigs were challenged with a P. aeruginosa infusion (1.6 x 10(7) CFU/kg/h for the first 24 h followed by 1.6 x 10(6) CFU/kg/h for the next 24 h) and observed for another 48 h. RESULTS: The two-hit group showed the following significant differences to the control group: higher APACHE II scores prior to sepsis induction, increased persisting mean pulmonary arterial pressure (MPAP) and pulmonary vascular resistance index (PVRI) during bacterial challenge. In contrast, systemic vascular resistance (SVRI) was reduced at the end of the study. Throughout the observation period, the mean arterial pressure (MAP) was significantly reduced. CONCLUSIONS: The present study shows that the clinical course and hemodynamic effects of a P. aeruginosa sepsis will be aggravated by a preceding hemorrhagic shock during an observation period of 96 h. This two-hit model represents a valid, clinically relevant experimental protocol in sepsis research.


Assuntos
Infecções por Pseudomonas/fisiopatologia , Pseudomonas aeruginosa , Sepse/fisiopatologia , Choque Hemorrágico/fisiopatologia , APACHE , Animais , Pressão Sanguínea , Doença Crônica , Citocinas/sangue , Modelos Animais de Doenças , Pulmão/patologia , Doenças Pulmonares Intersticiais/patologia , Doenças Pulmonares Intersticiais/fisiopatologia , Neutrófilos/citologia , Infecções por Pseudomonas/patologia , Pressão Propulsora Pulmonar , Sepse/patologia , Choque Hemorrágico/patologia , Suínos , Trombocitopenia/fisiopatologia , Resistência Vascular
15.
Surgery ; 130(6): 1005-10, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11742330

RESUMO

BACKGROUND: We hypothesized that intraoperative parathyroid hormone monitoring (IOPTH) reliably would detect double parathyroid adenomas. METHODS: This was a retrospective study of 20 patients undergoing conventional parathyroidectomy with resection of exactly 2 abnormal glands. Full exploration was performed regardless of IOPTH values, which were measured after anesthetic induction and 5 and 10 minutes following removal of the first abnormal parathyroid gland. Failure to fall below 50% of baseline value by 10 minutes following resection of the first gland indicated the presence of multiglandular disease. RESULTS: All patients were cured. All excised glands were hypercellular on histology. Mean IOPTH values in 9 of the 20 patients with true negative results (noncurative decrease, another gland present) were 66% +/- 7% at 5 minutes and 83% +/- 15% at 10 minutes. The IOPTH values in 11 of the 20 patients with false positive results (curative decrease, another gland present) were 28% +/- 4% at 5 minutes and 18% +/- 2% at 10 minutes. The false positive rate of IOPTH was 55%. CONCLUSIONS: We found that IOPTH failed to reliably detect the presence of double parathyroid adenomas. These data suggest that caution should be exercised when terminating limited parathyroid exploration based on a curative fall in IOPTH values.


Assuntos
Adenoma/diagnóstico , Monitorização Intraoperatória , Hormônio Paratireóideo/sangue , Neoplasias das Paratireoides/diagnóstico , Paratireoidectomia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
16.
Tierarztl Prax ; 21(3): 225-32, 1993 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-8346525

RESUMO

Bilateral blindness was diagnosed in a 5-year-old Hanoverian gelding presented for evaluation of a corneal opacity in one eye. About 12 months prior to the examination, the gelding had fallen head over, hitting his head and the cornea. Clinical and electroretinographic findings as well as pathohistologic and ultrastructural lesions of both eyes including the optic nerves are presented. Ophthalmoscopically visible pigment disruption of the non-tapetal fundus adjacent to the optic discs correlated morphologically with foci of degeneration and atrophy of the retina, whereas ophthalmoscopically visible accumulation of pigment was morphologically characterized by hypertrophy of the pigment epithelium, increased intracellular pigment accumulation and by migration of pigment cells into the inner lamina of the retina. Severe atrophy of the retinal neuronal layer was linked to traumatic optic nerve degeneration.


Assuntos
Cegueira/veterinária , Traumatismos Craniocerebrais/veterinária , Traumatismos Oculares/veterinária , Doenças dos Cavalos/etiologia , Animais , Cegueira/etiologia , Lesões da Córnea , Traumatismos Craniocerebrais/complicações , Eletrorretinografia/veterinária , Traumatismos Oculares/complicações , Cavalos , Hipertrofia , Masculino , Microscopia Eletrônica , Oftalmoscopia/veterinária , Nervo Óptico/patologia , Traumatismos do Nervo Óptico , Epitélio Pigmentado Ocular/patologia , Retina/patologia , Retina/ultraestrutura , Degeneração Retiniana/etiologia , Degeneração Retiniana/veterinária
17.
Ther Drug Monit ; 14(5): 397-401, 1992 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1448848

RESUMO

A sensitive high-performance liquid chromatographic method for the analysis of the immunosuppressant cyclosporin G (OG 37-325, Nva2-cyclosporine, CsG) in whole blood has been developed. Sample preparation, employing cyclosporin A (CsA) as internal standard, involves organic extraction with methyl t-butyl ether under sequential acidic and basic conditions. Chromatography is performed using a 2 mm inside diameter x 25 cm column packed with 5 microns octyl (C8) material. An isocratic mobile phase comprised of acetonitrile:methanol:water, at a flow rate of 0.4 ml/min, is utilized. Separation is monitored at 230 nm. Data are also presented that demonstrate the use of CsG as an alternative internal standard to cyclosporin D for liquid chromatographic determinations of CsA.


Assuntos
Ciclosporinas/sangue , Transplante/fisiologia , Cromatografia Líquida de Alta Pressão/métodos , Ciclosporina/sangue , Humanos , Padrões de Referência , Sensibilidade e Especificidade
18.
Transfusion ; 29(4): 298-303, 1989 May.
Artigo em Inglês | MEDLINE | ID: mdl-2497566

RESUMO

Medicare regulations and the guidelines of the Joint Commission on Accreditation of Healthcare Organizations require assessment of the appropriateness of transfusions by a hospital committee. A set of criteria maps for component transfusion review by nurses or technical personnel was designed, tested, and modified. The algorithms were based on written guidelines developed by a group of physicians. In the first part of the study, 196 medical records of patients from medical and surgical diagnosis-related groups with the highest utilization of blood (Group I) were screened. Forty patients were excluded because of a preexisting transfusion protocol. Of the remaining 156 patients, 146 (94%) received red cell transfusions, of which 96 percent were indicated, 1 percent not indicated, and 3 percent controversial. Thirty-five patients (22%) received fresh-frozen plasma transfusions, of which 69 percent were indicated, 11 percent not indicated, 17 percent controversial, and 6 percent indeterminate. In the second part of the study, medical records were screened from 99 randomly selected patients who had received red cell transfusions (Group II), and the results were similar to those in Group I. Physician review was necessary in 20 percent of the transfused patients screened with the criteria maps. It is concluded that algorithms for transfusion review can be developed and used easily to fulfill regulatory and accreditation requirements and to plan focused educational programs.


Assuntos
Algoritmos , Transfusão de Sangue/estatística & dados numéricos , Auditoria Médica , Adolescente , Adulto , Idoso , Transfusão de Sangue/economia , Transfusão de Sangue/normas , Transfusão de Eritrócitos , Fator VIII/administração & dosagem , Fibrinogênio/administração & dosagem , Humanos , Joint Commission on Accreditation of Healthcare Organizations , Auditoria Médica/métodos , Auditoria Médica/normas , Medicare , Pessoa de Meia-Idade , Plasma/transplante , Transfusão de Plaquetas , Controle de Qualidade , Distribuição Aleatória , Estados Unidos
19.
Genetics ; 117(2): 173-9, 1987 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-2959588

RESUMO

A PRM-cI-lacZ fusion inserted into the b2 region of bacteriophage lambda was used to isolate mutations affecting expression of both the lambda cI gene and the lacZ gene. One such mutation, a change in the cI initiator codon from AUG to AUA, reduces immunity of a lambda prophage to superinfection, and causes a 60-70% reduction in beta-galactosidase synthesis, even when repressor is supplied in trans. The effect of the mutation on lacZ gene expression is eliminated in a rho- bacterial strain, and the mutation has no effect on transcription initiated at PRM in vitro. Therefore, the effects of the mutation are due to premature p-dependent termination of transcription in the absence of translation of the cI gene, as if the mutation were a nonsense polar mutation.


Assuntos
Bacteriófago lambda/genética , Códon , Escherichia coli/genética , Galactosidases/genética , Genes Virais , Mutação , Biossíntese de Proteínas , RNA Mensageiro , Proteínas Repressoras/genética , Fatores de Transcrição/genética , beta-Galactosidase/genética , Sequência de Bases , Clonagem Molecular , Dados de Sequência Molecular , Transcrição Gênica
20.
Gene ; 54(2-3): 291-7, 1987.
Artigo em Inglês | MEDLINE | ID: mdl-2958391

RESUMO

A pRM-cI-lacZ fusion inserted into the b2 region of bacteriophage lambda imm21 was used to isolate mutations in the lambda pRM promoter. Among the mutations causing defects in synthesis of both repressor (cI gene product) and beta-galactosidase, new promoter mutations were identified at positions -11 and -32 relative to the cI transcription start point. Both mutations are changes in conserved (consensus) nucleotides in pRM, but the mutation at -11, which alters a more highly conserved nucleotide, has a somewhat greater effect on promoter function in vitro than does the mutation at -32. We also isolated a mutation at -69 in the repressor-binding site OR1, which presumably prevents activation of pRM by repressor.


Assuntos
Bacteriófago lambda/genética , Escherichia coli/genética , Mutação , Regiões Promotoras Genéticas , Sequência de Bases , Genes , Genes Bacterianos , Genes Virais , Transcrição Gênica , beta-Galactosidase/genética
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