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1.
Opt Lett ; 44(12): 3002-3005, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-31199366

RESUMO

We demonstrate a novel way to form and deplete a vapor-cell magneto-optic trap (MOT) using a reversible, solid-state alkali-metal source via an applied polarized voltage. Using ∼100 mW of electrical power, a trapped-atom number of 5×106 has been achieved, starting from near zero and the timescales of the MOT formation and depletion of ∼1 s. This fast, reversible, and low-power alkali-atom source is desirable in both tabletop and portable cold-atom systems. The core technology of this device should translate readily to other alkali and alkaline-earth elements that could find a wide range of uses in cold-atom systems and instruments.

2.
AJNR Am J Neuroradiol ; 40(3): 562-567, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30765383

RESUMO

BACKGROUND AND PURPOSE: Midnasal stenosis is a poorly defined entity that may be a component of other conditions of nasal obstruction contributing to respiratory distress in infants. We sought to establish whether midnasal vault narrowing is a component of well-defined syndromes of nasal narrowing, such as bilateral choanal atresia and pyriform aperture stenosis, and to characterize the nasal anatomy of patients with syndromic craniosynostosis. MATERIALS AND METHODS: A convenience sample of patients with pyriform aperture stenosis, bilateral choanal atresia, and Apert and Crouzon syndromes with maxillofacial CT scans was identified. Patients with Pierre Robin Sequence were used as controls. Nasal measurements were performed at the pyriform aperture, choana, and defined midnasal points on axial and coronal CT scans. Intra- and interrater reliability was quantified with the intraclass correlation coefficient. T tests with Bonferroni adjustment were used to assess differences from controls. RESULTS: The study included 50 patients: Eleven had pyriform aperture stenosis, 10 had Apert and Crouzon syndromes, 9 had choanal atresia, and 20 were controls. Measurements in patients with pyriform aperture stenosis and Apert and Crouzon syndromes were narrower than those of controls at all measured points (P < .001). Measurements in patients with choanal atresia were only narrow in the posterior half of the nose (P < .001). The intra- and interrater reliability of midnasal and pyriform measurements was very good to excellent (intraclass correlation coefficient > 0.87). The choanal measurement was good (intraclass correlation coefficient = 0.76-0.77). CONCLUSIONS: Pyriform aperture stenosis, Apert and Crouzon patients were narrower at all measured points compared to controls. Bilateral choanal atresia patients were only narrower in the posterior half of the nose. More research is needed to evaluate the clinical implications of these radiographic findings.


Assuntos
Doenças Nasais/patologia , Nariz/anormalidades , Benchmarking , Constrição Patológica/diagnóstico por imagem , Constrição Patológica/patologia , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Nariz/diagnóstico por imagem , Doenças Nasais/diagnóstico por imagem , Reprodutibilidade dos Testes , Tomografia Computadorizada por Raios X
3.
Geobiology ; 16(2): 179-189, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29384268

RESUMO

Phototrophic bacteria are among the most biogeochemically significant organisms on Earth and are physiologically related through the use of reaction centers to collect photons for energy metabolism. However, the major phototrophic lineages are not closely related to one another in bacterial phylogeny, and the origins of their respective photosynthetic machinery remain obscured by time and low sequence similarity. To better understand the co-evolution of Cyanobacteria and other ancient anoxygenic phototrophic lineages with respect to geologic time, we designed and implemented a variety of molecular clocks that use horizontal gene transfer (HGT) as additional, relative constraints. These HGT constraints improve the precision of phototroph divergence date estimates and indicate that stem green non-sulfur bacteria are likely the oldest phototrophic lineage. Concurrently, crown Cyanobacteria age estimates ranged from 2.2 Ga to 2.7 Ga, with stem Cyanobacteria diverging ~2.8 Ga. These estimates provide a several hundred Ma window for oxygenic photosynthesis to evolve prior to the Great Oxidation Event (GOE) ~2.3 Ga. In all models, crown green sulfur bacteria diversify after the loss of the banded iron formations from the sedimentary record (~1.8 Ga) and may indicate the expansion of the lineage into a new ecological niche following the GOE. Our date estimates also provide a timeline to investigate the temporal feasibility of different photosystem HGT events between phototrophic lineages. Using this approach, we infer that stem Cyanobacteria are unlikely to be the recipient of an HGT of photosystem I proteins from green sulfur bacteria but could still have been either the HGT donor or the recipient of photosystem II proteins with green non-sulfur bacteria, prior to the GOE. Together, these results indicate that HGT-constrained molecular clocks are useful tools for the evaluation of various geological and evolutionary hypotheses, using the evolutionary histories of both genes and organismal lineages.


Assuntos
Chloroflexi/genética , Cianobactérias/genética , Evolução Molecular , Redes e Vias Metabólicas/genética , Processos Fototróficos , Chlorobi/genética , Transferência Genética Horizontal
4.
Geobiology ; 15(4): 499-515, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28063184

RESUMO

Cryogenian cap carbonates that overlie Sturtian glacial deposits were formed during a post-glacial transgression. Here, we describe microfossils from the Kakontwe Formation of Zambia and the Taishir Formation of Mongolia-both Cryogenian age, post-Sturtian cap carbonates-and investigate processes involved in their formation and preservation. We compare microfossils from these two localities to an assemblage of well-documented microfossils previously described in the post-Sturtian Rasthof Formation of Namibia. Microfossils from both new localities have 10 ± 1 µm-thick walls composed of carbonaceous matter and aluminosilicate minerals. Those found in the Kakontwe Formation are spherical or ovoid and 90 ± 5 µm to 200 ± 5 µm wide. Structures found in the Taishir Formation are mostly spherical, 50 ± 5 µm to 140 ± 5 µm wide, with distinct features such as blunt or concave edges. Chemical and mineralogical analyses show that the walled structures and the clay fraction extracted from the surrounding sediments are composed of clay minerals, especially muscovite and illite, as well as quartz, iron and titanium oxides, and some dolomite and feldspar. At each locality, the mineralogy of the microfossil walls matched that of the clay fractions of the surrounding sediment. The abundance of these minerals in the walled microfossils relative to the surrounding carbonate matrix and microbial laminae, and the presence of minerals that cannot precipitate from solution (titanium oxide and feldspar), suggests that the composition represents the original mineralogy of the structures. Furthermore, the consistency in mineralogy of both microfossils and sediments across the three basins, and the uniformity of size and shape among mineral grains in the fossil walls indicate that these organisms incorporated these minerals by primary biological agglutination. The discovery of new, mineral-rich microfossil assemblages in microbially laminated and other fine-grained facies of Cryogenian cap carbonates from multiple localities on different palaeocontinents demonstrates that agglutinating eukaryotes were widespread in carbonate-dominated marine environments in the aftermath of the Sturtian glaciation.


Assuntos
Carbonatos/química , Eucariotos/isolamento & purificação , Fósseis , Organismos Aquáticos/isolamento & purificação , Sedimentos Geológicos/química , Namíbia
5.
Phys Rev Lett ; 115(16): 163003, 2015 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-26550873

RESUMO

In ponderomotive spectroscopy an amplitude-modulated optical standing wave is employed to probe Rydberg-atom transitions, utilizing a ponderomotive rather than a dipole-field interaction. Here, we engage nonlinearities in the modulation to drive dipole-forbidden transitions up to the fifth order. We reach transition frequencies approaching the sub-THz regime. We also demonstrate magic-wavelength conditions, which result in symmetric spectral lines with a Fourier-limited peak at the line center. Applicability to precision measurement is discussed.

6.
Science ; 297(5578): 75-8, 2002 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-12040088

RESUMO

Global distributions of thermal, epithermal, and fast neutron fluxes have been mapped during late southern summer/northern winter using the Mars Odyssey Neutron Spectrometer. These fluxes are selectively sensitive to the vertical and lateral spatial distributions of H and CO2 in the uppermost meter of the martian surface. Poleward of +/-60 degrees latitude is terrain rich in hydrogen, probably H2O ice buried beneath tens of centimeter-thick hydrogen-poor soil. The central portion of the north polar cap is covered by a thick CO2 layer, as is the residual south polar cap. Portions of the low to middle latitudes indicate subsurface deposits of chemically and/or physically bound H2O and/or OH.


Assuntos
Hidrogênio , Marte , Nêutrons , Gelo-Seco , Meio Ambiente Extraterreno , Raios gama , Gelo , Astronave , Espectrometria gama , Análise Espectral , Temperatura , Água
7.
AJNR Am J Neuroradiol ; 22(10): 1867-71, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11733318

RESUMO

BACKGROUND AND PURPOSE: Petrous apex cephaloceles (PACs) are uncommon lesions that are usually incidental but may be symptomatic. We reviewed MR and CT studies in 10 patients with PACs to identify characteristic imaging features that facilitate their diagnosis. METHODS: MR and CT studies from 10 patients with PACs were reviewed retrospectively. In each case the PAC was characterized by lesion center, signal intensity or attenuation, adjacent petrous apex pneumatization, and its relationship to Meckel's cave. Intraoperative findings were reviewed in the three cases in which surgery was performed. RESULTS: All 10 patients had lobulated expansile cystic petrous apex lesions centered along the posterolateral margin of Meckel's cave. All cysts were contiguous with Meckel's cave. Three patients had bilateral PACs. Four patients had symptoms that could potentially be explained by the PAC, while findings in the other six were incidental observations. Three patients underwent surgery, during which two lesions were diagnosed as meningoceles while the third was diagnosed as an arachnoid cyst protruding through a dural defect. CONCLUSION: PACs represent a protrusion of meninges and CSF from the posterolateral portion of Meckel's cave into the petrous apex, which is their characteristic imaging appearance. PACs are usually incidental but may be symptomatic. Surgical intervention should be approached cautiously and undertaken only when symptoms are clearly linked to the presence of this lesion.


Assuntos
Encefalocele/diagnóstico , Osso Petroso , Adulto , Idoso , Idoso de 80 Anos ou mais , Pré-Escolar , Diagnóstico Diferencial , Encefalocele/diagnóstico por imagem , Encefalocele/cirurgia , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Osso Petroso/diagnóstico por imagem , Osso Petroso/patologia , Tomografia Computadorizada por Raios X
8.
AJNR Am J Neuroradiol ; 22(8): 1566-9, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11559507

RESUMO

The case of a rare, mature teratoma of the oculomotor nerve manifesting as an interpeduncular cistern mass is presented. A basilar tip aneurysm initially was suspected on the basis of lesion location and MR imaging appearance. Subsequent CT and catheter angiography studies were atypical for aneurysm, leading to surgical biopsy. Pathologic analysis revealed a well-circumscribed mass composed of mature representatives of all three major cell lines characteristic of mature teratoma. The imaging findings are described, and a brief literature review is provided.


Assuntos
Neoplasias dos Nervos Cranianos/diagnóstico , Doenças do Nervo Oculomotor/diagnóstico , Teratoma/diagnóstico , Angiografia Digital , Feminino , Humanos , Imagem por Ressonância Magnética , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X
10.
AJNR Am J Neuroradiol ; 22(4): 786-94, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11290501

RESUMO

SUMMARY: Fifteen patients with neuropathic leg pain referable to the lumbosacral plexus or sciatic nerve underwent high-resolution MR neurography. Thirteen of the patients also underwent routine MR imaging of the lumbar segments of the spinal cord before undergoing MR neurography. Using phased-array surface coils, we performed MR neurography with T1-weighted spin-echo and fat-saturated T2-weighted fast spin-echo or fast spin-echo inversion recovery sequences, which included coronal, oblique sagittal, and/or axial views. The lumbosacral plexus and/or sciatic nerve were identified using anatomic location, fascicular morphology, and signal intensity as discriminatory criteria. None of the routine MR imaging studies of the lumbar segments of the spinal cord established the cause of the reported symptoms. Conversely, MR neurography showed a causal abnormality accounting for the clinical findings in all 15 cases. Detected anatomic abnormalities included fibrous entrapment, muscular entrapment, vascular compression, posttraumatic injury, ischemic neuropathy, neoplastic infiltration, granulomatous infiltration, neural sheath tumor, postradiation scar tissue, and hypertrophic neuropathy.


Assuntos
Aumento da Imagem , Perna (Membro)/inervação , Plexo Lombossacral/patologia , Imagem por Ressonância Magnética , Neuralgia/etiologia , Doenças do Sistema Nervoso Periférico/diagnóstico , Nervo Isquiático/patologia , Neuropatia Ciática/diagnóstico , Adolescente , Adulto , Idoso , Criança , Diagnóstico Diferencial , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade
11.
AJNR Am J Neuroradiol ; 20(9): 1609-12, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10543629

RESUMO

BACKGROUND AND PURPOSE: The prevalence of hippocampal sclerosis in the general nonepileptic patient population is not well described. While reports of its association with partial complex seizures are abundant, its absence in nonafflicted patients is generally presumed but not well documented. To test the hypothesis that hippocampal sclerosis is specific for epilepsy, we reviewed the MR imaging studies of 207 patients referred for hearing loss to determine whether high-resolution MR imaging could detect unsuspected hippocampal sclerosis in nonepileptic patients. METHODS: Our institution screens patients with hearing loss by using high-resolution coronal and axial temporal bone MR imaging that includes the hippocampus within the imaging volume. We retrospectively reviewed 207 studies randomly selected from this database. RESULTS: The hippocampus was normal in 205 patients; in the remaining two patients we identified one or more primary determinants for hippocampal sclerosis. Subsequent retrospective chart review revealed that both patients had had previously diagnosed seizure disorders. CONCLUSION: The imaging determinants of hippocampal sclerosis are not prevalent in nonepileptic patients. Incidental identification of hippocampal sclerosis on MR images is uncommon and significant, and should prompt further clinical investigation to exclude a seizure disorder.


Assuntos
Dano Encefálico Crônico/diagnóstico , Epilepsia/diagnóstico , Hipocampo/patologia , Imagem por Ressonância Magnética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Surdez/diagnóstico , Epilepsia Parcial Complexa/diagnóstico , Feminino , Humanos , Aumento da Imagem , Masculino , Pessoa de Meia-Idade , Neuroma Acústico/diagnóstico , Estudos Retrospectivos , Esclerose , Sensibilidade e Especificidade
12.
J Neurosci ; 19(12): 4705-17, 1999 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-10366604

RESUMO

Mutation of a conserved Asp (D98) in the rat serotonin (5HT) transporter (rSERT) to Glu (D98E) led to decreased 5HT transport capacity, diminished coupling to extracellular Na+ and Cl-, and a selective loss of antagonist potencies (cocaine, imipramine, and citalopram but not paroxetine or mazindol) with no change in 5HT Km value. D98E, which extends the acidic side chain by one carbon, affected the rank-order potency of substrate analogs for inhibition of 5HT transport, selectively increasing the potency of two analogs with shorter alkylamine side chains, gramine, and dihydroxybenzylamine. D98E also increased the efficacy of gramine relative to 5HT for inducing substrate-activated currents in Xenopus laevis oocytes, but these currents were noticeably dependent on extracellular medium acidification. I-V profiles for substrate-independent and -dependent currents indicated that the mutation selectively impacts ion permeation coupled to 5HT occupancy. The ability of the D98E mutant to modulate selective aspects of substrate recognition, to perturb ion dependence as well as modify substrate-induced currents, suggests that transmembrane domain I plays a critical role in defining the permeation pathway of biogenic amine transporters.


Assuntos
Proteínas de Transporte , Glicoproteínas de Membrana , Proteínas de Membrana Transportadoras , Proteínas do Tecido Nervoso , Serotonina/farmacocinética , Inibidores da Captação Adrenérgica/farmacologia , Alcaloides/farmacologia , Substituição de Aminoácidos/fisiologia , Animais , Ácido Aspártico , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/genética , Células COS , Proteínas de Ligação ao Cálcio/análise , Calnexina , Proteínas de Transporte/química , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Cocaína/análogos & derivados , Cocaína/farmacologia , Células HeLa , Humanos , Imipramina/farmacologia , Alcaloides Indólicos , Membranas Intracelulares/química , Radioisótopos do Iodo , Ativação do Canal Iônico/genética , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Dados de Sequência Molecular , N,N-Dimetiltriptamina/farmacologia , Oócitos/fisiologia , Estrutura Terciária de Proteína , Ratos , Homologia de Sequência de Aminoácidos , Proteínas da Membrana Plasmática de Transporte de Serotonina , Agonistas do Receptor de Serotonina/farmacologia , Cloreto de Sódio/farmacologia , Transfecção , Trítio , Xenopus
13.
Hum Hered ; 48(6): 343-5, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9813457

RESUMO

A novel microsatellite marker was found within 48.5 kb of the Fas gene. The observed heterozygosity in 160 healthy unrelated controls was 0.78. There was no evidence of linkage to type I diabetes mellitus in 120 diabetic children using the transmission disequilibrium test.


Assuntos
Diabetes Mellitus Tipo 1/genética , Grupo com Ancestrais do Continente Europeu/genética , Ligação Genética , Repetições de Microssatélites , Polimorfismo Genético , Receptor fas/genética , Sequência de Bases , Criança , Primers do DNA , Frequência do Gene , Heterozigoto , Humanos
14.
AJNR Am J Neuroradiol ; 19(4): 733-8, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9576664

RESUMO

PURPOSE: When troublesome MR imaging findings are noted in the petrous apex, the radiologist must determine if the area in question needs surgical therapy. Two nonsurgical entities, asymmetric fatty marrow and fluid-filled petrous air cells (trapped fluid), can be noted on conventional brain MR images and confused with pathologic lesions. Our observation that radiologists do not always confidently define the nonsurgical petrous apex lesions precipitated this investigation. METHODS: Twenty-three patients with either asymmetric fatty marrow (six) or unilateral effusion in a pneumatized petrous apex (17) on MR images were studied. Eighteen patients underwent high-resolution temporal bone CT. For all patients, the medical charts were reviewed retrospectively and/or the surgical and clinical follow-up findings were reviewed with the referring physician. RESULTS: In the patients with asymmetric fatty marrow, MR signal intensity followed fat on all sequences. The questioned apex in the patients with trapped fluid showed mixed MR signal characteristics (low to high T1 signal, high T2 signal). CT scans confirmed nonexpansile air-cell opacification. CONCLUSION: Asymmetric fatty marrow in the petrous apex and petrous air-cell effusions have characteristic MR and CT features that facilitate their correct diagnosis. Effusions with intermediate or high T1 signal are most frequently confused with cholesterol granulomas. In those patients, long-term CT follow-up may be helpful to confirm their stability.


Assuntos
Imagem por Ressonância Magnética , Osso Petroso/patologia , Tecido Adiposo/patologia , Adolescente , Adulto , Líquidos Corporais/metabolismo , Doenças Ósseas/diagnóstico , Medula Óssea/patologia , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Registros Médicos , Pessoa de Meia-Idade , Osso Petroso/diagnóstico por imagem , Osso Petroso/metabolismo , Tomografia Computadorizada por Raios X
15.
J Pediatr Orthop ; 18(1): 69-74, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9449105

RESUMO

The goal of selective dorsal rhizotomy (SDR) is to reduce surgically abnormal excitatory impulses to the lower extremities and thus to decrease spasticity in patients with cerebral palsy. One hundred thirty-one patients underwent SDR from 1986 to 1994 and were retrospectively reviewed for changes in tone, requirements for orthopedic intervention, and changes in ambulatory status. One hundred twelve patients had adequate follow-up. Postrhizotomy tone was decreased in all of the 112 patients, as measured by the Ashworth scale. No statistically significant change in ambulatory status was found. A total of 71 (65%) of 112 patients required orthopedic intervention for continued contractures and deformity. Of those judged "hypotonic" by the physiatrist postoperatively, 37% required subtalar stabilization for severe planovalgus. Hip subluxation was noted and treated (by femoral or pelvic osteotomy or both) in 27 (25%) of 112. Despite appropriately completed SDR, parents must understand the importance of periodic long-term follow-up and the possible, if not likely, need for additional surgery to alleviate contractures and stabilize subluxation of joints.


Assuntos
Paralisia Cerebral/cirurgia , Procedimentos Ortopédicos , Rizotomia , Adolescente , Adulto , Paralisia Cerebral/fisiopatologia , Criança , Pré-Escolar , Contratura/cirurgia , Seguimentos , Luxação do Quadril/cirurgia , Humanos , Reoperação , Estudos Retrospectivos , Caminhada
16.
Obes Res ; 5(5): 430-3, 1997 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9385617

RESUMO

The cloning of the murine obese (ob) gene and its human homologue has recently been reported. Mutations in the mouse ob gene result in hereditary obesity; however, the role of variations of OB in the regulation of bodyweight in humans has yet to be determined. The contribution of putative genetic variations in the human OB gene to total and regional fat mass in a normal twin population has been analyzed through linkage and association with a novel polymorphic marker, located in proximity to this gene. The polymorphic dinucleotide repeat, isolated from a P1 clone containing the human OB gene, was physically localized by long-range restriction mapping to within 30 kilobases of the OB locus. The marker was genotyped in a population of 47 healthy female/female dizygotic (DZ) twin pairs for which direct measures of central abdominal and whole body fat had been obtained by dual X-ray absorbtiometry. Possible linkage between the microsatellite marker and whole-body (p = 0.008), but not central abdominal (p = 0.09), fat deposits was indicated. No association between fat depot phenotype and marker genotype was detected. These results suggest that genetic variation in or close to the human OB gene may play a role in the size of body fat stores in healthy women.


Assuntos
Composição Corporal/genética , Repetições de Dinucleotídeos , Marcadores Genéticos , Obesidade/genética , Polimorfismo Genético , Tecido Adiposo , Feminino , Ligação Genética , Humanos , Hibridização de Ácido Nucleico , Reação em Cadeia da Polimerase , Gêmeos Dizigóticos
17.
J Neurosci ; 17(8): 2691-702, 1997 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-9092590

RESUMO

Chemical signaling by dopamine (DA) and L-norepinephrine (L-NE) at synapses is terminated by uptake via specialized presynaptic transport proteins encoded by the DA transporter (DAT) and L-NE transporter (NET) genes, respectively. In some vertebrate neurons, particularly the sympathetic neurons of amphibians, L-NE is converted to L-epinephrine (L-Epi, adrenaline) and released as the primary neurotransmitter. Although evidence exists for a molecularly distinct L-Epi transporter (ET) in the vertebrate brain and peripheral nervous system, a transporter specialized for extracellular L-Epi clearance has yet to be identified. To pursue this issue, we cloned transporter cDNAs from bullfrog (Rana catesbiana) paravertebral sympathetic ganglia and characterized functional properties via heterologous expression in non-neuronal cells. A cDNA of 2514 bp (fET) was identified for which the cognate 3.1 kb mRNA is highly enriched in frog sympathetic ganglia. Sequence analysis of the fET cDNA reveals an open reading frame coding for a protein of 630 amino acids. Inferred fET protein sequence bears 75, 66, and 48% amino acid identity with human NET, DAT, and the 5-hydroxytryptamine transporter (SERT), respectively. Transfection of fET confers Na+- and Cl--dependent catecholamine uptake in HeLa cells. Uptake of [3H]-L-NE by fET is inhibited by catecholamines in a stereospecific manner. L-Epi and DA inhibit fET-mediated [3H]-L-NE uptake more potently than they inhibit [3H]-L-NE uptake by human NET (hNET), whereas L-NE exhibits equivalent potency between the two carriers. Moreover, fET exhibits a greater maximal velocity (Vmax) for the terminal products of catecholamine biosynthesis (L-Epi > L-NE >> DA), unlike hNET, in which a Vmax rank order of L-NE > DA > L-Epi is observed. fET-mediated transport of catecholamines is sensitive to cocaine and tricyclic antidepressants, with antagonist potencies significantly correlated with hNET inhibitor sensitivity. Amino acid conservation and divergence of fET with mammalian catecholamine transporters help define residues likely to be involved in catecholamine recognition and translocation as well as blockade by selective reuptake inhibitors.


Assuntos
Proteínas de Anfíbios , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Gânglios Simpáticos/metabolismo , Proteínas de Membrana Transportadoras , Proteínas do Tecido Nervoso , Simportadores , Sequência de Aminoácidos , Animais , Sequência de Bases , Proteínas de Transporte/biossíntese , Bovinos , Clonagem Molecular , Sequência Conservada , Primers do DNA , Proteínas da Membrana Plasmática de Transporte de Dopamina , Epinefrina/metabolismo , Epinefrina/farmacologia , Células HeLa , Humanos , Cinética , Glicoproteínas de Membrana/química , Camundongos , Dados de Sequência Molecular , Proteínas da Membrana Plasmática de Transporte de Norepinefrina , Especificidade de Órgãos , Reação em Cadeia da Polimerase , Rana catesbeiana , Ratos , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Proteínas da Membrana Plasmática de Transporte de Serotonina , Transfecção
18.
Aust Dent J ; 41(3): 151-8, 1996 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8768636

RESUMO

All dentists registered in South Australia were surveyed in July 1993 in relation to removable prosthodontics. The replies indicated that removable prosthodontics constituted a significant part of most dental practices. Most dentists felt that removable prosthodontics should be an essential part of the undergraduate curriculum. They felt that more expertise is now required to manage the treatment of the ageing population with either their first or replacement removable prostheses. The majority of dentists felt that their own undergraduate training had equipped them well to manage removable prosthodontic treatment for their patients; however, many helpful suggestions were made on areas that they thought required more emphasis.


Assuntos
Atitude do Pessoal de Saúde , Prótese Dentária , Padrões de Prática Médica , Prostodontia , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Currículo , Prótese Dentária/estatística & dados numéricos , Reembasamento de Dentadura/estatística & dados numéricos , Reparação em Dentadura/estatística & dados numéricos , Prótese Total/estatística & dados numéricos , Prótese Parcial Removível/estatística & dados numéricos , Educação em Odontologia , Previsões , Humanos , Pessoa de Meia-Idade , Padrões de Prática Médica/estatística & dados numéricos , Prostodontia/educação , Prostodontia/tendências , Austrália do Sul/epidemiologia
19.
Dev Neurosci ; 18(5-6): 524-34, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8940628

RESUMO

Using degenerate oligonucleotide probes encoding conserved regions of the gamma-aminobutyric acid/norepinephrine transporter gene family, we have cloned a rat brain cDNA encoding a creatine transporter (rCREAT). rCREAT encodes a highly hydrophobic, 635-amino-acid protein possessing 12 potential transmembrane domains and canonical sites for N-linked glycosylation and protein phosphorylation. Transfection of rCREAT cDNA into mammalian cells results in the expression of [14C]creatine uptake, which is blocked by low micromolar concentrations of recognized creatine uptake inhibitors. Two rCREAT mRNAs are expressed in the rat brain, retina, kidney and heart. Whole-brain rCREAT mRNAs demonstrate a marked postnatal rise to steady-state adult levels. In situ hybridization studies indicate a widespread, differential rCREAT mRNA expression in adult rat brain, with high expression noted over myelinated fiber tracts, cerebellar granule cells, hippocampal pyramidal cells, brainstem nuclei and endothelial cells of the choroid plexus. These studies will allow the development of new molecular probes useful for defining the creatine transporter's cellular expression pattern, function in ATP homeostasis and association with disorders of cellular energy metabolism.


Assuntos
Encéfalo/metabolismo , Proteínas de Transporte/metabolismo , Células HeLa/metabolismo , Proteínas de Membrana Transportadoras , Ratos/metabolismo , Transfecção , Sequência de Aminoácidos , Animais , Animais Recém-Nascidos/metabolismo , Sequência de Bases , Proteínas de Transporte/genética , Expressão Gênica , Humanos , Dados de Sequência Molecular , RNA/metabolismo , Especificidade por Substrato , Distribuição Tecidual
20.
J Exp Biol ; 198(Pt 10): 2197-212, 1995 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-7500004

RESUMO

Transport of norepinephrine (NE+) by cocaine- and antidepressant-sensitive transporters in presynaptic terminals is predicted to involve the cotransport of Na+ and Cl-, resulting in a net movement of charge per transport cycle. To explore the relationship between catecholamine transport and ion permeation through the NE transporter, we established a human norepinephrine transporter (hNET) cell line suitable for biochemical analysis and patch-clamp recording. Stable transfection of hNET cDNA into HEK-293 (human embryonic kidney) cells results in lines exhibiting (1) a high number of transporter copies per cell (10(6)), as detected by radioligand binding and hNET-specific antibodies, (2) high-affinity, Na(+)-dependent transport of NE, and (3) inhibitor sensitivities similar to those of native membranes. Whole-cell voltage-clamp of hNET-293 cells reveals NE-induced, Na(+)-dependent currents blocked by antidepressants and cocaine that are absent in parental cells. In addition to NE-dependent currents, transfected cells posses an NE-independent mode of charge movement mediated by hNET. hNET antagonists without effect in non-transfected cells abolish both NE-dependent and NE-independent modes of charge movement in transfected cells. The magnitude of NE-dependent currents in these cells exceeds the expectations of simple carrier models using previous estimates of transport rates. To explain our observations, we propose that hNETs function as ion-gated ligand channels with an indefinite stoichiometry relating ion flux to NE transport. In this view, external Na+ and NE bind to the transporter with finite affinities in a cooperative fashion. However, coupled transport may not predict the magnitude or the kinetics of the total current through the transporter. We propose instead that Na+ gates NE transport and also the parallel inward flux of an indeterminate number of ions through a channel-like pore.


Assuntos
Agonistas alfa-Adrenérgicos/metabolismo , Antidepressivos/farmacologia , Proteínas de Transporte/metabolismo , Cocaína/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Rim/metabolismo , Norepinefrina/metabolismo , Simportadores , Proteínas de Transporte/genética , Linhagem Celular , Células Cultivadas , Humanos , Transporte de Íons , Rim/citologia , Rim/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Proteínas da Membrana Plasmática de Transporte de Norepinefrina , Técnicas de Patch-Clamp , Sódio/metabolismo , Transfecção
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