Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 34
Filtrar
1.
Braz J Biol ; 84: e281457, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38896729

RESUMO

Cowpea is a leguminous plant belonging to the fabaceae family cultivated in the North and Northeast regions of Brazil, with productive potential. Among the abiotic factors, water deficiency is one of the main environmental limitations that influence agricultural production in the world. The objective of this work was to study the relative water content and osmoregulators of cowpea plants subjected to water stress. The experiment was carried out in a greenhouse at the Universidade Federal Rural da Amazônia (UFRA, Belém, PA), cowpea plants BR-17 Gurguéia Vigna unguiculata (L.) Walp were used. The experimental design was completely randomized (DIC) in a 2 × 2 factorial scheme, two water conditions (control and water deficit) and two times of stress (four and six days of water suspension), with 7 replications, totaling 28 experimental units. The water deficit affected plants, causing a reduction in relative water content (69.98%), starch (12.84% in leaves and 23.48% in roots) and carbohydrates (84.34%), and an increase in glycine-betaine, sucrose (114.11% in leaves and 18.71% in roots) and proline (358.86%) at time 2. The relative water content was negatively affected by water conditions, with a decrease in relation to the interaction of the aerial part and the root system. Therefore, greater metabolic responses were noted in plants that were subjected to stress treatment at time 2 (6 days).


Assuntos
Vigna , Água , Desidratação , Osmorregulação/fisiologia , Betaína/análise
2.
Braz J Biol ; 83: e276264, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37937632

RESUMO

The water deficit in particular, reduces the productivity of vegetable crops. To minimize these harmful effects on agriculture, several agronomic and physiological practices are being studied, such as the use of bacteria and water stress attenuators, such as brassinosteroids. Considering the socioeconomic relevance of corn culture and its sensitivity when exposed to water deficit, the objective of the present study was to evaluate the action of brassinosteroids and azospirillum on nitrogen metabolism in corn plants subjected to water stress conditions. The experiment was carried out in a greenhouse, in a period of 47 days, with corn plants, using the hybrid K9606 VIP3. The design was completely randomized, in a 2x2x3 factorial scheme, with six replications. The first factor corresponds to two water regimes (presence and absence of water deficit). The second corresponds to inoculation via seed of Azospirillum brasiliense and absence of inoculation. And the third corresponds to the application of three concentrations of brassinosteroids (0, 0.3 and 0.6 µM). Were determined Nitrate; nitrate reductase; free ammonium; total soluble aminoacids; soluble proteins; proline; glycine betaine and glutamine synthetase. The lack of water in plants provided a reduction in the protein and nitrate reductase contents, in leaves and roots. For ammonium, plants with water deficit inoculated at a concentration of 0.3 µM, obtained an increase of 7.16 (70.26%) and 13.89 (77.04%) mmol NH4 + .Kg-1. DM (Dry mass) on the leaf and root respectively. The water deficit in the soil provided significant increases in the concentrations of glycine betaine, nitrate, proline and aminoacids, both in the leaves and in the roots of the corn plants. On the other hand, the contents of glutamine synthetase had a reduction in both leaves and roots.


Assuntos
Compostos de Amônio , Azospirillum brasilense , Zea mays , Brassinosteroides/metabolismo , Nitratos , Raízes de Plantas/metabolismo , Secas , Desidratação/metabolismo , Betaína/metabolismo , Glutamato-Amônia Ligase , Aminoácidos/metabolismo , Prolina/metabolismo , Nitrato Redutases/metabolismo , Nitrogênio/metabolismo
3.
Braz J Biol ; 83: e265991, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37255196

RESUMO

Water stress limits the initial growth and development of maize mass and grain, as well as the physiological process for absorbing the amount of mineral elements. The objective was to evaluate the effect of silicon on germination and growth of corn seedlings submitted to water deficit. The experiment was carried out in the laboratory and the experimental design was completely randomized (factorial 3 × 4), with three concentrations of calcium silicate (0.0; 1.0 and 2.0 mM) and 4 solutions of PEG-6000 to simulate different osmotic potentials (0, 0; -0.3; -0.6; -0.9 MPa). Germination percentage, germination speed index (GSI), mean germination time (MGT), percentage of non-germinated and abnormal germinated, length and dry matter of shoot, root and total seedlings were evaluated. Water deficiency reduced the parameters TG, GSI and MGT. The water deficit reduce the MSPA, MSR and MST with more than 80% reduction in mass from seedlings without deficiency to seedlings with deficiency. For CPA, CR and CT there was a reduction of at least 87%, 70% and 77%, respectively, among seeds without deficiency compared to seeds submitted to deficiency. The use of silicon in corn seeds did not attenuate the stress caused by water deficit simulated by PEG-6000.


Assuntos
Germinação , Plântula , Zea mays , Silício/farmacologia , Sementes
4.
Braz J Biol ; 82: e260818, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35857948

RESUMO

Cowpea (Vigna unguiculata (L.) Walp.) is a legume widely cultivated by small, medium and large producers in several Brazilian regions. However, one of the concerns for the production of cowpea in Brazil in recent years is the low rainfall activity in these regions, which generates the accumulation of salts on the surface. The objective of this work was to evaluate the effects of salt stress on growth parameters and enzyme activity in cowpea plants at different concentrations of brassinosteroids. Experiment was developed in a greenhouse using a completely randomized experimental design in a 3 x 3 factorial scheme. The treatments consisted of three levels of brassinosteroids (0, 3 and 6 µM EBL) and three levels of salt stress (0, 50 and 100 mM NaCl). Growth factors (height, diameter and number of leaves) decreased in the saline condition. With the presence of brassinosteroid the height did not increase, but the number of leaves did, mainly in the saline dosage of 100 mM NaCl. In the variable membrane integrity, brassinosteroid was efficient in both salinity dosages, the same not happening with the relative water content, where the saline condition did not affect the amount of water in the vegetable, with the application of brassino it remained high, decreasing only at dosage 100 mM NaCl. The nitrate reductase enzyme was greatly affected in the root system even with the application of increasing doses of brassino. Therefore, brassinosteroids as a promoter of saline tolerance in cowpea seedlings was positive. The concentration of 3µM of EBL provided the most satisfactory effect in tolerating the deleterious effects of the saline condition. The same cannot be concluded for the concentration of 6µM of EBL that did not promote tolerance to some variables.


Assuntos
Fabaceae , Vigna , Brassinosteroides/metabolismo , Brassinosteroides/farmacologia , Estresse Salino , Cloreto de Sódio/metabolismo , Cloreto de Sódio/farmacologia , Vigna/metabolismo , Água/metabolismo
5.
Radiat Prot Dosimetry ; 193(3-4): 228-236, 2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-33893735

RESUMO

Ambient dose equivalent rates were measured in the environment of the Fukushima prefecture using NaI(Tl)/CsI(Tl) scintillation detectors and CdZnTe/Ge semiconductor detectors. The dose rates obtained at the same locations varied beyond uncertainty (1σ). By replacing the spectrum-dose conversion operators obtained from the anterior-posterior geometry with those from the rotational geometry, the dose rates agreed with each other within uncertainties, except for a CsI(Tl) scintillation detector with a considerably flat crystal configuration, due to its excessive directional dependence.


Assuntos
Poluentes Radioativos do Ar , Monitoramento de Radiação , Radioatividade , Poluentes Radioativos do Ar/análise , Césio , Semicondutores
6.
Public Health ; 179: 84-89, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31739119

RESUMO

OBJECTIVES: Social relationships may help in maintaining functional status among older adults. This study examined the types of social relationships that were related to functional status among Japanese community-dwelling older adults. STUDY DESIGN: This is a prospective cohort study. METHODS: We used baseline data from 2008 and conducted follow-up surveys six years later. Participants included individuals older than 65 years who lived in a suburban community in Japan. The Index of Social Interaction measure was used to assess multiple elements of social relationships. Two functional status outcomes were set: (1) functional decline and (2) functional decline and mortality. A multiple logistic regression model was used to examine the association between social relationships and functional decline six years later. RESULTS: After controlling for age, sex, family structure and disease status in 2008, poor social curiosity (odds ratio [OR] = 1.31, 95% confidence interval [CI]: 1.02-1.69) and interaction (OR = 2.57, 95% CI: 1.20-5.51) were found to be associated with functional decline. Furthermore, social curiosity (OR = 1.39, 95% CI: 1.14-1.69) and interaction (OR = 2.84, 95% CI: 1.44-5.59) were also associated with the composite outcome. CONCLUSIONS: Social curiosity and interacting with others were significantly associated with functional status. Promotion of social interaction may be essential for preventing future need for care.


Assuntos
Relações Interpessoais , Desempenho Físico Funcional , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Vida Independente , Japão , Masculino , Estudos Prospectivos , Inquéritos e Questionários
7.
Neurol Med Chir (Tokyo) ; 40(6): 301-7; discussion 307-9, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10892266

RESUMO

The pathogenesis of optic neuropathy caused by neurovascular compression or by similar mechanisms is unclear. Thin-slice magnetic resonance (MR) imaging was performed in 69 patients with optic neuropathy without demonstrable ophthalmological lesions (57.0 +/- 17.1 years of age) and 102 normal subjects (57.7 +/- 13.9 years of age). The MR imaging features were classified into "no compression" by the internal carotid artery (ICA), "compression" by the ICA, "no contact" with the anterior cerebral artery (ACA) or the gyrus rectus, "contact" with either or both, "compression" by the ACA, and "compression" by the gyrus rectus. The Spearman correlation coefficients were calculated between patients or controls, the MR classification, and the age, and the number of patients in each MR classification were evaluated by the chi 2 test. Five of the 69 patients with rapidly progressive symptoms were operated on via the frontotemporal approach. The MR imaging feature of "compression" by the gyrus rectus was the best predictor of optic neuropathy (Spearman correlation coefficients rho = -0.23646, p < 0.0018). This MR imaging feature was observed in 38 of 69 patients and in 32 of 102 controls (p = 0.002). Compression of the nerve by the gyrus rectus or the ACA was confirmed in all five operated cases. Decompression of the nerve was fully achieved in four of the five patients, and their symptoms have not progressed since then. Optic neuropathies due to compression by the prolapsing gyrus rectus are not well understood. Such neuropathies may be detected by MR imaging.


Assuntos
Lobo Frontal/patologia , Síndromes de Compressão Nervosa/complicações , Síndromes de Compressão Nervosa/diagnóstico , Atrofia Óptica/etiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Artéria Cerebral Anterior/patologia , Artéria Carótida Interna/patologia , Estudos de Casos e Controles , Descompressão Cirúrgica , Diagnóstico Diferencial , Feminino , Glaucoma/diagnóstico , Humanos , Pressão Intraocular , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Síndromes de Compressão Nervosa/patologia , Síndromes de Compressão Nervosa/cirurgia , Atrofia Óptica/diagnóstico , Atrofia Óptica/cirurgia , Resultado do Tratamento , Campos Visuais
8.
J Bacteriol ; 182(11): 3142-50, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10809693

RESUMO

The effects of simultaneous expression of several efflux pumps on antibiotic resistance were investigated in Escherichia coli and Pseudomonas aeruginosa. Several combinations of efflux pumps have been studied: (i) simultaneous expression of a single-component efflux pump, which exports antibiotics into the periplasm, in combination with a multicomponent efflux pump that accomplishes efflux directly into the external medium; (ii) simultaneous expression of two single-component pumps; and (iii) simultaneous expression of two multicomponent pumps. It was found that when efflux pumps of different structural types were combined in the same cell (the first case), the observed antibiotic resistance was much higher than that conferred by each of the pumps expressed singly. Simultaneous expression of pairs of single-component or multicomponent efflux pumps (the second and third cases) did not produce strong increases in antibiotic resistance.


Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Proteínas de Transporte/metabolismo , Resistência a Múltiplos Medicamentos/fisiologia , Escherichia coli/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Antibacterianos/metabolismo , Transporte Biológico , Resistência ao Cloranfenicol/fisiologia , Modelos Biológicos , Resistência a Tetraciclina/fisiologia
9.
Biotechnol Bioeng ; 64(2): 194-9, 1999 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-10397855

RESUMO

A novel bioreactor using a hollow-fiber membrane was developed for the coupled transcription/translation system using T7 RNA polymerase and Escherichia coli S30 extract. The large surface area per the reaction volume of the reactor assured rapid mass transfers of substrates into the reaction mixture and of wastes out from it across the membrane by their molecular diffusion. The flux was large enough to maintain nucleotide concentrations for more than 3 h, which increased the protein synthesis greatly. In addition, the T7 terminator sequence downstream from the reporter genes was found to increase the synthesized protein significantly, especially when the product of polymerase chain reaction (PCR) was used as a template. Implementation of this finding and use of the bioreactor developed multiplied the productivity of protein by the in vitro direct expression from PCR template.


Assuntos
Reatores Biológicos , Reação em Cadeia da Polimerase/métodos , Biossíntese de Proteínas , Transcrição Gênica , Sequência de Bases , RNA Polimerases Dirigidas por DNA/metabolismo , Escherichia coli/genética , Dados de Sequência Molecular , Fatores de Tempo , Proteínas Virais
10.
J Biosci Bioeng ; 87(1): 97-102, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-16232432

RESUMO

A gene (named cell) homologous to the cellobiohydrolase I gene (cbhl) of Trichoderma reesei was isolated and sequenced from the white rot basidiomycete Irpex lacteus MC-2. The cell open reading frame consists of 1551 bp, which is interrupted by two introns, encoding a polypeptide of 517 amino acid residues with a calculated molecular mass of 54,522 Da. The deduced amino acid sequence showed that CEL1 (the protein encoded by cell) has a modular structure consisting of a catalytic domain of 449 amino acids and a C-terminal cellulose-binding domain (CBD) of 36 amino acids separated by a proline-, serine-, threonine-rich linker region of 32 amino acids. The CEL1 catalytic domain is homologous with fungal cellobiohydrolases (CBHs) belonging to family 7 of the glycosyl hydrolases. The transcription of cell was induced in the presence of various cellulosic substrates and repressed by glucose. It was therefore concluded that the reported sequence represents the first cellulase gene isolated from the basidiomycete Irpex.

11.
IEEE Trans Rehabil Eng ; 6(1): 21-31, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9535520

RESUMO

Interface pressures and shear stresses were measured at 13 sites on two unilateral below-knee amputee subjects ambulating with lower-limb patellar-tendon-bearing prostheses. Interface stresses at the time of the first peak in the shank axial force-time curve were investigated at different socket-shank alignment settings. Stress magnitudes ranged from 1.2 to 214.7 kPa for pressure and 0.4 to 79.6 kPa for resultant shear stress, and changes in stress due to misalignment ranged from 1.3 to 80.7 kPa for pressure and from 0.2 to 38.0 kPa for resultant shear stress. For both subjects interface stress changes were much greater in the anterior socket region than in the lateral or posterior regions. Thus, alignment changes had a localized effect on interface stresses. Plots of alignment versus pressure or resultant shear stress were nonlinear for both subjects, in a number of cases maximizing or minimizing at the nominal alignment, indicating complex interface stress-alignment relationships. Variation (standard deviation/mean) was not significantly different for nominal versus misaligned steps, indicating that the subjects adapted well to the alignment changes. Session to session differences in interface stresses were typically larger than interface stress differences induced by alignment modifications. Thus, while these subjects compensated well for alignment changes to maintain consistent interface stresses within a session, they did not do so for different sessions conducted weeks apart.


Assuntos
Amputação Traumática/reabilitação , Membros Artificiais , Marcha , Estresse Mecânico , Adulto , Fenômenos Biomecânicos , Humanos , Perna (Membro) , Masculino , Pessoa de Meia-Idade , Pressão , Desenho de Prótese , Ajuste de Prótese , Transdutores
12.
Arch Phys Med Rehabil ; 79(2): 162-8, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9473997

RESUMO

OBJECTIVE: To study mass and mass distribution effect on function of below-knee prostheses. DESIGN: Design modifications were done to produce proximal center of mass location versus distal center of mass location variations, and prosthesis weight was modified from 42% to 70% of normal limb weight. Work across joints of affected and unaffected extremities was compared to assess the ability of the prosthesis to substitute for function loss. SETTING: University biomechanics laboratory. PARTICIPANTS: Fifteen volunteers with below-knee amputations, residual limb length greater than 8.3 cm, but excluding Syme amputations. INTERVENTIONS: Patients walked with all configurations at self-selected walking speeds and 120 m/min. MAIN OUTCOME MEASURES: Self-selected walking speed and metabolic efficiency. Work across the joints of affected and unaffected sides was compared. RESULTS: Proximal center of mass location produced a more efficient gait. Weight change from 42% to 70% of normal had no significant effect. Mechanical studies show that the prosthesis is a relatively poor substitute for the normal limb; most work is done by the nonamputated side. Particularly, the prosthesis failed to produce effective forward impulses on the body, resulting from push-off and deceleration of the swing leg. CONCLUSIONS: For a proximal center of mass, lightweight distal components (e.g., feet) should be used; it is questionable whether further expenditure to develop ultralightweight prostheses would be cost effective for level walking.


Assuntos
Membros Artificiais , Marcha , Caminhada , Adolescente , Adulto , Idoso , Fenômenos Biomecânicos , Metabolismo Energético , Humanos , Pessoa de Meia-Idade , Desenho de Prótese
13.
J Rehabil Res Dev ; 34(1): 19-43, 1997 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9021623

RESUMO

Residual limb/prosthetic socket interface pressures and shear stresses were measured at 13 sites on two subjects with unilateral transtibial amputation (TTA) using total-contact patellar-tendon-bearing prostheses. Maximal interface stresses during stance phase for each of 13 transducer sites were determined, then means for all steps calculated. Maximal pressure and resultant shear stress during stance phase were shown at anterior distal or mid-limb sites and the maxima occurred during the first 50% of stance phase. Anterior medial and lateral proximal sites showed their greatest pressure during the second 50%. At lateral mid-limb and popliteal fossa sites, resultant shear stress directions suggest that soft tissue was displaced toward the socket brim during weight-bearing. Results also suggest that skin across the distal tibial crest was in tension at the times of the first and second peaks in the shank axial force-time curve in all sessions. Significant difference (p < 0.05) in maximal stresses between sessions conducted > 3 weeks apart were apparent for both subjects.


Assuntos
Cotos de Amputação/fisiopatologia , Amputação Cirúrgica/métodos , Membros Artificiais , Estresse Mecânico , Adulto , Fenômenos Biomecânicos , Humanos , Perna (Membro) , Masculino , Pessoa de Meia-Idade , Pressão , Desenho de Prótese , Transdutores , Suporte de Carga
14.
Microb Drug Resist ; 3(4): 359-63, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9442488

RESUMO

We found that when a growth medium contained glucose, wild-type cells of Haloferax volcanii were able to grow even in the presence of doxorubicin (DOX), an anti-cancer reagent, whereas they usually cannot grow in its presence. The reason was that cells grown in the presence of glucose (glucose-grown cells) showed high multi-drug efflux activity even though the growth medium contained no DOX or substrates of the transporter. This transporter was ATP-driven and the elevation of efflux activity was not due to an increase in intracellular ATP contents. The activity was increased not only by glucose but also by sugars that could be metabolized.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Carboidratos/farmacologia , Haloferax volcanii/metabolismo , Trifosfato de Adenosina/metabolismo , Antibióticos Antineoplásicos/metabolismo , Antibióticos Antineoplásicos/farmacologia , Meios de Cultura , Dicicloexilcarbodi-Imida/farmacologia , Doxorrubicina/metabolismo , Doxorrubicina/farmacologia , Glucose/metabolismo , Haloferax volcanii/efeitos dos fármacos , Potenciais da Membrana/fisiologia
15.
Comput Med Imaging Graph ; 18(3): 193-202, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-8025886

RESUMO

The epidural venous system (meningorachidian venous plexus) was analyzed utilizing gadolinium-diethylenetriamine pentaacetic acid (DTPA) (Gd-DTPA) enhanced volumetric magnetic resonance (MR) images in 11 patients with focal cervical spinal cord atrophy, clinically consistent with juvenile amyotrophy of distal upper extremity. In our series, all of the patients showed unusual posterior epidural venous enhancement at the C5-6 level, suggesting posterior epidural venous dilatation. Three patients also showed prominent dilatation of cervico-thoracic epidural veins surrounding the thecal sac. These MR findings were also demonstrated by spinal phlebography. Gd-DTPA enhanced MR images, especially high resolutional volumetric MR images, were efficient for evaluating these vessels. The observation of meningorachidian venous plexus along the disease course should be necessary for searching the pathogenesis of this disease.


Assuntos
Meios de Contraste , Dura-Máter/irrigação sanguínea , Gadolínio , Imageamento por Ressonância Magnética , Atrofia Muscular Espinal/patologia , Compostos Organometálicos , Ácido Pentético/análogos & derivados , Medula Espinal/irrigação sanguínea , Adolescente , Adulto , Braço , Atrofia , Dilatação Patológica/patologia , Feminino , Gadolínio DTPA , Humanos , Masculino , Pessoa de Meia-Idade , Atrofia Muscular/patologia , Atrofia Muscular Espinal/diagnóstico por imagem , Flebografia , Medula Espinal/patologia , Veias
16.
J Magn Reson Imaging ; 3(6): 889-93, 1993.
Artigo em Inglês | MEDLINE | ID: mdl-8280979

RESUMO

A total of 206 nongravid patients with various gynecologic problems underwent pelvic magnetic resonance (MR) examinations that included both sagittal T2-weighted and contrast agent-enhanced T1-weighted images. MR images were retrospectively reviewed to identify changes in endometrial configuration on serial images obtained during the same MR examination. In 20 MR examinations (all in women of reproductive age), endometrial distortion due to myometrial bulging was noted on T2-weighted or contrast-enhanced T1-weighted images. It was absent on other MR images obtained at different times. Myometrial bulging exhibited low signal intensity in 18 examinations. The finding resembled adenomyosis or leiomyoma on T2-weighted or contrast-enhanced T1-weighted images. These results evidence the presence of transient myometrial bulging and transient low-intensity myometrium in the nongravid uterus. This phenomenon is thought to represent uterine contraction. Clinicians should be aware of the potential presence of transient low-signal-intensity myometrial bulging that could present diagnostic problems in the normal uterus.


Assuntos
Imageamento por Ressonância Magnética , Contração Uterina , Doenças Uterinas/diagnóstico , Útero/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Erros de Diagnóstico , Endométrio/patologia , Feminino , Humanos , Ciclo Menstrual , Pessoa de Meia-Idade , Miométrio/patologia , Estudos Retrospectivos
17.
Radiology ; 187(1): 229-31, 1993 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8451418

RESUMO

The authors obtained midline sagittal T1-weighted magnetic resonance images of the pituitary gland in 30 female patients: five pregnant; two postpartum; and 23 nonpregnant, of childbearing age, and without evidence of pituitary gland disorder. In pregnant and postpartum patients, the relative signal intensity of the anterior lobe compared with the pons was statistically higher than that in the control group (P < .001). In the pregnant patients, positive correlation was noted between the signal intensity ratio of the anterior lobe and the pons and gestational age. The authors believe that the hyperintensity of the anterior pituitary lobe in pregnant and postpartum patients is a physiologic variation. Because the anterior lobe of an infant may also be hyperintense on T1-weighted images and because the anterior lobes of an infant and a pregnant woman are histologically similar, the mechanism responsible for the hyperintensity in each case may be the same. It is important to know that the anterior lobe may be hyperintense in pregnant or postpartum women, especially in cases of probable pituitary gland abnormality accompanying pregnancy, such as pituitary hemorrhage, Sheehan syndrome, or lymphocytic adenohypophysitis.


Assuntos
Imageamento por Ressonância Magnética , Hipófise/anatomia & histologia , Gravidez , Adulto , Feminino , Humanos , Período Pós-Parto
18.
J Comput Assist Tomogr ; 16(6): 845-8, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1430428

RESUMO

Seventeen normal pituitary glands were studied by midline sagittal (and in one case axial) dynamic MRI before and immediately after injection of Gd-DTPA, using spin-echo sequences with a short repetition time. Images were obtained at 1 min intervals for 6 min at 1.5 T. A well-defined focal area with marked enhancement was seen in the posterior portion of the pituitary gland on the first image after injection of Gd-DTPA. The size of the early enhancing area in the posterior pituitary (EEPP) was compared with the high signal of the posterior pituitary (HSPP) on the precontrast image. The EEPP was larger than the HSPP in 10 cases (59%). The two were equal in size in seven cases (41%). The EEPP was anteriorly convex in 11 cases (65%), whereas HSPP was anteriorly convex in 4 cases (24%). We believe that EEPP closely represents the real extent of the posterior lobe. Our results support the hypothesis that HSPP may involve only a portion of the posterior pituitary.


Assuntos
Meios de Contraste , Gadolínio , Imageamento por Ressonância Magnética/métodos , Compostos Organometálicos , Ácido Pentético , Neuro-Hipófise/anatomia & histologia , Gadolínio DTPA , Humanos , Aumento da Imagem , Adeno-Hipófise/anatomia & histologia
19.
J Comput Assist Tomogr ; 16(6): 865-7, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1430431

RESUMO

Postmortem MR images of two cases of posterior column degeneration were correlated with histopathological findings. The abnormal MR findings were volume loss and high signal intensity of the posterior columns associated with mild deformity of the dorsal surface of the spinal cord, corresponding to tract degeneration on histopathological examination. These results strongly suggest that further development of MR technique will permit in vivo detection of posterior column degeneration.


Assuntos
Ataxia/patologia , Imageamento por Ressonância Magnética , Degeneração Neural , Doenças da Medula Espinal/patologia , Adulto , Ataxia/diagnóstico , Doenças Desmielinizantes/patologia , Gânglios Espinais/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Síndrome POEMS/patologia , Medula Espinal/patologia , Doenças da Medula Espinal/diagnóstico
20.
Radiat Med ; 10(6): 215-22, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1287733

RESUMO

To investigate the fine vascular structures in the spinal and paraspinal region, the authors performed three-dimensional GRASS scanning after the administration of contrast material. The scan sequence was sagittal volume scan, TR/TE 100/16, with a flip angle of 45 degrees. First-order gradient moment nulling was employed. Four normal volunteers and 31 patients were studied. Using this technique, longitudinal anterior epidural veins and vertebral arteries were clearly identified. Paraspinal fine vessels of slow to moderate flow, including dilated anterior spinal artery, radiculo-medullary vein, and perimedullary coronal venous plexus, were demonstrated in pathological cases. In addition, with processing of the volume data set, phlebographic projection images of the ladder-shaped anterior epidural venous system could be generated. This method provided more detailed information on epidural and intradural vessels than conventional MR imaging.


Assuntos
Imageamento por Ressonância Magnética , Compostos Organometálicos , Ácido Pentético , Coluna Vertebral/irrigação sanguínea , Meios de Contraste , Gadolínio DTPA , Humanos , Processamento de Imagem Assistida por Computador , Medula Espinal/irrigação sanguínea
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...