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1.
Eur Arch Paediatr Dent ; 25(2): 237-246, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38643420

RESUMO

PURPOSE: The potential of combining teledentistry and engaging parents as underutilised resources to monitor paediatric dental health was emphasised during the COVID-19 pandemic and remains underexplored. This study aims to assess parental acceptance and use of a commercially available intraoral camera (IOC) for effective remote monitoring. METHODS: 47 child-parent dyads, where the parent was the main caregiver and the child was treated under general anaesthesia for early childhood caries, were recruited. Caregivers were trained to image their child's teeth on a commercially available IOC. Subsequently, submitted images were reviewed asynchronously by dentists for image quality, presence of dislodged fillings, abscesses, cavitation, and oral hygiene. Post-surgery monitoring was performed using teledentistry at 1 and 2 months and in-person at 4 months. A modified Telehealth Usability Questionnaire (TUQ) was used to record caregiver acceptance for study procedures. RESULTS: A mean TUQ of 6.09 out of 7 was scored by caregivers. Caregiver-reported issues were limited to problems with technique and child uncooperativeness. The number of clear images during the second teledentistry review was improved compared to the first (p = 0.007). 68% of children liked having images of their teeth taken. CONCLUSION: This study supports the feasibility of using an IOC as a clinically appropriate avenue for teledentistry with a high level of caregiver-child acceptance.


Assuntos
COVID-19 , Pais , Telemedicina , Humanos , Pré-Escolar , Telemedicina/métodos , Telemedicina/instrumentação , Feminino , Masculino , Cárie Dentária/diagnóstico por imagem , Assistência Odontológica para Crianças/métodos , Fotografia Dentária/instrumentação , Criança , SARS-CoV-2 , Adulto , Cuidadores
2.
Osteoporos Int ; 33(9): 1925-1935, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35654855

RESUMO

Because osteoporosis is under-recognized in patients with vertebral fractures, we evaluated characteristics associated with osteoporosis identification. Most patients with vertebral fractures did not receive evaluation or treatment for osteoporosis. Black, younger, and male participants were particularly unlikely to have had recognized osteoporosis, which could increase their risk of negative outcomes. INTRODUCTION: Vertebral fractures may be identified on imaging but fail to prompt evaluation for osteoporosis. Our objective was to evaluate characteristics associated with clinical osteoporosis recognition in patients who had vertebral fractures detected on their thoracolumbar spine imaging reports. METHODS: We prospectively identified individuals who received imaging of the lower spine at primary care clinics in 4 large healthcare systems who were eligible for osteoporosis screening and lacked indications of osteoporosis diagnoses or treatments in the prior year. We evaluated characteristics of participants with identified vertebral fractures that were associated with recognition of osteoporosis (diagnosis code in the health record; receipt of bone mineral density scans; and/or prescriptions for anti-osteoporotic medications). We used mixed models to estimate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: A total of 114,005 participants (47% female; mean age 65 (interquartile range: 57-72) years) were evaluated. Of the 8579 (7%) participants with vertebral fractures identified, 3784 (44%) had recognition of osteoporosis within the subsequent year. In adjusted regressions, Black participants (OR (95% CI): 0.74 (0.57, 0.97)), younger participants (age 50-60: 0.48 (0.42, 0.54); age 61-64: 0.70 (0.60, 0.81)), and males (0.39 (0.35, 0.43)) were less likely to have recognized osteoporosis compared to white participants, adults aged 65 + years, or females. CONCLUSION: Individuals with identified vertebral fractures commonly did not have recognition of osteoporosis within a year, particularly those who were younger, Black, or male. Providers and healthcare systems should consider efforts to improve evaluation of osteoporosis in patients with vertebral fractures.


Assuntos
Osteoporose , Fraturas por Osteoporose , Fraturas da Coluna Vertebral , Adulto , Idoso , Densidade Óssea , Feminino , Humanos , Masculino , Programas de Rastreamento , Osteoporose/complicações , Osteoporose/diagnóstico , Osteoporose/epidemiologia , Fraturas por Osteoporose/complicações , Fraturas por Osteoporose/etiologia , Fraturas da Coluna Vertebral/complicações , Fraturas da Coluna Vertebral/epidemiologia
3.
Nat Commun ; 10(1): 2821, 2019 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-31249302

RESUMO

Power laws in physics have until now always been associated with a scale invariance originating from the absence of a length scale. Recently, an emergent invariance even in the presence of a length scale has been predicted by the newly-developed nonlinear-Luttinger-liquid theory for a one-dimensional (1D) quantum fluid at finite energy and momentum, at which the particle's wavelength provides the length scale. We present experimental evidence for this new type of power law in the spectral function of interacting electrons in a quantum wire using a transport-spectroscopy technique. The observed momentum dependence of the power law in the high-energy region matches the theoretical predictions, supporting not only the 1D theory of interacting particles beyond the linear regime but also the existence of a new type of universality that emerges at finite energy and momentum.

4.
Dis Esophagus ; 32(1)2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30239646

RESUMO

Social media provides a useful platform for informal discussions about healthcare. Acceptability is key to the uptake of diagnostic devices and this can be difficult to gauge from questionnaires and qualitative studies. The aim of this study is to investigate whether Facebook could be used to gauge public perception toward uptake of a new diagnostic test for Barrett's esophagus called the Cytosponge. We retrospectively reviewed Facebook comments relating to a video on the Cytosponge. We categorized comments into: (1) Positive, (2) Negative, (3) Unknown and (4) Questions. Recurring themes that arose were compared to a qualitative study on the Cytosponge. The video received 22.5 million views and 2837 comments within four months. Of these, 525 comments were positive, 215 were unknown, 179 were negative, 71 were questions, and 1847 were 'Tagged' comments. Among positive comments, recurrent themes were that it was innovative, could lead to early cancer-detection, and more favorable than endoscopy. Among negative comments, a recurring theme was concern about the risk of gagging and vomiting. Among 'questions', a recurring theme was related to the risk of Cytosponge detachment. We compared our analysis to a published qualitative study and found similar themes arose across both studies. Facebook provides a rich source of qualitative data, which could be used to augment studies to gauge public perception toward a new diagnostic test.


Assuntos
Esôfago de Barrett/psicologia , Técnicas de Diagnóstico do Sistema Digestório/psicologia , Opinião Pública , Mídias Sociais/estatística & dados numéricos , Esôfago de Barrett/diagnóstico , Estudos Transversais , Feminino , Humanos , Masculino , Percepção , Pesquisa Qualitativa , Gravação em Vídeo/estatística & dados numéricos
5.
Obstet Med ; 10(2): 88-92, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28680470

RESUMO

Medical advances have increased survival of patients with congenital heart disease. However, cardiac disease in pregnancy carries significant maternal and fetal risks, posing enormous challenges to obstetricians. Cyanotic congenital heart disease is associated with maternal complications such as arrhythmias, thromboembolic events and death. Fetal complications include small for gestational age, miscarriage and prematurity. Cyanotic congenital heart disease patients who continue their pregnancies require holistic multidisciplinary team care with early and coordinated planning for delivery. Management of such patients include early counseling regarding pregnancy-associated risks, close monitoring of their cardiac function and regular scanning for fetal assessment. Choice of anesthesia for these patients requires meticulous planning to achieve a favorable balance between systemic and pulmonary vascular resistance, ensuring minimal change in right-to-left shunting. We report a case of a successfully managed pregnancy in a patient with complex congenital heart disease and a single ventricle of left ventricle morphology.

6.
Eur J Surg Oncol ; 43(7): 1148-1160, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28256346

RESUMO

Barrett's oesophagus is a condition which predisposes towards development of oesophageal adenocarcinoma, a highly lethal tumour which has been increasing in incidence in the Western world over the past three decades. There have been tremendous advances in the field of Barrett's oesophagus, not only in diagnostic modalities, but also in therapeutic strategies available to treat this premalignant disease. In this review, we discuss the past, present and future of Barrett's oesophagus. We describe the historical and new evolving diagnostic criteria of Barrett's oesophagus, while also comparing and contrasting the British Society of Gastroenterology guidelines, American College of Gastroenterology guidelines and International Benign Barrett's and CAncer Taskforce (BOBCAT) for Barrett's oesophagus. Advances in endoscopic modalities such as confocal and volumetric laser endomicroscopy, and a non-endoscopic sampling device, the Cytosponge, are described which could aid in identification of Barrett's oesophagus. With regards to therapy we review the evidence for the utility of endoscopic mucosal resection and radiofrequency ablation when coupled with better characterization of dysplasia. These endoscopic advances have transformed the management of Barrett's oesophagus from a primarily surgical disease into an endoscopically managed condition.


Assuntos
Esôfago de Barrett/diagnóstico , Esôfago de Barrett/terapia , Neoplasias Esofágicas/prevenção & controle , Esofagoscopia/métodos , Lesões Pré-Cancerosas/diagnóstico , Lesões Pré-Cancerosas/terapia , Anti-Inflamatórios não Esteroides/uso terapêutico , Esôfago de Barrett/patologia , Ablação por Cateter , Criocirurgia , Técnicas Citológicas/instrumentação , Ressecção Endoscópica de Mucosa , Neoplasias Esofágicas/etiologia , Esofagectomia , Humanos , Microscopia Confocal , Guias de Prática Clínica como Assunto , Lesões Pré-Cancerosas/patologia , Inibidores da Bomba de Prótons/uso terapêutico , Fator Trefoil-3/análise , Conduta Expectante
7.
Phys Rev Lett ; 114(19): 196401, 2015 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-26024184

RESUMO

Studying interacting fermions in one dimension at high energy, we find a hierarchy in the spectral weights of the excitations theoretically, and we observe evidence for second-level excitations experimentally. Diagonalizing a model of fermions (without spin), we show that levels of the hierarchy are separated by powers of R^{2}/L^{2}, where R is a length scale related to interactions and L is the system length. The first-level (strongest) excitations form a mode with parabolic dispersion, like that of a renormalized single particle. The second-level excitations produce a singular power-law line shape to the first-level mode and multiple power laws at the spectral edge. We measure momentum-resolved tunneling of electrons (fermions with spin) from or to a wire formed within a GaAs heterostructure, which shows parabolic dispersion of the first-level mode and well-resolved spin-charge separation at low energy with appreciable interaction strength. We find structure resembling the second-level excitations, which dies away quite rapidly at high momentum.

8.
Singapore Med J ; 52(6): 405-9, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21731991

RESUMO

INTRODUCTION: This study aimed to analyse the inter-fraction prostate motion and setup error during intensity-modulated radiotherapy for prostate cancer at the National Cancer Centre Singapore. METHODS: Gold seeds were implanted as fiducial markers. Daily portal films were taken and displacements of the gold seeds from the isocentre in each axis were recorded. Random and systematic errors were used to derive a margin recipe for each axis based on the van Herk formula. RESULTS: 1,077 fractions from 36 patients were analysed. 89.8 percent, 85.2 percent and 83.6 percent of the setup errors were within +/- 2 mm for the right-left (RL), superior-inferior (SI) and anterior-posterior (AP) axes, respectively. The population systematic errors were 0.71 mm, 0.84 mm and 0.87 mm; the population random errors were 1.32 mm, 1.59 mm and 1.70 mm; the overall population mean setup errors were -0.14 (range -2.27 to 1.15) mm, 0.11 (range -2.32 to 1.69) mm and 0.08 (range -1.33 to 1.46) mm; and the van Herk margin recipes were 2.69 mm, 3.22 mm and 3.37 mm for the RL, SI and AP axes, respectively. CONCLUSION: The setup errors and inter-fraction prostate movements were small. Gold seed implantation is a feasible and easy method of verifying the prostate position.


Assuntos
Movimento (Física) , Neoplasias da Próstata/radioterapia , Interpretação de Imagem Radiográfica Assistida por Computador/instrumentação , Radioterapia de Intensidade Modulada/métodos , Fracionamento da Dose de Radiação , Desenho de Equipamento , Humanos , Imobilização/métodos , Masculino , Oncologia/métodos , Neoplasias da Próstata/fisiopatologia , Reprodutibilidade dos Testes , Singapura , Tomografia Computadorizada por Raios X/métodos
9.
Ann Acad Med Singap ; 34(6): 152C-154C, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16010398

RESUMO

The Medical College Union (MCU) was formed in 1922 to encourage and promote comradeship and public spirit amongst the students of King Edward VII College of Medicine. The Medical College Union Society was founded and held its first meeting on 31 July 1936. However, the Annual Report for 1940-42 made no reference to the Society at all and it was hence considered to cease to exist as an official body. The Medical Society (Medsoc), headed by Mr Goon Sek Mun, was formed in 1949 and it organised various activities and events for the faculty. Some of these are still being held annually today, with the addition of several others and phasing out of some. These were organised by the individual subgroups in the Medical society, like the Social, Welfare, Sports and Publications committees. The Medsoc also acts as the students' voice in conveying their opinions to the administration and the Dean. With the expected advent of a new medical school in Singapore--a postgraduate one in the Outram Campus, the medical student community in Singapore will only get larger. There should be a role for Medsoc to foster closer ties between the student communities.


Assuntos
Grupos de Autoajuda/história , Sociedades Médicas/história , Estudantes de Medicina/história , História do Século XX , Humanos , Faculdades de Medicina/história , Singapura
10.
Br J Oral Maxillofac Surg ; 40(1): 60-3, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11883973

RESUMO

A randomized clinical trial was conducted to investigate the effect of the presence of a pharyngeal pack during endotracheal anaesthesia on the incidence of postoperative sore throat. The patients were anaesthetized with fentanyl, thiopentone and atracurium. Thirty-six patients were anaesthetized without placement of pharyngeal packs while 26 patients had pharyngeal packs inserted. There were no significant differences in the incidence or severity of sore throat postoperatively in the two groups (P=0.23). These results contradict previous studies, which showed an increase in the incidence of postoperative sore throat after the use of pharyngeal packs.


Assuntos
Anestesia Dentária/instrumentação , Intubação Intratraqueal/efeitos adversos , Procedimentos Cirúrgicos Bucais/efeitos adversos , Faringite/prevenção & controle , Tampões de Gaze Cirúrgicos , Anestesia Geral/instrumentação , Distribuição de Qui-Quadrado , Feminino , Humanos , Masculino , Faringite/etiologia , Cloreto de Sódio/uso terapêutico , Inquéritos e Questionários
11.
J Prosthodont ; 10(2): 105-7, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11512117

RESUMO

Dentures are routinely removed from the oral cavity before general anesthetic procedures. They are only reinserted much later when the patient returns to the room. This clinical report describes an edentulous patient who developed acute tongue swelling from venous congestion as a result of tongue recovery from general anesthesia. Her complete dentures were used to separate the residual ridges during the recovery period and relieved the congestion. Denture insertion increased the height and volume of the oral cavity, which reduced pressure on the tongue, preventing a cycle of tongue compression, congestion, and swelling. This unusual complication suggests that it may be prudent for the edentulous patient to be accompanied by their dentures in the perioperative period.


Assuntos
Anestesia Geral , Edema/etiologia , Complicações Pós-Operatórias , Doenças da Língua/etiologia , Obstrução das Vias Respiratórias/prevenção & controle , Período de Recuperação da Anestesia , Prótese Total , Edema/terapia , Feminino , Humanos , Pessoa de Meia-Idade , Boca Edêntula/complicações , Boca Edêntula/reabilitação , Língua/irrigação sanguínea , Doenças da Língua/terapia , Insuficiência Venosa/complicações , Dimensão Vertical
13.
Ann Acad Med Singap ; 29(4): 534-7, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11056788

RESUMO

INTRODUCTION: Treatment of mandibular fractures commonly involves the use of arch bars in temporary maxillo-mandibular fixation (also called intermaxillary fixation) to aid bone plating, for the postoperative application of light elastic traction to correct minor occlusal discrepancies and intermaxillary fixation for post reduction immobilisation. The purpose of this paper is to describe a quick and simple alternative for intermaxillary fixation. CLINICAL PICTURE: Three cases of mandibular fractures are presented to demonstrate the use of intermaxillary screws instead of conventional arch-bar wiring. TREATMENT: Two cases were treated with closed reduction methods while the other case was treated with open reduction. OUTCOME: Subsequent fracture healing was not compromised using this technique. CONCLUSIONS: With careful case selection, successful treatment outcome may be achieved using this time-saving and technically simple procedure. Some of the advantages and disadvantages of the intermaxillary screws are discussed.


Assuntos
Parafusos Ósseos , Fixação de Fratura/instrumentação , Fraturas Mandibulares/cirurgia , Maxila/cirurgia , Adulto , Desenho de Equipamento , Consolidação da Fratura , Humanos , Masculino , Fios Ortodônticos , Seleção de Pacientes , Cuidados Pós-Operatórios/instrumentação , Fatores de Tempo , Tração/instrumentação , Resultado do Tratamento
14.
Singapore Dent J ; 23(1 Suppl): 18-22, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11699358

RESUMO

Propofol and alfentanil are commonly used for sedation and pain control. A preliminary study to compare the usefulness of these drugs was carried out in ten healthy patients requiring bilateral wisdom tooth surgery. The operations were done in two appointments with the patient receiving a different drug on each occasion. Anxiety levels were recorded on visual analogue scales pre and post-operatively. Both agents caused a decrease in anxiety scores, with propofol causing a more significant reduction. Vomiting and nausea with alfentanil was noted in three patients. Propofol also had an amnesic effect which alfentanil did not have. In conclusion, propofol would appear to be the drug of choice within the limitations of this pilot study.


Assuntos
Alfentanil/administração & dosagem , Analgesia Controlada pelo Paciente , Anestesia Dentária/métodos , Anestésicos Intravenosos/efeitos adversos , Propofol/administração & dosagem , Extração Dentária , Adolescente , Adulto , Alfentanil/efeitos adversos , Estudos Cross-Over , Feminino , Humanos , Masculino , Dente Serotino/cirurgia , Projetos Piloto , Método Simples-Cego , Estatísticas não Paramétricas , Vômito/induzido quimicamente
16.
Ann Acad Med Singap ; 28(5): 625-9, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10597344

RESUMO

Sixty-seven consecutive mandibular fractures treated mainly in 1998 were surveyed retrospectively. Treatment was performed at the National University Hospital, Singapore. Males outnumbered females by 5:1, with Chinese the commonest racial group involved (56.7%). Most patients were between 20 and 29 years of age. Road traffic accidents formed the largest proportion (61.2%) followed by industrial accidents and assaults. The symphyseal and parasymphyseal regions were most commonly fractured (46.5%). Almost a third of the patients sustained other facial fractures. Treatment was commonly administered within one to two days of discovery of the fracture and open reduction was the treatment plan of choice in 79.1% of the time. Discussion on how aetiology affects the fracture pattern in Singapore is carried out.


Assuntos
Hospitais Universitários/estatística & dados numéricos , Fraturas Mandibulares/cirurgia , Acidentes de Trânsito/estatística & dados numéricos , Adolescente , Adulto , Distribuição por Idade , Fatores Etários , Idoso , Criança , Pré-Escolar , Ossos Faciais/lesões , Ossos Faciais/cirurgia , Feminino , Fixação Interna de Fraturas , Humanos , Masculino , Fraturas Mandibulares/epidemiologia , Fraturas Mandibulares/etiologia , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores Sexuais , Singapura/epidemiologia
17.
Stroke ; 30(12): 2735-41; discussion 2741-2, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10583005

RESUMO

BACKGROUND AND PURPOSE: Perinatal hypoxic-ischemic injuries can trigger a cascade of events leading to delayed deterioration and cell death several hours later. The objective of this study was to characterize the cerebral blood flow responses and the changes in extracellular glucose and lactate during the delayed phases of injury and to determine their relationships with the pathophysiological events after hypoxic-ischemic injury. METHODS: Two groups of near-term chronically instrumented fetal sheep were subjected to 30 minutes of cerebral hypoperfusion. In the first group, regional cerebral blood flow was measured over the next 24 hours with radiolabeled microspheres. In the second, cortical extracellular glucose and lactate were measured by microdialysis. Parietal electrocorticographic activity and cortical impedance were recorded continuously in both groups, and the extent of neuronal loss was determined histologically at 72 hours after injury. RESULTS: Cerebral blood flow was transiently impaired in the cortex during reperfusion, whereas during the delayed phase, there was a marked increase in cerebral blood flow. The severity of cortical neuronal loss was related to the degree of hypoperfusion in the immediate reperfusion period and inversely related to the magnitude of the delayed hyperperfusion. Cortical extracellular lactate was elevated after injury, and both glucose and lactate secondarily increased during the delayed phase of injury. CONCLUSIONS: The delayed phase is accompanied by a period of hyperperfusion that may protect marginally viable tissue.


Assuntos
Circulação Cerebrovascular , Glucose/metabolismo , Ataque Isquêmico Transitório/metabolismo , Ataque Isquêmico Transitório/fisiopatologia , Ácido Láctico/metabolismo , Animais , Morte Celular , Córtex Cerebral/metabolismo , Córtex Cerebral/patologia , Feto , Ataque Isquêmico Transitório/patologia , Microdiálise , Reperfusão , Ovinos , Fatores de Tempo
18.
Stroke ; 30(1): 160-70, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9880405

RESUMO

BACKGROUND AND PURPOSE: During focal cerebral ischemia, the ischemic penumbra or border-zone regions of moderate cortical blood flow reductions have a heterogeneous development of intracellular cortical acidosis. This experiment tested the hypotheses that (1) this acidosis is secondary to glucose utilization and (2) this intracellular acidosis leads to recruitment of potentially salvageable tissue into infarction. METHODS: Brain pHi, regional cortical blood flow, and NADH redox state were measured by in vivo fluorescent imaging, and infarct volume was assessed by triphenyltetrazolium chloride histology. Thirty fasted rabbits divided into 6 groups of 5 each were subjected to 4 hours of permanent focal ischemia in the presence of hypoglycemia ( approximately 2.8 mmol/L), moderate hyperglycemia ( approximately 11 mmol/L), and severe hyperglycemia (>28 mmol/L) under either normoxia or moderate hypoxia (PaO2 approximately 50 mm Hg). RESULTS: Preischemic hyperglycemia led to a more pronounced intracellular acidosis and retardation of NADH regeneration than in the hypoglycemia groups under both normoxia and moderate hypoxia in the ischemic penumbra. For example, 4 hours after ischemia, brain pHi in the severe hyperglycemia/normoxia group measured 6.46, compared with 6.84 in the hypoglycemia/normoxia group (P<0.01), and NADH fluorescence measured 173% compared with 114%. Infarct volume in the severe hyperglycemia/normoxia group measured 35.1+/-6.9% of total hemispheric volume, compared with 13.5+/-4.2% in the hypoglycemia/normoxia group (P<0.01). CONCLUSIONS: Hyperglycemia significantly worsened both cortical intracellular brain acidosis and mitochondrial function in the ischemic penumbra. This supports the hypothesis that the evolution of acidosis in the ischemic penumbra is related to glucose utilization. Furthermore, the observation that hypoglycemia significantly decreased infarct size supports the postulate that cortical acidosis leads to recruitment of ischemic penumbra into infarction.


Assuntos
Acidose/tratamento farmacológico , Isquemia Encefálica/tratamento farmacológico , Infarto Cerebral/tratamento farmacológico , Glucose/farmacologia , NAD/metabolismo , Oxigênio/farmacologia , Animais , Gasometria , Encéfalo/irrigação sanguínea , Encéfalo/metabolismo , Isquemia Encefálica/metabolismo , Infarto Cerebral/metabolismo , Circulação Cerebrovascular/fisiologia , Hiperglicemia/tratamento farmacológico , Hiperglicemia/metabolismo , Hipoglicemia/tratamento farmacológico , Hipoglicemia/metabolismo , Hipóxia Encefálica/tratamento farmacológico , Hipóxia Encefálica/metabolismo , Oxirredução , Oxigênio/sangue , Coelhos
19.
J Stroke Cerebrovasc Dis ; 8(6): 368-79, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-17895190

RESUMO

Within the ischemic penumbra, there is a heterogeneous development of cortical intracellular acidosis that is associated with selective neuronal injury. This experiment, which used a rabbit model of moderate focal cerebral ischemia, examined the time course for changes in intracellular brain pH, cortical blood flow, capillary bed density, and mitochondrial function in the ischemic penumbra. After cortical annotation of regions of intracellular acidosis in the ischemic penumbra, the animals underwent transcardiac carbon black perfusion for measurement of capillary bed density. Analysis of variance and Pearson's correlation coefficients were used to determine the relationship between capillary bed density, brain intracellular pH, mitochondrial function, and cortical blood flow. Thirty minutes after the onset of ischemia, cortical blood flow declined from 46+/-2 to 22+/-1 mL/100gm/min (P<.01) in all groups. The overall cortical intracellular brain pH measured 6.78+/-.01 compared with a preischemic value of 6.98+/-.01 (P<.05). Within this moderately ischemic cortex, there were small regions (1,000 to 45,000 mum(2)) of increased acidosis, meauring 6.68+/-.01, not associated with focal changes in cortical blood flow, occurring within 15 minutes of ischemia and persisting throughout the ischemic period. Capillary bed density progressively declined with ongoing ischemia occurring after the development of acidosis. For example, capillary bed density in preischemic controls was 338+/-6/mm(2), whereas after 1 hour of ischemia, it measured 147+/-12/mm(2), at 3 hours 97+/-23/mm(2), and at 6 hours 92+/-16/mm(2). Mitochondrial function was reduced coinciding with the decrease in capillary bed density. These data support the hypothesis that cortical acidosis in the ischemic penumbra facilitates the development of perfusion defects that subsequently lead to mitochondrial dysfunction.

20.
Pediatr Res ; 39(5): 791-7, 1996 May.
Artigo em Inglês | MEDLINE | ID: mdl-8726230

RESUMO

Several hours after an hypoxic-ischemic injury to the developing brain, hyperemia, then seizures, edema, and infarction can develop. The roles of nitric oxide (NO) synthesis and excitotoxin accumulation during these later phases of injury are not known. The time course of extracellular levels of amino acids within the parasagittal parietal cortex were measured with microdialysis during and for 3 d after 30 min of cerebral ischemia in nine chronically instrumented near-term fetal sheep (119-133 d). Cortical electroencephalographic (EEG) activity and extracellular space (ECS) were quantified simultaneously with real-time spectral analysis and cortical impedance measurements, respectively. Amino acid concentrations were measured using HPLC. During ischemia, citrulline (by-product of NO synthesis), glutamate, glycine, and gamma-aminobutyric acid (GABA) concentrations rose to 147 +/- 18%, 180 +/- 20%, 290 +/- 50% and 4800 +/- 1300% of baseline respectively (p < 0.05). The excitotoxic index ([glutamate] x [glycine]/[GABA]) decreased to 15 +/- 8%. Upon reperfusion, the cytotoxic edema and amino acid accumulation largely resolved within 1 h, and the EEG was depressed. Citrulline began to rise again by 4 h (p < 0.05), reaching a maximum (273 +/- 21%) at 32 +/- 2 h. Seizure activity developed at 7 +/- 2 h, and impedance plus the excitotoxic index then rose progressively and peaked at 32 +/- 2 h (480 +/- 170%). At 72 h, there was severe neuronal loss and laminar necrosis within the parasagittal cortex. These data suggest that, several hours after a severe hypoxicischemic injury, NO synthesis increased, then seizures arose, and edema developed concomitantly with the accumulation of excitotoxins.


Assuntos
Edema Encefálico/metabolismo , Citotoxinas/metabolismo , Hipóxia Fetal/metabolismo , Hipóxia Encefálica/metabolismo , Convulsões/metabolismo , Animais , Ácido Aspártico/metabolismo , Edema Encefálico/etiologia , Isquemia Encefálica/complicações , Isquemia Encefálica/metabolismo , Isquemia Encefálica/fisiopatologia , Eletroencefalografia , Espaço Extracelular/metabolismo , Feminino , Hipóxia Fetal/complicações , Hipóxia Fetal/fisiopatologia , Idade Gestacional , Ácido Glutâmico/metabolismo , Hipóxia Encefálica/complicações , Hipóxia Encefálica/fisiopatologia , Óxido Nítrico/metabolismo , Gravidez , Traumatismo por Reperfusão/complicações , Traumatismo por Reperfusão/metabolismo , Convulsões/etiologia , Ovinos , Fatores de Tempo , Ácido gama-Aminobutírico/metabolismo
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