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1.
Clin Biomech (Bristol, Avon) ; 110: 106126, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37883885

RESUMO

BACKGROUND: This study assessed the use of dual-energy computed tomography (CT) to evaluate sub-calcaneal plantar fat pad changes in people with diabetic neuropathy. METHODS: Dual-energy CT scans of people with diabetic neuropathy and non-diabetic controls were retrospectively included. Average CT values (in Hounsfield Units) and thickness (in centimeters) of the sub-calcaneal plantar fat pad were measured in mono-energetic images at two energy levels (40 keV and 70 keV). The CT values measured in patients with diabetic neuropathy were correlated to barefoot plantar pressure measurements performed during walking in a clinical setting. FINDINGS: Forty-five dual-energy CT scans of people with diabetic neuropathy and eleven DECT scans of non-diabetic controls were included. Mean sub-calcaneal plantar fat pad thickness did not significantly differ between groups (diabetes group 1.20 ± 0.34 cm vs. control group 1.21 ± 0.28 cm, P = 0.585). CT values at both 40 keV (-34.7 ± 48.7 HU vs. -76.0 ± 42.8 HU, P = 0.013) and 70 keV (-11.2 ± 30.8 HU vs. -36.3 ± 27.2 HU, P = 0.017) were significantly higher in the diabetes group compared to controls, thus contained less fatty tissue. This elevation was most apparent in patients with Type 1 diabetes. CT values positively correlated with the mean peak plantar pressure. INTERPRETATION: Dual-energy CT was able to detect changes in the plantar fat pad of people with diabetic neuropathy.


Assuntos
Diabetes Mellitus Tipo 1 , Pé Diabético , Neuropatias Diabéticas , Humanos , Pé Diabético/diagnóstico por imagem , Neuropatias Diabéticas/diagnóstico por imagem , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/métodos , Tecido Adiposo/diagnóstico por imagem
2.
Health Phys ; 122(2): 344-348, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-34995226

RESUMO

ABSTRACT: The objective of this paper is to evaluate the accuracy of the NASA BioSentinel Pixel Dosimeter (BPD) using gamma-ray and neutron sources in a standard calibration lab. The dosimeter tested here is the ground-based version of the BPD that will be onboard the BioSentinel mission. The BPD was exposed to radiation from 60Co, 137Cs, and 252Cf at selected distances (dose rates) at the Lawrence Livermore National Laboratory (LLNL) Radiation Calibration Laboratory (RCL), and the results were compared with NIST traceable benchmark values. It is recognized that these sources are not analogs for the space environment but do provide direct comparisons between BPD response and well characterized calibration lab values. For gamma rays, the BPD measured absorbed dose agrees to ≤ 3.8% compared with RCL benchmark values. For neutrons, the results show that the BPD is insensitive, i.e., the BPD detected only the gamma-ray dose component from 252Cf. The LET spectra obtained for gamma rays from 60Co and 252Cf are consistent with expectations for these gamma-ray energies, but the LET spectrum from the 137Cs gamma rays differs substantially. The potential causes for this difference are the high dose rate from 137Cs and the lower secondary electron energy produced by 137Cs gamma rays. However, neither of these results in errors in the absorbed dose. Based on comparisons with NIST-traceable standards, it is evident that the BPD can measure absorbed dose accurately from low LET charged particles. The sensor's insensitivity to neutrons is unlikely to be a limitation for the BioSentinel mission due to the expected low secondary neutron fluence.


Assuntos
Radioisótopos de Césio , Dosímetros de Radiação , Calibragem , Raios gama , Laboratórios , Nêutrons , Estados Unidos , United States National Aeronautics and Space Administration
3.
J Med Libr Assoc ; 108(1): 122-123, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31897062

RESUMO

An introduction to a series of essays honoring Erich Meyerhoff (1919-2015), AHIP, FMLA, who was active in and contributed to the Medical Library Association for generations.


Assuntos
Bibliotecários/história , Bibliotecas Médicas/história , Associações de Bibliotecas/história , História do Século XX , História do Século XXI , Humanos , Masculino , Estados Unidos
4.
Nature ; 565(7738): 198-201, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30626944

RESUMO

The geometry of the accretion flow around stellar-mass black holes can change on timescales of days to months1-3. When a black hole emerges from quiescence (that is, it 'turns on' after accreting material from its companion) it has a very hard (high-energy) X-ray spectrum produced by a hot corona4,5 positioned above its accretion disk, and then transitions to a soft (lower-energy) spectrum dominated by emission from the geometrically thin accretion disk, which extends to the innermost stable circular orbit6,7. Much debate persists over how this transition occurs and whether it is driven largely by a reduction in the truncation radius of the disk8,9 or by a reduction in the spatial extent of the corona10,11. Observations of X-ray reverberation lags in supermassive black-hole systems12,13 suggest that the corona is compact and that the disk extends nearly to the central black hole14,15. Observations of stellar-mass black holes, however, reveal equivalent (mass-scaled) reverberation lags that are much larger16, leading to the suggestion that the accretion disk in the hard-X-ray state of stellar-mass black holes is truncated at a few hundreds of gravitational radii from the black hole17,18. Here we report X-ray observations of the black-hole transient MAXI J1820+07019,20. We find that the reverberation time lags between the continuum-emitting corona and the irradiated accretion disk are 6 to 20 times shorter than previously seen. The timescale of the reverberation lags shortens by an order of magnitude over a period of weeks, whereas the shape of the broadened iron K emission line remains remarkably constant. This suggests a reduction in the spatial extent of the corona, rather than a change in the inner edge of the accretion disk.

5.
Obes Surg ; 28(7): 1997-2005, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29404935

RESUMO

BACKGROUND: Morbidly obese patients are at increased risk to develop venous thromboembolism (VTE), especially after bariatric surgery. Adequate postoperative thrombosis prophylaxis is of utmost importance. It is assumed that morbidly obese patients need higher doses of low molecular weight heparin (LMWH) compared to normal-weight patients; however, current guidelines based on relative efficacy in obese populations are lacking. OBJECTIVES: First, we will evaluate the relationship between body weight descriptors and anti-Xa activity prospectively. Second, we will determine the dose-linearity of LMWH in morbidly obese patients. SETTING: This study was performed in a general hospital specialized in bariatric surgery. METHODS: Patients were scheduled for a Roux-en-Y gastric bypass with a total bodyweight (TBW) of ≥ 140 kg. Patients (n = 50, 64% female) received a daily postoperative dose of 5700 IU of nadroparin for 4 weeks. Anti-Xa activity was determined 4 h after the last nadroparin administration. To determine the dose linearity, anti-Xa was determined following a preoperative dose of 2850 IU nadroparin in another 50 patients (52%). RESULTS: TBW of the complete group was 148.5 ± 12.6 kg. Mean anti-Xa activity following 5700 IU nadroparin was 0.19 ± 0.07 IU/mL. Of all patients, 32% had anti-Xa levels below the prophylactic range. Anti-Xa activity inversely correlated with TBW (correlation coefficient - 0.410) and lean body weight (LBW; correlation coefficient - 0.447); 67% of patients with a LBW ≥ 80 kg had insufficient anti-Xa activity concentrations. No VTE events occurred. CONCLUSIONS: In morbidly obese patients, a postoperative dose of 5700 IU of nadroparin resulted in subprophylactic exposure in a significant proportion of patients. Especially in patients with LBW ≥ 80 kg, a higher dose may potentially be required to reach adequate prophylactic anti-Xa levels.


Assuntos
Anticoagulantes/farmacocinética , Inibidores do Fator Xa/sangue , Nadroparina/farmacocinética , Obesidade Mórbida/sangue , Tromboembolia Venosa/prevenção & controle , Adulto , Idoso , Algoritmos , Anticoagulantes/uso terapêutico , Peso Corporal , Feminino , Derivação Gástrica/efeitos adversos , Humanos , Masculino , Pessoa de Meia-Idade , Nadroparina/uso terapêutico , Obesidade Mórbida/cirurgia , Período Pós-Operatório , Estudos Prospectivos , Tromboembolia Venosa/etiologia
6.
Eur J Surg Oncol ; 41(11): 1485-92, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26251342

RESUMO

BACKGROUND: Since the introduction of total mesorectal surgery the outcome of rectal cancer patients has improved significantly. Involvement of the circumferential resection margin (CRM) is an important predictor of increased local recurrence, distant metastases and decreased overall survival. Abdomino perineal excision (APE) is associated with increased risk of CRM involvement. Aim of this study was to analyze reporting of CRM and to identify predictive factors for CRM involvement. METHODS: A population-based dataset was used selecting 2153 patients diagnosed between 2008 and 2013 with primary rectal cancer undergoing surgery. Variation in CRM reporting was assessed and predictive factors for CRM involvement were calculated and used in multivariate analyses. RESULTS: Large variation in CRM reporting was found between pathology departments, with missing cases varying from 6% to 30%. CRM reporting increased from 77% in 2008 to 90% in 2012 (p < 0.001). CRM involvement significantly decreased from 12% to 6% over the years (p < 0.001). In multivariate analysis type of operation, low anterior resection or APE, did not influence the risk of CRM involvement. Clinical T4-stage [odds ratio (OR) = 3.51; 95% confidence interval (CI) = 1.85-6.65) was associated with increased risk of CRM involvement, whereas neoadjuvant treatment (5 × 5 gray radiotherapy [OR 0.39; CI 0.25-0.62] or chemoradiation therapy [OR 0.30; CI 0.17-0.53]) were associated with significant decreased risk of CRM involvement. CONCLUSION: Although significant improvements are made during the last years there still is variation in reporting of CRM involvement in the Southern Netherlands. In multivariate analysis APE was no longer associated with increased risk of CRM involvement.


Assuntos
Colectomia/métodos , Recidiva Local de Neoplasia/epidemiologia , Vigilância da População/métodos , Neoplasias Retais/cirurgia , Sistema de Registros , Adolescente , Adulto , Idoso , Feminino , Seguimentos , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Países Baixos/epidemiologia , Neoplasias Retais/diagnóstico , Neoplasias Retais/epidemiologia , Estudos Retrospectivos , Taxa de Sobrevida/tendências , Adulto Jovem
7.
Appl Clin Inform ; 6(2): 305-17, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26171077

RESUMO

OBJECTIVE: To better understand the literature searching preferences of clinical providers we conducted an institution-wide survey assessing the most preferred knowledge searching techniques. MATERIALS AND METHODS: A survey regarding literature searching preferences was sent to 1862 unique clinical providers throughout Mayo Clinic. The survey consisted of 25 items asking respondents to select which clinical scenarios most often prompt literature searches as well as identify their most preferred knowledge resources. RESULTS: A total of 450 completed surveys were returned and analyzed (24% response rate). 48% of respondents perform literature searches for more than half of their patient interactions with 91% of all searches occurring either before or within 3 hours of the patient interaction. When a search is performed 57% of respondents prefer synthesized information sources as compared to only 13% who prefer original research. 82% of knowledge searches are performed on a workstation or office computer while just 10% occur on a mobile device or at home. CONCLUSION: Providers in our survey demonstrate a need to answer clinical questions on a regular basis, especially in the diagnosis and therapy domains. Responses suggest that most of these searches occur using synthesized knowledge sources in the patient care setting within a very short time from the patient interaction.


Assuntos
Centros Médicos Acadêmicos/estatística & dados numéricos , Prática Clínica Baseada em Evidências/estatística & dados numéricos , Pessoal de Saúde/estatística & dados numéricos , Bases de Conhecimento , Sistemas Automatizados de Assistência Junto ao Leito/estatística & dados numéricos , Inquéritos e Questionários , Registros Eletrônicos de Saúde/estatística & dados numéricos , Hábitos , Fatores de Tempo
8.
Obes Surg ; 24(11): 1835-42, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25027982

RESUMO

BACKGROUND: Severely obese patients have an increased risk for developing metabolic complications such as type 2 diabetes mellitus (T2DM), dyslipidaemia (DL) and hypertension (HT). The aim of the present study is to research the effect of a primary laparoscopic Roux-en-Y gastric bypass (LRYGB) on T2DM, HT and DL in the long-term. METHODS: Fifty-two out of 89 (58 %) adult severely obese patients with T2DM who had received a LRYGB between January 2000 and December 2008 were evaluated. Primary outcome of evaluation was remission of T2DM according to the definition of 2009 consensus statement. Complete remission was defined as achievement fasting plasma glucose (FPG) of <5.6 mmol/l (<100.8 mg/dL) and HbA1c <42 mmol/mol (<6.0 %)) without glucose-lowering medication for at least 1 year. Partial remission was defined as a FPG of 5.6-6.9 mmol/l (100.8-124.2 mg/dL) and HbA1c 42-48 mmol/mol (6.0-6.5 %), without glucose-lowering medication for at least 1 year. Remission of T2DM was considered if the patient met the criteria for complete or partial remission. Secondary outcomes were remission of HT, DL and changes in medication use. RESULTS: Patients had a mean age of 47.5 ± 9.6 years, body mass index of 46.6 ± 6.4 kg/m(2) and a mean duration of T2DM of 6.1 ± 5.4 years at the time of surgery. The mean post-operative follow-up period was 6.9 ± 2.3 years. At the end of the follow-up, mean weight loss was 60 ± 24 % excess weight loss (EWL) and 26 ± 10 % total body weight loss (TBWL). Mean HbA1c level had significantly decreased from 64.8 ± 19.7 mmol/mol to 46.4 ± 12.9 mmol/l (p < 0.0001). Overall medication use was reduced from 85 % to 37 % of the patients (p < 0.0001), while the number of insulin users was reduced from 40 % to 6 % (p < 0.0001). Nineteen percent of the patients had a relapse of T2DM during follow-up. Pre-operative HbA1ac level (odds ratio 0.911, p = 0.020) and duration of T2DM (odds ratio 0.637, p = 0.010) were independent risk factors for failed remission of T2DM. The number of patients with HT was significantly reduced from 73 % to 54 % (p = 0.042), and number of patients with DL was non-significantly decreased from 71 % to 54 % (p = 0.068). CONCLUSIONS: The laparoscopic RYGB operation results in a sustained EWL of 60 % (26 % TBWL) with 52 % long-term remission of T2DM. However, 19 % of the patients had a relapse of their T2DM. Furthermore, HT and DL improved markedly.


Assuntos
Derivação Gástrica/métodos , Obesidade Mórbida/cirurgia , Adulto , Glicemia , Diabetes Mellitus Tipo 2/complicações , Dislipidemias/complicações , Feminino , Hemoglobinas Glicadas/metabolismo , Humanos , Hipertensão/complicações , Laparoscopia/métodos , Masculino , Pessoa de Meia-Idade , Obesidade Mórbida/sangue , Obesidade Mórbida/complicações , Período Pós-Operatório , Resultado do Tratamento , Redução de Peso
10.
Haemophilia ; 18(4): 584-92, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22250892

RESUMO

Carriers of haemophilia face difficult choices regarding prenatal diagnosis, but little is known about the determinants that influence their decisions. The aim of this study was to assess the incidence of prenatal diagnosis and potential determinants affecting the choice for prenatal diagnosis. A nationwide survey was performed among all women who underwent carriership testing for haemophilia in the Netherlands between 1992 and 2004. Prenatal diagnosis was assessed in 207 carriers of haemophilia A or B who had been pregnant. Prenatal diagnosis was categorized into early first trimester (Y-PCR testing or chorionic villus sampling) often intended to prevent the birth of a child with haemophilia, and into late prenatal diagnosis (amniocentesis or ultrasound assessment) aimed at obstetrical management. Of 207 carriers 112 (54%) underwent prenatal diagnosis. Forty-eight women underwent early prenatal diagnosis and 64 women underwent late prenatal diagnosis. In 26 pregnancies early prenatal diagnosis was positive for haemophilia, and in 18 of these pregnancies termination was opted for. The choice for early prenatal diagnosis was associated with a liberal view towards termination of pregnancy (relative risk (RR) 12.5; 95% confidence interval (CI) 3.1-51.2), severe haemophilia in the family (RR 20.2; CI 2.7-153.6), absence of a religion (RR 1.9; CI 1.1-3.1) and older age (RR 2.0; CI 1.0-3.9). The choice for late prenatal diagnosis was associated with birth year after 1970 (RR 2.3; CI 1.5-3.5) and a previous child with haemophilia (RR 2.2; CI 1.4-3.4). More than half of all Dutch haemophilia carriers underwent prenatal diagnosis. Several determinants were strongly associated with prenatal diagnosis.


Assuntos
Hemofilia A/diagnóstico , Hemofilia B/diagnóstico , Heterozigoto , Diagnóstico Pré-Natal/estatística & dados numéricos , Adulto , Comportamento de Escolha , Feminino , Hemofilia A/genética , Hemofilia B/genética , Humanos , Países Baixos , Gravidez , Diagnóstico Pré-Natal/psicologia , Inquéritos e Questionários
11.
Blood Cancer J ; 1(7): e29, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22829185

RESUMO

Aberrant activation of Janus kinase 2 (JAK2) caused by somatic mutation of JAK2 (JAK2V617F) or the thrombopoietin receptor (MPLW515L) plays an essential role in the pathogenesis of myeloproliferative neoplasms (MPNs), suggesting that inhibition of aberrant JAK2 activation would have a therapeutic benefit. Our novel JAK2 inhibitor, NS-018, was highly active against JAK2 with a 50% inhibition (IC(50)) of <1 n, and had 30-50-fold greater selectivity for JAK2 over other JAK-family kinases, such as JAK1, JAK3 and tyrosine kinase 2. In addition to JAK2, NS-018 inhibited Src-family kinases. NS-018 showed potent antiproliferative activity against cell lines expressing a constitutively activated JAK2 (the JAK2V617F or MPLW515L mutations or the TEL-JAK2 fusion gene; IC(50)=11-120 n), but showed only minimal cytotoxicity against most other hematopoietic cell lines without a constitutively activated JAK2. Furthermore, NS-018 preferentially suppressed in vitro erythropoietin-independent endogenous colony formation from polycythemia vera patients. NS-018 also markedly reduced splenomegaly and prolonged the survival of mice inoculated with Ba/F3 cells harboring JAK2V617F. In addition, NS-018 significantly reduced leukocytosis, hepatosplenomegaly and extramedullary hematopoiesis, improved nutritional status, and prolonged survival in JAK2V617F transgenic mice. These results suggest that NS-018 will be a promising candidate for the treatment of MPNs.

12.
J Med Libr Assoc ; 98(1): 49-56, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20098655

RESUMO

OBJECTIVE: The 2009 Janet Doe Lecture reflects on the continuing value and increasing return on investment of librarian-mediated services in the constantly evolving digital ecology and complex knowledge environment of the health sciences. SETTING: The interrelationship of knowledge, decision making based on knowledge, technology used to access and retrieve knowledge, and the important linkage roles of expert librarian intermediaries is examined. METHODOLOGY: Professional experiences from 1969 to 2009, occurring during a time of unprecedented changes in the digital ecology of librarianship, are the base on which the evolving role and value of librarians as knowledge coaches and expert intermediaries are examined. CONCLUSION: Librarian-mediated services linking knowledge and critical decision making in health care have become more valuable than ever as technology continues to reshape an increasingly complex knowledge environment.


Assuntos
Bibliotecários , Bibliotecas Digitais/organização & administração , Bibliotecas Médicas/organização & administração , Papel Profissional , Tomada de Decisões , História do Século XX , História do Século XXI , Humanos , Conhecimento , Bibliotecários/história , Bibliotecas Digitais/história , Bibliotecas Médicas/história , Informática Médica/história , Informática Médica/tendências , Papel Profissional/história
13.
J Med Libr Assoc ; 96(3): 242-8, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18654657

RESUMO

OBJECTIVE: The international consulting and publishing activities of Estelle Brodman, PhD, are placed in the context of Medical Library Association (MLA) international activities. DESCRIPTION: Through multiple consulting engagements in Asia, Dr. Brodman developed an extensive knowledge of the practice and history of health sciences librarianship in countries she visited. International activities in the form of publications, consulting visits, and international meetings occurred sporadically in a career that spanned over forty years and are examined in the context of the international activities of MLA. METHOD: Selected publications and Dr. Brodman's oral history transcript were reviewed. RESULTS/CONCLUSION: Dr. Brodman was a keen observer of the international practice of health sciences librarianship and used her considerable skills in writing and historical research to capture the essence of the cultures she visited. Reports and journal articles form a solid record of scholarship and were complementary to MLA international activities occurring during her career. She approached her assignments with empathy, candor, and respect for the cultures she visited.


Assuntos
Internacionalidade , Bibliotecários , Bibliotecas Médicas/organização & administração , Papel Profissional , Feminino , História do Século XX , História do Século XXI , Humanos , Sociedades
14.
J Neurosurg ; 102(2): 391-6, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15739574

RESUMO

Mayo Clinic founders, William J. Mayo and Charles H. Mayo, and Harvey W. Cushing were among the most significant pioneers of modem American surgery. A review of their personal correspondence reveals a special relationship among these three individuals, particularly between William Mayo and Cushing. Their interactions within the Society of Clinical Surgery initiated their close personal and professional association, which would endure for 39 years. William Mayo strongly supported Cushing's efforts to develop the specialty of neurological surgery, and Cushing sought Mayo's advice in making important career-related decisions. Their supportive friendship and professional alliance remains an example for future generations of neurological surgeons.


Assuntos
Correspondência como Assunto/história , Amigos , Neurocirurgia/história , História do Século XIX , História do Século XX , Humanos , Masculino , Estados Unidos
15.
Cancer Epidemiol Biomarkers Prev ; 13(1): 87-93, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14744738

RESUMO

Risk estimation in breast cancer families is often estimated by use of the Claus tables. We analyzed the family histories of 196 counselees; compared the Claus tables with the Claus, the BRCA1/2, the BRCA1/2/ models; and performed linear regression analysis to extend the Claus tables with characteristics of hereditary breast cancer. Finally, we compared the Claus extended method with the Claus, the BRCA1/2, and the BRCA1/2/u models. We found 47% agreement for Claus table versus Claus model; 39% agreement for Claus table versus BRCA1/2 model; 48% agreement for Claus table versus BRCA1/2/u model; 37% agreement for Claus extended method versus Claus model; 44% agreement for Claus extended model versus BRCA1/2 model; and 66% agreement for Claus extended method versus BRCA1/2/u model. The regression formula (Claus extended method) for the lifetime risk for breast cancer was 0.08 + 0.40 (*) Claus Table + 0.07 (*) ovarian cancer + 0.08 (*) bilateral breast cancer + 0.07 (*) multiple cases. This new method for risk estimation, which is an extension of the Claus tables, incorporates information on the presence of ovarian cancer, bilateral breast cancer, and whether there are more than two affected relatives with breast cancer. This extension might offer a good alternative for breast cancer risk estimation in clinical practice.


Assuntos
Neoplasias da Mama/etiologia , Família , Genes BRCA1 , Genes BRCA2 , Modelos Logísticos , Neoplasias Ovarianas/etiologia , Medição de Risco/métodos , Feminino , Humanos , Masculino
16.
Nature ; 424(6944): 44-7, 2003 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-12840752

RESUMO

The relativistic plasma flows onto neutron stars that are accreting material from stellar companions can be used to probe strong-field gravity as well as the physical conditions in the supra-nuclear-density interiors of neutron stars. Plasma inhomogeneities orbiting a few kilometres above the stars are observable as X-ray brightness fluctuations on the millisecond dynamical timescale of the flows. Two frequencies in the kilohertz range dominate these fluctuations: the twin kilohertz quasi-periodic oscillations (kHz QPOs). Competing models for the origins of these oscillations (based on orbital motions) all predict that they should be related to the stellar spin frequency, but tests have been difficult because the spins were not unambiguously known. Here we report the detection of kHz QPOs from a pulsar whose spin frequency is known. Our measurements establish a clear link between kHz QPOs and stellar spin, but one not predicted by any current model. A new approach to understanding kHz QPOs is now required. We suggest that a resonance between the spin and general relativistic orbital and epicyclic frequencies could provide the observed relation between QPOs and spin.

17.
Minerva Endocrinol ; 27(3): 141-55, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12091790

RESUMO

Hyperhomocysteinemia is a well-established risk factor for cardiovascular disease. Various factors, both modifiable and non-modifiable, interact with the homocysteine metabolism and determine the plasma homocysteine concentrations. These include genetic abnormalities, age, sex and various nutritional and hormonal determinants, all of which play a role in atherosclerosis and accelerated peripheral and cardio-vascular disease (CVD). Several hormones modulate homocysteine metabolism and hence may play a role in the pathogenesis of CVD. The mechanisms involved are unclear. The association of hyperhomocysteinemia with diabetes mellitus is complex and may explain some of the risk of CVD in diabetics not explained by traditional risk factors. Much conflicting data exists in the literature on the role of insulin on homocysteine metabolism, although insulin affects the enzymes regulating the homocysteine metabolism. Treatment of hyperhomocysteinemia with vitamins lowers plasma homocysteine concentrations. Little data is available on the effect of this intervention on cardiovascular outcomes. This review briefly outlines the homocysteine metabolism, summarizes its hormonal determinants, and discusses the role of hyperhomocysteinemia in diabetes, hyperlipidemia and other endocrine disorders.


Assuntos
Homocisteína/sangue , Hormônios/sangue , Angiopatias Diabéticas/fisiopatologia , Homocisteína/metabolismo , Hormônios/fisiologia , Humanos , Hiper-Homocisteinemia/tratamento farmacológico , Hiperlipidemias/sangue , Metionina/sangue , Metionina/metabolismo , Doenças Vasculares/sangue
18.
J Med Libr Assoc ; 90(1): 80-5, 2002 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11838464

RESUMO

As the Medical Library Association (MLA) enters its second century, its role in providing leadership and focus for the education of health information professionals in a changing environment will be critical. MLA members face dramatic changes in the health care environment as well as significant opportunities and must position themselves to thrive in the new environment. This paper examines new roles for health information professionals, new approaches to education and training, and related issues of credentialing, certification/and licensure.


Assuntos
Bibliotecas Médicas/normas , Associações de Bibliotecas/normas , Biblioteconomia/normas , Papel Profissional , Certificação , Credenciamento , Educação em Saúde/normas , Humanos , Liderança , Desenvolvimento de Coleções em Bibliotecas , Licenciamento , Política Organizacional , Educação de Pacientes como Assunto/normas , Estados Unidos
19.
Brain Res Dev Brain Res ; 131(1-2): 103-11, 2001 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-11718841

RESUMO

Superior sagittal sinus blood flow (Q(ss)) was studied over a 6-h period in nine chronically catheterized fetal sheep as a continuous measure of cerebral blood flow to determine the change in blood flow values and in measures of blood flow variability in relation to behavioural state activity. Mean Q(ss) was increased during the low voltage (LV)/rapid eye movement (REM) state compared to the high voltage (HV)/NREM state by approximately 25%, and was further increased during periods of LV/REM with fetal breathing movements. The increase in Q(ss) was abrupt and began at the transition to LV/REM, with the rate of change 2-fold greater than that during transition to HV/NREM, where the decrease in Q(ss) was gradual and began prior to the evident state change. Q(ss) showed considerable fluctuation, which tended to be greater during the HV/NREM state compared to the LV/REM state when analyzed using measures of longer term variability. Q(ss) thus provides for a continuous measure of cerebral blood flow in the ovine fetus, with the approximately 25% increase with change from the HV/NREM to LV/REM state similar to that previously reported using radioactive microspheres. The abrupt increase in Q(ss) at the transition to LV/REM versus the gradual decrease in Q(ss) before transition to HV/NREM would suggest that the state-related change in brain blood flow is better linked to the presence of the LV electrocorticogram and favours its active generation.


Assuntos
Circulação Cerebrovascular/fisiologia , Cavidades Cranianas/embriologia , Cavidades Cranianas/fisiologia , Animais , Comportamento Animal/fisiologia , Cateterismo , Eletromiografia , Eletroculografia , Feto/fisiologia , Consumo de Oxigênio/fisiologia , Ovinos , Sono REM/fisiologia
20.
J Physiol ; 535(Pt 3): 879-88, 2001 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-11559782

RESUMO

1. The impact of repeated umbilical cord occlusion on the normal maturation of fetal heart rate (FHR) and mean arterial pressure (MAP) and the cardiovascular responses to successive umbilical cord occlusion was investigated over a 21 day period in the latter part of gestation. 2. Fifteen chronically instrumented sheep (control group n = 6; occlusion group n = 9) were studied for 21 days (113-133 days of gestation, term = 145 days) with umbilical cord occlusions (90 s duration) performed every 30 min for 1-4 h each day. On days 1, 9 and 18, FHR, FHR variation and MAP were monitored continuously and fetal arterial blood gases, pH and metabolites were measured at predetermined intervals. The baroreflex response to 75-100 microg phenylephrine (I.V.) was tested on days 1 and 18. 3. Basal FHR decreased (DeltaFHR: control, 34.6 +/- 3.6 beats x min(-1); occlusion, 36.9 +/- 2.7 beats x min(-1)) and MAP increased (DeltaMAP: control, 3.1 +/- 1.7 mmHg; occlusion, 5.2 +/- 2.1 mmHg) to a similar extent in control and occlusion groups between days 1 and 21 of the study. There was a small decline in FHR variation over the 21 day study in occlusion, but not control, group fetuses. 4. The magnitude of the fall in FHR decreased and the rise in MAP increased, despite similar changes in blood gases in response to umbilical cord occlusion, over the course of the 21 day study. Despite a significant decline in the ratio of DeltaFHR to DeltaMAP on days 9 and 18 compared to day 1, there was no difference between control and occlusion groups in baroreflex sensitivity. However DeltaFHR/DeltaPO2, an index of chemoreceptor sensitivity, had decreased by day 9 and 18 compared to day 1. 5. The cardiovascular responses to umbilical cord occlusion are altered with repetitive occlusions during the latter part of gestation, with a decrease in DeltaFHR/DeltaMAP, which does not involve changes in baroreflex sensitivity, but may involve changes in chemoreceptor sensitivity. However, repeated umbilical cord occlusion appears to have no impact on baseline cardiovascular control since there was no change in the normal maturational decrease in FHR and rise in MAP.


Assuntos
Adaptação Fisiológica/fisiologia , Hemodinâmica/fisiologia , Cordão Umbilical/fisiologia , Adaptação Fisiológica/efeitos dos fármacos , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Barorreflexo/efeitos dos fármacos , Barorreflexo/fisiologia , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Gasometria , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Feminino , Frequência Cardíaca Fetal/efeitos dos fármacos , Frequência Cardíaca Fetal/fisiologia , Hemodinâmica/efeitos dos fármacos , Fenilefrina/farmacologia , Gravidez , Ovinos
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