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1.
Osteoarthritis Cartilage ; 26(6): 797-806, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29578045

RESUMO

OBJECTIVE: Mutations on chromosomes 5p (CCAL2) and 8q (CCAL1) have been linked to familial forms of calcium pyrophosphate deposition disease (CPDD). Mutations in the ANKH gene account for CCAL2, but the identity of CCAL1 has been elusive. Recently, a single Dutch kindred with a mutation in the Tumor Necrosis Factor Receptor Super Family member 11B (TNFRSF11B) gene coding for osteoprotegerin (OPG) was described as a gain-of-function mutation. Affected family members had premature generalized osteoarthritis (PGOA) and CPDD. As the TNFRSF11B gene is on 8q, we sought additional evidence that TNFRSF11B was CCAL1, and investigated potential disease mechanisms. DESIGN: DNA from two novel PGOA/CPDD families was screened for sequence variants in the TNFRSF11B gene. Mutations were verified by genotype analysis of affected and unaffected family members. We also investigated effects of normal and mutant OPG on regulators of CPP crystal formation in porcine cartilage. RESULTS: The identical TNFRSF11B mutation described in the Dutch family was present in two novel PGOA/CPDD families. ANKH was normal in affected patient fibroblasts. Exogenous OPG did not alter ANKH mRNA or protein levels, affect translocation of ANKH to the membrane, nor increase [pyrophosphate (PPi)] or other key regulators of CPDD. CONCLUSION: We have firmly established the identity of CCAL1 as TNFRSF11B (OPG). Our findings suggest that this mutation produces disease in an ANKH-independent manner via novel mechanisms not primarily targeting cartilage. This work rationalizes further investigation of OPG pathway components as potential druggable targets for CPDD.


Assuntos
Condrocalcinose/genética , Mutação , Osteoprotegerina/genética , Adulto , Condrocalcinose/diagnóstico , Humanos , Linhagem
2.
Curr Oncol ; 24(6): 374-382, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29270049

RESUMO

BACKGROUND: Palliative care, a specialty aimed at providing optimal care to patients with life-limiting and chronic conditions, has several benefits. Although palliative care is appropriate for neurosurgical conditions, including brain cancer, few studies have examined the views of brain cancer patients about palliative care. We aimed to explore the thoughts of brain cancer patients about palliative care, their opinions about early palliative care, and their preferred care setting. METHODS: Semi-structured interviews and the qualitative research methodologies of grounded theory were used to explore perceptions of palliative care on the part of 39 brain cancer outpatients. RESULTS: Seven overarching actions emerged: ■Patients would prefer to receive palliative care in the home.■Increased time with caregivers and family are the main appeals of home care.■Patients express dissatisfaction with brief and superficial interactions with health care providers.■Patients believe that palliative care can contribute to their emotional well-being.■Patients are open to palliative care if they believe that it will not diminish optimism.■There is a preconceived idea that palliative care is directly linked to active dying, and that supposed link generates fear in some patients.■Patients prefer to be educated about palliative care as an option early in their illness, even if they are fearful of it. CONCLUSIONS: Overall, when educated about the true meaning of palliative care, most patients express interest in accessing palliative care services. Although the level of fear concerning palliative care varies in patients, most recognize the associated benefits.

3.
Br J Anaesth ; 116(6): 811-21, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27099154

RESUMO

BACKGROUND: Awake craniotomy (AC) is performed for the resection of brain tumours in close proximity to areas of eloquent brain function to maximize reduction of tumour mass and minimize neurological injury. This study compares the efficacy and safety of dexmedetomidine vs propofol-remifentanil-based conscious sedation, during AC for supratentorial tumour resection. METHODS: Prospective, randomized, controlled trial including 50 adult patients undergoing AC who were randomly assigned to a dexmedetomidine (DEX group, n=25) or propofol-remifentanil group (P-R group, n=25). The primary outcome was the ability to perform intraoperative brain mapping assessed on a numeric rating scale (NRS). Secondary outcome was the efficacy of sedation measured by the modified Observer's Assessment of Alertness/Sedation (OAA/S) scale. Other outcome measures including haemodynamic and respiratory variables, pain, sedation and anxiety scores, adverse events, and patient satisfaction were also compared. RESULTS: There were no differences between DEX and P-R groups regarding the ability to perform intraoperative brain mapping [mean NRS score (95% CI): 10.0 (9.9-10.0) vs 9.7 (9.5-10.0), P=0.13] and level of sedation during mapping [mean OAA/S score (95% CI): 4.1 (3.5-4.7) vs 4.3 (3.9-4.7), P=0.51], respectively. Respiratory adverse events were more frequent in the P-R group (20 vs 0%, P=0.021). Heart rate was significantly lower in the DEX group across time (P<0.001); however, the need for treatment of bradycardia was not different between groups. CONCLUSIONS: Quality of intraoperative brain mapping and efficacy of sedation with dexmedetomidine were similar to propofol-remifentanil during AC for supratentorial tumour resection. Dexmedetomidine was associated with fewer respiratory adverse events. CLINICAL TRIAL REGISTRATION: NCT01545297.


Assuntos
Sedação Consciente/métodos , Craniotomia/métodos , Dexmedetomidina , Hipnóticos e Sedativos , Piperidinas , Propofol , Adulto , Idoso , Idoso de 80 Anos ou mais , Mapeamento Encefálico , Sedação Consciente/efeitos adversos , Dexmedetomidina/efeitos adversos , Método Duplo-Cego , Feminino , Hemodinâmica/efeitos dos fármacos , Humanos , Hipnóticos e Sedativos/efeitos adversos , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Piperidinas/efeitos adversos , Propofol/efeitos adversos , Estudos Prospectivos , Remifentanil , Mecânica Respiratória/efeitos dos fármacos , Neoplasias Supratentoriais/cirurgia , Vigília
4.
Ann Oncol ; 26(2): 407-14, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25421877

RESUMO

BACKGROUND: Four international study groups undertook a large study in resectable osteosarcoma, which included two randomised controlled trials, to determine the effect on survival of changing post-operative chemotherapy based on histological response. PATIENTS AND METHODS: Patients with resectable osteosarcoma aged ≤40 years were treated with the MAP regimen, comprising pre-operatively of two 5-week cycles of cisplatin 120 mg/m(2), doxorubicin 75 mg/m(2), methotrexate 12 g/m(2) × 2 (MAP) and post-operatively two further cycles of MAP and two cycles of just MA. Patients were randomised after surgery. Those with ≥10% viable tumour in the resected specimen received MAP or MAP with ifosfamide and etoposide. Those with <10% viable tumour were allocated to MAP or MAP followed by pegylated interferon. Longitudinal evaluation of quality of life was undertaken. RESULTS: Recruitment was completed to the largest osteosarcoma study to date in 75 months. Commencing March 2005, 2260 patients were registered from 326 centres across 17 countries. About 1334 of 2260 registered patients (59%) were randomised. Pre-operative chemotherapy was completed according to protocol in 94%. Grade 3-4 neutropenia affected 83% of cycles and 59% were complicated by infection. There were three (0.13%) deaths related to pre-operative chemotherapy. At definitive surgery, 50% of patients had at least 90% necrosis in the resected specimen. CONCLUSIONS: New models of collaboration are required to successfully conduct trials to improve outcomes of patients with rare cancers; EURAMOS-1 demonstrates achievability. Considerable regulatory, financial and operational challenges must be overcome to develop similar studies in the future. The trial is registered as NCT00134030 and ISRCTN 67613327.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Ósseas/tratamento farmacológico , Osteossarcoma/tratamento farmacológico , Adolescente , Neoplasias Ósseas/cirurgia , Criança , Cisplatino/administração & dosagem , Cisplatino/efeitos adversos , Terapia Combinada , Doxorrubicina/administração & dosagem , Doxorrubicina/efeitos adversos , Etoposídeo/administração & dosagem , Etoposídeo/efeitos adversos , Feminino , Humanos , Ifosfamida/administração & dosagem , Ifosfamida/efeitos adversos , Interferon-alfa/administração & dosagem , Interferon-alfa/efeitos adversos , Masculino , Metotrexato/administração & dosagem , Metotrexato/efeitos adversos , Terapia Neoadjuvante , Osteossarcoma/cirurgia , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/efeitos adversos , Qualidade de Vida , Projetos de Pesquisa , Adulto Jovem
7.
Magn Reson Chem ; 51(10): 649-54, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24038382

RESUMO

A novel data-evaluation procedure for the automatic atom to peak or multiplet assignment of 1H-NMR spectra of small molecules has been developed using a fast and robust expert system. The applicability and reliability of the method are demonstrated by comparison of a manually assigned database of 1H-NMR spectra with the assignments produced by the automatic procedure. The results of this analysis show an excellent success ratio, indicating that this new algorithm can have a major impact as a time saving tool for the organic chemist. A new graphical feature used to illustrate both the stability and quality of the elementary assignments is also introduced.

8.
Vet Parasitol Reg Stud Reports ; 30: 100710, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35431068

RESUMO

Toxoplasmosis is a worldwide parasitic zoonosis caused by Toxoplasma gondii. Pigs can become infected by consuming water or food contaminated with sporulated oocysts, or by carnivorism (like the consumption of infected rodents). In pigs most infections are asymptomatic. In certain countries, pig meat containing tissue cysts is a major source of infection for human beings. The aims of this study were to estimate the seroprevalence of toxoplasmosis and to identify which factors were related with the increase of the risk of infection in Argentina. The seroprevalence of T. gondii was determined in 240 pigs from 27 farms in the central-western area of Buenos Aires province, Argentina. Serum samples were analyzed using indirect fluorescent antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA) techniques. Prevalence determined was 53.33% and 32.08% by IFAT and ELISA, respectively. Results showed that 81.5% (22/27) of the farms were seropositive to T. gondii. Seropositivity for T. gondii was related with the following risk factors (p value ≤0.05): presence of felids and rodents in the farms, feeding with waste of human food and storage of food outdoors with free access to felids and to the reservoirs when applying both serological techniques. Our results strongly suggest that the risk of infection with T. gondii in pigs is related to the outdoor/extensive type of production system with low infrastructure conditions, which allows both felids and rodents to have free access to pigs and stored food. Also, the high seroprevalence detected in the present study could indicate a potential role of pork in human infections in the region.


Assuntos
Doenças dos Suínos , Toxoplasma , Toxoplasmose Animal , Animais , Anticorpos Antiprotozoários , Argentina/epidemiologia , Fazendas , Fatores de Risco , Estudos Soroepidemiológicos , Sus scrofa , Suínos , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/parasitologia , Toxoplasmose Animal/epidemiologia , Toxoplasmose Animal/parasitologia
9.
Magn Reson Imaging ; 85: 168-176, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34666159

RESUMO

A recently developed compact 3 T (C3T) MRI scanner with high performance gradients [1, 2] has a dedicated radiofrequency (RF) transmit coil that exposes only the head, neck and a small portion of the upper body region during head-first scanning. Due to the unique coil geometry and patient positioning, the established SAR model used for a conventional whole-body scanner cannot be directly translated to the C3T. Here a specific absorption rate (SAR) estimation and validation framework was developed and used to implement a dedicated and accurate SAR prediction model for the C3T. Two different SAR prediction models for the C3T were defined and evaluated: one based on an anatomically derived exposed mass, and one using a fixed anatomical position located caudally to the RF coil to determine the exposed mass. After coil modeling and virtual human body simulation, the designed SAR prediction model was implemented on the C3T and verified with calorimetry and in vivo scan power monitoring. The fixed-demarcation exposed mass model was selected as appropriate exposed mass region to accurately estimate the SAR deposition in the patient on the C3T.


Assuntos
Imageamento por Ressonância Magnética , Ondas de Rádio , Simulação por Computador , Humanos , Posicionamento do Paciente , Imagens de Fantasmas
10.
Parasitol Int ; 83: 102328, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33713809

RESUMO

The allelic combination of ROP18/ROP5 genes of Toxoplasma gondii has been shown to be highly predictive of mouse virulence in canonical isolates and strains. The aims of this study were to analyze the alleles present in the ROP18/ROP5 genes from T. gondii isolates obtained in Argentina, to associate the results with the virulence registered in mouse model, and to compare with other isolates and reference strains using a phylogenetic network. Fourteen T. gondii isolates from Argentina were analyzed by nPCR-RFLP for ROP18/ROP5. Phylogenetic network analysis was inferred using the ToxoDB genotypes and the ROPs molecular markers. All isolates and reference strains were categorized as lethal or non-lethal. As results, combinations 2/2, 3/3 and 4/3 for ROP18/ROP5 were detected in 12 isolates, whereas only alleles 1 and 2 of ROP5 were detected in 2 isolates. The majority of the isolates had a mouse virulence matching to that predicted by the ROP18/ROP5 allele combination. The 3 isolates that differed from the expected virulence presented non-clonal genotypes. ROPs incorporation increased the accuracy of the phylogenetic network relations among the T. gondii samples, prevailing the clustering according to regions. Our results indicate a predominance of type 3 allele in both ROP18 and ROP5 markers and an association of allelic profiles 3/3 and 4/3 of non-clonal genotypes from Argentina, both with virulent and avirulent profiles in mice.


Assuntos
Proteínas Serina-Treonina Quinases/genética , Toxoplasma/genética , Toxoplasma/patogenicidade , Toxoplasmose Animal/parasitologia , Toxoplasmose/parasitologia , Alelos , Animais , Modelos Animais de Doenças , Camundongos , Camundongos Endogâmicos ICR , Filogenia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Protozoários , Virulência/genética
11.
AJNR Am J Neuroradiol ; 42(10): 1853-1858, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34615646

RESUMO

BACKGROUND AND PURPOSE: Vestibular schwannomas are common cerebellopontine angle tumors arising from the vestibulocochlear nerve and can result in cranial nerve dysfunction. Conventional MR imaging does not provide information that could correlate with cranial nerve compression symptoms of hearing loss or imbalance. We used multitensor tractography to evaluate the relationship between the WM microstructural properties of cranial nerves and tumor volume in a cohort of patients with vestibular schwannomas. MATERIALS AND METHODS: A retrospective study was performed in 258 patients with vestibular schwannomas treated at the Gamma Knife clinic at Toronto Western Hospital between 2014 and 2018. 3T MR images were analyzed in 160 surgically naïve patients with unilateral vestibular schwannomas. Multitensor tractography was used to extract DTI-derived metrics (fractional anisotropy and radial, axial, and mean diffusivities of the bilateral facial and vestibulocochlear nerves [cranial nerves VII/VIII]). ROIs were placed in the transition between cisternal and intracanalicular segments, and images were analyzed using the eXtended Streamline Tractography reconstruction method. Diffusion metrics were correlated with 3D tumor volume derived from the Gamma Knife clinic. RESULTS: DTI analyses revealed significantly higher fractional anisotropy values and a reduction in axial diffusivity, radial diffusivity, and mean diffusivity (all P < .001) within the affected cranial nerves VII and VIII compared with unaffected side. All specific diffusivities (axial, radial, and mean diffusivity) demonstrated an inverse correlation with tumor volume (axial, radial, and mean diffusivity, P < .01). CONCLUSIONS: Multitensor tractography allows the quantification of cranial nerve VII and VIII WM microstructural alterations in patients with vestibular schwannomas. Our findings support the hypothesis that tumor volume may cause microstructural alterations of the affected cranial nerves VII and VIII. This type of advanced imaging may represent a possible avenue to correlate diffusivities with cranial nerve function.


Assuntos
Neuroma Acústico , Nervos Cranianos , Nervo Facial , Humanos , Neuroma Acústico/diagnóstico por imagem , Estudos Retrospectivos , Carga Tumoral , Nervo Vestibulococlear/diagnóstico por imagem
12.
Lymphology ; 54(1): 1-11, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34506083

RESUMO

Breast cancer-related lymphedema (BCRL) affects more than one in five women treated for breast cancer, and women remain at lifelong risk. Screening for BCRL is recommended by several national and international organizations for women at risk of BCRL, and multiple methods of objective screening measurement exist. The goal of this study was to compare the use of perometry and bioimpedance spectroscopy (BIS) for early identification of BCRL in a cohort of 138 prospectivelyscreened patients. At each screening visit, a patient's relative volume change (RVC) from perometer measurements and change in L-Dex from baseline (ΔL-Dex) using BIS was calculated. There was a negligible correlation between RVC and ΔL-Dex (r=0.195). Multiple thresholds of BCRL were examined: RVC ≥5% and ≥10% as well as and ΔL-Dex ≥6.5 and ≥10. While some patients developed an elevated RVC and ΔL-Dex, many demonstrated elevations in only one threshold category. Moreover, the majority of patients with RVC ≥5%, ΔL-Dex ≥6.5, or ΔL-Dex ≥10 regressed to non-elevated measurements without intervention. These findings suggest a role for combining multiple screening methods for early identification of BCRL; furthermore, BCRL diagnosis must incorporate patient symptoms and clinical evaluation with objective measurements obtained from techniques such as perometry and bioimpedance spectroscopy.


Assuntos
Linfedema Relacionado a Câncer de Mama , Neoplasias da Mama , Linfedema , Braço , Linfedema Relacionado a Câncer de Mama/diagnóstico , Linfedema Relacionado a Câncer de Mama/etiologia , Neoplasias da Mama/complicações , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/terapia , Feminino , Humanos , Linfedema/diagnóstico , Análise Espectral
13.
Sustain Sci ; 16(2): 703-708, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33686348

RESUMO

Enduring sustainability challenges requires a new model of collective leadership that embraces critical reflection, inclusivity and care. Leadership collectives can support a move in academia from metrics to merits, from a focus on career to care, and enact a shift from disciplinary to inter- and trans-disciplinary research. Academic organisations need to reorient their training programs, work ethics and reward systems to encourage collective excellence and to allow space for future leaders to develop and enact a radically re-imagined vision of how to lead as a collective with care for people and the planet. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11625-021-00909-y.

14.
Magn Reson Chem ; 48(7): 516-22, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20535780

RESUMO

A simple, cheap and flexible flowcell based on a standard 5 mm NMR tube, designed for the monitoring of reactions but of wide applicability, is described. No modification of the NMR instrument is needed, allowing the system to be employed with any conventional NMR probe and magnet. The system is robust and economical in use of reagents, and can be used for studying both homogeneous and heterogeneous reactions.


Assuntos
Fenômenos Químicos , Espectroscopia de Ressonância Magnética/instrumentação , Espectroscopia de Ressonância Magnética/métodos , Desenho de Equipamento , Esterificação , Hidrólise , Cinética , Estrutura Molecular , Fenetilaminas/química , Fenilacetatos/química
15.
Ambio ; 49(10): 1658-1675, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32060791

RESUMO

Community involvement may be essential for conservation programme success. We focus on farmers, asking how and why they believe conservation interventions will work, or not. Here we test models of folk theories of the human motivational factors required for behaviour change, in 3 rural central Chilean communities. We hypothesize that different models will be supported by farmers with different experiences with conservation programmes, and that socioeconomic and production system variation will explain further variation in who supports each working model. We use a multiple methods approach, combining a questionnaire with participant-observation. We find support for three of the working models of human behavioural change, among different socio-economic profiles of farmers. We believe that the schema of working models provides a boundary object to facilitate communication between conservationists and stakeholders, and can help improve conservation project design and implementation.


Assuntos
Fazendeiros , Motivação , Agricultura , Chile , Participação da Comunidade , Humanos , Inquéritos e Questionários
16.
Trends Cell Biol ; 4(7): 236-40, 1994 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-14731662

RESUMO

The flagella of the biflagellate unicellular alga Chlamydomonas have long been known to contain the microtubule-dependent motor protein dynein, but recent findings indicate they also contain multiple members of the kinesin superfamily. Two of these kinesin-like proteins are restricted to a single central-pair microtubule, raising the question of how proteins are targeted to specific microtubules within the flagellum. The kinesin-like proteins on the central-pair microtubules may cause the central-pair apparatus to rotate or twist during flagellar beating. Other kinesins within the flagellum may participate in movements associated with the flagellar membrane.

17.
J Cell Biol ; 101(6): 2374-82, 1985 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-3905826

RESUMO

SEC53, a gene that is required for completion of assembly of proteins in the endoplasmic reticulum in yeast, has been cloned, sequenced, and the product localized by cell fractionation. Complementation of a sec53 mutation is achieved with unique plasmids from genomic or cDNA expression banks. These inserts contain the authentic gene, a cloned copy of which integrates at the sec53 locus. An open reading frame in the insert predicts a 29-kD protein with no significant hydrophobic character. This prediction is confirmed by detection of a 28-kD protein overproduced in cells that carry SEC53 on a multicopy plasmid. To follow Sec53p more directly, a LacZ-SEC53 gene fusion has been constructed which allows the isolation of a hybrid protein for use in production of antibody. With such an antibody, quantitative immune decoration has shown that the sec53-6 mutation decreases the level of Sec53p at 37 degrees C, while levels comparable to wild-type are seen at 24 degrees C. An eightfold overproduction of Sec53p accompanies transformation of cells with a multicopy plasmid containing SEC53. Cell fractionation, performed with conditions that preserve the lumenal content of the endoplasmic reticulum (ER), shows Sec53p highly enriched in the cytosol fraction. We suggest that Sec53p acts indirectly to facilitate assembly in the ER, possibly by interacting with a stable ER component, or by providing a small molecule, other than an oligosaccharide precursor, necessary for the assembly event.


Assuntos
Retículo Endoplasmático/fisiologia , Proteínas Fúngicas/metabolismo , Saccharomyces cerevisiae/genética , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Citoplasma/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/imunologia , Genes Fúngicos , Técnicas Imunológicas , Peso Molecular , Mutação
18.
J Cell Biol ; 125(6): 1313-26, 1994 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8207060

RESUMO

The kinesin superfamily of mechanochemical proteins has been implicated in a wide variety of cellular processes. We have begun studies of kinesins in the unicellular biflagellate alga, Chlamydomonas reinhardtii. A full-length cDNA, KLP1, has been cloned and sequenced, and found to encode a new member of the kinesin superfamily. An antibody was raised against the nonconserved tail region of the Klp1 protein, and it was used to probe for Klp1 in extracts of isolated flagella and in situ. Immunofluorescence of whole cells indicated that Klp1 was present in both the flagella and cell bodies. In wild-type flagella, Klp1 was found tightly to the axoneme; immunogold labeling of wild-type axonemal whole mounts showed that Klp1 was restricted to one of the two central pair microtubules at the core of the axoneme. Klp1 was absent from the flagella of mutants lacking the central pair microtubules, but was present in mutant flagella from pf16 cells, which contain an unstable C1 microtubule, indicating that Klp1 was bound to the C2 central pair microtubule. Localization of Klp1 to the C2 microtubule was confirmed by immunogold labeling of negatively stained and thin-sectioned axonemes. These findings suggest that Klp1 may play a role in rotation or twisting of the central pair microtubules.


Assuntos
Chlamydomonas reinhardtii/genética , Flagelos/ultraestrutura , Proteínas Associadas aos Microtúbulos/genética , Microtúbulos/ultraestrutura , Sequência de Aminoácidos , Animais , Sequência de Bases , Fracionamento Celular , Chlamydomonas reinhardtii/ultraestrutura , Clonagem Molecular , Imunofluorescência , Regulação da Expressão Gênica , Imuno-Histoquímica , Cinesinas/genética , Microscopia Imunoeletrônica , Proteínas Associadas aos Microtúbulos/isolamento & purificação , Microtúbulos/química , Dados de Sequência Molecular , Mutação , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos
19.
Science ; 226(4674): 564-6, 1984 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-6436975

RESUMO

Blood in mouth, nose, and eye tissues of birds cools by evaporation, then flows to a cephalic vascular heat exchanger, the ophthalmic rete. There, acting as a heat sink, blood from the evaporative surfaces cools arterial blood flowing counter-current to it toward the brain. The brain thus remains cooler than the body core. Data for unanesthetized domestic pigeons (Columba livia) suggest that in addition to losing heat, blood perfusing the evaporative surfaces also exchanges oxygen and carbon dioxide with air. In the heat exchanger, this blood apparently gives up oxygen to, and gains carbon dioxide from, arterial blood. The consequent increase in oxygen and decrease in carbon dioxide in the brain's arterial blood enhance diffusion of these gases in, and oxygen supply to, the brain. Such events may help birds maintain the brain's oxygen supply during the high systemic demand of exercise and at the reduced oxygen availability of high altitude.


Assuntos
Química Encefálica , Oxigênio/análise , Animais , Regulação da Temperatura Corporal , Encéfalo/metabolismo , Dióxido de Carbono/análise , Dióxido de Carbono/líquido cefalorraquidiano , Circulação Cerebrovascular , Columbidae , Concentração de Íons de Hidrogênio , Oxigênio/líquido cefalorraquidiano , Pressão Parcial
20.
Science ; 283(5405): 1135-8, 1999 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-10024233

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) in water ice were exposed to ultraviolet (UV) radiation under astrophysical conditions, and the products were analyzed by infrared spectroscopy and mass spectrometry. Peripheral carbon atoms were oxidized, producing aromatic alcohols, ketones, and ethers, and reduced, producing partially hydrogenated aromatic hydrocarbons, molecules that account for the interstellar 3.4-micrometer emission feature. These classes of compounds are all present in carbonaceous meteorites. Hydrogen and deuterium atoms exchange readily between the PAHs and the ice, which may explain the deuterium enrichments found in certain meteoritic molecules. This work has important implications for extraterrestrial organics in biogenesis.


Assuntos
Evolução Química , Exobiologia , Gelo , Hidrocarbonetos Policíclicos Aromáticos/química , Raios Ultravioleta , Álcoois/química , Fenômenos Astronômicos , Astronomia , Deutério/química , Éteres/química , Hidrogênio/química , Espectrometria de Massas , Meteoroides , Origem da Vida , Oxirredução , Fotólise , Quinonas/química , Espectrofotometria Infravermelho
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