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OBJECTIVE: Although pathology at the first mobile segment above a lumbosacral transitional vertebra (LSTV) is a known source of spinal symptoms, nerve root compression below an LSTV, has only sporadically been reported. Our objective was to assess the prevalence of nerve root entrapment below an LSTV, review the causes of entrapment, and correlate with presenting symptoms. MATERIALS AND METHODS: A retrospective review of MR and CT examinations of the lumbar spine was performed over a 5.5-year period in which the words "transitional vertebra" were mentioned in the report. Nerve root compression below an LSTV was assessed as well as the subtype of transitional vertebra. Correlation with clinical symptoms at referral was made. MR and CT examinations were also reviewed to exclude any other cause of symptoms above the LSTV. RESULTS: One hundred seventy-four patients were included in the study. Neural compression by new bone formation below an LSTV was demonstrated in 23 patients (13%). In all of these patients, there was a pseudarthrosis present on the side of compression due to partial sacralization with incomplete fusion. In three of these patients (13%), there was symptomatic correlation with no other cause of radiculopathy demonstrated. A further 13 patients (57%) had correlating symptoms that may in part be attributable to compression below an LSTV. CONCLUSIONS: Nerve root compression below an LSTV occurs with a prevalence of 13% and can be symptomatic in up to 70% of these patients. This region should therefore be carefully assessed in all symptomatic patients with an LSTV.
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Vértebras Lombares/anormalidades , Imageamento por Ressonância Magnética/estatística & dados numéricos , Radiculopatia/diagnóstico , Radiculopatia/epidemiologia , Sacro/anormalidades , Tomografia Computadorizada por Raios X/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Feminino , Humanos , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/patologia , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores de Risco , Sacro/diagnóstico por imagem , Sacro/patologia , Reino Unido/epidemiologia , Adulto JovemRESUMO
INTRODUCTION: We studied racial differences in post-stroke outcomes using a prospective, population-based cohort of stroke survivors as part of the Brain Attack Surveillance in Corpus Christi (BASIC) project. METHODS: Neurologic (NIHSS, range of 0-42, higher scores are worse), functional (ADLs/IADLs, range 1-4, higher scores are worse), and cognitive (3MSE, range 0-100, higher scores are better) outcomes were measured 90 days after stroke. Cox proportional hazards and negative binomial linear regression models were used to examine the associations between race and 90-day all-cause mortality and NIHSS, respectively, whereas linear regression was used for ADLs/IADLs and 3MSE scores. Covariates included demographics, initial NIHSS, comorbidities, prior stroke history, tPA treatment status, pre-stroke disability, and pre-stroke cognition. The mortality model was also adjusted for DNR status. RESULTS: At 90 days post-stroke, Black American individuals (BAs) (n = 122) had a median (IQR) NIHSS of 2 (1,6) compared to NIHSS of 1 (0,3) in non-Hispanic White American individuals (NHWs) (nâ¯=â¯795). BAs had a median (IQR) ADL/IADL score of 2.41 (1.50, 3.39) compared to 2.00 (1.27, 2.95) in NHWs. BAs scored a median of 84 (75, 92) on the 3MSE compared to NHWs' score of 91.5 (83, 96). Death occurred in 23 (8%) of BAs and 268 (15%) of NHWs within 90 days among those who participated in baseline. After adjustment for covariates, functional outcomes at 90 days were worse in BAs compared to NHWs, with 15.8% (95% CI=5.2, 26.4) greater limitations in ADLs/IADLs and 43.9% (95% CI=12.0, 84.9) greater severity of stroke symptoms. Cognition at 90 days was 6.5% (95% CI=2.4, 10.6) lower in BAs compared to NHWs. BAs had a 35.4% lower (95% CI=-9.8, 61.9) hazard rate of mortality than NHWs. CONCLUSIONS: In this prospective, population-based community sample, BAs had worse neurologic, functional and cognitive outcomes at 90 days compared to NHWs. Future research should investigate how social determinants of health including structural racism, neighborhood factors and access to preventive and recovery services influences these racial disparities.
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Acidente Vascular Cerebral , Brancos , Humanos , Estados Unidos/epidemiologia , Negro ou Afro-Americano , Estudos Prospectivos , Fatores de Risco , Acidente Vascular Cerebral/epidemiologiaRESUMO
Charcot-Marie-Tooth disease (CMTD) is an uncommon progressive neuromuscular disorder of the peripheral nervous system and primarily leads to distal extremity weakness and sensory deficits. Frequently, affected patients manifest pes cavus, drop foot, and digit contractures that may pose significant challenges in ambulation and grasping objects. Although there are numerous articles of this syndrome in the medical literature, there is a limited number of dental publications. The objective of this article is to review the general and head and neck/oral and maxillofacial features of CMTD. General guidelines for dental management are also provided.
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Doença de Charcot-Marie-Tooth , Assistência Odontológica , HumanosRESUMO
Acute-onset chronic inflammatory demyelinating polyneuropathy (A-CIDP) is an immune mediated neuropathy characterized by progressive weakness and sensory impairment lasting over 2 months. Guillain-Barré-Strohl syndrome (GBS) is an immune mediated polyneuropathy with a similar presentation often over less than 4 weeks. While some have argued for the existence of recurrent GBS, most classify the syndrome as a form of relapsing-remitting CIDP. However, there are cases of GBS with treatment-related fluctuations that must be distinguished from A-CIDP as patients with A-CIDP require long-term immunotherapy. In this case report, we discuss a patient with multiple relapses over 3 years, who is more likely to have A-CIDP. His ganglioside profile, which has rarely been reported in A-CIDP, included high concentrations of anti-GM1, anti-GD1a, and anti-GD1b antibodies, which may account for his severe disease course.
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Neuralgic Amyotrophy (NA) is a rare, acute onset inflammatory brachial plexopathy that frequently presents with acute pain followed by shoulder girdle muscle weakness. Phrenic nerve involvement affecting the diaphragms occurs in 7-10% of cases. We present the case of a 52-year-old man with neuralgic amyotrophy with phrenic nerve involvement and bilateral diaphragmatic paralysis with marked respiratory symptoms and sleep hypoventilation, who was treated with non-invasive ventilation with volume assured pressure support mode. By 21 months post disease onset, the patient had experienced marked improvement in orthopnea, sleep quality and functional status. This is the first reported case of the use of this mode of noninvasive ventilation in neuralgic amyotrophy.
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INTRODUCTION: Objective outcome measures are needed to facilitate clinical trials of much needed treatments for calcinosis in systemic sclerosis (SSc). Our primary aim was to compare radiography, computed tomography (CT) and magnetic resonance imaging (MRI) to measure calcinotic lesions. Secondary objectives included to examine reproducibility of radiography and MRI, and inter-rater reliability of MRI. MATERIALS AND METHODS: 15 patients with SSc and clinically apparent calcinosis were studied. On one hand, radiography, CT and MRI were performed. The number (all techniques), area (radiography) and volume (CT and MRI) of calcinotic areas were extracted by 'blinded' musculoskeletal radiologists. RESULTS: No significant difference (Pâ¯=â¯0.289) in the mean (SD) number of lesions (per hand) was seen between radiography: 5.4 (4.6), CT: 6.3 (6.5) and MRI: 5.2 (3.9). Mean (SD) lesion volumes were systematically higher as measured by CT: 656.7 (1939.9) mm3 compared to MRI: 442 (1083.2) mm3. Radiographic area was highly correlated (P = <0.0001) with volume for both CT and MRI (rho=0.91 and 0.87, respectively). DISCUSSION: It was possible to measure calcinotic lesions by radiography, CT and MRI, with CT volume being higher than MRI volume. Radiographic area was highly correlated with CT and MRI volume, suggesting that low cost radiographs may give comparable information to 3-dimensional imaging. Our findings provide further insight into the development of objective outcome measures to facilitate future calcinosis clinical trials.
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Calcinose/diagnóstico por imagem , Articulação da Mão/diagnóstico por imagem , Imageamento por Ressonância Magnética , Radiografia , Escleroderma Sistêmico/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
This guideline provides a framework for the arrangement of point-of-care testing (POCT) services, previously known as near patient testing (patient self-testing not covered). POCT is defined as any analytical test performed outside the laboratory. Primary users are often non-laboratory healthcare workers. The guidance applies to units within hospitals as well as general practioner surgeries, community clinics and pharmacies. The head of the haematology laboratory or a point of care coordinator must take responsibility for all aspects of the POCT service, including quality and training. Depending on the size and nature of the POCT practice, a local POCT manager may also be required. Equipment selected should have received a successful independent performance evaluation. If an independent evaluation has not been performed the purchaser should assess the device according to the protocol in this document. POCT devices should generate results that are comparable to those of the local laboratory. An accredited external quality assessment programme and internal quality control system must be established. Manufacturers promoting POCT devices designed for non-laboratory sites, e.g. pharmacies, should undertake training and annual competency assessment, perhaps using a web-based system. A diagram to illustrate the stages for the implementation of a POCT service is illustrated.
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Testes Hematológicos/normas , Sistemas Automatizados de Assistência Junto ao Leito/normas , Acreditação , Testes Hematológicos/instrumentação , Hematologia/educação , Hematologia/organização & administração , Humanos , Capacitação em Serviço/normas , Prontuários Médicos/normas , Sistemas Automatizados de Assistência Junto ao Leito/organização & administração , Garantia da Qualidade dos Cuidados de SaúdeRESUMO
This Viewpoint discusses the need to improve the quality of care in neuromuscular disease for all individuals, no matter their race and ethnicity.
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Etnicidade , Grupos Raciais , Humanos , Estados UnidosRESUMO
OBJECTIVE: Inflammatory pseudotumor of the temporal bone is a benign, idiopathic inflammatory process that is locally invasive and a cause of significant morbidity. This study reviews our experience with seven patients and is currently the largest series to date. STUDY DESIGN: Retrospective review from January 1, 2014 to January 1, 2016. SETTING: Single tertiary medical center. PATIENTS: There were five male and two female (nâ=â7) subjects with a diagnosis of temporal bone inflammatory pseudotumor. The mean age at presentation was 41 years old. The most common presenting symptoms were hearing loss (7/7) and headache (4/7). Four patients demonstrated an inflammatory aural polyp. Two patients experienced facial nerve paralysis. INTERVENTION(S): Seven patients underwent computed tomography and six underwent magnetic resonance imaging. Corticosteroids and antibiotics were the initial treatment of choice. Five patients also underwent surgery. As adjuvant therapy, two patients received Rituximab, one patient received radiation, and one received mycophenolate mofetil. MAIN OUTCOME MEASURE(S): Clinical courses were followed with focus on symptoms, disease recurrence, duration, and treatment. Mean follow-up was 17.8 months. RESULTS: The primary lesions demonstrated T2 hypo-intensity and enhancement as well as diffuse dural thickening on magnetic resonance imaging in five of six patients. Histopathology demonstrated chronic inflammation in the setting of hyalinized fibrosis (7/7). All the patients are currently symptomatically stable. CONCLUSION: Inflammatory pseudotumor of the temporal bone can cause devastating effects on neurological function and quality of life. Recognition of characteristic imaging and histopathology can expedite appropriate treatment. Patients may require chronic steroid therapy. Adjunctive therapy with radiation and immuno-modulation are currently being explored.
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Doenças Ósseas/diagnóstico , Granuloma de Células Plasmáticas/diagnóstico , Osso Temporal/diagnóstico por imagem , Adolescente , Adulto , Idoso , Doenças Ósseas/diagnóstico por imagem , Doenças Ósseas/patologia , Doenças Ósseas/terapia , Criança , Feminino , Granuloma de Células Plasmáticas/diagnóstico por imagem , Granuloma de Células Plasmáticas/patologia , Granuloma de Células Plasmáticas/terapia , Humanos , Imunossupressores/uso terapêutico , Masculino , Pessoa de Meia-Idade , Ácido Micofenólico/uso terapêutico , Qualidade de Vida , Estudos Retrospectivos , Rituximab/uso terapêutico , Osso Temporal/patologia , Tomografia Computadorizada por Raios X , Resultado do Tratamento , Adulto JovemRESUMO
BACKGROUND: Renal cell carcinoma is well known for its frequency to metastasise, particularly to lungs, liver, bones and brain. Metastasis to the skin is much less common. Presentation as a result of the skin lesion is even more unusual, with only 14 previously reported cases in the English literature. The majority of these cases have been reported in patients with recurrent disease or with other metastases. CASE PRESENTATION: We present only the second case of non-recurrent renal cell carcinoma with a solitary cutaneous facial metastasis reported in the English literature. CONCLUSION: Clinicians should conduct a careful inspection of the skin in patients with renal cell carcinoma and also have a high index of suspicion of primary internal organ malignancy in patients presenting with a skin lesion.
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The genetic basis of many muscular disorders, including many of the more common muscular dystrophies, is now known. Clinically, the recent genetic advances have improved diagnostic capabilities, but they have not yet provided clues about treatment or management. Thanks to better management strategies and therapeutic interventions, however, many patients with a muscular dystrophy are more active and are living longer. Physical therapists, therefore, are more likely to see a patient with a muscular dystrophy, so understanding these muscle disorders and their management is essential. Physical therapy offers the most promise in caring for the majority of patients with these conditions, because it is unlikely that advances in gene therapy will significantly alter their clinical treatment in the near future. This perspective covers some of the basic molecular biological advances together with the clinical manifestations of the muscular dystrophies and the latest approaches to their management.
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Complexo de Proteínas Associadas Distrofina/fisiologia , Distrofias Musculares , Modalidades de Fisioterapia , Adolescente , Adulto , Animais , Criança , Pré-Escolar , Humanos , Lactente , Recém-Nascido , Pessoa de Meia-Idade , Distrofias Musculares/classificação , Distrofias Musculares/genética , Distrofias Musculares/fisiopatologia , Distrofias Musculares/terapiaAssuntos
Calcinose/etiologia , Dedos/diagnóstico por imagem , Escleroderma Sistêmico/complicações , Ferimentos e Lesões/complicações , Calcinose/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Escleroderma Sistêmico/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Ferimentos e Lesões/diagnóstico por imagemRESUMO
BACKGROUND: Peripheral neuropathy is the dose limiting toxicity of bortezomib in patients with multiple myeloma (MM). OBJECTIVES: To examine the safety, feasibility and efficacy of acupuncture in reducing bortezomib-induced peripheral neuropathy (BIPN) symptoms. METHODS: Patients with MM experiencing persistent BIPN ≥grade 2 despite adequate medical intervention and discontinuation of bortezomib received 10 acupuncture treatments for 10 weeks (2×/week for 2 weeks, 1×/week for 4 weeks, and then biweekly for 4 weeks). Responses were assessed by the Clinical Total Neuropathy Score (TNSc), Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-Ntx) questionnaire, and the Neuropathy Pain Scale (NPS). Repeated-measures analysis of variance was used to test for monotonic decline in scores on each of the measures. Serial serum levels of proinflammatory and neurotrophic cytokines were obtained at baseline and weeks 1, 2, 4, 8, and 14. RESULTS: Twenty-seven patients with MM were enrolled in the trial. There were no adverse events associated with the acupuncture treatments. TNSc data were deemed invalid and therefore were not reported. At weeks 10 and 14, FACT/GOG-Ntx and NPS showed significant reduction suggesting decreased pain, and improved function (P values were <.0001 for both FACT/GOG-Ntx and NPS at weeks 10 and 14). However, nerve conduction studies did not significantly change between baseline assessment and end of study. There was no correlation in serum cytokines for responders versus none responders. CONCLUSIONS: Acupuncture is safe, feasible and produces subjective improvements in patients' symptoms. A follow-up randomized controlled trial is warranted.
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Terapia por Acupuntura/métodos , Ácidos Borônicos/efeitos adversos , Mieloma Múltiplo/tratamento farmacológico , Doenças do Sistema Nervoso Periférico/terapia , Pirazinas/efeitos adversos , Terapia por Acupuntura/efeitos adversos , Idoso , Antineoplásicos/uso terapêutico , Ácidos Borônicos/uso terapêutico , Bortezomib , Citocinas/metabolismo , Estudos de Viabilidade , Humanos , Pessoa de Meia-Idade , Medição da Dor , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Projetos Piloto , Pirazinas/uso terapêutico , Fatores de Tempo , Resultado do TratamentoRESUMO
X-linked spinobulbar muscular atrophy (Kennedy's disease) affects muscles and motor neurons, manifesting as weakness and wasting of bulbar, facial, and proximal limb muscles due to loss of anterior horn cells in the brain and spinal cord. We present the case of a patient with X-linked spinobulbar muscular atrophy with rapidly worsening bulbar symptoms caused by laryngopharyngeal irritation associated with a viral upper respiratory tract infection, seasonal allergies and laryngopharyngeal reflux, who dramatically improved with multimodality therapy.
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UNLABELLED: In vitro studies demonstrating excessive wear in polyethylene cups sterilized using gamma irradiation and stored in air led to the abandonment of this sterilization technique. We evaluated the clinical wear performance of a metal femoral component on a polyethylene cup in a hip prosthesis from a selected subset of implants in a group of patients followed for at least 20 years and assessed the time dependency of variation in penetration rates. We measured penetration in 33 polyethylene cups in 25 patients who had a Charnley low-friction arthroplasty between 1982 and 1984. All patients had Charnley Ogee cups implanted for more than 20 years and sterilized using the gamma irradiation in air technique. If degradation occurred over time in vivo, it was not reflected by an increased penetration rate with increasing time in vivo; even after 20 years of implantation, the degree of wear remained low. This suggests gamma irradiation affects wear on ultra-high-molecular-weight polyethylene by reducing wear secondary to the crosslinking, by increasing wear as shown through in vitro studies of heavily oxidized samples, or by oxidation resulting from prolonged shelf life. The effect of progressive oxidation in vivo does not appear to affect wear in vivo. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
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Artroplastia de Quadril/instrumentação , Cimentos Ósseos , Prótese de Quadril , Osteoartrite do Quadril/cirurgia , Polietileno , Acetábulo/diagnóstico por imagem , Acetábulo/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Artrografia/métodos , Artroplastia de Quadril/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Osteoartrite do Quadril/diagnóstico por imagem , Falha de Prótese , Estudos Retrospectivos , Resultado do TratamentoRESUMO
To identify proteins expressed abnormally in facioscapulohumeral muscular dystrophy (FSHD), we extracted soluble proteins from deltoid muscle biopsies from unaffected control and FSHD patients and analyzed them using two-dimensional electrophoresis, mass spectrometry and immunoblotting. Muscles from patients with FSHD showed large increases over controls in a single soluble, 34 kDa protein (pI=5.08) identified by mass spectrometry and immunoblotting as mu-crystallin (CRYM). Soluble fractions of biopsies of several other myopathies and muscular dystrophies showed no appreciable increases in mu-crystallin. Mu-crystallin has thyroid hormone and NADPH binding activity and so may influence differentiation and oxidative stress responses, reported to be altered in FSHD. It is also linked to retinal and inner ear defects, common in FSHD, suggesting that its up-regulation may play a specific and important role in pathogenesis of FSHD.
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Cristalinas/biossíntese , Distrofia Muscular Facioescapuloumeral/metabolismo , Biópsia , Eletroforese em Gel Bidimensional , Humanos , Immunoblotting , Músculo Esquelético/metabolismo , Doenças Musculares/metabolismo , Estresse Oxidativo/fisiologia , Corantes de Rosanilina , Coloração pela Prata , Regulação para Cima/fisiologia , Cristalinas muRESUMO
OBJECTIVE: We examined the sarcolemma of skeletal muscle from patients with facioscapulohumeral muscular dystrophy (FSHD1A) to learn if, as in other murine and human muscular dystrophies, its organization and relationship to nearby contractile structures are altered. METHODS: Unfixed biopsies of control and FSHD deltoid and biceps muscles, snap-frozen at resting length, were cryosectioned, indirectly immunolabeled with fluorescent antibodies to sarcolemmal and myofibrillar markers, and examined with confocal microscopy to localize the immunolabeled proteins. Glutaraldehyde-fixed samples were stained with heavy metals, embedded, thin-sectioned, and examined with electron microscopy to determine the relationship between the sarcolemma and the underlying myofibrils. RESULTS: Confocal microscopy showed that some of the structures at the sarcolemma in FSHD samples were misaligned with respect to the underlying contractile apparatus. Electron microscopy showed a significant increase in the distance between the sarcolemma and the nearest myofibrils, from less than 100 nm in controls to values as high as 550 nm in FSHD. INTERPRETATION: Our results show that the pathophysiology of FSHD includes novel changes in the organization of the sarcolemma and its association with nearby contractile structures and suggest that, as in other muscular dystrophies, the integrity of the sarcolemma may be compromised in FSHD.
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Músculo Esquelético/patologia , Distrofia Muscular Facioescapuloumeral/patologia , Distrofia Muscular Facioescapuloumeral/fisiopatologia , Sarcolema/fisiologia , Citoesqueleto/fisiologia , Imunofluorescência/métodos , Humanos , Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/ultraestrutura , Sarcolema/metabolismo , Sarcolema/ultraestrutura , Espectrina/metabolismoRESUMO
Myasthenia gravis (MG) is an autoimmune disorder characterized clinically by proximal weakness and bulbar symptoms and pathologically by damage to the post-synaptic membrane at the neuromuscular junction. Ocular myasthenia gravis (ocular MG) is a form of myasthenia gravis whereby the patients' weakness is limited to the muscles of the eyes and eyelids (levator palpebrae superioris). Although not life-threatening, the limitations posed by ocular myasthenia gravis can prove disabling and distressing to patients. Acetylcholinesterase inhibitors such as pyridostigmine or neostigmine are the preferred first-line treatment for ocular myasthenia gravis, with mild cases requiring no additional intervention. However, in moderate or severe cases, treatment must be tailored to the needs and desires of the patient. Intravenous immunoglobulin, although costly, is safe and effective at treating MG. Corticosteroids are effective at reducing or eliminating symptoms and may modify the long-term course of the illness. Steroid-sparing agents such as azathioprine and mycophenolate mofetil are reasonably safe and well-tolerated alternatives to steroids. Surgical interventions such as strabismus surgery and eyelid suspension serve to correct impairments refractory to medical management. Thymectomy, although less frequently recommended, is a reasonable consideration, especially for young adults, given the potential for long-term benefit.
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Autoanticorpos/sangue , Doença Celíaca/diagnóstico , Doença Celíaca/genética , Testes Genéticos , Procedimentos Desnecessários , Adulto , Doença Celíaca/sangue , Reações Falso-Positivas , Feminino , Predisposição Genética para Doença , Antígenos HLA-DQ/genética , Humanos , Deficiência de IgA/sangueRESUMO
Small ankyrin 1, or sAnk1, is a small, alternatively spliced product of the erythroid ankyrin gene, ANK1, that is expressed in striated muscle and concentrated in the network sarcoplasmic reticulum (SR) surrounding the Z disks and M lines. We have characterized sAnk1 in muscle homogenates and SR vesicles, and have identified the region that targets it to the network SR. Selective extractions and partitioning into Triton X-114 show that sAnk1 behaves like the SR Ca-ATPase and so is an integral protein of the SR membrane. Mild proteolytic treatment of isolated SR vesicles indicates that sAnk1 is oriented with its hydrophilic, C-terminal sequence exposed to the solution, which is equivalent to the cytoplasmic face of the SR membrane in situ. SDS-PAGE in non-reducing gels suggests that sAnk1 is present as dimers and larger oligomers in the native SR. These results suggest that sAnk1 is oligomeric and oriented with its C-terminus exposed to the cytoplasm, where it may interact with proteins of the contractile apparatus. The N-terminal 29 amino acid hydrophobic sequence of sAnk1, which is predicted to span the SR membrane, is sufficient to target proteins to and anchor them in internal membranes of HEK 293 cells. It also targets reporter proteins to the network SR of skeletal myofibers and is thus the first example of a sequence that targets proteins to a particular compartment of the SR.