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1.
Nurs Open ; 10(8): 5098-5107, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37040438

RESUMO

AIM: This study aimed to develop a tool to measure paediatric specialist nurses' core competencies and examine the scale's validity and reliability. DESIGN: An exploratory quantitative study. METHODS: This study was performed in April 2022 with 302 paediatric specialist nurses in mainland China. Items were created through a literature review, a qualitative interview, and the Delphi method. The data were evaluated using descriptive statistics, independent sample t-test, explanatory factor analysis, Pearson correlation coefficient, Cronbach's alpha coefficient and split-half reliability. RESULTS: The final scale consisted of five factors and 32 items. The factors were communication, coordination and judgement abilities; professional technology mastery ability; specialist knowledge mastery ability; medical-related processes; and evidence-based nursing competencies. The explained total variance of the five factors was 62.216%. The scale-level and item-level CVI of this scale was 1.00, and the mean CVR of the total scale was 0.788. The Pearson correlation coefficients of each dimension and the total dimension of the scale was 0.709-0.892, and within each dimension, it was 0.435-0.651. The Cronbach's α of this scale was 0.944, and its split-half reliability was 0.883.


Assuntos
Enfermeiras e Enfermeiros , Criança , Humanos , Reprodutibilidade dos Testes , Psicometria/métodos , Inquéritos e Questionários , China
2.
Int Wound J ; 20(1): 46-54, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35535660

RESUMO

We performed a meta-analysis to evaluate the influences of closed incisions in orthopaedic trauma surgery (OTS) by negative pressure wound treatment (NPWT) compared with conventional dressings. A systematic literature search up to March 2022 was done and 14 studies included 3935 subjects with OTS at the start of the study; 2023 of them used NPWT and 1912 were conventional dressings. They were reporting relationships between the influences of closed incisions in OTS by NPWT compared with conventional dressings. We calculated the odds ratio (OR) with 95% confidence intervals (CIs) to assess the influences of closed incisions in OTS by NPWT compared with conventional dressings using the dichotomous methods with a random or fixed-effect model. NPWT had significantly lower deep surgical site infections (SSIs) (OR, 0.65; 95% CI, 0.48-0.87, P = .004), superficial SSIs (OR, 0.34; 95% CI, 0.19-0.61, P < .001), and wound dehiscence (OR, 0.41; 95% CI, 0.21-0.80, P = .009) compared with conventional dressings in subjects with closed incisions in OTS. NPWT showed a beneficial effect on deep SSIs, superficial SSIs, and wound dehiscence compared with conventional dressings in subjects with closed incisions in OTS. Further studies are required to validate these findings.


Assuntos
Tratamento de Ferimentos com Pressão Negativa , Ortopedia , Ferida Cirúrgica , Humanos , Bandagens , Tratamento de Ferimentos com Pressão Negativa/métodos , Complicações Pós-Operatórias , Ferida Cirúrgica/terapia , Deiscência da Ferida Operatória/terapia , Infecção da Ferida Cirúrgica/prevenção & controle , Cicatrização
3.
Int Wound J ; 20(2): 261-268, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35833263

RESUMO

We performed a meta-analysis to evaluate the effect of serologic malnutrition on postoperative wound infection problems after total joint arthroplasty. A systematic literature search up to April 2022, was performed and 446 501 subjects with total joint arthroplasty at the baseline of the studies; 200 433 of them were confirmed serologic malnutrition, and 246 068 were confirmed normal nutrition. Odds ratio (OR) and 95% confidence intervals (CIs) were calculated to assess the effect of serologic malnutrition on postoperative wound infection problems after total joint arthroplasty using the dichotomous method with a random or fixed-effect model. The serologic malnutrition subjects had a significantly higher wound disruption (OR, 1.97; 95% CI, 1.53-2.53, P < 0.001), higher superficial incisional surgical site infection (OR, 2.89; 95% CI, 1.67-5.01, P < 0.001), higher deep incisional surgical site infection (OR, 3.06; 95% CI, 2.36-3.96, P < 0.001), and higher organ space surgical site infection (OR, 3.15; 95% CI, 2.34-4.24, P < 0.001) in subjects after total joint arthroplasty compared with normal nutrition. The serologic malnutrition subjects had a significantly higher wound disruption, superficial incisional surgical site infection, deep incisional surgical site infection, and organ space surgical site infection in subjects after total joint arthroplasty compared with normal nutrition. The analysis of outcomes should be with caution because of the low number of studies in certain comparisons.


Assuntos
Desnutrição , Infecção da Ferida Cirúrgica , Humanos , Artroplastia/efeitos adversos , Desnutrição/etiologia , Desnutrição/complicações , Estado Nutricional , Razão de Chances , Infecção da Ferida Cirúrgica/diagnóstico , Infecção da Ferida Cirúrgica/epidemiologia , Infecção da Ferida Cirúrgica/etiologia
4.
Comput Math Methods Med ; 2022: 2938380, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35872952

RESUMO

Background: Knee osteoarthritis (KOA) is a chronic disease that seriously endangers the health of the elderly. Choosing appropriate surgery for knee osteoarthritis patients is especially important. Objective: To investigate the safety and efficacy of unicondylar knee prosthesis treatment for unicompartmental osteoarthritis of the knee. Materials and Methods: One hundred patients with unicondylar osteoarthritis of the knee treated in our hospital from June 2019 to June 2021 were selected as retrospective study subjects and were divided into 50 cases each in the comparison group and the observation group according to the different surgical methods. Among them, the comparison group was treated with unicondylar knee arthroplasty (UKA), and the observation group was treated with unicondylar knee prosthesis replacement, and the differences in AKS score, knee flexion angle, tibial angle orthosis, joint mobility, and postoperative recovery were compared between the two groups. Results: The AKS score and knee flexion angle score of the observation group were higher than those of the comparison group after surgery. However, the tibial angle orthopedic score of the observation group was significantly lower than that of the comparison group after surgery for comparison, and the VAS score of the observation group was lower than that of the comparison group. However, the Lysholm score of the observation group was higher than that of the control group after surgery (P < 0.05). The complication rate of patients in the observation group was significantly lower than that of the comparison group, and the HSS score, VAS score, and knee mobility (ROM) of the two groups were statistically significant (P < 0.05) when compared at 7 d after surgery and 6 months after surgery. Conclusion: The clinical efficacy of unicondylar knee prosthesis replacement for osteoarthritis of the knee is better than that of unicondylar knee arthroplasty (UKA) treatment.


Assuntos
Artroplastia do Joelho , Prótese do Joelho , Osteoartrite do Joelho , Idoso , Artroplastia do Joelho/efeitos adversos , Artroplastia do Joelho/métodos , Humanos , Articulação do Joelho/cirurgia , Osteoartrite do Joelho/cirurgia , Amplitude de Movimento Articular , Estudos Retrospectivos , Resultado do Tratamento
5.
Head Neck Pathol ; 16(2): 550-559, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34224080

RESUMO

Primordial odontogenic tumor (POT) is a rare, mixed odontogenic neoplasm composed of spindled and stellate-shaped cells in myxoid stroma resembling dental papilla, surfaced by cuboidal-to-columnar odontogenic epithelium. Most POTs present in the posterior mandible as a well-demarcated radiolucency associated with a developing tooth in children and adolescents. POT is treated conservatively with no recurrences documented to-date. To describe the clinicopathological features of a recurrent POT. A 19-year-old female presented with an asymptomatic swelling, and panoramic radiograph revealed a multiloculated radiolucency in the mandibular body and ramus, with buccal and lingual perforation. The tumor was composed of plump spindle and stellate cells in a delicately collagenous and myxoid stroma, surfaced by columnar epithelial cells with reverse nuclear polarization. There was extensive epithelial proliferation forming invaginations within the tumor mass and organoid/enamel organ-like structures with enameloid-like deposits, dentinoid, and dystrophic calcifications. This was similar to the POT that had been excised four years prior from the same location. The patient underwent hemi-mandibulectomy and currently is free of disease at a thirteen-month follow-up. This report describes the first recurrent POT exhibiting extensive epithelial proliferation.


Assuntos
Tumores Odontogênicos , Adolescente , Adulto , Criança , Epitélio/patologia , Feminino , Humanos , Mandíbula/patologia , Tumores Odontogênicos/patologia , Adulto Jovem
6.
J Healthc Eng ; 2021: 6663892, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33708366

RESUMO

More and more people pay attention to the printing speed and quality of 3D printing tools. In order to understand whether the 3D printing rehabilitation brace can play a role in the treatment and repair of joint trauma, we used 3D printing technology to print the rehabilitation brace and compared with the traditional rehabilitation brace. The printed parts were analyzed in detail. The experimental results prove that the rehabilitation braces made by the two methods can play a role in the repair of joint trauma. However, 3D printed rehabilitation braces can better meet the needs of patients with detailed patient data in application. The braces are more suitable, and their production speed is about 35% faster than traditional methods. Through the survey of patients and doctors, it is found that the satisfaction of patients and doctors with printed braces is above 89%, while the satisfaction with traditionally made braces is only about 60%. This shows that the rehabilitation brace based on the Internet of Things 3D printing technology has a more significant role in the treatment and repair of joint trauma, and the effect is better.


Assuntos
Braquetes , Internet das Coisas , Humanos , Impressão Tridimensional
7.
Am J Speech Lang Pathol ; 28(4): 1625-1637, 2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31618056

RESUMO

Purpose The study aims to investigate, using anodal transcranial direct current stimulation (A-tDCS), over which site, the left lip region of primary motor cortex (M1) or the Broca's area, there would be better recovery from apraxia of speech (AoS) in patients with poststroke aphasia and to examine for altered activation in speech-related areas after tDCS with nonlinear electroencephalography (EEG). Method Fifty-two patients with AoS were randomized into A-tDCS over the left M1 (A-tDCS-M1), Broca's area, and sham tDCS groups who underwent 10 sessions of tDCS and speech treatment for 5 days. The EEG nonlinear index of approximate entropy was calculated for 6 subjects in each group before and after treatment. Results After treatment, the change in speech-language performance improved more significantly in the A-tDCS-M1 group than the other 2 groups (p < .05). EEG approximate entropy indicated that both A-tDCS groups could activate the stimulated sites; the improvement in the A-tDCS-M1 group was correlated with high activation in the dorsal lateral prefrontal cortex and Broca's areas of the left hemisphere in addition to the stimulated site. Conclusion A-tDCS over the left M1 can improve the speech function in patients with poststroke aphasia and severe AoS and excite and recruit more areas in the motor speech network.


Assuntos
Apraxias/terapia , Reabilitação do Acidente Vascular Cerebral/métodos , Acidente Vascular Cerebral/complicações , Estimulação Transcraniana por Corrente Contínua/métodos , Adulto , Idoso , Apraxias/etiologia , Apraxias/fisiopatologia , Eletroencefalografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Pré-Frontal/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Resultado do Tratamento , Adulto Jovem
8.
Am J Speech Lang Pathol ; 28(4): 1381-1387, 2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31498703

RESUMO

Purpose Severe dysphagia with weak pharyngeal peristalsis after dorsal lateral medullary infarction (LMI) requires long-term tube feeding. However, no study is currently available on therapeutic effectiveness in severe dysphagia caused by nuclear damage of vagus nerve after dorsal LMI. The purpose of the present investigation was to explore the potential of transcutaneous vagus nerve stimulation (tVNS) to improve severe dysphagia with weak pharyngeal peristalsis after dorsal LMI. Method We assessed the efficacy of 6-week tVNS in a 28-year-old woman presented with persisting severe dysphagia after dorsal LMI who had been on nasogastric feeding for 6 months. tVNS was applied for 20 min twice a day, 5 days a week, for 6 weeks. The outcome measures included saliva spitted, Swallow Function Scoring System, Functional Oral Intake Scale, Clinical Assessment of Dysphagia With Wallenberg Syndrome, Yale Pharyngeal Residue Severity Rating Scale, and upper esophagus X-ray examination. Results After tVNS, the patient was advanced to a full oral diet without head rotation or spitting. No saliva residue was found in the valleculae and pyriform sinuses. Contrast medium freely passed through the upper esophageal sphincter. Conclusion Our findings suggest that tVNS might provide a useful means for recovery of severe dysphagia with weak pharyngeal peristalsis after dorsal LMI. Supplemental Material https://doi.org/10.23641/asha.9755438.


Assuntos
Infartos do Tronco Encefálico/complicações , Transtornos de Deglutição/terapia , Bulbo/irrigação sanguínea , Estimulação Elétrica Nervosa Transcutânea/métodos , Estimulação do Nervo Vago/métodos , Adulto , Transtornos de Deglutição/etiologia , Feminino , Humanos , Resultado do Tratamento
9.
Mod Pathol ; 28(4): 545-51, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25431238

RESUMO

Recent studies have shown that immunohistochemical evaluation of MYC protein expression in diffuse large B-cell lymphoma is a useful prognostic tool with high concordance rate among pathologists. Concordance in these studies was assessed among few pathologists from one institution by scoring tissue microarrays. In daily practice, MYC evaluation is performed on entire tumor sections by a diverse group of pathologists. In our study, nine hematopathologists from two institutions scored whole-tissue sections of two sets of cases. The training set included 13 cases of diffuse large B-cell lymphoma and 4 cases of Burkitt lymphoma. The validation set included 18 cases of diffuse large B-cell lymphoma and 1 case of Burkitt lymphoma. MYC positivity was defined as ≥40% of tumor cells demonstrating nuclear staining similar to prior studies. The mean score for each case was used to determine MYC status with discrepant cases defined as having any score causing a different MYC status designation. Discrepant cases from the training set were characterized by staining heterogeneity, extensive necrosis or crush artifact and had mean scores within 15 percentage points of 40%. Cases from the validation set that demonstrated any of these features were scored twice on two different days. Overall concordance was moderate (Kappa score: 0.68, P-value<0.001) with no significant change between the two sets (Kappa scores: 0.69 vs 0.67). Thirty-nine percent of cases were discrepant. The findings indicate that a significant number of diffuse large B-cell lymphomas are inherently difficult to score due to staining heterogeneity. The effect of heterogeneity can be under-represented when concordance is measured among few pathologists scoring tissue microarrays. Careful scoring strategy in our study failed to improve concordance. In the absence of specific instructions on how to deal with heterogeneity, caution is advised when evaluating MYC expression in diffuse large B-cell lymphoma.


Assuntos
Linfoma de Burkitt/metabolismo , Linfoma Difuso de Grandes Células B/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Linfoma de Burkitt/patologia , Humanos , Imuno-Histoquímica , Linfoma Difuso de Grandes Células B/patologia , Reprodutibilidade dos Testes
10.
Case Rep Hematol ; 2013: 386147, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23738160

RESUMO

Posttransplant lymphoproliferative disorder (PTLD) comprises a spectrum ranging from polyclonal hyperplasia to aggressive monoclonal lymphomas. The majority of PTLDs are of B-cell origin while T-cell PTLDs and Hodgkin lymphoma-like PTLDs are uncommon. Here, we report a unique case of a 56-year-old man in whom a lymphoma with two distinct components developed as a duodenal mass seventeen years following a combined kidney-pancreas transplant. This PTLD, which has features not previously reported in the literature, consisted of one component of CD20 positive and EBV negative monomorphic diffuse large B-cell lymphoma. The other component showed anaplastic morphology, expressed some but not all T-cell markers, failed to express most B-cell markers except for PAX5, and was diffusely EBV positive. Possible etiologies for this peculiar constellation of findings are discussed and the literature reviewed for "composite-like" lymphomas late in the posttransplant setting.

11.
Int J Clin Exp Pathol ; 1(2): 185-97, 2008 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-18784807

RESUMO

Fulminant Epstein-Barr virus (EBV)-driven clonal T-cell lymphoproliferative disorder (T-LPD) is rare and most patients are of Asian origin. The disease usually develops shortly after primary acute EBV infection and the mechanism remains poorly understood. Here we report such a rare case in a 28-year-old Caucasian female with systemic lupus erythematosus (SLE). Immunophenotypic and molecular studies revealed that the proliferating lymphoid cells displayed a CD8(+) T-cell phenotype with clonal rearrangement of the T-cell receptor gamma gene. Epstein-Barr virus-encoded RNA was also observed in the clonal lymphoid cells by in situ hybridization. The patient subsequently developed fatal virus-associated hemophagocytic syndrome one month after the primary acute EBV infection. The case represents the first report of fulminant EBV-driven CD8(+) T-LPD occurring in an immunocompromised Caucasian SLE patient. This study, along with studies of similar Asian cases reported in the literature, suggests that dysregulated immunity due to either acquired or genetically determined susceptibility may result in an abnormal response to primary EBV infection and contribute to the pathogenesis of EBV-mediated fatal T-LPD.

12.
Zhonghua Yi Xue Za Zhi ; 88(8): 524-6, 2008 Feb 26.
Artigo em Chinês | MEDLINE | ID: mdl-18649766

RESUMO

OBJECTIVE: To investigate the effects of alprostadil (Lipo PGE1) in prevention of portal vein thrombogenesis (PVT) after splenectomy for portal hypertension. METHODS: Seventy-six patients with portal hypertension undergoing splenectomy and pericardial devascularization were randomly divided into 2 groups :treatment group (n = 40), receiving intravenous drip of injection of radix Salviae miliorrhazae (RSM) 40 ml and alprostadil 20 microg, both once a day since the third day after operation for 2 weeks and then oral administration of dropping pill of SM, and control group (n = 36), receiving intravenous drip of injection of RSM and taking enteric coated aspirin 3 times a day for 2 weeks and then taking dropping pill of SM. Platelets (PLT), prothrombin time (PT), and liver function were detected periodically. Color Doppler ultrasonography was conducted every week to observe the blood flow velocity and diameter of the portal and splenic veins, and if PVT event and ascites occurred. All patients were followed up for 8 - 20 months. RESULTS: No prolongation of coagulation time and bleeding tendency was found in both groups. The PLT number increased remarkably in the 7th to 14th days after operation without significant difference between the 2 groups (P >0.05). The PVT rate of the treatment group was 5.0%, significantly lower than that of the control group (25.0%, chi2 = 6.12, P < 0.05). The ascites rate of the treatment group was 10.0%, significantly lower than that of the control group (33.3%, chi2 = 7.44, P <0.01). The levels of ALT and total bilirubin 7 and 16 days after operation of the treatment group were all significantly lower than those of the control group (all P <0.05). CONCLUSION: Use of alprostadil early after devascularization is an effective and safe measure to prevent PVT, improve liver function, and decrease ascites rate.


Assuntos
Alprostadil/uso terapêutico , Hipertensão Portal/cirurgia , Complicações Pós-Operatórias/prevenção & controle , Esplenectomia/métodos , Trombose/prevenção & controle , Quimioterapia Combinada , Medicamentos de Ervas Chinesas/uso terapêutico , Seguimentos , Humanos , Fígado/irrigação sanguínea , Fígado/efeitos dos fármacos , Fígado/fisiopatologia , Veia Porta/patologia , Veia Porta/fisiopatologia , Veia Porta/cirurgia , Complicações Pós-Operatórias/etiologia , Estudos Prospectivos , Salvia miltiorrhiza/química , Esplenectomia/efeitos adversos , Trombose/etiologia , Fatores de Tempo , Resultado do Tratamento , Vasodilatadores/uso terapêutico
13.
J Cutan Pathol ; 35 Suppl 1: 32-7, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18544058

RESUMO

Adult T-cell leukemia/lymphoma (ATLL) is a rare malignancy caused by human T-cell leukemia virus-1. ATLL is endemic to Japan, and to date, there are only four case reports of patients from Romania who have developed ATLL. Here, we describe a woman living in Madison, Wisconsin, originally from Romania, who presented with an atypical papulosquamous eruption and was ultimately diagnosed with smoldering ATLL. Narrow-band ultraviolet-B (UV-B) therapy and mid-potency topical steroids resulted in skin clearing for approximately 5 months after diagnosis; however, she subsequently relapsed with disease refractory to both narrow band UV-B and psoralen plus ultraviolet A (PUV-A), progressed to acute ATLL and expired secondary to complications.


Assuntos
Infecções por HTLV-I/complicações , Leucemia-Linfoma de Células T do Adulto/patologia , Leucemia-Linfoma de Células T do Adulto/fisiopatologia , Terapia Ultravioleta , Corticosteroides/uso terapêutico , Adulto , Feminino , Citometria de Fluxo , Infecções por HTLV-I/patologia , Infecções por HTLV-I/fisiopatologia , Humanos , Imuno-Histoquímica , Leucemia-Linfoma de Células T do Adulto/radioterapia , Reação em Cadeia da Polimerase , Infecções Respiratórias/patologia , Romênia , Vitiligo/patologia
14.
Invest New Drugs ; 25(1): 49-55, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17001523

RESUMO

PURPOSE: The integrin alphavbeta3 is an adhesion molecule expressed by proliferating endothelial cells and antibodies blocking this integrin inhibit angiogenesis in preclinical models. MEDI-522 is a second generation humanized anti-alphavbeta3 antibody designed for antiangiogenic therapy. The purpose of this study was to examine potential effects of this agent on blood vessels. EXPERIMENTAL DESIGN: In a phase I dose escalation study, MEDI-522 was administered by weekly infusions to 25 adult patients with advanced solid organ malignancies. As a surrogate angiogenesis assay, a wound was created by punch biopsy of the arm skin. This wound site was re-biopsied after a 7-day interval. Dual-label immunofluorescence experiments followed by computer-assisted image analysis were conducted to analyze the vasculature. RESULTS: Sequential pretreatment and 4-week treatment skin biopsy pairs were available on 4 patients, who had received 6 or 10 mg/kg of MEDI-522. MEDI-522 was detected in the dermal blood vessels as well as the dermal interstitium both in intact and wounded skin sites following treatment. No statistically significant difference was found between pretreatment and treatment samples of skin for vascular area, endothelial cell proliferation and apoptosis, or beta3 integrin levels. Phosphorylated focal adhesion kinase (pFAK) was significantly diminished in skin wound vessels during MEDI-522 treatment compared to the pretreatment samples. CONCLUSIONS: MEDI-522 was detectable both in quiescent and in angiogenically active skin blood vessels as well as in the dermal interstitial space. The levels of pFAK were reduced during MEDI-522 treatment, suggesting a modulating effect on this signaling molecule.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Integrina alfaVbeta3/imunologia , Neoplasias/prevenção & controle , Neovascularização Patológica/prevenção & controle , Adulto , Inibidores da Angiogênese/administração & dosagem , Inibidores da Angiogênese/farmacocinética , Inibidores da Angiogênese/uso terapêutico , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/farmacocinética , Apoptose/efeitos dos fármacos , Vasos Sanguíneos/efeitos dos fármacos , Vasos Sanguíneos/patologia , Relação Dose-Resposta a Droga , Esquema de Medicação , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Endotélio Vascular/patologia , Imunofluorescência/métodos , Quinase 1 de Adesão Focal/antagonistas & inibidores , Quinase 1 de Adesão Focal/metabolismo , Humanos , Processamento de Imagem Assistida por Computador/métodos , Infusões Intravenosas , Integrina alfaVbeta3/antagonistas & inibidores , Linfoma/patologia , Linfoma/fisiopatologia , Linfoma/prevenção & controle , Neoplasias/irrigação sanguínea , Neoplasias/metabolismo , Pele/efeitos dos fármacos , Pele/metabolismo , Pele/patologia , Fatores de Tempo
15.
J Muscle Res Cell Motil ; 25(2): 167-75, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15360132

RESUMO

Microtubules may influence smooth muscle contraction either via involvement in signal transduction processes or by serving as an internal load that opposes contraction. To test the latter hypothesis, microtubule distribution and the unloaded shortening velocity were investigated in freshly isolated single vascular smooth muscle cells (VSMCs) treated with microtubule modulating drugs. Immunocytochemical studies showed that microtubules run mainly longitudinally in relaxed VSMCs. They are oriented more obliquely, almost transversely to the long axis of the cells after contraction, suggesting that microtubules are compressed during shortening, and thus might impart an internal passive load. Quantitative immunocytochemical analysis revealed that, relative to the control group, colchicine (15 microM) decreased the microtubule density by 40% while taxol (10 microM) increased the microtubule density by 46%. However, alteration of microtubule polymerization status by these microtubule-modulating drugs did not have a significant effect on unloaded shortening velocity in alpha-toxin permeabilized VSMCs under maximal activating conditions or submaximal activating conditions (about 36% of maximal velocity). These results suggest that microtubules do not present an appreciable internal load to dampen single VSMCs shortening in the present experimental system, and that their influence on smooth muscle contraction is primarily via signal transduction mechanisms.


Assuntos
Microtúbulos/fisiologia , Miócitos de Músculo Liso/fisiologia , Actinas/metabolismo , Animais , Cálcio/farmacologia , Adesão Celular/fisiologia , Permeabilidade da Membrana Celular , Forma Celular/efeitos dos fármacos , Forma Celular/fisiologia , Colchicina/farmacologia , Imuno-Histoquímica , Cinética , Microscopia de Fluorescência , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Nocodazol/farmacologia , Paclitaxel/farmacologia , Coelhos
16.
J Physiol ; 552(Pt 3): 845-57, 2003 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-12923217

RESUMO

Cardiac troponin I (cTnI) is a phosphoprotein subunit of the troponin-tropomyosin complex that is thought to inhibit cardiac muscle contraction during diastole. To investigate the contributions of cTnI phosphorylation to cardiac regulation, transgenic mice were created with the phosphorylation sites of cTnI mutated to alanine. Activation of protein kinase C (PKC) by perfusion of hearts with phorbol-12-myristate-13-acetate (PMA) or endothelin-1 (ET-1) inhibited the maximum ATPase rate by up to 25 % and increased the Ca2+ sensitivity of ATPase activity and of isometric tension by up to 0.15 pCa units. PKC activation no longer altered cTnI phosphorylation, depressed ATPase rates or enhanced myofilament Ca2+ sensitivity in transgenic mice expressing cTnI that could not be phosphorylated on serines43/45 and threonine144 (PKC sites). Modest changes in myosin regulatory light chain phosphorylation occurred in all mouse lines, but increases in myofilament Ca2+ sensitivity required the presence of phosphorylatable cTnI. For comparison, the beta-adrenergic agonist isoproterenol caused a 38 % increase in maximum ATPase rate and a 0.12 pCa unit decrease in myofilament Ca2+ sensitivity. These beta-adrenergic effects were absent in transgenic mice expressing cTnI that could not be phosphorylated on serines23/24 (protein kinase A, PKA, sites). Overall, the results indicate that PKC and PKA exert opposing effects on actomyosin function by phosphorylating cTnI on distinct sites. A primary role of PKC phosphorylation of cTnI may be to reduce the requirements of the contractile apparatus for both Ca2+ and ATP, thereby promoting efficient ATP utilisation during contraction.


Assuntos
Citoesqueleto de Actina/fisiologia , Adenosina Trifosfatases/metabolismo , Cálcio/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Miocárdio/metabolismo , Proteína Quinase C/metabolismo , Troponina I/metabolismo , Adenosina Trifosfatases/antagonistas & inibidores , Agonistas Adrenérgicos beta/farmacologia , Alanina/genética , Substituição de Aminoácidos , Animais , Endotelina-1/farmacologia , Ativação Enzimática/fisiologia , Técnicas In Vitro , Contração Isométrica/efeitos dos fármacos , Isoproterenol/farmacologia , Camundongos , Camundongos Transgênicos , Mutação , Contração Miocárdica/efeitos dos fármacos , Miocárdio/citologia , Fosforilação , Acetato de Tetradecanoilforbol/farmacologia , Troponina I/genética
17.
Circ Res ; 90(6): 649-56, 2002 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-11934831

RESUMO

The cardiac myofilament protein troponin I (cTnI) is phosphorylated by protein kinase C (PKC), a family of serine/threonine kinases activated within heart muscle by a variety of agonists. cTnI is also a substrate for cAMP-dependent protein kinase (PKA) activated during beta-adrenergic signaling. To investigate the role of cTnI phosphorylation in contractile regulation by these pathways, we generated transgenic mice harboring a mutated cTnI protein lacking phosphorylation sites for PKC (serine(43/45) and threonine(144) mutated to alanine) and for PKA (serine(23/24) mutated to alanine). Transgenic mice were interbred with cTnI-knockout mice to ensure the absence of endogenous phosphorylatable cTnI. Here, we report that regulation of myocyte twitch kinetics by beta-stimulation and by endothelin-1 was altered in myocytes containing mutant cTnI. In wild-type myocytes, the beta-agonist isoproterenol decreased twitch duration and relaxation time constant (tau) by 37% to 44%. These lusitropic effects of isoproterenol were reduced by about half in nonphosphorylatable cTnI mutant myocytes and were absent in cTnI mutants also lacking phospholamban (generated by crossing cTnI mutants with phospholamban-knockout mice). These observations are consistent with important roles for both cTnI and phospholamban phosphorylation in accelerating relaxation after beta-adrenergic stimulation. In contrast, endothelin-1 increased twitch duration by 32% and increased tau by 58%. These endothelin-1 effects were substantially blunted in nonphosphorylatable cTnI myocytes, indicating that PKC phosphorylation of cTnI slows cardiac relaxation and increases twitch duration. We propose that beta-agonists and endothelin-1 regulate cardiac twitch dynamics in opposite directions in part through phosphorylation of the myofilament protein cTnI on distinct sites.


Assuntos
Coração/fisiologia , Contração Miocárdica/fisiologia , Troponina I/fisiologia , Animais , Cálcio/fisiologia , Cardiotônicos/farmacologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Estimulação Elétrica , Endotelina-1/farmacologia , Regulação da Expressão Gênica/fisiologia , Técnicas In Vitro , Isoproterenol/farmacologia , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Mutação , Contração Miocárdica/efeitos dos fármacos , Fosforilação , Proteína Quinase C/metabolismo , Transdução de Sinais , Troponina I/genética
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