RESUMO
People with late-stage Parkinson's disease (PD) often suffer from debilitating locomotor deficits that are resistant to currently available therapies. To alleviate these deficits, we developed a neuroprosthesis operating in closed loop that targets the dorsal root entry zones innervating lumbosacral segments to reproduce the natural spatiotemporal activation of the lumbosacral spinal cord during walking. We first developed this neuroprosthesis in a non-human primate model that replicates locomotor deficits due to PD. This neuroprosthesis not only alleviated locomotor deficits but also restored skilled walking in this model. We then implanted the neuroprosthesis in a 62-year-old male with a 30-year history of PD who presented with severe gait impairments and frequent falls that were medically refractory to currently available therapies. We found that the neuroprosthesis interacted synergistically with deep brain stimulation of the subthalamic nucleus and dopaminergic replacement therapies to alleviate asymmetry and promote longer steps, improve balance and reduce freezing of gait. This neuroprosthesis opens new perspectives to reduce the severity of locomotor deficits in people with PD.
Assuntos
Estimulação Encefálica Profunda , Transtornos Neurológicos da Marcha , Doença de Parkinson , Masculino , Animais , Humanos , Doença de Parkinson/complicações , Doença de Parkinson/terapia , Transtornos Neurológicos da Marcha/etiologia , Transtornos Neurológicos da Marcha/terapia , Marcha/fisiologia , Medula EspinalRESUMO
Glanzmann thrombasthenia is an inherited bleeding disorder arising from quantitative or qualitative defects of the alphaIIbbeta3 integrin of platelets. Here, we report that PCR-SSCP analysis and DNA sequencing revealed a homozygous single base pair substitution in exon 12 of the IIb gene leading to a Glu(324) (E) to Lys (K) substitution in the alphaIIb subunit in a patient with Type I disease. As this mutation is found on at least 3 continents, the codon for Glu(324) may be a mutational hotspot of the disease. To better understand this mutation, we analyzed the effect of substituting E(324) with A(324), L(324), D(324), Q(324), N(324), S(324), as well as K(324), looking at both alphaIIbbeta3 maturation and cell surface expression in transiently transfected Cos-7 cells. The maturation state of the receptor clearly correlated with the level of cell membrane expression. Maturation efficiency was dependent on the electric charge as well as the size of the side chain of the amino acid present in what is a highly conserved N-terminal position in the third beta-strand of blade 5 of the alphaIIbeta beta-propeller.
Assuntos
Mutação de Sentido Incorreto , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Glicoproteína IIb da Membrana de Plaquetas/genética , Trombastenia/genética , Substituição de Aminoácidos , Clonagem Molecular , Análise Mutacional de DNA , Feminino , Homozigoto , Humanos , Mutagênese Sítio-Dirigida , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/química , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Conformação Proteica , Subunidades Proteicas/genéticaRESUMO
Glanzmann's thrombasthenia (GT) is a hereditary bleeding disorder caused by a quantitative or qualitative defect in the integrin alphaIIbbeta3. A new mutation, a T to C substitution at base 258 in the alphaIIb gene, leading to the replacement of Leu55 with Pro, was found by sequence analysis of a patient's alphaIIb cDNA. In transfection experiments using COS7 cells, the cells co-transfected with the mutated alphaIIb cDNA containing C258 and wild-type beta3 cDNA scarcely expressed the alphaIIbbeta3 complex. The Leu55 to Pro substitution in the alphaIIb gene was found to be responsible for this case of Glanzmann's thrombasthenia.
Assuntos
Substituição de Aminoácidos , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/genética , Trombastenia/genética , Adulto , Análise Mutacional de DNA , DNA Complementar/genética , Feminino , Humanos , Mutação de Sentido IncorretoRESUMO
The reasons why tumor cells metastasize to bone remain obscure. There is some evidence to support the theory that integrins (acting as cell surface adhesion receptors) play a role in mediating metastasis in certain organs. Here, we report that overexpression of a functionally active integrin alpha(v)b3 in Chinese hamster ovary (CHO) tumor cells drastically increased the incidence, number, and area of bone metastases in nude mice compared with those observed in mock-transfected CHO cells (CHO dhfr+) or in CHO cells expressing a functionally inactive integrin alpha(v)b3 (CHO beta3Delta744). Moreover, a breast cancer cell line (B02) established from bone metastases caused by MDA-MB-231 cells constitutively overexpressed integrin alpha(v)b3, whereas the cell surface expression level of other integrins remained unchanged. In vivo, the extent of bone metastases in B02-bearing mice was significantly increased compared with that of MDA-MB-231-bearing mice. In vitro, B02 cells and CHO cells expressing a functionally active integrin alpha(v)b3 exhibited substantially increased invasion of and adhesion to mineralized bone, bone sialoprotein, and collagen compared with those found with MDA-MB-231, CHO dhfr+, and CHO beta3Delta744 cells, respectively. Overall, our findings suggest that integrin alpha(v)b3 expression in tumor cells accelerates the development of osteolytic lesions, presumably through increased invasion of and adhesion to bone.
