RESUMO
Within the genome, expressed genes marked by "open" chromatin are often adjacent to silent, heterochromatic regions. There are also regions containing neighboring active genes with different programs of expression. In both cases, DNA sequence elements may function as insulators, either providing barriers that prevent the incursion of heterochromatic signals into open domains or acting to block inappropriate contact between the enhancer of one gene and the promoter of another. The mechanisms associated with insulation are diverse: Enhancer-blocking insulation is largely associated with the ability to stabilize the formation of loop domains within the nucleus. Barrier insulation is often associated with the ability to block propagation of silencing histone modifications. Here, we provide examples of both kinds of insulator action, derived initially from studies of the compound insulator element at the 5' end of the chicken ß-globin locus. Such elements appear to have more general regulatory roles in the genome that have been exploited to provide insulator function where necessary to demarcate separate domains within the nucleus.
Assuntos
Cromatina/metabolismo , Elementos Isolantes/genética , Processamento Alternativo/efeitos dos fármacos , Processamento Alternativo/genética , Animais , Fator de Ligação a CCCTC , Galinhas , DNA (Citosina-5-)-Metiltransferases/metabolismo , Elementos Facilitadores Genéticos/genética , Heterocromatina/metabolismo , Ácidos Hidroxâmicos/farmacologia , Modelos Biológicos , Ligação Proteica/efeitos dos fármacos , Proteínas Repressoras/metabolismo , Ribonuclease III/metabolismo , Globinas beta/genética , DNA Metiltransferase 3BRESUMO
This case report gives the first published description of the use of dorsal column stimulation in the management of a patient with intractable angina pectoris that was unresponsive to maximal medical therapy, who was unsuitable for coronary artery revascularization surgery.
Assuntos
Angina Pectoris/terapia , Terapia por Estimulação Elétrica/métodos , Bloqueio Nervoso Autônomo , Feminino , Humanos , Pessoa de Meia-IdadeRESUMO
Twenty-one patients had acupuncture treatment for chronic, disabling pain. Ten (47.5%) thought they had obtained worthwhile relief by the time treatment was completed. Six (30%) had no or negligible benefit and five (25%) had some aggravation of their pain at some stage of the procedure. In this group of patients, with the technique we describe, we were unable to achieve the high degree of short-term success claimed by other workers. Until further scientific studies can confirm the value of acupuncture in medical practice, we urge caution in the use of this procedure.
