Electroporation of cells in microfluidic devices: a review.

In recent years, several publications on microfluidic devices have focused on the process of electroporation, which results in the poration of the biological cell membrane. The devices involved are designed for cell analysis, transfection or pasteurization. The high electric field strengths needed are induced by placing the electrodes in close proximity or by creating a constriction between the electrodes, which focuses the electric field. Detection is usually achieved through fluorescent labeling or by measuring impedance. So far, most of these devices have only concerned themselves solely with the electroporation process, but integration with separation and detection processes is expected in the near future. In particular, single-cell content analysis is expected to add further value to the concept of the microfluidic chip. Furthermore, if advanced pulse schemes are employed, such microdevices can also enhance research into intracellular electroporation.

The role of mechanical and neural restraints to joint range of motion during passive stretch.

UNLABELLED: Musculoskeletal flexibility is typically characterized by maximum range of motion (ROM) in a joint or series of joints. Resistance to passive stretch in the mid-range of motion is a function of the passive mechanical restraints to motion. However, an active contractile response may contribute resistance at terminal ROM. PURPOSE: The purpose of this study was to examine whether maximum straight leg raise (SLR) ROM was limited by passive mechanical forces or stretch-induced contractile responses to stretch. METHODS: An instrumented SLR stretch was applied to the right leg of 16 subjects ending at the point of discomfort. Torque was measured with a load cell attached to the ankle. An electrogoniometer was placed on the hip, and the knee was braced in extension. Surface electrodes were placed over the rectus and biceps femoris muscles. Following the instrumented SLR test, maximum ROM was measured goniometrically by a physical therapist using the standard SLR test (PT SLR ROM). Torque/ROM curves were plotted for each subject. RESULTS: PT SLR ROM was positively related to total energy absorbed (area under the curve) (r = 0.49, P = 0.044), negatively related to the increase in torque from 20 to 50 degrees (r = -0.81, P < 0.0001) and negatively related to energy absorbed from 20 to 50 degrees (r = -0.73, P < 0.001). Minimal stretch-induced hamstring activity was elicited (3 +/- 1% MVC), and the EMG activity was unrelated to PT SLR ROM (r = -0.06, P = 0.8). A combination of the increase in torque from 20 to 50 degrees and total energy absorbed improved the relationship to PT SLR ROM (r = 0.89, P = 0.001). Seventy-nine percent of the variability in maximum SLR ROM could be explained by the passive mechanical response to stretch. CONCLUSIONS: These data lend support to the concept that musculoskeletal flexibility can be explained in mechanical terms rather than by neural theories.

Young children of affectively ill parents: a longitudinal study of psychosocial development.

The course of social-emotional development of young children of affectively ill and well parents was assessed. The families were classified by mother's diagnosis: bipolar illness (N = 22), unipolar depression (N = 41), and normal (N = 37). Father's diagnosis also was obtained. Pairs of siblings were studied; the younger was between 1 1/2 and 3 1/2 years and the older between 5 and 8 years when the study began. They were seen again 3 years later. Psychiatric assessment and mother's report were used to evaluate children's disruptive behavior, anxiety, and depressive characteristics. The frequency of problem-level behavior changed over time in relation to mother's diagnosis. By middle and late childhood, significantly more children of affectively ill than well mothers had depressive and disruptive problems and multiple behavior problems. Offspring of unipolar mothers developed problems earlier and both siblings were more likely to have behavior problems.