In vivo quantification of the 3D kinematics and coupling of the thumb base joints.

Full thumb mobility is required to execute tasks of daily living and results from the combined motions of the thumb joints. In this study, we focus on the coupling between the proximal joints of the thumb, the radioscaphoid (RS), scaphotrapezial (ST) and trapeziometacarpal (TMC) joints. We quantified the 3D kinematics of these joints during maximal thumb extension and abduction in a group of healthy volunteers using an image-based technique. Semi-dynamic CT scans of the dominant hand of 36 healthy subjects with the thumb in different standardized positions were used. The maximal range of motion of each joint in the different planes was calculated using a markerless bone registration method. Inter-joint coupling was assessed by performing a regression analysis between the range of motion of the joints during both thumb movements. Strong inter-joint coupling was found between the RS and ST joints during thumb extension and abduction, whereas coupling between the other joints was moderate to weak. This study provides valuable information on the in vivo 3D kinematics of the RS, ST and TMC joints during thumb movement. This can be used as input for modeling studies, where the coupling between the joints can decrease the degrees of freedom of the model. Moreover, these baseline data of a healthy cohort can be used for comparison with the kinematics of patients with TMC osteoarthritis or other pathologies and aid our understanding of motion deficits resulting from these joint disorders.

Lysosomal hydrolases of the epidermis. 5. Variation with depth in the cow snout.

The activity of twelve acid hydrolases has been measured in serial horizontal sections of cow snout epidermis. The majority of these enzymes showed a clear peak in the basal and lower spinous cell layers; acid phosphatase, however, was found mainly in the keratinizing zone. These findings suggest that two discrete populations of lysosomes may occur in epidermis. Those present in the lower layers possess a typical pattern of hydrolase activity and probably correspond to the 'orthodox' lysosomes observed by electron microscopy techniques, whereas those found in the keratinizing zone possess an unusual hydrolase profile and may correspond to the bodies identified morphologically as keratinosomes (Odland bodies, membrane-coating granules).

Horizontal distribution of three dehydrogenases in the cow snout epidermis.

A technique is described for quantifying enzyme activities in the various layers of the epidermis of the cow snout. Values for glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and lactate dehydrogenase are reported. In general, the amount of each enzyme is largest in the basal layers and diminished towards the stratum corneum. The exception was G6PD whose highest peak of activity was in the region of the stratum spinosum.