Characterization of multijoint finger stiffness: dependence on finger posture and force direction

The two-dimensional static stiffness of the index finger was measured with the interphalangeal joints in flexed and extended postures. The stiffness of the relaxed finger was compared with the stiffness when voluntary force was exerted in different directions. The finger stiffness was found to be anisotropic, with the direction of greatest stiffness being approximately parallel to the proximal phalange of the finger. This direction was relatively unaffected by finger posture or direction of finger force. Finger stiffness was more anisotropic when the interphalangeal joints were extended than flexed. The stiffness was most anisotropic when the interphalangeal joints were extended and force was being exerted in the direction of pointing, while it was least anisotropic when the interphalangeal joints were flexed and force was being exerted in directions normally associated with pinching and tapping actions. The stiffness of the individual finger joints was computed and the relation between stiffness and joint torque was examined. Previous studies, which examined single finger joints in isolation, had found that joint stiffness varied in a linear fashion with net joint torque. In contrast, we did not find a monotonic relation between joint stiffness and net joint torque, which we attributed to the need to vary the amount of cocontraction of antagonistic muscles when controlling the direction of finger force.     

Mixed-dye staining method for protein detection in polyacrylamide gel electrophoresis using calconcarboxylic acid and rhodamine B

We have developed a new mixed-dye protein staining method that is simple, rapid, and sensitive. A freshly prepared mixture of calconcarboxylic acid (NN, 0.02%) and rhodamine B (RB, 0.04%) in 40% methanol/7% acetic acid, was used as a staining solution. RB acts as an auxiliary agent to inhibit the binding of NN to the gel matrix, reducing the background staining and therefore enhancing the protein staining by NN. This mixed-dye staining method reduces the total staining and destaining time to less than an hour, and increases the sensitivity to 25 ng of bovine serum albumin, which is greater than the 100 ng sensitivity limit of Coomassie Brilliant Blue R-250 (CBBR) staining.     

Biomechanical evaluation of the medial collateral ligament of the elbow

Anatomical dissection and biomechanical testing were used to study twenty-eight cadaveric elbows in order to determine the role of the medial collateral ligament under valgus loading. The medial collateral ligament was composed of anterior, posterior, and occasionally transverse bundles. The anterior bundle was, in turn, composed of anterior and posterior bands that tightened in reciprocal fashion as the elbow was flexed and extended. Sequential cutting of the ligament was performed while rotation caused by valgus torque was measured. The anterior band of the anterior bundle was the primary restraint to valgus rotation at 30, 60, and 90 degrees of flexion and was a co-primary restraint at 120 degrees of flexion. The posterior band of the anterior bundle was a co-primary restraint at 120 degrees of flexion and a secondary restraint at 30 and 90 degrees of flexion. The posterior bundle was a secondary restraint at 30 degrees only. The reciprocal anterior and posterior bands have distinct biomechanical roles and theoretically may be injured separately. The anterior band was more vulnerable to valgus overload when the elbow was extended, whereas the posterior band was more vulnerable when the elbow was flexed. The posterior bundle was not vulnerable to valgus overload unless the anterior bundle was completely disrupted. The intact elbows rotated a mean of 3.6 degrees between the neutral position and the two-newton-meter valgus torque position. Cutting of the entire anterior bundle caused an additional 3.2 degrees of rotation at 90 degrees of flexion, where the effect was greatest. CLINICAL RELEVANCE: Physical findings in a patient who has an injury of the anterior bundle may be subtle, and an examination should be performed with the elbow in 90 degrees of flexion for greatest sensitivity. As the anterior bundle is the major restraint to valgus rotation, reconstructive procedures should focus on anatomical reproduction of that structure. Parallel limbs of tendon graft placed from the inferior aspect of the medial epicondyle to the area of the sublimis tubercle will simulate the reciprocal bands of the anterior bundle. Temporary immobilization with the elbow in flexion may relax the critically important anterior band of the reconstruction during healing.     

Fourier-transform Raman spectra of ivory. III: Identification of mammalian specimens

The FT-Raman spectra of six mammalian ivories, other than elephant and mammoth, are presented and spectral differences formulated into a protocol for the identification of animal species from the ivory samples. In this study, sperm whale, walrus, wart hog, narwhal, hippopotamus and domestic pig are considered. The results, which are obtained non-destructively from a variety of specimens, suggest that FT-Raman spectroscopy provides a potentially useful method for the identification of mammalian ivory.     

Genetic variation of herpesvirus saimiri subgroup A transforming protein and its association with cellular src

Herpesvirus saimiri strain 11 of subgroup A contains a gene called the saimiri transformation-associated protein, STP, which is not required for viral replication but is required for in vitro immortalization and for the lymphoma-inducing capacity of the virus. To assess the effects of sequence variation on STP function, STP genes from six subgroup A isolates were cloned and sequenced. Sequence comparisons revealed extensive amino acid substitutions within the central region, but the acidic amino terminus and the hydrophobic carboxyl terminus were well conserved. Amino acid identities varied from 73 to 99% among all two-way comparisons. The highly conserved YAEV/I motif at amino acid residues 115 to 118 was preceded by negatively charged glutamic acid residues and thus matched very well the consensus sequence for binding to SH2 domains of src family kinases. The STPs of these subgroup A strains were shown to associate with cellular src and to be an in vitro substrate for src kinase. Mutational analysis of STP-A11 showed that binding to src kinase required the tyrosine residue at 115, showing that YAEV/I is a likely binding motif for src. Also, tyrosine phosphorylation of STP-A11 by src led to subsequent binding to lck and fyn in vitro. Thus, the association of STP with src is likely to be important for T-cell transformation by subgroup A strains of herpesvirus saimiri.     

Key issues in managed competition

All managed competition proposals for health system reform must confront several key issues. The premiums paid to health care purchasing cooperatives will need to be subsidized for those who cannot pay full fare; the amount and sources of the subsidies are controversial political issues. The payments passed on by purchasing cooperatives to health plans must be risk adjusted to account for differences in the health care needs of their enrolled populations. This is essential to create a level playing field for competition and to eliminate incentives for plans to use risk assessment for attracting enrollees. The data and methods needed for risk adjustment, however, are not adequate at present. The Clinton Administration's plan to limit expenditure increases raises a host of thorny issues. Maintaining quality of care will require health plan quality report cards to be supplemented by external quality assurance systems. Assuring quality will be particularly problematic for traditional indemnity plans. The structure and governance of the system, administration simplification, and other issues need to be addressed. The size and voluntariness of the purchasing cooperatives greatly influence all of these considerations. Physicians should inform their political representatives on how these issues should be resolved as compromise bills are drafted by the United States Congress this year.