Faculty Bibliography

Native myosin filaments from rabbit psoas muscle are always 1.5 micrometer long. The regulated assembly of these filaments is generally considered to occur by an initial antiparallel and subsequent parallel aggregation of identical myosin subunits. In this schema myosin filament length is controlled by either a self-assembly or a Vernier process. We present evidence which refines these ideas. Namely, that the intact myosin bare zone assemblage nucleates myosin filament assembly. This suggestion is based on the following experimental evidence. (1) A native bare zone assemblage about 0.3 micrometer long can be formed by dialysis of native myosin filaments to either a pH 8 or a 0.2 M-KCl solution. (2) Upon dialysis back to 0.1 M-KCl, bare zone assemblages and distal myosin molecules recombine to form 1.5 micrometer long bipolar filaments. (3) The bare zone assemblage can be separated from the distal myosin molecules by column chromatography in 0.2 M-KCl. Upon dialysis of the fractionated subsets back to 0.1 M-KCl, the bare zone assemblage retains its length of about 0.3 micrometer. However, the distal molecules reassemble to form filaments about 5 micrometers long. (4) Filaments are formed from mixes of the isolated subsets. The lengths of these filaments vary with the amount of distal myosin present. (5) When native filaments, isolated bare zone assemblages or distal myosin molecules are moved sequentially to 0.6 M-KCl and then to 0.1 M-KCl, the final filament lengths are all about 5 micrometers. The capacity of the bare zone assemblage to nucleate filament assembly may be due to the bare zone myosin molecules, the associated M band components or both.

Current evidence indicates that polymorphonuclear leukocyte (PMN) chemotaxis and phagocytosis are effected by an actin-myosin contractile system. However, the structural relationship of the contractile cytoskeleton to cell motility is still in question. In addition, while evidence suggests that microtubules are responsible for orientation during chemotaxis, the role of microtubules in degranulation is unresolved. To determine the organizational relationship between these cytoskeletal elements and phagocytosis, we examined whole-mount preparations of PMNs engulfing bacteria. These preparations were examined in the transmission electron microscope (EM) and photographed as stereo pairs. Two important observations were made. First, there was an increased density of cytoskeletal elements in the pseudopod surrounding bacteria. Second, microtubule elements were intimately associated with lysosomal granules, vesicles, and phagosomes. Lysosomal granules and vesicles aligned along microtubules and clustered around phagosomes. This suggests that the microtubules may provide a tracking mechanism whereby lysosomes are specifically parceled out to phagocytic vacuoles. These results also suggest that phagocytosis and degranulation may involve different effector mechanisms.

The utility of any index depends on its validity, reliability, and administrative feasibility. The Oral Hygiene Skill Achievement Index (S.A.I.) was found to be a valid measure of oral hygiene skill in that registered dental hygienists received greater than 90% of the total possible points. The S.A.I. was found to have an initial reliability of r greater than or equal to 0.91 and a repeat reliability of r greater than or equal to 0.96. The S.A.I. requires less than 10 minutes to administer, 40 minutes to teach, and 1 hour and 40 minutes to learn. The results suggest that S.A.I. should be a useful instrument for both clinical and research use.

The oral hygiene Skill Achievement Index (S.A.I.) is a general method for the direct, quantitative evaluation of oral hygiene skill. The S.A.I. evaluates a person's ability to manipulate a toothbrush and floss in a given fashion. It is applicable to any brushing or flossing procedure. The Index was developed to fulfill all the postulated requirements of a perfect measuring instrument. The key feature of the Index is the evaluation of the position and the motion of the cleaning device on each tooth surface. Consequently, the Index provides a format for the instruction and evaluation of oral hygiene skill. Furthermore, if used in conjunction with other dental indices, it enables one evaluate hygiene procedures and devices in a controlled fashion.

Radionuclide images of hospital patients were examined for abnormal areas within the jaws. Fourteen of 25 subjects studied showed one or more abnormal image areas, most of which were attributable to common dental lesions revealed by oral examinations. The lesions detectable on images included healing bone sites, periodontal and pulpal disease, residual osteitis and irritations caused by ill-fitting dentures.