The pectoral anatomy of selected Ostariophysi. I. The Characiniformes.

The muscles and bones of the pectoral fin of Serrasalmus nattereri, the piranha, resemble those of generalized, lower teleosts with specializations related to a body shape adapted for high-speed carnivory; the pectoral fins being highly mobile with strong ligaments to the rays. The presence of two occipital nerves appears primitive, while the emergence of the subclavian artery within the branchial cavity, as in Gasteropelecus sternicla, appears specialized. The muscles and bones of the latter fish, a fresh-water flying fish, are specialized for self-propelled, aerial flight in the fusion of the right and left girdles greatly expanded for insertions of complex appendicular (flight) muscles, and in the consolidation of the rays and radials into one functional unit moving vertically in flight through contraction of vertical, massive ventral flight muscles. The bony pectoral anatomy of Electrophorus electricus, the electric eel, is specialized in having a mobile joint between the primary girdle and the cleithrum, the former being suspended vertically from the cleithrum by ligaments. The proximal radials and rays are very numerous and vertically aligned. The cleithrum is shaped to accommodate the extensive sternohyoid and pharyngocleithral muscles. The sheet-like appendicular muscles extend beyond the special joint and control its movement. The deeper muscles do not cross this joint. The arterial system is specialized in lacking a deep brachial artery.     

The low-temperature mechenical relaxation of elastin. I. The dry protein.

The low-temperature relaxation of native ox Ligamentum nuchae elastin and of two purified elastin samples has been investigated in the dry state by means of the Rheovibron DDV II viscoelastometer, at the fixed frequencies of 3.5, 11, 35, and 110 Hz. Besides the glass transition at about 200°C, a relatively strong secondary loss-tangent peak, whose activation energy is about 13 kcal/mol, is found for all samples below room temperature. The peak maximum is at ?71°C for the 3.5-Hz frequency. On the basis of its location, intensity, and width, it is attributed to a main-chain relaxation of the pure protein. When suitable reduced variables are used, the loss-tangent-temperature curves obtained at different frequencies can be satisfactorily superimposed to give a master curve. Comparison of the data with the prediction of a semiempirical viscoelastic model can also be considered satisfactory.     

The chemical composition of wool. XV. The cell membrane couplex.

The cell membrane complex of wool has been examined by electron microscopy of stained cross sections after immersion of the wool in formic acid. The cell membrane complex of the cortex is considerably modified by the treatment, but that of the cuticle appears unchanged. Resistant membranes from cuticle cells, cortical cells and wool have been prepared by treatment with performic acid-ammonia. Amino acid analyses show that the resistant membranes from the cuticle contain citrulline but those from cortical cells do not. It is concluded that the cell membrane complex of the cuticle differs from that of the cortex. Because of the high lysine content of the resistant membranes, their resistance to chemical attack, the hydrophobicity of epicuticle and the observation of a small amount of epsilon-(gamma-glutamyl)lysine, it is postulated that the resistant membranes may contain an appreciable amount of epsilon-(gamma-glutamyl)lysine cross links.     

The A.M.A. Session

The use of liquid nitrogen for the removal of warts has advantages over electrocautery in certain circumstances. Although the incidence of recurrences after liquid nitrogen is higher than after cautery, it causes considerably less scarring. It is most useful in dealing with peri-ungual and multiple warts. The technique is simple and a supply of liquid nitrogen can be kept on hand in the office at relatively low cost.