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The purpose of this study was to investigate the effect of partial excision of the A2 and A4 pulleys on digital angular rotation and the energy required to flex the finger. Partial excision of A2 resulted in a statistically significant decrease in angular rotation of 3 and 5% after 50 and 75% excision, respectively. Partial excision of A4 failed to produce any significant differences in angular rotation. Combined partial excision of A2 and A4 resulted in a significant decrease of 5 and 8% after 50 and 75% excision, respectively. Significant differences in work of flexion occurred only after excision of 75% of the A2 pulley. Although optimal finger function relies on the integrity of the A2 and A4 pulleys which maintain the efficiency of the digital flexor system, these data suggest that 25% of the A2 pulley, up to 75% of the A4 and 25% of the A2 and A4 together can be excised without significant effects on angular rotation.

Background: Articular cartilage vesicles (ACVs) participate in cell communication, protein secretion, and pathologic mineralization. Results: ACV release from chondrocytes is regulated in concert with autophagy and is caspase-3-and Rho/ROCK-dependent. Conclusion: Autophagy participates in chondrocyte ACV release. Significance: This work identifies a potential mechanism of ACV formation and presents opportunities to manipulate quantity and content of these important organelles.

The interosseous membrane is a structure deep in the forearm that joins the radius and the ulna. It is made up of membranous and ligamentous regions. Two main ligamentous structures have been described: a prominent central fiber group, the "central band," and a smaller proximal fibrous band, the "oblique cord." Many authors believe that the central band plays a biomechanical role in the normal and fractured forearm and that it may function much like a ligament. The objective of this study was to determine the tensile properties of the central band. Eighteen fresh frozen forearms from cadavers (45-70 years of age, both sexes) were used. A fiber bundle of the central band was subjected to a uniaxial tensile test to failure in a materials testing machine, and its tensile properties were calculated. Stiffness, ultimate load, and energy absorbed to failure were expressed as a function of specimen width. The central band structure had a stiffness of 13.1 +/- 3.0 N/mm per mm width and an ultimate load of 56.6 +/- 15.1 N per mm width (mean +/- SD). The tissue of the central band displayed a modulus of 608.1 +/- 160.2 MPa, ultimate tensile strength of 45.1 +/- 10.3 MPa, and strain at failure of 9.0 +/- 2.0%. This study demonstrated that the central band is comprised of strong tissue. The material properties of the central band compare with those of patellar tendon: modulus is 120% and ultimate tensile strength is 84% that of patellar tendon. As a structure, the interosseous membrane is stiff and capable of bearing high loads. Although load distribution across the central band is unknown, a 1.7 cm wide, evenly loaded homogenous portion of the central band would possess a stiffness comparable with that of the anterior cruciate ligament. The results of this study provide a basis for future analyses of radioulnar stability and load transfer.

Summary:The interosseous membrane is a structure deep in the forearm that joins the radius and the ulna. It is made up of membranous and ligamentous regions. W o main ligamentous structures have been described: a prominent central fiber group, the "central band," and a smaller proximal fibrous band, the "oblique cord." Many authors believe that the central band plays a biomechanical role in the normal and fractured forearm and that it may function much like a ligament. The objective of this study was to determine the tensile properties of the central band. Eighteen fresh frozen forearms from cadavers (45-70 years of age, both sexes) were used. A fiber bundle of the central band was subjected to a uniaxial tensile test to failure in a materials testing machine, and its tensile properties were calculated. Stiffness, ultimate load, and energy absorbed to failure were expressed as a function of specimen width. The central band structure had a stiffness of 13.1 t-3.0 N/mm per mm width and an ultimate load of 56.6 2 15.1 N per mm width (mean t-SD). The tissue of the central band displayed a modulus of 608.1 2 160.2 MPa, ultimate tensile strength of 45.1 t-10.3 MPa, and strain at failure of 9.0 t-2.0%. This study demonstrated that the central band is comprised of strong tissue. The material properties of the central band compare with those of patellar tendon: modulus is 120% and ultimate tensile strength is 84% that of patellar tendon. As a structure, the interosseous membrane is stiff and capable of bearing high loads. Although load distribution across the central band is unknown, a 1.7 cm wide, evenly loaded homogenous portion of the central band would possess a stiffness comparable with that of the anterior cruciate ligament. The results of this study provide a basis for future analyses of radioulnar stability and load transfer.The interosseous membrane is a structure in the deep forearm that joins the radius and the ulna, spanning the interosseous space. The interosseous membrane is made up of ligamentous and membranous regions. Two main ligamentous structures have been described: a prominent central fiber group, the "central band," and a smaller proximal fibrous band, the "oblique cord." The central band is comprised of thin, flat bundles of fibrous tissue that originate proximally from the radius and insert distally on the ulna. The oblique cord is not present in all specimens and is located on the dorsal aspect of the radius and ulna, near the elbow (2,4,6,10,15,18).Traditionally, anatomists have viewed the interosseous membrane as a structure that functions to bind

We studied the elongation and excursion of cadaveric ulnar nerves during elbow flexion in control conditions and after in situ decompression and anterior subcutaneous transposition. We found that the normal nerve had the greatest elongation (23%) and excursion (14 mm) in the epicondylar groove. Decompression did not alter the excursion, but significantly reduced the elongation in the groove (6%) and increased it proximally (19%). After anterior subcutaneous transposition, the nerve segment which was originally in the groove elongated with elbow extension to the same extent as occurred with the normal nerve during flexion.

The work described in this paper is a continuation of observations already made in this laboratory on the antidiuretic action of nicotine (Burn, Truelove, and Burn, 1945; Walker, 1948). Taylor and Walker (1951) have recently shown that the action is followed by the appearance of an antidiuretic substance in the urine of man resembling in its properties the posterior lobe hormone and not nicotine.If a man drinks water, the onset of diuresis indicates the arrest of the normal secretion of antidiuretic hormone. When posterior lobe extract is injected intravenously at this point, inhibition of the diuresis occurs and lasts for a time depending on the amount injected. We have determined the dose-response relationship in three subjects. We have also estimated the proportion of antidiuretic hormone excreted in the urine after the intravenous injection of posterior lobe extract in varying amounts. A few experiments have been done in which the antidiuretic response to nicotine (either inhaled in tobacco smoke or injected) has been determined, and the amount of antidiuretic hormone excreted has been measured. METHODSThe observations were made on three male subjects in the afternoon. Each of them emptied his bladder every 15 minutes and recorded the volume. In certain experiments in which the antidiuretic effect was expected to be small, this period was reduced to 5 minutes. At the beginning of an experiment, the subject was required to show that he was not already very hydrated by producing two volumes, each of less than 25 ml. Then he drank one litre of water in 1-2 minutes. About 45 minutes later, when the volume of urine produced in the previous 15 minutes was more than 70 ml., the injection was given, or, in some experiments, the smoking was begun. The diuresis was then usually inhibited for a varying time, after which it increased to reach a second peak. The urine output was recorded until this peak was passed.The pituitary (posterior lobe) extract (PLE) was prepared by British Drug Houses, Ltd. Nicotine was injected as a solution of nicotine hydrogen tartrate in saline. This salt contains one-third by weight of nicotine base. All injections were made intravenously. The doses were usually contained in 0.5 ml., except the large doses of PLE and nicotine, which were in 1 ml.