We have discovered a novel mitosis-specific human autoantigen that arises at the centromeres of prophase chromosomes, but ultimately participates in formation of an organelle that bisects the cell at late anaphase and during telophase. The organelle, discernible as a three-dimensional disc by confocal microscopy, encompasses the entire midzone diameter, and its distribution survives disassembly of interpolar microtubules by cold temperature treatment and detergent lysis of cells. Cytokinetic furrow contraction proceeds normally in dihydrocytochalasin B (DCB)-treated cells, and antigen distribution in the furrow is unaltered. In DCB, the furrow retracts in early interphase, coincident with loss of normal membrane association with the disc, resulting in the formation of binucleate cells. The midzone disc in both drug-treated and normal cells is present at the correct time and position to play a central role in cytokinesis. By immunocytochemistry, the disc appears to contain myosin but not actin. The position of the disc and the possible presence of myosin suggest that cytokinesis may involve the interaction of the disc organelle with actin in the cell cortex to produce cleavage in mammalian cells.
In this study we evaluated the physiological variation of free and total prostatespeci®c antigen (PSA) levels to determine how the percent freeatotal PSA was affected. Twenty four patients had blood drawn for ten consecutive weekdays. The percent coef®cient of variation (%CV) of biological variation was calculated. The results were log-normally distributed with geometric means of 12.0% CV, 7.3% CV, and 8.8% CV for free, total, and percent freeatotal PSA, respectively. When applied, the percent freeatotal, PSA would need to¯uctuate by 31% to indicate that a signi®cant change (critical difference, P`0.05) between two measurements had occurred. Biological variation of PSA measurements is substantial.
After several years of occupational exposure to vibration, a man developed episodic vibratory hand swelling, erythema, and pruritus. He subsequently developed symptoms compatible with carpal tunnel syndrome, but his median nerve conduction velocity remained normal. After experimental vibration of the forearm, plasma histamine levels in the ipsilateral antecubital vein rose in association with localized angioedema and slowed median nerve conduction velocity. There was no evidence of other causes of angioedema. Occupational exposure to vibration may predispose to the development of vibratory angioedema, which may predispose to intermittent compression neuropathy.
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