Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Example Input: Abstract: Measurements of muscle pH (pHm) with the homogenate technique are routinely made when extensive phosphagen hydrolysis has occurred. Upon exposure of the homogenate to 37 degrees C in the pH meter, phosphocreatine and ATP were rapidly degraded to 35 and 60% of control concentrations after 30 s. Attempts at chemically arresting this hydrolysis were unsuccessful. Therefore we examined the significance of phosphagen hydrolysis on pHm measurement in human biopsies taken at rest and following intense electrical stimulation. To accomplish this, pHm was measured at 0 degree C, where extensive hydrolysis did not occur. On the same homogenate, pHm was measured at 0 degree C with phosphagens and at 0 and 37 degrees C after phosphagen hydrolysis. The effect of phosphagen hydrolysis on pHm at 0 degrees C was used to estimate this effect at 37 degrees C. In resting samples, phosphagen hydrolysis produced a nonsignificant acidification of 0.008 pH units and, in electrically stimulated samples, a nonsignificant alkalinization of 0.033 units. Measurements of homogenate PCO2 suggested that most of the CO2 remained in the sample during pHm measurement at 37 degrees C. The present work substantiates the use of the homogenate technique as an accurate and practical method for the estimation of intracellular pH in resting and exercise human muscle samples.
Example Output: pH measurement in human skeletal muscle samples: effect of phosphagen hydrolysis.

Example Input: Abstract: Pathologic studies were performed on two specimens of eyelid that had been treated with permanent eyeliner (tattooing with ferrous oxide), one specimen excised four days after injection of the pigment, and the other obtained 12 months later. Each patient had undergone an ectropion repair of the lower eyelid that provided the specimen. The specimen studied four days after injection revealed by light microscopy scattered pigment granules within the epidermis and fine granules and small aggregates dispersed within the dermis. No acute or chronic inflammatory cells were observed in relationship to the deposits. The specimen obtained 12 months after eyeliner injection was studied by both light and electron microscopy. No pigment particles were observed within the epidermis, but rather there were coarse clumps of granular material in the dermis. Apart from scattered mast cells, which occasionally contained fine granules, and apart from the macrophages which appeared to have ingested the pigment granules, no other acute and chronic inflammatory cells were found. Electron microscopy demonstrated that while most of the granular material had been phagocytosed by macrophages, occasional granules were found in small dispersions within the cytoplasm of mast cells and fibroblasts of the dermis. Minimal migration of pigment within macrophages occurred to locations around lymphatic channels and within the superficial orbicularis muscle connective tissue.
Example Output: Light and electron microscopic findings with permanent eyeliner.

Example Input: Abstract: Cultured normal human pulmonary alveolar macrophages and peripheral blood monocyte-derived macrophages were studied for their capacity to metabolize [3H]25-hydroxyvitamin D3 (25OHD3). Incubation of macrophages with bacterial lipopolysaccharide (LPS) resulted in the conversion of [3H]25OHD3 to a more polar vitamin D3 metabolite (up to 15 pmol/10(6) cells). Untreated macrophages did not synthesize this metabolite. Several findings suggested that the metabolite was the biologically active form of vitamin D3, namely 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. (1) The metabolite comigrated with chemically synthesized 1,25-(OH)2D3 on four different high performance liquid chromatographic systems. (2) The metabolite had the same affinity for the chick intestinal 1,25-(OH)2D3 receptor as authentic 1,25-(OH)2D3. (3) The biological activity of the macrophage metabolite in vivo (stimulation of intestinal calcium absorption and bone calcium mobilization in rachitic chicks) was identical to the activity of chemically synthesized 1,25-(OH)2D3. The LPS-stimulated synthesis of the 1,25-(OH)2D3-like compound by macrophages was dose dependent in a linear fashion; a half-maximal response was typically found with 100-200 ng LPS/10(6) cells. Polymyxin B abolished the effects of LPS on 25OHD3 metabolism in macrophages. Our data suggest that LPS-stimulated macrophages can modulate, on a local level, the function of 1,25-(OH)2D3-responsive cells by releasing the 1,25-(OH)2D3-like metabolite.
Example Output:
25-Hydroxyvitamin D3 metabolism by lipopolysaccharide-stimulated normal human macrophages.