instruction:
Given an abstract, indicate which of the provided candidate titles (Option1 and Option2) best describes it (respond with the text of the title, not option1/2).
question:
Abstract: Healthy male rats were exposed to a chronic ingesta of an isotonic NaCl solution during a period of four months. Two different preparations were utilized to study the effect of this treatment on the active mechanisms of Na+ reabsorption of kidney proximal tubular cells: outermost kidney cortex slices (rich in proximal tubules) and inside-out basolateral plasma membrane vesicles prepared from the same tissue. It was found that the activity of the ouabain-insensitive, Na-pump of basolateral plasma membranes of kidney proximal tubular cells was increased in about 70%, whereas the ouabain-sensitive, Na,K-pump activity did not change with the experimental treatment. These results represent a strong support to the two Na-pump's hypothesis since the treatment affected the Na-pump differentially without affecting the Na,K-pump.
Which is the apt title for the abstract? option1: Effect of a high NaCl diet on the active mechanisms of Na+ extrusion in rat kidney. option2: Cutaneous and subcutaneous metastases of lung cancer. Clinical characteristics.
answer:
Effect of a high NaCl diet on the active mechanisms of Na+ extrusion in rat kidney.

question:
Abstract: The relationship between the perfusion flow rate and cerebral oxygen consumption during deep hypothermic cardiopulmonary bypass at 20 degrees C was investigated in dogs. In 10 dogs the perfusion flow rate was decreased in steps from 100 to 60, 30, and 15 ml/kg/min every 30 minutes. Although cerebral blood flow decreased as perfusion flow rate decreased, the ratio of cerebral blood flow to the perfusion flow rate increased significantly (p less than 0.05) at a perfusion flow rate of 15 ml/kg/min compared to that at a perfusion flow rate of 100 or 60 ml/kg/min. The arterial-sagittal sinus blood oxygen content difference increased as perfusion flow rate decreased. Consequently, cerebral oxygen consumption did not vary significantly at perfusion flow rates of 100 (0.48 +/- 0.10), 60 (0.43 +/- 0.14), and 30 ml/kg/min (0.44 +/- 0.12 ml/100 gm/min), and it decreased significantly to 0.31 +/- 0.22 ml/100 gm/min at a perfusion flow rate of 15 ml/kg/min. In five dogs the perfusion flow rate was decreased in one step from 100 to 15 ml/kg/min, and after 60 minutes' perfusion at a perfusion flow rate of 15 ml/kg/min, the perfusion flow rate was returned to 100 ml/kg/min. Cerebral oxygen consumption decreased significantly during 60 minutes' perfusion at a perfusion flow rate of 15 ml/kg/min and did not return to its initial value after the perfusion flow rate was returned to 100 ml/kg/min. These data indicate that the optimal perfusion flow rate for the brain during deep hypothermic cardiopulmonary bypass at 20 degrees C appears to be 30 ml/kg/min, with a possible oxygen debt in the brain resulting in anaerobic metabolism if the perfusion flow rate is kept at 15 ml/kg/min or less.
Which is the apt title for the abstract? option1: Optimal perfusion flow rate for the brain during deep hypothermic cardiopulmonary bypass at 20 degrees C. An experimental study. option2: Buried transverse abdominal myocutaneous flap and silicone implants to reconstruct pectus excavatum and bilateral mastectomy deformity.
answer:
Optimal perfusion flow rate for the brain during deep hypothermic cardiopulmonary bypass at 20 degrees C. An experimental study.

question:
Abstract: As measured by fluorescence microscopy and radioligand binding, C3b/C4b receptors (CR1) became attached to the detergent-insoluble cytoskeleton of human neutrophils when receptors were cross-linked by affinity-purified polyclonal F(ab')2 anti-CR1, dimeric C3b, or Fab monoclonal anti-CR1 followed by F(ab')2 goat anti-mouse F(ab')2. CR1 on neutrophils bearing monovalent anti-CR1 was not attached to the cytoskeleton. In contrast, cross-linked CR1 on erythrocytes and cross-linked MHC Class I on neutrophils were not cytoskeleton associated. A possible role for filamentous actin (F-actin) in the binding of cross-linked CR1 to neutrophil cytoskeleton was suggested by three observations. When neutrophils were differentially extracted with either Low Salt-detergent buffer or High Salt-detergent buffer, stained with FITC-phalloidin, and examined by fluorescent flow cytometry, the residual cytoskeletons generated with the former buffer were shown to contain polymerized F-actin, whereas cytoskeletons generated with the latter buffer were found to be depleted of F-actin. In parallel experiments, High Salt-detergent buffer was also found to release cross-linked CR1 from neutrophils. Second, depolymerization of F-actin by DNAse I released half of the cytoskeletal-associated cross-linked CR1. Third, immunoadsorbed neutrophil CR1, but not MHC Class I or erythrocyte CR1, specifically bound soluble 125I-actin. In addition, Fc receptor and CR3, other phagocytic membrane proteins of neutrophils, specifically bound 125I-actin. These data demonstrate that CR1 cross-linked on neutrophils becomes associated with detergent-insoluble cytoskeleton and that this interaction is mediated either directly or indirectly by actin.
Which is the apt title for the abstract? option1: Differential interaction of the C3b/C4b receptor and MHC class I with the cytoskeleton of human neutrophils. option2: The kingdoms of organisms [letter]
answer:
Differential interaction of the C3b/C4b receptor and MHC class I with the cytoskeleton of human neutrophils.