instruction:
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
question:
Context: The pulmonary endothelium plays an important role in the metabolism of the amino acid arginine, the exclusive precursor molecule for nitric oxide (NO). Despite decreased circulating arginine levels, endothelial NO production is elevated during endotoxemia. However, the regulation of pulmonary artery endothelial arginine transport has not been studied. We hypothesized that endotoxin stimulates carrier-mediated arginine transport by the pulmonary endothelium.', 'The relative contributions of the various transport systems to total arginine transport by porcine pulmonary artery endothelial cells (PAECs) was determined by assaying the uptake of 3H-L-arginine in the presence or absence of Na+. PAECs were then incubated with various concentrations of Escherichia coli endotoxin, and y(+)-mediated arginine transport was measured at different time points thereafter. Kinetic studies were performed over a range of arginine concentrations to determine changes in transport affinity and maximum rate of metabolism. To address the role of RNA and protein synthesis in the increased transport, uptake was measured after exposure of cells to the transcriptional inhibitor actinomycin D and the protein synthesis inhibitor cycloheximide.', 'Most (75%) of arginine transport by PAECs was mediated by the high-affinity Na(+)-independent transport system y+. Endotoxin stimulated y(+)-mediated arginine transport by PAECs twofold to fivefold, a response that was time and dose dependent. The accelerated transport was detectable within 2 hours and maximal at 12 hours. Kinetic studies revealed that the accelerated arginine transport was the result of a 68% increase in the maximal transport velocity (1519 +/- 65 pmol/mg protein/30 sec in endotoxin-treated cells vs 903 +/- 96 in control cells; p < 0.01) without a change in transport affinity. The endotoxin-mediated increase in arginine uptake was abrogated by actinomycin D and cycloheximide.\Question: Does endotoxin stimulate arginine transport in pulmonary artery endothelial cells?
answer:
Endotoxin stimulates Na(+)-independent arginine transport by PAECs through a process that requires de novo RNA and protein synthesis, possibly of the transporter itself. This response may be designed to support arginine-dependent biosynthetic pathways in the lung during septic states.

question:
Context: Monitoring renal function is crucial in children undergoing chemotherapy. To date, a combination of routine serum creatinine (SCR) monitoring with occasional determination of creatinine clearance ratio (CCR) is widely used as clinical standard for this purpose. Both methods have their limitations regarding diagnostic value (SCR) or practicability (CCR), especially in young children. Diagnostic alternatives, such as glomerular filtration rate (GFR) estimation formulas have not been proved to be superior. The aim of the study was to evaluate whether serum cystatin C (CysC) may have a diagnostic impact on pediatric patients.', 'CysC, SCR, several GFR estimation formulas (Counahan-Barratt, Ghazali-Barratt, Schwartz, Shull, Traub), and CCR were studied in 80 pediatric cancer patients (age range: 0.17-17.9 years) during their chemotherapy. Special attention was given to children under the age of 3 in whom accurate urine collection for CCR is difficult.', 'All parameters correlated similarly well with CCR. Total accuracy was 66% and 67% for CysC and SCR, respectively. In very young children (<3 years), correlation with CCR was for CysC r = -0.74 with an area under the curve (AUC) of 0.646, and for SCR r = -0.27 with AUC = 0.594. Total accuracy was 60% for CysC, 50% for SCR.\Question: Is serum cystatin C a suitable marker for routine monitoring of renal function in pediatric cancer patients , especially of very young age?
answer:
CysC represents a suitable marker for monitoring renal function in pediatric cancer patients. In young children (<3 years), CysC may have a better diagnostic value than SCR. Future studies should show if CysC can improve renal monitoring by replacing SCR, especially in very young children.

question:
Context: Ptosis and strabismus are 2 common presenting complaints of preschool-age patients. In both cases, these conditions can be benign and require no further workup. However, sudden onset of these findings can indicate a more serious neurologic problem. If a patient presents with multiple neurologic signs, a sudden onset eye turn, or ptosis, the patient must undergo a workup to rule out a pathologic etiology, specifically a brain tumor. The workup should include neuroimaging. If the results of the neuroimaging are normal, and the findings are variable, myasthenia gravis should be considered, and additional testing should be ordered to assist in the diagnosis.', 'This case report presents a 3-year-old boy who presented with a sudden onset of ptosis and hypertropia. Diagnosis of myasthenia gravis was made based on clinical presentation and response to ice pack testing. The patient was treated with pyridostigmine (Mestinon; Valent Pharmaceuticals, Costa Mesa, California) and has shown improvement in his clinical signs.\Question: Do ptosis and cranial nerve IV palsy reveal juvenile myasthenia gravis?
answer:
Although rare, myasthenia should be considered a diagnosis in children who present with variable ptosis or strabismus. Patients can be successfully treated with medication.