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.

[Q]: Context: Somatic cells in vitro have a finite life expectancy before entering a state of senescence, but it is unclear whether this state occurs in vivo in kidney development, growth, and aging. We previously showed that human kidney cortex displays telomere shortening with age. In this study, we compared the structural and functional changes in rat kidney with age to phenomena associated with cellular senescence in vitro.', 'We assessed the changes in Fischer 344 rat kidneys from age 1 to 9 months to define growth and development and from age 9 to 24 months to define aging.', 'Rat kidney telomeres were approximately 35 to 40 kb long and did not shorten significantly. Expression of mRNA for p16INK4a, a characteristic senescence gene in vitro, was undetectable in most young rats but rose 27 fold during growth and a further 72-fold during aging. p16INK4a protein was localized to the nucleus and increased with age. p16INK4a mRNA also increased in other tissues. Lipofuscin and senescence-associated beta-galactosidase increased in epithelium with growth and aging and their occurrence was significantly associated with each other. Lipofuscin was particularly found in atrophic nephrons.\Question: Does cell senescence in rat kidneys in vivo increase with growth and age despite lack of telomere shortening?
[A]: We conclude that cell senescence occurs in both growth and aging in rat kidney and may contribute to the age-related pathology. These changes are not due to telomere shortening, but may reflect cumulative environmental stress.


[Q]: Context: Ventriculo-peritoneal shunting is the most commonly used method for the treatment of paediatric hydrocephalus. The programmable valve with the ability to adjust the opening pressure non-invasively has made it easier to find exactly the right opening pressure for each child and reduce the risk of over- or under-drainage. The aim of this investigation was to study our clinical experience with the adult Codman Hakim programmable valve in children, with reference to complications and economic impact.', 'A seven-year retrospective study of 122 hydrocephalic children (aged from children born prematurely to 15 years old) shunted with the adult Codman Hakim programmable valve was performed.', 'The programmable valve was the first shunt in 76 children and in 14 after prior ventricular drainage. The remaining 46 had different non-programmable systems as their first shunt. The most common reason for changing to a programmable valve was over-drainage. With the programmable valve, catheter-related complications, e.g. proximal (36%) or distal obstructions (30%), were the main reasons for surgical revision. Non-invasive pressure adjustment was performed in 73% of the children. Among the children with the programmable valve as their first shunt, 57 (75%) were adjusted, 12 (21%) had severe symptoms of over-drainage and would have required urgent surgical change of the valve if it had not been adjustable. A resetting of the opening pressure after MRI was found in 38% and accidental resetting occurred in 4%. Programmable valves are about twice as expensive as non-programmable valves. We estimated the increased cost of the valve and compared it with the savings from a reduction in the number of re-operations. The total cost for the programmable valve (as the primary shunt) in our study was less than that for expected re-operations due to over- or under-drainage when using non-programmable valves.\Question: Is the programmable adult Codman Hakim valve useful even in very small children with hydrocephalus . A 7-year retrospective study with special focus on cost/benefit analysis?
[A]: The programmable valve was easy to handle; only one size was required and the adjustment made it possible to achieve an optimal intraventricular pressure with a lower total cost, reduced hospital stay as well as an increased quality of life for the children.


[Q]: Context: Motor evoked potentials (MEPs) and inhibition of voluntary contraction to transcranial magnetic stimulation (TMS) of the motor cortex have longer latencies than normal in patients with incomplete spinal cord injury (iSCI) when assessed using surface EMG. This study now examines the modulation of single motor unit discharges to TMS with the aim of improving resolution of the excitatory and inhibitory responses seen previously in surface EMG recordings.', 'A group of five patients with iSCI (motor level C4-C7) was compared with a group of five healthy control subjects. Single motor unit discharges were recorded with concentric needle electrodes from the first dorsal interosseus muscle during weak voluntary contraction (2%-5% maximum). TMS was applied with a 9 cm circular stimulating coil centred over the vertex. Modulation of single motor unit discharges was assessed using peristimulus time histograms (PSTHs).', 'Mean (SEM) threshold (expressed as percentage of maximum stimulator output (%MSO)) for the excitatory peak (excitation) or inhibitory trough (inhibition) in the PSTHs was higher (p<0.05) in the patients (excitation = 47.1 (5.9) %MSO; inhibition = 44.3 (3.2) %MSO) than in controls (excitation=31.6 (1.2) %MSO; inhibition = 27.4 (1.0) %MSO). Mean latencies of excitation and inhibition were longer (p<0.05) in the patients (excitation=35 (1.8) ms; inhibition = 47.1 (1.8) ms) than in the controls (excitation = 21.1 (1.6) ms; inhibition = 27 (0.4) ms). Furthermore, the latency difference (inhibition-excitation) was longer (p<0.05) in the patients (10.4 (2.1) ms) than in the controls (6.2 (0.6) ms).\Question: Does modulation of single motor unit discharge using magnetic stimulation of the motor cortex in incomplete spinal cord injury?
[A]:
Increased thresholds and latencies of excitation and inhibition may reflect degraded corticospinal transmission in the spinal cord. However, the relatively greater increase in the latency of inhibition compared with excitation in the patients with iSCI may reflect a weak or absent early component of cortical inhibition. Such a change in cortical inhibition may relate to the restoration of useful motor function after iSCI.


