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: To examine peripheral nerve stimulation (PNS) thresholds for normal human subjects in magnetic resonance imaging (MRI) gradient coils, and determine if observed thresholds could be predicted based on gross physiologic measurements.', 'PNS thresholds for 21 healthy normal subjects were measured using a whole-body gradient coil. Subjects were exposed to a trapezoidal echo-planar imaging (EPI) gradient waveform and the total change in gradient strength (DeltaG) required to cause PNS as a function of the duration of the gradient switching time (tau) were measured. Correlation coefficients and corresponding P values were calculated for the PNS threshold measurements against simple physiologic measurements taken of the subjects, including weight, height, girth, and average body fat percentage, in order to determine if there were any easily observable dependencies.', 'No convincing correlations between threshold parameters and gross physiologic measurements were observed.\Question: Do simple anatomical measurements correlate significantly to individual peripheral nerve stimulation thresholds as measured in MRI gradient coils?
answer:
These results suggest it is unlikely that a simple physiologic measurement of subject anatomy can be used to guide the operation of MRI scanners in a subject-specific manner in order to increase gradient system performance while avoiding PNS.


question:
Context: Carotid stiffening is considered a key element in the pathogenesis of stroke. However, results of studies evaluating the association between carotid stiffness and incident stroke have been inconsistent.', 'This study investigated whether carotid stiffness (as determined by ultrasonography) is associated with incident stroke and whether this association is independent of aortic stiffness as estimated by carotid-femoral pulse wave velocity (cfPWV). Additionally, we evaluated the incremental value of carotid stiffness for stroke risk prediction beyond Framingham risk factors and cfPWV.', 'This study included a systematic review and meta-analyses of aggregate and individual participant data (IPD), the latter of which was obtained by requesting individual-level data of all cohort studies with available data on carotid stiffness and cfPWV.', 'Ten studies (n\xa0= 22,472) were included in the aggregate data meta-analysis and 4 (n\xa0= 4,540) in the IPD meta-analysis. After adjusting for cardiovascular (CV) factors, the aggregate data meta-analysis showed that greater carotid stiffness (per SD) was associated with stroke (hazard ratio: 1.18; 95% confidence interval: 1.05 to 1.33). In addition, carotid stiffness was associated with total CV events and CV and all-cause mortality, but not with coronary heart disease events. In the IPD meta-analysis, additional adjustment for cfPWV did not materially change these associations. Carotid stiffness did improve stroke risk prediction beyond Framingham and cfPWV (integrative discrimination improvement: 0.4 percentage point [95% confidence interval: 0.1 to 0.6 percentage point] and continuous net reclassification improvement: 18.6% [95% confidence interval: 5.8% to 31.3%]).\Question: Is carotid stiffness associated with incident stroke : a systematic review and individual participant data meta-analysis?
answer:
Carotid stiffness is associated with incident stroke independently of CV factors and aortic stiffness. In addition, carotid stiffness improves stroke risk prediction beyond Framingham and aortic stiffness.


question:
Context: We evaluated the incidence of cryptorchidism and inguinal hernias in patients with posterior urethral valves, and compared characteristics in patients with and without cryptorchidism or inguinal hernia.', 'A total of 200 patients with posterior urethral valves treated between 1953 and 2003 were identified from a hospital database. Patient records were retrospectively reviewed. The state of testicular descent and the presence of inguinal hernias were recorded in 192 patients. Patient characteristics were analyzed.', 'Of 192 patients 31 (16%) had cryptorchidism, which was bilateral in 9 (29%). A total of 21 patients (11%) had inguinal hernias that were not associated with cryptorchid testes. The patients with cryptorchidism, and to some extent the patients with hernias, appeared to have a more severe form of posterior urethral valves than those without cryptorchidism. At the time of diagnosis the median serum creatinine concentration was 100 mumol/l (range 38 to 460) in boys with cryptorchidism and 87 (14 to 593) in boys without cryptorchidism (p = 0.131). At 6-month followup the median serum creatinine levels were 90 mumol/l (range 31 to 573) in patients with cryptorchidism and 45 (19 to 504) in patients without cryptorchidism (p = 0.006). Cryptorchidism was also more common in cases diagnosed neonatally compared to those diagnosed at a later age (14 of 52 patients, 27% vs 14 of 112, 12.5%, respectively, p = 0.027).\Question: Are posterior urethral valves often associated with cryptorchidism and inguinal hernias?
answer:

The incidence of cryptorchidism and inguinal hernias requiring surgery is high in patients with posterior urethral valves. Patients with cryptorchidism appear to have a more severe form of posterior urethral valves than those with normal testes.