Mechanisms of cerebrospinal fluid secretion by the choroid plexus epithelium: Application to various intracranial pathologies.

The choroid plexus (CP) is a small yet highly active epithelial tissue located in the ventricles of the brain. It secretes most of the CSF that envelops the brain and spinal cord. The epithelial cells of the CP have a high fluid secretion rate and differ from many other secretory epithelia in the organization of several key ion transporters. One striking difference is the luminal location of, for example, the vital Na+-K+-ATPase. In recent years, there has been a renewed focus on the role of ion transporters in CP secretion. Several studies have indicated that increased membrane transport activity is implicated in disorders such as hydrocephalus, idiopathic intracranial hypertension, and posthemorrhagic sequelae. The importance of the CP membrane transporters in regulating the composition of the CSF has also been a focus in research in recent years, particularly as a regulator of breathing and hemodynamic parameters such as blood pressure. This review focuses on the role of the fundamental ion transporters involved in CSF secretion and its ion composition. It gives a brief overview of the established factors and controversies concerning ion transporters, and finally discusses future perspectives related to the role of these transporters in the CP epithelium.

Morphology of the knee after guided growth using tension-band devices: a retrospective multicenter study of 222 limbs and 285 implants.

BACKGROUND AND PURPOSE: Temporary hemiepiphysiodesis by tension-band devices is commonly applied to correct angular limb deformities in children. We aimed to evaluate knee joint morphology after guided growth using these devices. PATIENTS AND METHODS: In a retrospective multicenter study we analyzed standardized anteroposterior long-leg radiographs of 222 limbs (285 implants) of patients treated by temporary hemiepiphysiodesis with either eight-Plates or FlexTacks for coronal angular deformities of the knee joint between 2013 and 2019. Femoral floor angle (FFA), femoral notch-intercondylar distance (FNID), and tibial roof angle (TRA) were measured pre- and postoperatively to assess the central knee joint morphology. Statistical exploratory analyses were performed using linear mixed models, t-tests, Wilcoxon signed-rank test, and Mann-Whitney U test. RESULTS: 217 FlexTacks (femur 106, tibia 111) in 104 children and 68 eight-Plates (femur 61, tibia 7) in 35 children were identified. Median time period under growth guidance was 11 months (range 4-42). No statistically significant change in the FFA was detected (eight-Plate: P = 0.2; FlexTack: P = 0.3). A statistically significant difference of the FNID was found in the eight-Plate group (P = 0.02), but not in the FlexTack group (P = 0.3). While TRA increased in both groups, a statistical significance was observed only in the FlexTack group (P < 0.01). CONCLUSION: We found minor but clinically irrelevant changes in knee morphology after the treatment.

Dynamic geometry of the left ventricular outflow tract of pigs with induced supravalvular aortic stenosis.

OBJECTIVES: Detailed information about the dynamic geometry of the left ventricular outflow tract (LVOT) is of great importance for transcatheter aortic valve implantation (TAVI), since these valves utilize the LVOT as a landing zone for optimum placement and fixation. The LVOT is generally considered circular in shape and stable in its conformation. However, recent studies indicate that this may not be the case. METHODS: Twenty-two 5-kg pigs (± 0.47 kg) were randomly allocated to either aortic banding (n = 14) or sham operation (n = 8). LVOT dynamic geometry was assessed using cardiovascular-magnetic resonance imaging, 9 weeks after banding of the ascending aorta. RESULTS: All the banded animals developed significant left ventricular hypertrophy (P = 0.01) compared with controls. All the animals demonstrated significant reduction in eccentricity index (P(intervention) < 0.01, P(control) < 0.05) and longest internal diameter (P(intervention) < 0.01, P(control) = 0.02) when comparing measurements from end-diastole to end-systole. No significant systolic or diastolic differences were found between the two groups. CONCLUSIONS: The main findings were: the LVOT (i) undergoes substantial geometric alterations throughout the cardiac cycle and (ii) is ellipsoid throughout the cardiac cycle, (iii) geometric changes during the cardiac cycle stems from compression of the long-axis of the LVOT and (iv) dynamic geometry did not change significantly after induction of significant LV hypertrophy. Thus, our data suggest that assumptions made in daily practice, of a circular and stable LVOT geometry, need to be revised.