A Study of Late Ventral Body Wall Degeneration in the Embryonic Chick, with Special Reference to the Cell Cycle

<p>The cell kinetics and morphological changes during late ventral body wall development of the embryonic chick were studied, particularly midline degeneration and the medial migration of lateral tissues. An histological examination of these events was undertaken, along with autoradiography to determine the duration of the cell cycle, followed by teratological studies involving the prevention of differentiative events in the cell death pathway, using BrDU and Janus B Green as agents. The effects of cell cycle blockade on rates of cell death were also examined, as was the tissues ability to express differentiative features in vitro. Ventral body wall (VBW) cell death was classified as apoptosis, and was involved in two distinct events. Medial migration of lateral tissues began at day 5 of development, with widespread VBW apoptosis being seen by day 6, limited to the original mesoderm of the region. A later precise line of apoptosis (the VBL), involving both ectodermal cells of the midline ectodermal ruffle and the underlying mesodermal cells, was observed at day 7, spreading in a rostral to caudal fashion down the embryo, appearing as the migratory lateral tissues fused in the midline body wall. Increases in the amount of cell death are matched by decreases in the MI, such that at its peak (day 7.5 of development) the cell death rate is sufficiently greater than both the cell proliferation and immigration rates that a state of negative tissue growth ensues. The histological half-life of the apoptotic bodies approximates 3.8 hours. The ability to undergo apoptosis at day 7 is dependent upon a differentiative event around day 4 of incubation, and involves signal mechanisms intrinsic to the VBW tissues. BrDU application was found to inhibit apoptotic differentiation, in contrast to Janus B Green, which had a more generalised teratogenic effect on the region as a whole. Tissue culturing experiments revealed that an ectodermal-mesodermal interaction is important in regulating the extent of mesodermal apoptosis, the ectoderm playing a maintenance role for the mesoderm. Dead cells derive from the cycling cell population, as shown by the occurrence of labelled dead cells after autoradiography, and by the prevention of apoptosis by a cell cycle blockade, and by the production of a semi-synchronised wave of apoptoses after release of this blockade. These cell blockading results further suggest that entry into the apoptotic death program requires cells to be in a particular cell cycle stage, and it seems most likely that the decision to die was made in early G1. Tissue and cell growth rates, cell loss and death rates, cell birth rates and cell immigration rates were all determined for the VBW region throughout the time period studied.</p>

A Study of Late Ventral Body Wall Degeneration in the Embryonic Chick, with Special Reference to the Cell Cycle

<p>The cell kinetics and morphological changes during late ventral body wall development of the embryonic chick were studied, particularly midline degeneration and the medial migration of lateral tissues. An histological examination of these events was undertaken, along with autoradiography to determine the duration of the cell cycle, followed by teratological studies involving the prevention of differentiative events in the cell death pathway, using BrDU and Janus B Green as agents. The effects of cell cycle blockade on rates of cell death were also examined, as was the tissues ability to express differentiative features in vitro. Ventral body wall (VBW) cell death was classified as apoptosis, and was involved in two distinct events. Medial migration of lateral tissues began at day 5 of development, with widespread VBW apoptosis being seen by day 6, limited to the original mesoderm of the region. A later precise line of apoptosis (the VBL), involving both ectodermal cells of the midline ectodermal ruffle and the underlying mesodermal cells, was observed at day 7, spreading in a rostral to caudal fashion down the embryo, appearing as the migratory lateral tissues fused in the midline body wall. Increases in the amount of cell death are matched by decreases in the MI, such that at its peak (day 7.5 of development) the cell death rate is sufficiently greater than both the cell proliferation and immigration rates that a state of negative tissue growth ensues. The histological half-life of the apoptotic bodies approximates 3.8 hours. The ability to undergo apoptosis at day 7 is dependent upon a differentiative event around day 4 of incubation, and involves signal mechanisms intrinsic to the VBW tissues. BrDU application was found to inhibit apoptotic differentiation, in contrast to Janus B Green, which had a more generalised teratogenic effect on the region as a whole. Tissue culturing experiments revealed that an ectodermal-mesodermal interaction is important in regulating the extent of mesodermal apoptosis, the ectoderm playing a maintenance role for the mesoderm. Dead cells derive from the cycling cell population, as shown by the occurrence of labelled dead cells after autoradiography, and by the prevention of apoptosis by a cell cycle blockade, and by the production of a semi-synchronised wave of apoptoses after release of this blockade. These cell blockading results further suggest that entry into the apoptotic death program requires cells to be in a particular cell cycle stage, and it seems most likely that the decision to die was made in early G1. Tissue and cell growth rates, cell loss and death rates, cell birth rates and cell immigration rates were all determined for the VBW region throughout the time period studied.</p>

The diagnostic accuracy of MRI and nonenhanced CT for high-risk vertebral artery anatomy for subaxial anterior cervical spine surgery safety

OBJECTIVE Medial migration of the vertebral artery (VA) can be a risk factor for injury during anterior procedures. CT angiography (CTA) has been considered the gold standard for the evaluation of various areas of the arterial anatomy. MRI and nonenhanced CT are more commonly used as routine preoperative imaging studies, but it is unclear if these modalities can safely exclude the anomalous course of the VA. The aims of this cross-sectional observational study were to investigate risk factors for medially migrated VA on CTA and to evaluate the diagnostic accuracy of MRI and nonenhanced CT for high-risk VA anatomy in the subaxial cervical spine. METHODS The records of 248 patients who underwent CTA for any reason at a single academic institution between 2007 and 2018 were reviewed. The authors included MRI and nonenhanced CT taken within 1 year before or after CTA. An axial VA position classification was used to grade VA anomalies in the subaxial cervical spine. The multivariable linear regression analysis with mixed models was performed to identify the risk factors for medialized VA. The sensitivity and specificity of MRI and nonenhanced CT for high-risk VA positions were calculated. RESULTS A total of 175 CTA sequences met the inclusion criteria. The mean age was 63.8 years. Advanced age, disc and pedicle levels, lower cervical levels, and left side were independent risk factors for medially migrated VA. The sensitivities of MRI and nonenhanced CT for the detection of grade 1 or higher VA position were only fair, and the sensitivity of MRI was lower than that of nonenhanced CT (0.31 vs 0.37, p < 0.001), but the specificities were similarly high for both modalities (0.97 vs 0.97). With the combination of MRI and nonenhanced CT, the sensitivity significantly increased to 0.50 (p < 0.001 vs MRI and vs CT alone) with a minimal decrease in specificity. CONCLUSIONS Axial images of MRI and nonenhanced CT demonstrated high specificities but only fair sensitivities. Nonenhanced CT demonstrated better diagnostic value than MRI. When combining both modalities the sensitivity improved, but a substantial proportion of medialized VAs could not be diagnosed.

Can the Bone Mineral Density of the Non-fractured Contralateral Hip Predict Medial Migration of Helical Blade-type Lag Screws in Osteoporotic Hip Fractures?

Background: In this study, we performed a biomechanical tests on the osteoporotic femoral heads to validate whether the bone mineral density (BMD) measured at the non-fractured contralateral hip can predict the BMD and potential medial migration of helical blade-type lag screws on the fractured femoral head.Methods: Twenty-four osteoporotic femoral heads were retrieved from patients with femoral neck fracture undergoing hip arthroplasty. The patients had their BMD measured from the contralateral hip using dual-energy X-ray absorptiometry prior to surgery. The BMD of the retrieved femoral heads was measured using micro-computed tomography. The mechanical properties for the medial migration of lag screw were measured by performing an uniaxial compression test on the femoral head using a helical blade-type lag screw. Statistical analysis was performed to determine the correlation among the BMDs of the non-fractured contralateral hip and the retrieved femoral head and the mechanical properties of the fractured femoral head.Results: The mean BMD of the contralateral hip was 0.60±0.14 g/cm2 in the neck region and 0.63±0.15 g/cm2 in the total proximal femur. The mean BMD of the fractured femoral head was 463.3±48.05 mg HA/cm3. The mechanical properties of the fractured femoral head were measured to be 0.92 kN for the maximum compressive load and 14.50±5.48 kN for the accumulated compression load. In the analysis of the correlation among the parameters, we found no correlation between the BMD of the non-fractured contralateral hip and the mechanical properties of the fractured femoral head. In addition, we observed no correlation between the BMD of the fractured femoral head and that of the contralateral hip.Conclusions: Our results indicate that the BMD of the contralateral hip does not reflect the BMD or the mechanical properties of the fractured femoral head. Therefore, helical blade-type lag screw migration may not be predicted from the BMD of the non-fractured contralateral hip.

The results of screw augmentation of acetabular cement spacers for the treatment of periprosthetic hip joint infection

Introduction Prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) is widely used in two-stage revision arthroplasty in periprosthetic joint infection (PJI) after total hip arthroplasty (THA). In our institution, we encountered several cases of acetabular cement spacer dislodgement. The aim of this study was to compare the results of two-stage revision arthroplasties with antibiotic-loaded cement spacers with or without screws on the acetabulum for PJI. Patients and methods This retrospective study included 44 patients who underwent a two-stage revision THA for PJI from June 2007 to May 2017. We divided the patients into two groups: group 1 consisted of 21 patients (21 hips) who underwent two-stage revision arthroplasty with screw augmentation, while group 2 consisted of 23 patients (23 hips) who underwent the same surgery without screw augmentation at the acetabular cement spacer. We compared the migration and dislodgement of the acetabular cement spacer between the two groups. Results Before the second-stage surgery, there was less vertical migration of the cement spacer in group 1 compared to group 2 (1.2 mm vs 3.1 mm, p < 0.001). There was also less medial migration of the cement spacer in group 1 (0.6 mm vs 1.6 mm, p = 0.001). After the first stage, the mean Harris Hip score was significantly higher in group 1 than in group 2 (75 vs 65, p = 0.033). Cement spacer rotation or total movement out of the acetabular area occurred in six patients, all in group 2. After first stage reinfection occurred in two patients, one in each group. Conclusions Screw augmentation to the acetabulum in the first-stage surgery provides better stability of acetabular antibiotic cement spacers without increasing reinfection rate.

Intrapelvic migration of the hip screw of a proximal femoral nail: report of two cases and review of the literature

<p>Two cases of medial migration of the hip screw in cases of cephalon-medullary nailing for the treatment of extra-articular proximal femoral fractures are reported. The first case was revised to hemiarthroplasty, that was subsequently complicated with infection and death of the patient, while the second was revised to a similar devise with favorable outcome. A review of the literature is performed in order to identify the contributing factors that result in the medial migration of the hip screw. Emphasis is given in further reporting of similar cases in order to abolish this potentially lethal complication. </p>

A case report on continent isolated male epispadias.

Epispadias is a rare congenital anomaly in which the urethral opening is on the dorsal surface of penis. Its incidence is 1 in 117000 newborn males and 1 in 484000 in newborn females. Its etiology is considered as because of failure of medial migration of mesenchyme between the ectodermal and endodermal layers of cloacal membrane due to premature rupture of cloacal membrane. Epispadias often presents as exstrophy epispadias complex, a wide spectrum of abnormalities that consist of classic bladder exstrophy, Epispadias and cloacal exstrophy. This case was not a part of exstrophy epispadias complex and it was an isolated continent epispadias which is extremely rare and it was managed with Cantwell Ransley epispadias repair technique.