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At least 325 records · Page 18Linked to original sources
PubMed1992

The repetitive calcium waves in the fertilized ascidian egg are initiated near the vegetal pole by a cortical pacemaker.

Ascidian eggs respond to fertilization with a series of repetitive calcium waves that originate mostly from the vegetal/contraction pole region (J. E. Speksnijder, C. Sardet, and L. F. Jaffe, 1990, Dev. Biol. 142, 246-249), where the myoplasm is concentrated during the first phase of ooplasmic segregation. This suggests that the myoplasm may be involved in initiating these calcium waves. To test this possibility, the starting position of the calcium waves was determined in eggs that had the subcortical, mitochondria-rich part of the myoplasm displaced by centrifugation. Such centrifuged eggs display four cytoplasmic layers: a large centrifugal yolk zone, a narrow clear zone, a mitochondria-rich layer, and a small clear zone at the centripetal pole. Imaging of the cytosolic calcium in centrifuged eggs that were injected with the calcium-specific photoprotein aequorin reveals a series of repetitive calcium waves after fertilization. About 70% of these waves start in the vegetal/contraction pole area, which is similar to the number of waves previously found to start in this area in uncentrifuged eggs. In contrast, only about 25% of the waves start close to the displaced mitochondria-rich layer. From this result it is concluded that the main wave initiation site is not displaced by the centrifugal forces that displace the subcortical, mitochondria-rich part of the myoplasm. Moreover, the observation that the animal-vegetal polarity of cortical components such as actin filaments and the endoplasmic reticulum has been retained after centrifugation further suggests that a cortical component located in the vegetal hemisphere--most likely the endoplasmic reticulum network in the cortical region of the myoplasm--is involved in initiating the repetitive calcium waves in the fertilized ascidian egg.

Aequorin↗
PubMed1996

Three-dimensional analysis of the angular momentum of a pole-vaulter.

A method to determine the three orthogonal components of the angular momentum of a human body about its center of gravity is applied to the pole-vault. The angular momentum and the pole force are used in the analysis of pole-vaulting and are also compared with Gros's data (1982, Ph.D. thesis, University of Alberta) and Hubbard and Barlow's results (1980, Proc. Biomechanics Symp. Indian State Board of Health, pp. 33-48). This study tries to show how such results can be useful in many sporting activities and are necessary for optimization of athletic movement.

Arm↗
PubMed1975

Bilateral complete renal duplication with total obstruction of both lower pole collecting systems.

Sepsis and a flank mass developed in a twenty-two-year-old primagravida two days after a normal delivery. Urography showed normal upper pole collecting structures bilaterally. A spherical mass containing curvilinear calcification occupied the left lower pole, and a large inflammatory mass filled the right inferior renal fossa. Angiography and retrograde pyelography demonstrated marked bilateral lower pole hydronephrosis with complete obstruction of the water to each inferior duplicated collecting system.

Adult↗
PubMed1984

Fates and states of determination of single vegetal pole blastomeres of X. laevis.

Vegetal pole cells of Xenopus morulae contribute progeny to all three germ layers, but from the midblastula stage onward they contribute only to the endoderm. We have investigated whether this restriction in fate reflects cell determination by implanting labeled vegetal pole cells into the blastocoels of host embryos and asking which structures later include labeled progeny. Single vegetal pole cells from the morula and also from the midblastula stage can contribute progeny to all germ layers. At the early gastrula stage the cells can contribute only to the endoderm. Thus the restriction of fate in the midblastula does not reflect cell determination. However, the cells do become determined by the beginning of gastrulation.

Animals↗
PubMed1992

Microdialysis administration of vasopressin and vasopressin antagonists into the septum during pole-jumping behavior in rats.

Wistar rats (n = 95) were trained in a pole-jumping apparatus (10 trials/session/day) to investigate the involvement of centrally and peripherally released endogenous AVP in their acquisition rate and to examine the feasibility of the microdialysis technique for the administration of peptides during a behavioral test. After session 1, a microdialysis probe was implanted into the septum; during sessions 2 and 3 the probe was perfused with artificial cerebrospinal fluid (aCSF) alone or containing either AVP (delivered amount via the probe: 0.2 ng) or the V1 (d(CH2)5Tyr(Me)AVP, 5.0 ng) or the V2/V1 (d(CH2)5-D-Tyr(Et)VAVP, 5.0 ng) antagonist. Administration of AVP via microdialysis into the septum failed to alter the acquisition rate of pole jumping. Also, ip application of both hypertonic saline and the AVP V1 antagonist (10 micrograms) in another experiment failed to show a significant effect upon behavior. Septal administration of the V1 or the V2/V1 antagonist via microdialysis, however, produced a significantly impaired performance. The results indicate that AVP release within the septum is involved in the acquisition of pole-jumping behavior probably mediated by the V1 receptor subtype. An additional involvement of the V2 receptor subtype, however, cannot be entirely excluded. The microdialysis technique proved to be a potent tool to administer substances concomitantly with behavioral tests.

Animals↗
PubMed1990

Studies on the expression of intracellular and surface polarity in animal pole cells of Xenopus embryos cultured on various substrata.

The expression of intracellular and surface polarity in animal pole cells of Xenopus embryos (stage 10) cultured on various substrata was studied by electron microscopy. When animal pole cells of Xenopus embryos were cultured on type I collagen- or gelatin-coated dishes until control embryos reached stage 23, the cells in confluent layers expressed an apical-basal polarity so that the apical surface membrane domain faced the culture medium. However, the cells in confluent layers cultured on naked plastic dishes were suppressed to express intracellular and surface polarity. In addition, single attached cells which were formed by being sparsely plated neither spread on any substrata nor displayed the apical-basal polarity perpendicular to the dishes. These results indicate that the expression of intracellular and surface polarity in cultured animal pole cells of Xenopus embryos requires not only cell-cell contact but also an adhesive substrata such as type I collagen or gelatin.

Animals↗
PubMed2006

Primary transpupillary thermotherapy for 18 small posterior pole uveal melanomas.

PURPOSE: To evaluate transpupillary thermotherapy (TTT) for the treatment of small uveal melanomas of the posterior pole. DESIGN: Prospective, nonrandomized interventional case series. METHODS: Eighteen patients underwent TTT for small uveal melanomas located in the posterior pole of the eyes. Tumors were between 2.5 and 4 mm in thickness. TTT was performed with a diode laser at 810 nm. Patients had between one and three TTT sessions, with an intensity adapted to the coloration of the fundus impact. Biomicroscopic examination, ultrasonographic measurements, and angiography were performed before and two months, four months, and six months after treatment, then regularly during follow-up. RESULTS: Eight of the 18 tumors regressed and 10 recurred. The one- and two-year metastasis-free survival rates calculated by the Kaplan-Meier method were, respectively, 61.11% to 44.44% (95% confidence interval). Recurrences were managed with enucleation (three patients), proton beam therapy (six), or additional thermotherapy (one). After treatment, visual acuity was maintained or improved for the eight patients with nonrecurrent tumors. Pathologic analysis of the three enucleated eyes revealed scleral invasion. CONCLUSIONS: Despite encouraging initial short-term results obtained with TTT for the management of small choroidal melanomas, the occurrence of severe complications, especially recurrences and insufficient local tumor control, should raise concern about indications for primary TTT given as isolated treatment for small melanomas of the posterior pole.

Adult↗
PubMed2004

XRHAMM functions in ran-dependent microtubule nucleation and pole formation during anastral spindle assembly.

BACKGROUND: The regulated assembly of microtubules is essential for bipolar spindle formation. Depending on cell type, microtubules nucleate through two different pathways: centrosome-driven or chromatin-driven. The chromatin-driven pathway dominates in cells lacking centrosomes. RESULTS: Human RHAMM (receptor for hyaluronic-acid-mediated motility) was originally implicated in hyaluronic-acid-induced motility but has since been shown to associate with centrosomes and play a role in astral spindle pole integrity in mitotic systems. We have identified the Xenopus ortholog of human RHAMM as a microtubule-associated protein that plays a role in focusing spindle poles and is essential for efficient microtubule nucleation during spindle assembly without centrosomes. XRHAMM associates both with gamma-TuRC, a complex required for microtubule nucleation and with TPX2, a protein required for microtubule nucleation and spindle pole organization. CONCLUSIONS: XRHAMM facilitates Ran-dependent, chromatin-driven nucleation in a process that may require coordinate activation of TPX2 and gamma-TuRC.

Animals↗
PubMed2006

Resection of the scaphoid distal pole for symptomatic scaphoid nonunion after failed previous surgical treatment.

PURPOSE: To evaluate the results of resection of the scaphoid distal pole for symptomatic scaphoid nonunion after failed prior surgical treatment. METHODS: Thirteen patients who were treated with resection of the scaphoid distal pole for persistent nonunion after previous surgical treatment were included in this study. The mean follow-up period was 5 years. Evaluation included measurement of wrist range of motion, assessment of pain, and evaluation of radiographic parameters. The Disabilities of the Arm, Shoulder, and Hand score was used to determine the functional outcome after the excision. RESULTS: Before surgery all but 1 patient reported pain. After surgery 2 patients presented with mild pain during strenuous activity. Mean wrist flexion and extension increased significantly, by 23 degrees and 29 degrees, respectively. The postoperative Disabilities of the Arm, Shoulder, and Hand score was 25 +/- 19 points. There was a significant increase in the radiolunate angle, indicating dorsal intercalated segment instability deformity in 6 patients. CONCLUSIONS: Scaphoid distal pole excision remains a valuable treatment option for patients for whom multiple attempts at union have failed previously and who have no associated complete scapholunate ligament tears. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.

Adult↗
PubMed2006

A capsular-based vascularized distal radius graft for proximal pole scaphoid pseudarthrosis.

PURPOSE: To evaluate the clinical results of the application of a capsular-based dorsal distal radius vascularized bone graft in scaphoid proximal pole nonunions. METHODS: Thirteen patients with symptomatic nonunion at the proximal pole of the scaphoid (10 with avascular necrosis) were treated and reviewed retrospectively. The vascularized bone graft was harvested from the distal aspect of the dorsal radius and was attached to a wide distally based strip of the dorsal wrist capsule. It was inserted press-fit into a dorsal trough across the nonunion site after scaphoid fixation with a Herbert screw. RESULTS: After a mean follow-up period of 19 months 10 of the 13 nonunions (8 of the 10 with avascular necrosis) achieved solid bone union. No complications other than the 3 persistent nonunions occurred. CONCLUSIONS: Results of the use of a capsular-based vascularized bone graft from the distal radius for proximal pole scaphoid nonunions compare favorably with the results of pedicled or free vascularized grafts. It is a simple technique that eliminates the need for dissection of small-caliber pedicle or microsurgical anastomoses. No donor site morbidity was observed. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.

Adult↗
PubMed2006

A myxobacterial S-motility protein dances with poles.

Coordinated movement of packs of S-motile Myxococcus xanthus cells relies on extrusion and retraction of pili that are located at one cell pole. At regular intervals the pili switch their polar location and cells reverse direction. Recently, the FrzS S-motility protein was observed to localize predominantly to the piliated pole. In time, FrzS was redeployed to the opposite pole and its sequestration at the new site coincided with cell reversal. The C-terminal region of FrzS, a response regulator homolog, is rich in coiled-coil motifs and is required for dynamic localization and proper motility. These results raise the possibility that proper spatial control of FrzS has an important role in the regulation of cell reversal and S-motility.

Bacterial Proteins↗
PubMed2005

Cardiac neural crest is necessary for normal addition of the myocardium to the arterial pole from the secondary heart field.

In cardiac neural-crest-ablated embryos, the secondary heart field fails to add myocardial cells to the outflow tract and elongation of the tube is deficient. Since that study, we have shown that the secondary heart field provides both myocardium and smooth muscle to the arterial pole. The present study was undertaken to determine whether addition of both cell types is disrupted after neural crest ablation. Marking experiments confirm that the myocardial component fails to be added to the outflow tract after neural crest ablation. The cells destined to go into the outflow myocardium fail to migrate and are left at the junction of the outflow myocardium with the nascent smooth muscle at the base of the arterial pole. In contrast, the vascular smooth muscle component is added to the arterial pole normally after neural crest ablation. When the myocardium is not added to the outflow tract, the point where the outflow joins the pharynx does not move caudally as it normally should, the aortic sac is smaller and fails to elongate resulting in abnormal connections of the outflow tract with the caudal aortic arch arteries.

Animals↗
PubMed2006

Animal pole determinants define oral-aboral axis polarity and endodermal cell-fate in hydrozoan jellyfish Podocoryne carnea.

Cnidarians, in contrast with bilaterians, are generally considered to exhibit radial symmetry around a single body axis (oral-aboral) throughout their life-cycles. We have investigated how the oral-aboral axis is established in the hydrozoan jellyfish Podocoryne carnea. Vital labeling experiments showed that the oral end of the blastula derives from the animal pole region of the egg as has been demonstrated for other cnidarian species. Gastrulation is restricted to the oral pole such that the oral 20% of blastula cells give rise to endoderm. Unexpectedly, bisection experiments at the 8-cell stage showed that animal regions are able to develop into normally polarized larvae, but that vegetal (aboral) blastomeres completely fail to develop endoderm or to elongate. These vegetal-derived larvae also failed to polarize, as indicated by a lack of oral-specific RFamide-positive nerve cells and a disorganized tyrosinated tubulin-positive nerve net. A different result was obtained following bisection of the late blastula stage: aboral halves still lacked the capacity to develop endoderm but retained features of axial polarity including elongation of the larva and directional swimming. These results demonstrate for the first time in a cnidarian the presence of localized determinants responsible for axis determination and endoderm formation at the animal pole of the egg. They also show that axial polarity and endoderm formation are controlled by separable pathways after the blastula stage.

Alkaline Phosphatase↗
PubMed2006

Cardiac arterial pole alignment is sensitive to FGF8 signaling in the pharynx.

Morphogenesis of the cardiac arterial pole is dependent on addition of myocardium and smooth muscle from the secondary heart field and septation by cardiac neural crest cells. Cardiac neural crest ablation results in persistent truncus arteriosus and failure of addition of myocardium from the secondary heart field leading to malalignment of the arterial pole with the ventricles. Previously, we have shown that elevated FGF signaling after neural crest ablation causes depressed Ca2+ transients in the primary heart tube. We hypothesized that neural crest ablation results in elevated FGF8 signaling in the caudal pharynx that disrupts secondary heart field development. In this study, we show that FGF8 signaling is elevated in the caudal pharynx after cardiac neural crest ablation. In addition, treatment of cardiac neural crest-ablated embryos with FGF8b blocking antibody or an FGF receptor blocker rescues secondary heart field myocardial development in a time- and dose-dependent manner. Interestingly, reduction of FGF8 signaling in normal embryos disrupts myocardial secondary heart field development, resulting in arterial pole malalignment. These results indicate that the secondary heart field myocardium is particularly sensitive to FGF8 signaling for normal conotruncal development, and further, that cardiac neural crest cells modulate FGF8 signaling in the caudal pharynx.

Animals↗
PubMed1994

A new option for splenic preservation in normal sized spleen based on preserved histology and phagocytic function of the upper pole using upper short gastric vessels.

Despite the recognized desirability of splenic salvage, forced splenectomy remains the rule in many operative situations, including trauma and pancreatic cancer. An anatomic study was conducted to assess whether the upper short gastric arteries provide sufficient collateral circulation to the spleen that the upper pole could remain viable even when the hilum is resected and the splenic artery and vein no longer intact. The anatomy of the upper short gastric vessels was studied in 59 human spleens and 18 albino rat spleens. Fifty-four human specimens (92%) and 18 (100%) of the rat spleens showed at least 1 upper short gastric artery and 1 vein connecting the fundus of the stomach with the interior of the upper pole of the spleen with no connection to the major hilar vessels. Lower two-thirds splenectomy, which included excision of the hilum of the spleen after ligation of both the splenic artery and vein, was performed on 14 of the 18 rats. The remaining 4 rats served as control animals. The upper pole of the spleen was preserved solely on the upper short gastric vessels that pass directly between the stomach and the interior of the spleen. Structure and macrophage function in the residual splenic tissue was shown to be preserved at 1 hour and 2 weeks postoperatively, based on results of the India ink technique for demonstrating phagocytic function and on results of regular histologic examination. Preservation was attributed to the fact that blood supply for the residual splenic tissue after splenic mass reduction remained adequate through the upper short gastric vessels. Splenic mass reduction is essential to improve perfusion to the residual splenic tissue if excision of the splenic hilum or ligation of the main splenic vessels becomes an operative necessity.

Animals↗
PubMed2001

The efficacy of extracorporeal shock wave lithotripsy for isolated lower pole calculi compared with isolated middle and upper caliceal calculi.

PURPOSE: We assess the efficacy of extracorporeal shock wave lithotripsy monotherapy for isolated lower pole nephrolithiasis, and compare it to that for isolated middle and upper caliceal calculi. MATERIALS AND METHODS: We treated 714 renal units in 687 patients with isolated caliceal stones using a Lithostar lithotriptor (Siemens Medical Systems, Erlangen, Germany). The stones were localized in the lower, mid and upper calices in 455, 104 and 128 patients, respectively. Stone load was recorded in cm.2. Patients were stratified into 3 groups based on stone burden. The energy and shock waves, use of anesthesia, number of treatment sessions, auxiliary measures and complications were noted. Patients were evaluated with intravenous urogram or plain film of kidneys, ureters and bladder, and ultrasonography when stone-free, or clinically significant residual fragment status, including nonobstructive and noninfectious insignificant fragments 4 mm. or less, was noted at the fluoroscopic control 2 to 4 weeks after the last session. Final clinically significant residual fragment decision was made 10 to 12 weeks after the last session. Extracorporeal shock wave lithotripsy was considered a failure if no fragmentation was noted after session 3 and continued if fragmentation was noted. Results regarding caliceal localization were compared. RESULTS: Complete data were available on 591 renal units. Auxiliary procedures were used in 81 (14%) units before treatment. Anesthesia was given to 101 (17%) patients. The mean number of shock waves and energy used were 2,022 and 17.4 kV., respectively. The difference in shock wave, energy and treatment rate among 3 caliceal locations reached statistical significance only for energy delivered to the lower and upper calices. The effectiveness quotient of extracorporeal shock wave lithotripsy was 36%, 46% and 41% for lower, middle and upper pole stone disease, respectively (p = 0.4). There was a highly significant correlation between stone-free and re-treatment rates, and stone burden. The overall stone-free rate was 66%, and 63%, 73% and 71% for lower, middle and upper caliceal stones, respectively (p = 0.1). For the group with stones greater than 2 cm.2 overall stone-free rate decreased to 49%, and 53%, 60% and 23% in lower, middle and upper caliceal locations, respectively. Overall, extracorporeal shock wave lithotripsy monotherapy failed in 46 (7.7%) renal units. Steinstrasse developed in 39 (6.5%) patients who were then treated with repeat lithotripsy. CONCLUSIONS: Extracorporeal shock wave lithotripsy appears to be successful for management of isolated caliceal stone disease. Treatment efficacy was not significantly different among stones localized in lower, middle and upper poles. We recommend it as the primary treatment of choice for stones less than 2.0 cm.2 in all caliceal locations. Treatment should be individualized for management of caliceal stones greater than 2.0 cm.2 until large prospective randomized trials comparing shock wave lithotripsy and percutaneous nephrolithotomy are available.

Adolescent↗
PubMed1994

Management of lower pole nephrolithiasis: a critical analysis.

The results of extracorporeal shock wave lithotripsy (ESWL*) and percutaneous nephrostolithotomy for the treatment of lower pole nephrolithiasis were examined in 32 consecutive patients undergoing percutaneous nephrostolithotomy at the Methodist Hospital of Indiana and through meta-analysis of publications providing adequate stratification of treatment results. Of 101 cases managed with percutaneous nephrostolithotomy 91 (90%) were stone-free, a result significantly better than that achieved with ESWL (1,733 of 2,927 stone-free, 59%). Stone-free rates with percutaneous nephrostolithotomy were independent of stone burden, whereas stone-free rates with ESWL were inversely correlated to the stone burden treated. The morbidity of patients undergoing percutaneous nephrostolithotomy at our hospital was minimal, with a mean hospital stay of 4.7 +/- 2.8 days. No blood transfusions were required. All patients became stone-free. The percentage of urolithiasis patients with lower pole calculi is increasing. Because of the significantly greater efficacy of percutaneous nephrostolithotomy for lower pole calculi, particularly stones larger than 10 mm. in diameter, further consideration should be given to an initial approach with percutaneous nephrostolithotomy.

Adult↗
PubMed1997

Excitatory amino acids and monoamines in parahippocampal gyrus and frontal cortical pole of adults with Down syndrome.

Aspartate (ASP), glutamate (GLU), noradrenaline (NA), dopamine (DA) and its acidic metabolites DOPAC and HVA, serotonin (5-HT) and its metabolite 5-HIAA were simultaneously investigated in post-mortem tissue samples from right parahippocampal gyrus (temporal cortex) and frontal cortical pole (frontal cortex) of adults with Down syndrome (DS), and of neurologically healthy controls by use of high performance liquid chromatography (HPLC). In parahippocampal gyrus, ASP, GLU, NA, DOPAC and 5-HT levels were significantly decreased in patients with DS, compared to levels found in control subjects (approximately 50%). No significant changes were observed in frontal pole. ASP and GLU levels were significantly lower in parahippocampal gyrus than in frontal pole of DS, a regional distribution that could not be observed in control subjects. In conclusion, the results of this study suggest that the temporal cortex would be more affected than the frontal cortex in adult patients with DS, a finding in line with reports showing a marked hypometabolism and extensive cell loss in temporal cortex of DS, and with those showing that parahippocampal gyrus abnormality may correlate with the extent of mental retardation affecting this type of patients.

Biogenic Monoamines↗