Polar Vessel Research Articles

Laparoscopic Transposition of Lower Pole Crossing Vessels (Vascular Hitch) in Children with Pelviureteric Junction Obstruction: How to Be Sure of the Success of the Procedure?

To report a series of children with pelviureteric junction obstruction (PUJO) due to lower polar crossing vessels who underwent laparoscopic vascular transposition. In order to confirm the relief of the obstruction and avoid unnecessary additional procedures, we suggest performing an intraoperative measure of the ureteral opening pressure. From January 2007 and January 2014, 11 children underwent laparoscopy to treat well-documented PUJO by polar vessels. In the first 7 cases, children underwent a careful dissection of the polar vessels that were transposed cranially in the pelvis. In the last 4 cases, a percutaneous needle was inserted into the renal pelvis, and the ureteral opening pressure was obtained intraoperatively, before and after the vascular hitch procedure, in 3 cases. No vascular relocation was necessary except in 1 case with a polar vessel unrelated to the obstruction. The laparoscopic procedure was feasible in all cases. Median operative time was 90 minutes without intraoperative complications. In the last 3 cases, a decrease in the renal pelvic pressure was demonstrated just after releasing the ureter from the polar vessels, confirming the extrinsic obstruction. In 1 case, the intraoperative pelvic pressure measurement showed that there was no vascular compression but that obstruction was due to renal rotation. During follow-up (range, 12-96 months) all patients reported resolution of their symptoms, nine children showed a decrease in the hydronephrosis grade, and all but one with poor function had improved drainage on diuretic renography. Intraoperative measurement of ureteral opening pressure may help to confirm that the vascular hitch procedure has relieved the pelvic obstruction, precluding the need for dismembered procedures. We believe that in some doubtful cases, with the addition of intraoperative pelvic pressure measurement, vascular hitch may be considered a safe procedure to treat selected cases of PUJO in children.

This was no Antarctic pleasure cruise

After his polar vessel became trapped in shifting sea ice, Chris Turney defends the scientific basis of the expedition.

Hydronephrosis in children

Hydronephrosis is a common illness in children and consists in the dilatation of the renal collector system. It may be congenital, and in this case is called fetal hydronephrosis, or it can be acquired, which is less frequent. The fetal hydronephrosis may be diagnosed during the intrauterine life through obstetric ultrasound. Mild to moderate dilatations may resolve spontaneously before or after birth. However, larger dilatations can be causes of urinary tract infection, damage to the renal parenchyma, and may require surgical treatment. The main causes of persistent fetal hydronephrosis after birth are ureteropelvic junction stenosis, vesicoureteral reflux, ureterovesical junction stenosis, ureteric duplication associated or not with ureterocele, and posterior urethra valve. In relation to the acquired hydronephrosis, the most common etiology is the angulation of the proximal ureter resulting from an anomalous polar vessel; however, it can also be due to ureterolithiasis, which is uncommon. In these cases, the hydronephrosis is usually diagnosed as the result of propaedeutics of chronic recurrent abdominal pain in older children. The initial conduct in cases of fetal hydronephrosis, shortly after birth, is the use of urinary tract ultrasound to confirm and classify the degree of hydronephrosis. The ultrasound findings will assist to decide if it is necessary to extend the propaedeutics or maintain a waiting conduct. The follow-up by a nephrologist and pediatric-surgeon in the subsequent treatment of these children is

Prevalence of the Polar Vessel Sign in Parathyroid Adenomas on the Arterial Phase of 4D CT

The "polar vessel" sign has been previously described on sonography of parathyroid adenomas. We estimated the 4D CT prevalence of the polar vessel sign and determined features of parathyroid adenomas that are associated with this sign. Twenty-eight consecutive patients with parathyroid adenomas underwent 4D CT between 2008 and 2012 at 2 institutions. 4D CT images were reviewed for the presence of the polar vessel sign and a second vascular finding of an enlarged ipsilateral inferior thyroid artery. The polar vessel sign was correlated with adenoma weight and size and arterial phase CT attenuation. Thirty-two parathyroid adenomas in 28 patients were studied, with a mean adenoma weight of 0.66 ± 0.65 g, a mean maximal CT diameter of 11.1 ± 4.9 mm, and a mean arterial attenuation of 148 ± 47 HU. The polar vessel sign was seen in 20/32 (63%) adenomas. Adenomas with a polar vessel had higher arterial phase attenuation than adenomas without a polar vessel (163 and 122 HU, respectively, P < .01). Size and weight were not significantly different for adenomas with and without polar vessels. An enlarged inferior thyroid artery was seen in only 2/28 (7%) patients with unilateral disease. The polar vessel sign was present in nearly two-thirds of parathyroid adenomas on 4D CT and was more likely to be present in adenomas that had greater arterial phase enhancement. This sign can be used along with enhancement characteristics to increase the radiologist's confidence that a visualized lesion is a parathyroid adenoma rather than a thyroid nodule or lymph node.

The place names of Zemlya Frantsa-Iosifa: Leigh Smith'sEiraexpeditions, 1880 and 1881–1882

ABSTRACTIn the summer of 1880, the British explorer Benjamin Leigh Smith made the first reconnaissance of the western reaches of Zemlya Frantsa-Iosifa [Franz Josef Land] in the specially built polar research vesselEira. This was the first expedition to go ashore in the archipelago after its acknowledged discovery by Weyprecht and Payer in 1873. Combined with his brief reconnaissance in 1881 beforeEirasank near Cape Flora, Leigh Smith added a total of 41 place names, 37 of which are still in use, to its geographic nomenclature during his two expeditions, 1880 (39 place names) and 1881–1882 (2). The 1880 names were a post-expedition collaboration, between Leigh Smith and Clements Markham, Secretary of the Royal Geographic Society (RGS). Leigh Smith provided the names of colleagues and scientists who had either been with him in 1880 or on one of his earlier expeditions to Svalbard, or those of favoured relatives, while Markham, along with Sir George Nares as an RGS peer reviewer, added the names of particularly influential individuals in geographical circles as well as a variety of museum curators who identified natural history collections returned by the expedition. Additionally, two place names are connected to the DutchWillem Barentsexpedition of 1879.

Sonography of intrathyroid parathyroid adenomas: Are there distinctive features that allow for preoperative identification?

ObjectiveThe purpose of our study was to determine if intra-thyroid parathyroid adenomas can be accurately identified by applying proposed criteria to preoperative ultrasound examinations in patients with primary hyperparathyroidism. Materials/methodsFifty-three patients with pathology proven intra-thyroid parathyroid adenomas and pre-operative ultrasounds were identified from a surgical database for a blinded, retrospective review. A contemporary, age-matched cohort of 54 patients with extra-thyroid parathyroid adenomas was identified as a control. A total of 64 patients within these cohorts had co-existing thyroid nodules. Proposed ultrasound criteria for identifying a parathyroid adenoma included solid composition, profound hypoechogenicity, and presence of a feeding polar vessel. Parathyroid adenomas were classified as extra-thyroid or intra-thyroid (partial or complete) based on their relationship with the thyroid gland during ultrasound evaluation and results were compared to surgical and histopathology reports as the gold standard. The results from the blinded, retrospective review during which the proposed, specific ultrasound criteria were applied were compared to the initial, pre-operative reports during which the proposed criteria were not applied. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the blinded, retrospective review and initial, pre-operative reports were calculated. Additionally, in patients with co-existing thyroid nodules, an attempt was made to differentiate parathyroid adenomas from the thyroid nodules. ResultsApplication of the proposed ultrasound criteria during blinded retrospective review yielded a sensitivity and specificity for detecting intra-thyroid parathyroid adenomas of 76% and 92%, respectively. The sensitivity and specificity of ultrasound for detecting intra-thyroid parathyroid adenomas on the initial reports was 29% and 95%, respectively. The sensitivity and specificity for differentiating an intra-thyroid parathyroid adenoma from a thyroid nodule was 78% and 86%, respectively. ConclusionApplication of specific ultrasound criteria facilitates pre-operative diagnosis of intra-thyroid parathyroid adenomas and facilitates surgical planning. This large series confirms previous, largely anecdotal reports of ultrasound's utility in detecting intra-thyroid parathyroid adenomas.

횡충격하중을 받는 빙해선박 구조물의 파단에 관한 연구

Single frame structures with notches were fractured by applying drop impact loadings at room temperature and low temperature. Johnson-Cook shear failure model has been employed to simulate the fractured single frame structures. Through several numerical analyses, material constants for Johnson-Cook shear failure model have been found producing the cracks resulted from experiments. Fracture strain-stress triaxiality curves at both room temperature and low temperature are presented based on the extracted material constants. It is expected that the fracture strain-stress triaxiality curves can offer objective fracture criteria for the assessment of structural fractures of polar class vessel structures fabricated from DH36 steels. The fracture experiments of single frame structures revealed that the structure on low temperature condition fractures at much lower strain than that on room temperature condition despite the same stress states at both temperatures. In conclusion, the material properties on low temperature condition are essential to estimate the fracture characteristics of steel structures operated in the Northern Sea Route.

Robotic-Assisted Approach in Relapsed Ureteropelvic Junction Obstruction

Purpose Ureteropelvic junction syndrome (UPJS) is the most frequent cause of ureteral obstruction in children. Since our robotic experience starts in 2006 with da Vinci surgical system®, we initiate a series thinking about the benefits in terms of surgical precision and outcomes. We present the clinical case of a patient with relapsed ureteropelvic junction obstruction treated by means of a robotic-assisted approach Material and Methods We present a 21 years old patient with history of open right pyeloplasty at 9 years, who complains of right low back pain since several months. A renogram with obstructive pattern and an abdominal computed tomography (CT) with three-dimensional (3D) image reconstruction, reported a proximal ureteral stenosis secondary to a polar vessel. A robotic-assisted transperitoneal pyeloplasty is performed with the use of 3 robotic trocars and a 5 mm. trocar for the assistant. The ureteral suture is done using 6-0 Monocryl® Results Total surgical time was 180 minutes with a console time of 110 minutes. Blood loss was insignificant and patient was discharged 48 hours after surgery with a double J stent, which was removed 4 weeks later with sedative medication. A renogram indicated 3 months postoperatively conforms absence of obstruction. Conclusions Robotic approach allows a good surgical performance, comfortable for the surgeon with 3D vision; enabling an excellent dissection and reconstruction (anastomosis) in tissues already injured. The patient's recovery is fast with satisfactory esthetic and functional outcomes.

PUJ obstruction with crossing renal vessels - a case report of failed laparoscopic vascular hitch

Purpose Dismembered pyeloplasty has been the traditional technique in the management of pelviureteric junction obstruction (PUJO) secondary to crossing renal vessels in children. Laparoscopic transposition of lower pole vessels for PUJO has been described in children as well as adults. Material and Methods We report a child with PUJO secondary to lower pole renal vessels who underwent laparoscopic transposition of vessels. The child had persistent PUJO, which was later treated with laparoscopic dismembered pyeloplasty. Results After transposition of the lower polar vessel, the patient had persistent PUJO. Conclusions Laparoscopic transposition of renal vessels is a simple technique, and requires less operating time. It involves no anastomosis or insertion of temporary DJ stent. However as of now there are no imaging techniques or Intraoperative procedures to confirm that the crossing renal vessels are the sole etiology for PUJO. Till such time one should use this option carefully.

Contributions of the Retroperitoneoscopy to the Diagnose of the Ureteropelvic Junction Obstruction in Children: New Surgical Alternatives to Conventional Pyeloplasty

PURPOSE To assess:The correlation between pre and post-retroperitoneoscopy diagnose of the ureteropelvic junction obstruction (UPJO) causes. The impact of Retroperitoneoscopy on the surgical technique used for the resolution of the extrinsic UPJO. MATERIAL AND METHODS Between 2004 and 2006 we have treated 14 patients, with congenital hydronephrosis due to UPJO, by retroperitoneoscopic approach. The mean age of surgery was 22 months (range between 3 months and 12 years). In all patients preoperative study included: ultrasound (US), cystography, diuretic renography and renal scintigraphy; and uro-angio-Magnetic Resonance in 10. Preoperative diagnose was: intrinsic UPJO in 10 patients and extrinsic UPJO due to crossing polar vessels in 4. The mean postoperative follow-up has been 16 months (range between 8 and 20 months). The postoperative outcome has been evaluated by US, renography and renal scintigraphy. RESULTS After -retroperitoneoscopy the diagnose became: intrinsic UPJO in 6, and extrinsic UPJO in 8, due to posterior polar vessel in 2, peri-UPJ fibrosis in 4, and anterior polar vessel in 2. UPJO is due to extrinsic causes in 57% of the patients. These findings resulted in the variation of the surgical technique in 6 patients (42.5%). We performed video-assisted ureteropyeloplasty in 6, pyelopyeloplasty in 2, ureterolysis in 4, and pelvic transposition and pexia in 2. There were no intra - or postoperative complications. The average length of stay was 1,6 days. The postoperative result was improvement of the obstruction in 100%, without differences between those who underwent some kind of plastia from those who did not. CONCLUSIONS Retroperitoneoscopy is an effective method for diagnose and minimally invasive treatment of the ureteropelvic junction obstruction. Retroperitoneoscopy raises new surgical alternatives to ureteropyeloplasty. Surgical technique should be based on Retroperitoneoscopical findings.

Aurora Borealis—Development of a New Research Icebreaker with Drililng Capability

No abstract available. doi:10.2204/iodp.sd.5.10.2007

New U.S. icebreaker to advance Arctic Marine Science

The decades‐long planning for a U.S. icebreaking vessel dedicated to Arctic marine science reached its goal with the entry into service of the UGCGC Healy, a polar research vessel operated by the U.S. Coast Guard for the U.S. science community. The ship is named for Captain Michael A. Healy, a legendary figure of Alaskan history who served as commanding officer of the U.S. Revenue Cutters Corwin (1884–1885) and Bear (1886–1895).Healy is 128 m long, 25 m wide, displaces 14,900 metric tons, and traverses up to 1.4 m ice at 1.65 m s−1, propelled by two 11.1‐MW AC synchronous motors fed from DC diesel electric engines through cycloconverters. Thus, Healy is more powerful and somewhat larger than the German polar research vessel Polarstern or the Canadian icebreaker Louis S. St‐Laurent. Healy's power system responds quickly to the load changes common in icebreaking. The ship has a conventional icebreaker bow. The hull provides a sea‐kindly ride and more stable work conditions in open water than do the U.S. Coast Guard Polar‐class icebreakers. The ship is designed to work in any Arctic season.

Surface ozone observations during voyages to the Arctic and Antarctic regions

Surface ozone concentration and UV-B data between 75° N and 70° S were obtained aboard the Chinese polar scientific vessel “Xue -long” (Snow-Dragon) during the first voyage to the Arctic and the 16th to the Antarctic in 1999–2000. Analysis of these data presents that variations of the surface ozone concentration have small amplitude during voyages except the mid-latitude in the Northern Hemisphere. As a whole, average surface ozone concentration in the Northern Hemisphere is higher than that in the Southern, and high value occurred when the ship sailed close to the continents. The average diurnal variations of the surface ozone in the Northern Hemisphere are also higher compared to the southern counterparts, and high diurnal variations were found at low latitudes, and relative low level in the polar region.

Glacial history of East Greenland explored

To study the glacial and environmental history of East Greenland dating back to late Quaternary time, the polar research vessel Polarstern took its third cruise to the East Greenland Sea from August 17 to October 6, 1994, where it served as a platform for shipboard investigations and field observations. A variety of techniques were employed: sediment coring and seismic profiling were carried out in the fjords as well as on the continental shelf and slope. And, for the first time, these investigations were supplemented by profiling and coring in periglacial lakes.

Trace Analysis of Heavy Metals in Aerosols Over the Atlantic Ocean from Antarctica to Europe

Abstract The particulate heavy metal concentrations of Tl, Cu, Cd, Pb, Zn, Ni, Cr, and Fe were determined in the atmosphere over the Atlantic Ocean from 77°S (Antarctica) to 54°N (Europe) using the analytical method of isotope dilution mass spectrometry. The samples were collected on board of the German polar research vessel “Polarstern” during four different expedition legs from September 1987 to March 1990. Analyses of the crustal reference element Fe resulted in the calculation of enrichment factors EF(Fe), which were used for interpretation of crustal influences on heavy metal contents as well as for contamination control. The variations in concentration of the dominant crust element Fe run up to five orders of magnitude (0.22–36200 ng m−3). The region between the equator and 20°N was strongly influenced by crustal material transported by the north-eastern trades out of the Sahara. EF(Fe) values around unity and the highest measured concentrations of the dominant crustal elements Fe (36200 ng m−3), Cr...

Renal duplex sonography: Evaluation of clinical utility

With the exception of conventional angiography, no previously proposed screening test has the necessary sensitivity/specificity to guide further evaluation for correctable renovascular disease. Recently, renal duplex sonography has been suggested as a useful substitute in such screening for renovascular disease. This report analyzes our data collected over the past 10 months in evaluation of renal duplex sonography to examine its diagnostic value. The study population for renal duplex sonography validity analysis consisted of 74 consecutive patients who had 77 comparative renal duplex sonography and standard angiographic studies of the arterial anatomy to 148 kidneys. Renal duplex sonography results from six kidneys (4%) were considered inadequate for interpretation. This study population contained 26 patients (35%) with severe renal insufficiency (mean 3.6 mg/dl) and 67 hypertension (91%). Fourteen patients (19%) had 20 kidneys with multiple renal arteries. Bilateral disease was present in 22 of the 44 patients with significant renovascular disease. Renal duplex sonography correctly identified the presence of renovascular disease in 41 of 44 patients with angiographically proven lesions, and renovascular disease was not identified in any patient free of disease. When single renal arteries were present (122 kidneys), renal duplex sonography provided 93% sensitivity, 98% specificity, 98% positive predictive value, 94% negative predictive value, and an overall accuracy of 96%. These results were adversely affected when kidneys with multiple (polar) renal arteries were examined. Although the end diastolic ratio was inversely correlated with serum creatinine (r = −0.3073, p = 0.009), low end diastolic ratio in 35 patients submitted to renovascular reconstruction did not preclude beneficial blood pressure or renal function response. We conclude from this analysis that renal duplex sonography can be a valuable screening test in the search for correctable renovascular disease causing global renal ischemia and secondary renal insufficiency (ischemic nephropathy). Renal duplex sonography does not, however, exclude polar vessel renovascular disease causing hypertension alone nor does it predict hypertension or renal function response after correction of renovascular disease.

Renal duplex sonography: Evaluation of clinical utility

With the exception of conventional angiography, no previously proposed screening test has the necessary sensitivity/specificity to guide further evaluation for correctable renovascular disease. Recently, renal duplex sonography has been suggested as a useful substitute in such screening for renovascular disease. This report analyzes our data collected over the past 10 months in evaluation of renal duplex sonography to examine its diagnostic value. The study population for renal duplex sonography validity analysis consisted of 74 consecutive patients who had 77 comparative renal duplex sonography and standard angiographic studies of the arterial anatomy to 148 kidneys. Renal duplex sonography results from six kidneys (4%) were considered inadequate for interpretation. This study population contained 26 patients (35%) with severe renal insufficiency (mean 3.6 mg/dl) and 67 hypertension (91%). Fourteen patients (19%) had 20 kidneys with multiple renal arteries. Bilateral disease was present in 22 of the 44 patients with significant renovascular disease. Renal duplex sonography correctly identified the presence of renovascular disease in 41 of 44 patients with angiographically proven lesions, and renovascular disease was not identified in any patient free of disease. When single renal arteries were present (122 kidneys), renal duplex sonography provided 93% sensitivity, 98% specificity, 98% positive predictive value, 94% negative predictive value, and an overall accuracy of 96%. These results were adversely affected when kidneys with multiple (polar) renal arteries were examined. Although the end diastolic ratio was inversely correlated with serum creatinine (r = -0.3073, p = 0.009), low end diastolic ratio in 35 patients submitted to renovascular reconstruction did not preclude beneficial blood pressure or renal function response. We conclude from this analysis that renal duplex sonography can be a valuable screening test in the search for correctable renovascular disease causing global renal ischemia and secondary renal insufficiency (ischemic nephropathy). Renal duplex sonography does not, however, exclude polar vessel renovascular disease causing hypertension alone nor does it predict hypertension or renal function response after correction of renovascular disease.

Particle-laden Eurasian Arctic sea ice: observations from July and August 1987

During the summer 1987 expedition of the polar research vessel‘Polarstern’in the Eurasian Basin of the Arctic Ocean, sea ice at about 84-86°N and 20-30°E was found to have high concentrations of particulate material. The particle-laden ice occurred in patches which often darkened more than half the ice surface at our northernmost positions. Much of this ice appeared to be within the Siberian Branch of the Transpolar Drift stream, which transports deformed, multi-year ice from the Siberian shelves westward across the Eurasian Basin. Lithogenic sediment, which is the major component of the particulate material, may have been incorporated during ice formation on the shallow Siberian seas. Diatoms collected from the particle-rich ice surfaces support this conclusion, as assemblages were dominated by a marine benthic species similar to that reported from sea ice off the coast of northeast Siberia. Based on drift trajectories of buoys deployed on the ice it appears that much of the particle-laden ice exited the Arctic Ocean through the Fram Strait and joined the East Greenland Current. Very different sea ice characteristics were found east of the Yermak Plateau and north of Svalbard and Frans Josef Land up to about 83-84°N. Here sea ice was thinner, less deformed, with lower amounts of lithogenic sediment and diatoms. The diatom assemblage was dominated by planktonic freshwater species. Trajectories of buoys deployed on sea ice in this region indicated a tendency for southward transport to the Yermak Plateau or into the Barents Sea.

The Fram: Profile of a Famous Polar Exploration Vessel

... In 1884, Eskimos hunting off the south coast of Greenland found a number of relics from the Jeanette on an ice floe, including a provisions note written by its commander, De Long. The drift pattern of Siberian timbers and now the startling relics from the Jeanette convinced Fridtjof Nansen that a ship deliberately set into the grip of the polar ice pack in the right place would drift with the ice over, or at least close to, the North Pole. ... [This is an account of the remarkable construction of the Fram and a brief description of its noteworthy journeys: the Norwegian North Pole Expedition, a scientific polar expedition which became a remarkable four-year voyage of discovery and exploration in the Canadian High Arctic where the expedition members mapped and explored 300 000 sq km of territory and collected 50 000 plants and 2000 jars of organic specimens, Amundsen's successful South Pole Expedition and Nielsen's 20 month oceanographic survey between Africa and South America. Although Fram had the distinction of having reached farthest south as well as north, she was abandoned until Otto Sverdrup began the long struggle to save the Fram in 1916.] Today the impressive old ship is joined by other vessels, including Viking ships and Amundsen's Gjoa, which was also rescued from the scrap heap. There can be little doubt that the person most responsible for Fram's rescue was the strong helmsman who navigated her through some of the most severe conditions a ship could face. Otto Sverdrup and the Fram will always be remembered together.

Chlorofluoromethanes in the Arctic mediterranean seas: evidence for formation of bottom water in the Eurasian Basin and deep-water exchange through Fram Strait

During July–August of 1984, the polar research vessel R.V. Polarstern occupied sections of oceanographic stations in and north of Fram Strait and across the Greenland Sea (Boreas Basin) south of Fram Strait. The temperature, salinity and chlorofluoromethane (CFM) data for the Polarstern stations within the Eurasian Basin reveal two deep-water masses, Eurasian Basin Bottom Water (EBBW) which lies below the σ 2 = 37.46 density surface and Eurasian Basin Deep Water (EBDW) which lies above this surface. The depth of this surface is close to the 2600 m sill depth of Fram Strait. The CFM, temperature and salinity distributions suggest that EBBW is partially composed of dense, high salinity shelf water advected into the deep Eurasian Basin, where it probably circulates around the basin in a deep cyclonic boundary current. An upper limit of about 0.1 Sv was estimated from the CFM data for the transport of pure high salinity shelf water into the Eurasian Basin below 3000 m. These data together with data collected on previous cruises to the Norwegian and Greenland seas reveal that EBDW exchanges with water masses south of Fram Strait, first flowing through Fram Strait in a narrow (<10 km) deep boundary current, then mixing with Greenland Sea Deep Water in the periphery of the Greenland Gyre to form new Norwegian Sea Deep Water (NSDW). Some of this new NSDW flows southeastward into the Norwegian Sea and a mixture of old and new NSDW flows northward on the eastern side of Fram Strait, returning to the Eurasian Basin. We estimate the volume transport of EBDW southwrd through Fram Strait to be 0.80–0.93 Sv. Volume transports between the deep Greenland and deep Norwegian seas and between the surface and deep Greenland Sea were also estimated with respective values of 0.80–0.93 Sv and 0.50 –0.52 Sv.