bluuebunny/crossref_metadata_2025 huggingface dataset:
Seventeen‐year experience with routine shunting in carotid artery surgery
Authors: Javid Hushang , Julian Ormand C. , Dye William S. , Hunter James A. , Najafi Hassan , Goldin Marshall D. , Serry Cyrus , DeLaria Giacomo A.
Published: April 2005

Safety of carotid artery surgery depends on proper case selection, meticulous surgical technique, and appropriate protection of the brain during carotid artery cross‐clamping. Various methods have been devised to determine the adequacy of collateral circulation, none of which has been proven practical and totally reliable. Attempts at increasing cerebral perfusion to the ischemic portion of the brain by induced hypertension, hypercarbia, and hypocarbia have been ineffective.

The purpose of this presentation is to report our experience with routine intraluminal shunting in carotid artery surgery during the past 17 years. Advantages of routine shunting include maintenance of regional cerebral blood flow at the preclamping level and the elimination of any need for monitoring and haste during surgery. Insertion of the tube, properly done, does not injure the arterial wall and should not cause embolization. The presence of the tube within the arterial lumen does not interfere with exposure of the atheroma, yet it facilitates repair of the incision and prevents stricture by faulty suturing technique. Results of carotid artery surgery measured by the incidence of stroke are compared between shunted and nonshunted series. A review of the literature confirms our impression that shunting reverses ischemic changes detected by EEG and regional cerebral blood flow determinations. The usefulness of shunting in the surgical management of internal carotid aneurysm, kinked carotid artery, carotid body tumor, and carotid‐subclavian bypass graft is also described.
Fibromuscular dysplasia of the internal carotid artery
Authors: Effeney David J. , Ehrenfeld William K. , Stoney Ronald J. , Wylie Edwin J.
Published: April 2005

Sixty‐eight patients underwent 104 operations for symptomatic fibromuscular dysplasia between 1965 and 1977. In 8 of the early operations, the artery was resected and primarily anastomosed or replaced with saphenous vein. The remainder of the patients had graduated dilatation of the carotid artery combined, if necessary, with a bifurcation endarterectomy. Four patients had a contralateral endarterectomy for atherosclerosis. There were no operative deaths. Two patients had neurologic deficits after operation, while 7 had 1 transient ischemic attack or amaurosis in the early postoperative period. The follow‐up period extends from 6 months to 12 years. One patient developed a deficit that could be attributed to the carotid artery at the site of the prior dilatation, and 2 patients developed neurologic difficulties secondary to subarachnoid hemorrhage. The exact nature of the disease, its incidence in the community, and the mechanism of symptom production remain unknown. Symptomatic fibromuscular dysplasia is not a benign disorder, and there are no data available to confirm or deny the benefit of medical treatment. Intraluminal dilatation, however, is a safe, durable operation that relieves symptoms and offers prophylaxis against further neurologic sequelae.
Surgical management of atheroma of the aortic dome and origin of supra‐aortic trunks
Authors: Thevenet André
Published: April 2005

During a 14‐year period, 607 obstructive lesions of supraaortic vessels originating from the aortic arch in 506 patients were submitted to arterial reconstruction. Among these, 28 patients presented multiple proximal aortic arch lesions associated with extensive aortic involvement—an “aortic dome syndrome.” Transsternal revascularization procedures were performed in 28 patients, including 7 in whom endarterectomy of the aortic dome was done under hypothermic circulatory arrest. In addition, in 11 patients, multiple bypass grafts were constructed from the ascending aorta, and in 10 other patients, sequential great vessel endarterectomies were performed, with transposition of the left common carotid artery in 5 patients. Twenty‐four of the 27 survivors are asymptomatic at an average of 6.9 years postoperatively. Progressive atherosclerosis in distal lesions has been observed in 2 patients, and late mortality has occurred in 5 others. Long‐term arterial patency has been demonstrated for follow‐up periods of from 1 to 14 years.
The ophthalmic blood pressure in thyroidectomized patients
Authors: Cardan Emil , Pop Rodica
Published: April 2005

A parallel investigation of the blood pressure changes in the brachial and ophthalmic arteries was carried out in a group of 23 patients following subtotal thyroidectomy, and the results were compared with those obtained in a control group of 21 patients operated on for other diseases. A pronounced decrease of the pressure in the ophthalmic artery was found in the thyroidectomized patients. It appeared immediately after surgery, lasted 2 or 3 days, and disappeared spontaneously. The pressure decrease might be correlated with the headache that is frequently encountered in patients after thyroidectomy and that occurred in 17 of the 23 thyroidectomized patients. Changes in carotid blood flow due to the patient's position on the operating table, removal of the thyroid tissue, and liberation of bradykinin are discussed as possible factors that might explain this finding.
Experience with routine postoperative choledochoscopy via the T‐tube sinus tract
Authors: Yamakawa Tatsuo , Komaki Fumio , Shikata Jun‐ichi
Published: April 2005

In the 40‐month period from April, 1974 to July, 1977, postoperative choledochoscopy was performed 566 times in 186 patients at Teikyo University Hospital. Included in this series were 56 patients with retained common bile duct stones and 23 patients with intrahepatic stones; the stones were removed by postoperative choledochoscopy in 52 and 20 of these patients, respectively. In some patients, unsuspected stones were detected endoscopically after a completion T‐tube cholangiogram was reported as negative for stones. Our experience to date indicates that this technique is of substantial diagnostic and therapeutic value in the management of biliary calculi. Therefore, routine use of postoperative choledochoscopy as an adjunct to T‐tube cholangiography is strongly advocated. Failure of attempts to remove retained stones endoscopically and complications in this series were all attributable to inadequate insertion of the T‐tube into the common bile duct at the time of operation. To overcome this problem, a T‐tube of at least No. 18 Fr. caliber, and preferably of No. 20 Fr. caliber, should be inserted at operation into the common bile duct at a right angle, so as to avoid a tortuous sinus tract and produce a tract of sufficient caliber to permit postoperative choledochoscopy.
Nonoperative instrument extraction of retained bile duct stones
Authors: Burhenne H. Joachim
Published: April 2005

Reoperation for removal of retained bile duct stones after cholecystectomy and common duct exploration can now be avoided by the technique of nonoperative instrument extraction of stones through the sinus tract from the indwelling T tube. In our institution, 380 patients underwent this new procedure of nonoperative percutaneous stone extraction from the biliary tract during the past 7 years. The extraction was accomplished in ambulatory patients under fluoroscopic control. It carried a success rate of 95% and only 5% of the patients required a second operation for stone removal. There was a complication rate of about 5%, and there were no bile duct perforations or mortality. When compared to other therapeutic methods for removing retained stones, such as reoperation, choledochoscopic instrumentation, and attempts at chemical stone dissolution, the nonoperative percutaneous method appears to be the procedure of choice. The nonoperative technique is now practiced in at least 100 institutions in the United States, and successful extractions have also been reported from other countries.
Primary common bile duct stones
Authors: Madden John L.
Published: April 2005

Primary or stasis stones in the common duct are a distinct clinical, anatomical, and pathological entity. In the older patient with chills, fever, and jaundice, it is axiomatic that a primary or stasis stone will be found in a common duct that measures 20 mm or more in diameter. Furthermore, about 20% of such patients will not have stones in the gallbladder. The symptom of chills, having not been observed in patients with cancer of the head of the pancreas, is considered a diagnostic aid in the differentiation of jaundice secondary to common duct stones from jaundice due to malignant obstruction. The primary or stasis stone is the most common type of common duct stone. When present, a definitive operation, preferably choledochoduodenostomy, is advised. A simplified classification of biliary tract stones, preferably that of Aschoff, should be established as the universal standard. Also, based on this standard, worldwide prospective clinical studies should be initiated to obtain data for comparative evaluations to determine the true incidence of primary common duct stones.
Resection for carcinoma of the superior mediastinal segment of the esophagus
Authors: Ong G. B. , Lam K. H. , Lam Peter H. M. , Wong John
Published: April 2005

During the past 13 years, 86 patients with carcinoma of the esophagus situated at the superior mediastinal segment were admitted and treated at the Queen Mary Hospital, Hong Kong. Only 17 of these patients underwent resection. The resection technique was based on what was described in 1957 by Waddell and Scannell and by Cauchoix and Binet. The whole of the esophagus was removed in each case and the reconstruction, using the stomach, was accomplished by anastomosing the fundus to the cricopharyngeus. In 1 patient an isolated jejunal segment was used in the esophagoplasty, while in another the colon was utilized. There were 3 postoperative deaths, 1 due to a gastrotracheal fistula from erosion by the tracheostomy tube, a second due to hemorrhage, and a third due to bronchopneumonia. Four patients are currently alive and well without evidence of cancer. The longest survivor has lived for 5 years and 3 months. Ten of the patients who were discharged from the hospital lived for from 2 to 15 months, with an average of 8.7 months. This compares favorably with the 6.9 months average survival reported by Procter in patients with carcinoma of the upper third of the esophagus who were treated by radiotherapy. While the mortality rate is still high, the results are encouraging and continued use of surgical treatment is certainly warranted.
Follow‐up results after resection of thoracic esophageal carcinoma
Authors: Kasai Morio , Mori Shozo , Watanabe Toshio
Published: April 2005

During the past 14.5 years, we have treated 430 patients with carcinoma of the thoracic esophagus. The resection rate was 72% and the overall operative mortality rate was 16%. During the past 5 years, the operative mortality rate has been markedly reduced to 4.5%. The low operative mortality rate in recent years is the result of selection of the operative procedure according to the criteria that we have established for one‐stage radical resection. The overall 5‐year survival rate was 16.5%. Prophylactic postoperative irradiation improved long‐term survival in patients who underwent curative resection; their 5‐year survival rate was 34.6%. Prophylactic irradiation was especially effective in patients who did not have lymph node metastases. The 5‐year survival rate was 87.5% in these patients. The majority of long‐term survivors were leading a normal life for their age.
Fundoplication for the treatment of gastroesophageal reflux in hiatal hernia
Authors: Rossetti M. , Hell K.
Published: April 2005

Fundoplication, using an abdominal approach, is advocated to create an adequate substitute for the insufficient sphincter in gastroesophageal reflux associated with hiatus hernia. To achieve success, correct indications for surgical treatment are important. Based on experience with approximately 1,400 patients over the past 20 years, these include: (a) a retrosternal burning sensation (in 90% of our cases); (b) objective confirmation of reflux by means of x‐ray and endoscopic examination, together with biopsy examination of the esophageal mucosa and gastric acid evaluation; and (c) evidence of organic complications such as endobrachyesophagus with ulcerostenotic changes at the junction between the esophageal and gastric mucosa. Long‐term follow‐up of 590 patients with simple reflux esophagitis who underwent fundoplication showed that 87.5% were symptom free. In 44 patients with complicated gastroesophageal reflux disease, fundoplication produced clinical healing in 84.1%.
Complications of surgery for gastroesophageal reflux
Authors: Skinner David B.
Published: April 2005

In the course of approximately 350 operations for gastroesophageal reflux and 1,500 evaluations of patients previously operated on or being assessed for therapy, a number of complications and undesirable side effects of antireflux surgery have been encountered. This report describes unfavorable outcomes including postoperative dysphagia, “gas‐bloat syndrome,” postoperative gastric dilatation, unplanned vagotomy, failure to relieve symptoms, persistence or recurrence of reflux or hiatal hernia, perforation of the esophagus or stomach, postoperative bleeding, unplanned splenectomy, and persistence of stricture, which have followed the antireflux repairs introduced by Belsey, Nissen, or Hill, the gastroplasty procedures described by Thal, and by Collis, intrathoracic fundoplication, and esophageal resection with gastrointestinal interposition.
The current status of low‐dose heparin in the prophylaxis of thrombophlebitis and pulmonary embolism
Authors: Kakkar V. V.
Published: April 2005

The efficacy of low‐dose heparin in preventing postoperative venous thromboembolism has been well established in 27 clinical trials which have been published during the last 3 years. The largest study has been with patients undergoing general abdominal, thoracic, and urological operations. The incidences of isotopic deep vein thrombosis (25%) and extending thrombi likely to produce major pulmonary emboli (6.0%) in the control group have been reduced to 7% and 0.6%, respectively, in those who received heparin. The crucial question concerns the effect of low‐dose heparin in the prevention of fatal pulmonary embolism. This endpoint has been evaluated in a multicenter prospective randomized, controlled trial involving 4,121 patients; 2,076 of these were in the control group and 2,045 received heparin. Sixteen patients in the control group and only 2 in the heparin group were found to have died due to massive pulmonary embolism proved at autopsy. The difference was statistically significant (p<0.005). A careful objective analysis of operative and postoperative bleeding in 1,475 patients showed no statistically significant difference in the blood transfusion requirements or in the fall in the postoperative hemoglobin level either in the individual operative groups or in the group as a whole. However, the experience in patients undergoing total hip replacement demonstrates less evidence of benefit than in other groups of surgical patients. The published evidence and the clinical experience with low‐dose heparin prophylaxis should now be used to influence the practice habits of the profession for preventing fatal pulmonary embolism occurring after major surgery.
The aarhus county vagotomy trial
Authors: Andersen Daniel , Høstrup Hans , Amdrup Erik
Published: April 2005

In a prospective clinical trial, vagotomy for duodenal ulcer (DU) and prepyloric ulcer (PPU) was performed in 748 patients, 353 of whom were randomly allocated to selective gastric vagotomy and drainage (SGV + D), 54 to SGV + antrectomy (A), 273 to parietal cell vagotomy (PCV), and 68 to PCV + D. By 3 months postoperatively, basal acid secretion (BAO) had not stabilized. During the following year patients with SGV + A showed a decrease, while those with the other operations showed a rise in BAO, significant for SGV + D. One year after operation the level of BAO was the same after the 3 operations that did not remove the antrum. Peak acid output after pentagastrin stimulation (PAOPg) continued to decrease from 3 months to 1 year after SGV + A, while the other operations were followed by an increase, statistically significant for PCV. After 1 year the postoperative reduction in PAOPg was 90% for SGV + A, 45% for PCV, and approximately 60% for SGV + D and PCV + D. Overall clinical grading showed more failures following PCV than after SGV. Since failures after PCV were mainly ulcer recurrences, the final grading (after treatment of the failures) showed an equal number of failures for the 2 operations. Calculation of the probability of ulcer recurrence suggested a 6% rate after SGV + D and an 11% rate after PCV. However, when calculations took into account the location of the primary ulcer, the recurrence rate was the same after SGV + D for DU and PPU, while PCV showed a similar rate when used for DU but an incidence of 22% when used for PPU. The risk of recurrence was found to be constant from month to month during the first 2 1/2 years, after which no new recurrent ulcers were observed. It is suggested that for DU, PCV is preferable to SGV + D because the recurrence rate is the same but the incidence of sequelae is lower. When PCV is used for PPU, a higher ulcer recurrence rate may be expected.
Prediction of geomagnetic storms from solar wind data with the use of a neural network
Authors: Lundstedt H. , Wintoft P.
Published: April 2005

Abstract. An artificial feed-forward neural network with one hidden layer and error back-propagation learning is used to predict the geomagnetic activity index (Dst) one hour in advance. The Bz-component and ΣBz, the density, and the velocity of the solar wind are used as input to the network. The network is trained on data covering a total of 8700 h, extracted from the 25-year period from 1963 to 1987, taken from the NSSDC data base. The performance of the network is examined with test data, not included in the training set, which covers 386 h and includes four different storms. Whilst the network predicts the initial and main phase well, the recovery phase is not modelled correctly, implying that a single hidden layer error back-propagation network is not enough, if the measured Dst is not available instantaneously. The performance of the network is independent of whether the raw parameters are used, or the electric field and square root of the dynamical pressure.
New stratospheric UV/visible radiance measurements
Authors: Marceau F. J. , Rigaud P. , Huguenin D. , Albukerque J.
Published: April 2005

Abstract. A stratospheric balloon was launched on 12 October 1986 from the "CNES" base at Aire sur l'Adour (France) to record twilight radiance in the stratosphere. The near-UV and visible radiances were continuously monitored by a photometer during sunrise. Some observations are presented for different viewing azimuthal planes and viewing elevation angles. They show the influence of aerosols layers and clouds which can be also seen on related photographs. The results as a whole may be used for testing some radiative models, especially for twilight conditions.
Neutral gas composition changes and E×B vertical plasma drift contribution to the daytime equatorial F2-region storm effects
Authors: Mikhailov A. V. , Förster M. , Skoblin M. G.
Published: April 2005

Abstract. Theoretical model calculations along with ground-based observations from Huancayo ionosonde station and ESRO-4 gas analyzer data, were used to estimate the contribution of neutral gas composition changes and E×B vertical plasma drift to the observed F2-layer storm effects at the geomagnetic equator. Atomic oxygen concentration increase may give the main contribution to the positive NmF2 effect when drift velocity changes are small, but negative storm effects, on the other hand, are related mostly to vertical drift variations.
Proposal for an ionosphere/plasmasphere monitoring system
Authors: Jakowski N. , Bettac H.-D.
Published: April 2005

Abstract. A space-based satellite system suited for long-term monitoring of the Earth's ionosphere/plasmasphere systems is proposed. The monitoring system consists of a network of radio beacon satellites capable of measuring the ionospheric and plasmaspheric electron content on a continuous base with high time resolution. It takes advantage of the geometrical relationship between the orbit of geostationary satellites and the position of the plasmapause region characterized by a steep electron density gradient. A combination of geostationary and nongeostationary satellites may explore the three-dimensional structure of the plasmasphere. Taking into account plasmaspheric characteristics some criteria for an effective arrangement of the satellites are derived and discussed. Since the plasmapause position is very sensitive to changes or distortions in the solar wind and the related geomagnetic activity, a continuous monitoring of the position of the plasmapause would be helpful in understanding solar-terrestrial relationships.
First considerations on the structure and development of the Iberian thermal low-pressure system
Authors: Alonso S. , Portela A. , Ramis C.
Published: April 2005

Abstract. During the summer a thermal low-pressure system is locked over the Iberian Peninsula. We present a first analysis of such a system using the potential vorticity approach. Our results show that its main characteristic is the existence of a negative potential vorticity (PV) dome and a funnel-like structure for potential temperature, both located at the centre of the low. The build-up and evolution of this PV dome can be understood in terms of the dot products of the absolute vorticity and the gradient of diabetic heating vectors and the curl of the friction forces and the gradient of potential temperature vectors. The inhibition of the Algerian Mediterranean cyclogenesis during the summer seems to bear some relation to the existence of this kind of low-pressure disturbance over the Iberian Peninsula.
Observations of Pc5 micropulsation-related electric field oscillations in the equatorial ionosphere
Authors: Reddy C. A. , Ravindran Sudha , Viswanathan K. S. , Krishna Murthy B. V. , Rao D. R. K. , Araki T.
Published: April 2005

Abstract. A 54.95-MHz coherent backscatter radar, an ionosonde and the magnetometer located at Trivandrum in India (8.5°N, 77°E, 0.5°N dip angle) recorded large-amplitude ionospheric fluctuations and magnetic field fluctuations associated with a Pc5 micropulsation event, which occurred during an intense magnetic storm on 24 March 1991 (Ap=161). Simultaneous 100-nT-level fluctuations are also observed in the H-component at Brorfelde, Denmark (55.6°N gm) and at Narsarsuaq, Greenland (70.6°N gm). Our study of the above observations shows that the E-W electric field fluctuations in the E- and F-regions and the magnetic field fluctuations at Thumba are dominated by a near-sinusoidal oscillation of 10 min during 1730-1900 IST (1200-1330 UT), the amplitude of the electric field oscillation in the equatorial electrojet (EEJ) is 0.1-0.25 mV m-1 and it increases with height, while it is about 1.0 mV m-1 in the F-region, the ground-level H-component oscillation can be accounted for by the ionospheric current oscillation generated by the observed electric field oscillation in the EEJ and the H-component oscillations at Trivandrum and Brorfelde are in phase with each other. The observations are interpreted in terms of a compressional cavity mode resonance in the inner magnetosphere and the associated ionospheric electric field penetrating from high latitudes to the magnetic equator.
Simultaneous two hemisphere observations of the presence of polar patches in the nightside ionosphere
Authors: Rodger A. S. , Pinnock M. , Dudeney J. R. , Waterman J. , de la Beaujardiere O. , Baker K. B.
Published: April 2005

Abstract. The presence of polar patches as observed simultaneously in the same magnetic meridian of opposite nightside ionospheres by coherent and incoherent scatter radars are described. The patches appear to be related to variations either in the Bz or By component of the interplanetary magnetic field which cause transient merging on the dayside magnetopause. The passage and characteristics of polar patches as they traverse the polar cap into the nightside auroral oval are not significantly affected by the occurrence of small substroms. This study illustrates how the observations of polar patches in the nightside high-latitude ionosphere could be of great value in determining their formation process.
The temperature minimum at tidal fronts
Authors: Bowers D. G. , Lwiza K. M. M.
Published: April 2005

Abstract. This paper presents a mechanism to explain the observed formation of a surface temperature minimum at tidal fronts in shelf seas. Tidal fronts mark the boundary between water which is kept vertically mixed by fast tidal currents and water which stratifies in summer. The fronts are associated with strong horizontal surface gradients of several water properties, including temperature. In the early studies of tidal fronts, a minimum in surface temperature was occasionally observed between the cool surface waters on the mixed side of the front and the warm surface waters on the stratified side. It was suggested that this was caused by upwelling of deep water at the front. In this paper we describe an alternative and simpler explanation based on the local balance of heating and stirring. The net heat flux into the sea in spring and early summer is greater on the mixed side of the front than on the stratified side. This happens because the heat loss mechanism is dependent on sea surface temperature and stratified waters, having a higher surface temperature, lose more heat. The stratified water near the front therefore has lower heat content (and lower depth-mean temperature) than the mixed water. If some of the stratified water becomes mixed, for example with increased tidal stirring at spring tides, a zone of minimum surface temperature will be formed at the front. A numerical model for the study of this mechanism shows that the temperature minimum at tidal fronts can be explained by the process described above. The minimum appears most clearly at spring tides, but can still be present in a weaker form at neap tides. A further prediction of the model is an increase of the horizontal temperature gradient at spring tides, which is in agreement with observations. An unexpected outcome of the modelling is the prediction of the formation of a marked sea surface temperature minimum, not yet observed, occurring in the autumn and located at the summer position of the tidal front.
Modelling the water mass circulation in the Aegean Sea. Part I: wind stresses, thermal and haline fluxes
Authors: Valioulis I. A. , Krestenitis Y. N.
Published: April 2005

Abstract. The aim of this work is to develop a computer model capable of simulating the water mass circulation in the Aegean Sea. There is historical, phenomenological and recent experimental evidence of important hydrographical features whose causes have been variably identified as the highly complex bathymetry, the extreme seasonal variations in temperature, the considerable fresh water fluxes, and the large gradients in salinity or temperature across neighbouring water masses (Black Sea and Eastern Mediterranean). In the approach taken here, physical processes are introduced into the model one by one. This method reveals the parameters responsible for permanent and seasonal features of the Aegean Sea circulation. In the first part of the work reported herein, wind-induced circulation appears to be seasonally invariant. This yearly pattern is overcome by the inclusion of baroclinicity in the model in the form of surface thermohaline fluxes. The model shows an intricate pattern of sub-basin gyres and locally strong currents, permanent or seasonal, in accord with the experimental evidence.
Transport and structure of the Weddell Gyre
Authors: Fahrbach E. , Rohardt G. , Schröder M. , Strass V.
Published: April 2005

Abstract. A cyclonic gyre controls the advection of source waters into the formation areas of bottom water in the southern and western parts of the Weddell Sea and the subsequent transport of modified water masses to the north. Determination of the structure of the Weddell Gyre and of the associated transports was one of the objectives of the "Weddell Gyre Study" which began in September 1989 and ended in January 1993. The collected data set comprises records of moored current meters and profiles of temperature and salinity distributed along a transect between the northern tip of the Antarctic Peninsula and Kapp Norvegia. The circulation pattern on the transect is dominated by stable boundary currents of several hundred kilometers width at the eastern and western sides of the basin. They are of comparable size on both sides and provide nearly 90% of the volume transport of the gyre which amounts to 29.5 Sv. In the interior, a weak anticyclonic cell of 800 km diameter transports less than 4 Sv. Apart from the continental slopes, the near-bottom currents flow at some locations in an opposite direction to those in the water column above, indicating a significant baroclinic component of the current field. The intensity of the boundary currents is subject to seasonal fluctuations, whereas in the interior, time scales from days to weeks dominate. The large-scale circulation pattern is persistent during the years 1989 to 1991. The heat transport into the southern Weddell Sea is estimated to be 3.48×1013 W. This implies an equivalent heat loss through the sea surface of 19 W m-2, as an average value for the area south of the transect. The derived salt transport is not significantly different from zero; consequently, the salt gain by sea ice formation has to compensate almost entirely the fresh water gain from the melting ice shelves and from precipitation. Estimation of water mass formation rates from the thermohaline differences of the inflow and outflow through the transect indicates that 6.0 Sv of Warm Deep Water are transformed into 2.6 Sv of Weddell Sea Bottom Water, into 1.2 Sv of Weddell Sea Deep Water, and into 2.2 Sv of surface water.
Small- and medium-scale effects of high-flying aircraft exhausts on the atmospheric composition
Authors: Karol I. L. , Ozolin Y. E.
Published: April 2005

Abstract. Following numerous model studies of the global impacts of sub- and supersonic aircraft on the atmosphere, this paper assesses the separate aircraft engine exhaust effects of the 45°N cruise flight and at the 10- and 18-km levels of the July atmosphere. A box diffusion photochemical model in the cross-section plane of the flight trajectory is used to compute the effects of gas-phase and heterogeneous reactions on the condensation trail particles in the troposphere, and on the sulphate aerosols in the stratosphere. The enhanced horizontal dispersion of the exhaust plume is considered in the model. A significant but short term depletion of ozone is predicted, which is 99% restored in about 1 h in the wide plume with enhanced horizontal dispersion, but requires more than 24 h in the narrow plume without it. The oxidation rate of NO and NO2 into the HNO3 depends on the OH content in the exhausts and varies in all the cases. The heterogeneous photochemistry has only a small influence on the initial evolution of N2O5 and HO2 in the plume.
Potential effects on ozone of future supersonic aircraft/2D simulation
Authors: Ramaroson R. , Louisnard N.
Published: April 2005

Abstract. In a previous work, the stratospheric effect of a future supersonic aircraft fleet on ozone has been simulated, by using a photochemical diffusive 1D model and a 2D photochemical, radiative dynamical model. The fleet scenario was defined by Aerospatiale and Snecma for a current technology Mach-2 aircraft; the models were limited to simplified homogeneous phase reactions. The results indicated a global ozone decrease of about 1.5% in steady-state conditions. Now the 2D model has been upgraded and includes the classical heterogeneous reactions with Polar Stratospheric Clouds (PSC) and aerosol. It also takes into account the natural or anthopogenic evolution of the background atmosphere. The scenario has been optimized to meet more realistic conditions. Thus, new results are presented. The main conclusion concerning the calculated impact of a realistic fleet for the next 20-50 years is still weaker than in the previous work: the decrease for the total ozone would always be lower than 0.3%. These results are commented, with the help of a parametric study, pointing out the importance of the background atmosphere and especially the total chlorine loading and the aerosol surface area.
ELF plasma waves in hot and cold plasma fluxes observed by Prognoz-8 in the magnetospheric tail
Authors: Blecki J. , Nikutowski B. , Koperski P. , Popielawska B. , Kossacki K. , Romanov S. A. , Savin S. P.
Published: April 2005

Abstract. We present Prognoz-8 observations of low-frequency plasma waves (2-105 Hz) associated with plasma fluxes near the outer boundary of the plasma sheet. These plasma fluxes were different from the regular plasma sheet boundary layer and consisted of tailward flowing warm proton and cold oxygen beams accompanied by rather cold electrons (Te less than 100 eV). Observed plasma characteristics were used in the numerical solution of the dispersion relation for the ion-beam acoustic instability. Detailed analysis shows that this instability can be a source of observed emissions at frequencies up to 25 Hz.
A Monte Carlo simulation of the effect of ion self-collisions on the ion velocity distribution function in the high-latitude F-region
Authors: Barghouthi I. A. , Barakat A. R. , Schunk R. W.
Published: April 2005

Abstract. Non-Maxwellian ion velocity distribution functions have been theoretically predicted and confirmed by observations, to occur at high latitudes. These distributions deviate from Maxwellian due to the combined effect of the E×B drift and ion-neutral collisions. The majority of previous literature, in which the effect of ion self-collisions was neglected, established a clear picture for the ion distribution under a wide range of conditions. At high altitudes and/or for solar maximum conditions, the ion-to-neutral density ratio increases and, hence, the role of ion self-collisions becomes appreciable. A Monte Carlo simulation was used to investigate the behaviour of O+ ions that are E×B-drifting through a background of neutral O, with the effect of O+ (Coulomb) self-collisions included. Wide ranges of the ion-to-neutral density ratio ni/nn and the electrostatic field E were considered in order to investigate the change of ion behaviour with solar cycle and with altitude. For low altitudes and/or solar minimum (ni/nn≤ 10-5), the effect of self-collisions is negligible. For higher values of ni/nn, the effect of self-collisions becomes significant and, hence, the non-Maxwellian features of the O+ distribution are reduced. For example, the parallel temperature Ti\\Vert increases, the perpendicular temperature Ti⊥ decreases, the temperature anisotropy approaches unity and the toroidal features of the ion distribution function become less pronounced. Also, as E increases, the ion-neutral collision rate increases, while the ion-ion collision rate decreases. Therefore, the effect of ion self-collisions is reduced. Finally, the Monte Carlo results were compared to those that used simplified collision models in order to assess their validity. In general, the simple collision models tend to be more accurate for low E and for high ni/nn.
Some studies on low-frequency signal in relation to X-ray flares and climatic conditions
Authors: Sarkar S. K. , De B. K.
Published: April 2005

Abstract. The statistical behaviour of the sudden enhancement in signal strength (SES) in relation to solar X-ray flares has been studied for the near east-west propagation of 40 kHz radio waves from Sanwa (36°11'N; 139°51'E) in Japan to Calcutta (22°34'N; 88°24'E) over a long distance path of 5100 km for a period of two years. The period has been divided into four phases - P1, P2, P3 and P4, according to the position of the overhead sun. The change in signal strength during X-ray flares is dependent on the solar zenith angle and climatic conditions. The statistical modal values of the time lag of the SES peak with respect to that solar X-ray flare is found to increase as solar zenith angle increases. The relative rates of increase and decrease of the signal strength (RRISS and RRDSS respectively) have been evaluated for a number of SES which are related to large X-ray flares. Their characteristics have also been investigated. The modal values of the relaxation time have been found to be highly correlated with climatic conditions like temperature and humidity of the propagation path.
The dynamic cusp at low altitudes: a case study utilizing Viking, DMSP-F7, and Sondrestrom incoherent scatter radar observations
Authors: Watermann J. , de la Beaujardière O. , Lummerzheim D. , Woch J. , Newell P. T. , Potemra T. A. , Rich F. J. , Shapshak M.
Published: April 2005

Abstract. Coincident multi-instrument magnetospheric and ionospheric observations have made it possible to determine the position of the ionospheric footprint of the magnetospheric cusp and to monitor its evolution over time. The data used include charged particle and magnetic field measurements from the Earth-orbiting Viking and DMSP-F7 satellites, electric field measurements from Viking, interplanetary magnetic field and plasma data from IMP-8, and Sondrestrom incoherent scatter radar observations of the ionospheric plasma density, temperature, and convection. Viking detected cusp precipitation poleward of 75.5° invariant latitude. The ionospheric response to the observed electron precipitation was simulated using an auroral model. It predicts enhanced plasma density and elevated electron temperature in the upper E- and F-regions. Sondrestrom radar observations are in agreement with the predictions. The radar detected a cusp signature on each of five consecutive antenna elevation scans covering 1.2 h local time. The cusp appeared to be about 2° invariant latitude wide, and its ionospheric footprint shifted equatorward by nearly 2° during this time, possibly influenced by an overall decrease in the IMF Bz component. The radar plasma drift data and the Viking magnetic and electric field data suggest that the cusp was associated with a continuous, rather than a patchy, merging between the IMF and the geomagnetic field.
Urea cycle defects: Management and outcome
Authors: Nassogne M. C. , Héron B. , Touati G. , Rabier D. , Saudubray J. M.
Published: April 2005

This paper reviews the clinical presentation of 217 patients with urea cycle defects, including 121 patients with neonatal‐onset forms and 96 patients with late‐onset forms. Long‐term outcome of these patients is also reported with the severity of the neonatal forms of these disorders, mostly for ornithine carbamoyltransferase‐deficient males. Patients with late‐onset forms may present at any age and carry a 28% mortality rate and a subsequent risk of subsequent disabilities.
Molecular mechanism of dominant expression in 3‐methylcrotonyl‐CoA carboxylase deficiency
Authors: Baumgartner M. R.
Published: April 2005

Most enzyme deficiencies in humans are inherited as autosomal recessive traits. The term dominant negative is applied to mutant alleles in which a mutant protein interferes in one way or another with the function of the normal protein being produced from the wild‐type allele in a heterozygote. Such a dominant negative effect usually involves homomeric or heteromeric proteins. 3‐Methylcrotonyl‐CoA carboxylase (MCC) is a heteromeric mitochondrial enzyme comprised of biotin containing MCCα subunits and smaller MCCβ subunits, encoded by the genes MCCA and MCCB, respectively. Mutations in these genes cause isolated MCC deficiency, an autosomal recessive disorder with a variable phenotype ranging from severe neonatal to asymptomatic adult forms. Patients with MCC deficiency have a characteristic organic aciduria with greatly increased excretion of 3‐hydroxyisovaleric acid (3‐HIVA) and 3‐methylcrotonyl‐glycine (3‐MCG). Here, two patients with elevated excretion of 3‐MCG and 3‐HIVA and partial deficiency of MCC are discussed, one of them with severe neurological symptoms. Both showed evidence of biotin responsiveness and were heterozygous for the missense mutation MCCA‐R385S. Evidence is presented that MCCA‐R385S is a dominant negative allele leading to biochemical abnormalities and clinical symptoms in heterozygous individuals and that it is responsive to pharmacological doses of biotin in vivo.
Congenital brain anomalies in distal cholesterol biosynthesis defects
Authors: Hennekam R. C. M.
Published: April 2005

Cholesterol is known to be a significant constituent of the central nervous system. It also plays an important role in developmental pathways to form the human brain, such as the Sonic Hedgehog pathway. Disturbances in the formation of cholesterol may therefore be expected to cause brain malformations and brain dysfunctions. Here a short review of the consequences of defects of the distal cholesterol pathways to brain formation and functioning is provided.
Methylmalonic and propionic acidaemias: Management and outcome
Authors: De Baulny H. Ogier , Benoist J. F. , Rigal O. , Touati G. , Rabier D. , Saudubray J. M.
Published: April 2005

Organic acidurias comprise many various disorders. Methylmalonic aciduria (MMA) and propionic aciduria (PA) are the most frequent diseases and the two organic acidurias for which we have better knowledge of the long‐term outcome.

Comparing the outcome of patients born before and after 1990, it appears that better neonatal and long‐term management have improved the survival rate. Less than 20% of the patients died in either the neonatal period or before the age of 10 years. However, most surviving patients showed poor nutritional status with growth retardation and about 40% present some kind of visceral or neurological impairment. The developmental outcome may have improved in MMA patients, with IQ higher than 75 in about 40% patients aged more than 4 years. Conversely, poor intellectual development is the rule in PA patterns, with 60% having an IQ less than 75 and requiring special education. Successful liver and/or renal transplantations, in a few patients, have resulted in better quality of life but have not necessarily prevented neurological and various visceral complications. These results emphasize the need for permanent metabolic follow‐up whatever the therapeutic strategy.
Dominantly inherited hyperinsulinaemic hypoglycaemia
Authors: De Lonlay P. , Giurgea I. , Sempoux C. , Touati G. , Jaubert F. , Rahier J. , Ribeiro M. , Brunelle F. , Nihoul‐Fékété C. , Robert J.‐J. , Saudubray J.‐M. , Stanley C. , Bellanné‐Chantelot C.
Published: April 2005

Congenital hyperinsulinism (HI), the most important cause of hypoglycaemia in early infancy, is a heterogeneous disease with two types of histological lesions, focal and diffuse, with major consequences in terms of surgical approaches. In contrast to focal islet‐cell hyperplasia, always sporadic to our knowledge, diffuse hyperinsulinism is a heterogeneous disorder involving several genes, various mechanisms of pathogenic mutations and different transmissions: (i) channelopathy involving the genes encoding the sulphonylurea receptor (SUR1) or the inward‐rectifying potassium channel (Kir6.2) in recessively inherited HI or more rarely dominantly inherited HI; (ii) metabolic disorders implicating the short‐chain L‐3‐hydroxyacyl‐CoA dehydrogenase (SCHAD) enzyme inrecessi‐vely inherited HI, the glucokinase gene (GK), the glutamate dehydrogenase gene (GLUD1) when hyperammonemia is associated, dominant exercise‐induced HI with still‐unknown mechanism, and more recently the human insulin receptor gene in dominantly inherited hyperinsulinism. Thus, dominant HI disorders always correspond to diffuse HI, where most hypoglycaemia occur in infancy, and are sensitive to medical treatment. Channel causes could be due to dominant negative mutation with one abnormality in channels composed of four Kir6.2 subunits and four SUR1 subunits, leading to a complete destruction of the channel structure or function, or due to haploinsufficiency with only one functional allele, leading to 50% of functional protein, which is not sufficient to obtain enough opened channels to maintain the membrane depolarized. Metabolic causes are due to a gain of function of enzyme activity (deregulated enzymes), except for physical exercise‐induced hyperinsulinaemic hypoglycaemia, of still‐unknown cause. Congenital hyperinsulinism (HI) is the most important cause of hypoglycaemia in early infancy (Aynsley‐Green et al 2000; Cornblath et al 1990; Pagliara et al 1973; Thomas et al 1977). The inappropriate oversecretion of insulin is responsible for profound hypoglycaemia that requires aggressive treatment to prevent severe and irreversible brain damage (Volpe 1995). HI is a heterogeneous disease associated with several genes, various mechanisms of pathogenic mutations and different transmissions (Dunne et al 2004).
Oligodendrocytes and stem cell transplantation: their potential in the treatment of leukoencephalopathies
Authors: Duncan I. D.
Published: April 2005

Cell transplantation is being extensively explored as a means of treating many human degenerative diseases. The leukodystrophies are examples of neurological disorders where new therapeutic strategies, either cellular or molecular, will be required to repair the central nervous system (CNS) of affected patients. Much hope is being pinned on the use of human embryonic stem (ES) cells as the exogenous source of neurons and glia to replace dysfunctional or dying cells in the CNS. In the case of leukoencephalopathies, the goal is to generate oligodendrocytes or other myelinating cells such as Schwann cells from ES cells, to myelinate or remyelinate CNS axons on transplantation. Experimental data suggests that mouse ES cells have this capacity, but at present differentiation of oligodendrocytes in sufficient numbers from human ES cells is not possible. It may in fact be more feasible to isolate oligodendrocytes from human neural stem cells derived from the fetal brain, but the source of these is in short supply and, like that of ES cells, is ethically controversial. None the less, it appears certain that either of these two sources will eventually give rise to sufficient numbers of neural stem cells or oligodendrocyte progenitors that have greater capacity for repair than such cells derived from the adult brain. Once the primary technical issues concerning human ES cell differentiation have been overcome, the most likely first clinical target will be Pelizaeus–Merzbacher disease. However, widespread dissemination of cells throughout the CNS may be required for functional improvement; hence diseases such as adrenoleukodystrophy may also be considered as therapeutic targets.