bluuebunny/crossref_metadata_2025 huggingface dataset:
Intubating laryngeal mask and rapid sequence induction in patients with cervical spine injury
Authors: Schuschnig C. , Waltl B. , Erlacher W. , Reddy B. , Stoik W. , Kapral S.
Published: March 2003

The Intubating Laryngeal Mask (FastrachTM), a modified conventional laryngeal mask airway, and its prototype cuffed silicone tube, continue to be an appropriate intubating tool in combination with fibreoptic bronchoscopy in the emergency situation. This is an account of two patients with suspected cervical spine fracture admitted to our emergency room in a haemodynamically unstable condition and requiring a rapid sequence induction of anaesthesia, in whom we successfully applied this newly developed intubating device for the first time. Provided that there are no intubation difficulties, direct laryngoscopy is still the fastest method of securing an airway; however, this procedure leads to an extension of the cervical spine, which may be hazardous in the case of a cervical spine injury. Intubation by means of the Intubating Laryngeal Mask avoids dangerous hyperextension of the occipito‐atlanto‐axial complex, a fact that we were able to verify by lateral cervical spine fluoroscopy during intubation.
Electroencephalographic arousal response during tracheal intubation and laryngeal mask airway insertion after induction of anaesthesia with propofol
Authors: Inada T. , Shingu K. , Nakao S. , Hirose T. , Nagata A.
Published: March 2003

Laryngoscopy and tracheal intubation, or insertion of a laryngeal mask airway may lead to an arousal response on the electroencephalogram. We studied whether more intense stimulation (laryngoscopy and tracheal intubation) causes a greater arousal response than less intense stimulation (laryngeal mask airway insertion). Thirty‐four patients (ASA I–II) were anaesthetised with propofol 3 mg.kg−1, followed by vecuronium 0.15 mg.kg−1 and a propofol infusion of 10 mg.kg−1.h−1. Three minutes after induction of anaesthesia, either laryngoscopy and tracheal intubation (n = 18), or laryngeal mask airway insertion (n = 16) was performed. Laryngoscopy and tracheal intubation caused a significantly greater increase in blood pressure (but not heart rate) than laryngeal mask airway insertion (p < 0.05). Electroencephalogram responses were not different. More intense stimulation does not cause a greater arousal response during propofol anaesthesia.
Anaesthesia Clinical Directors in the United Kingdom: organisation, objectives and support needs
Authors: Thoms G. M. M. , McHugh G. A. , Pollard B. J. , Moore J.
Published: March 2003

A postal survey of all 269 acute hospital trusts identified in the United Kingdom was carried out to study the work of Clinical Directors of anaesthesia. Initial responses from 163 Clinical Directors and 129 completed questionnaires were analysed. Four main areas of concern revealed by the survey were contracts and objectives, funding of managerial sessions, access to information and perceived need for support. Most Clinical Directors had no job description and most had no formal written objectives, despite a substantial body of advice that these should be provided. There was generally substantial underfunding of managerial hours compared with those actually worked and approximately 20% of Clinical Directors surveyed had no funding for managerial duties. Clinical Directors' ratings of the information available to assist their decision making were also a cause of concern. Clinical Directors perceived that they need better networking, more training particularly on human resource management and improved management information.
Respiratory mechanics during and after anaesthesia for major vascular surgery
Authors: Volta C. A. , Verri M. , Righini E. R. , Ragazzi R. , Pavoni V. , Alvisi R. , Gritti G.
Published: March 2003

To evaluate the effects of major vascular surgery on respiratory mechanics, 11 patients undergoing general anaesthesia for abdominal aortic surgery were studied. Before aortic cross‐clamping, chest wall elastance and resistance both increased (by 126% and 58%, respectively) when surgical retractors were placed. After aortic cross‐clamping, lung elastance increased by 29%, accompanied by a decrease in cardiac index (22%) and an increase in pulmonary (17%) and systemic (15%) vascular resistance. After aortic unclamping, lung elastance decreased, although it remained higher than baseline values (by 12%). All cardiovascular variables returned to the values obtained before aortic cross‐clamping.
A comparison of two silicone‐reinforced tracheal tubes with different bevels for use with the intubating laryngeal mask
Authors: Murashima K. , Fukutome T. , Brimacombe J.
Published: March 2003

Seventy consecutive patients were randomly allocated for intubation through the intubating laryngeal mask airway using a straight reinforced silicone tracheal tube with either a conventional or a modified bevel. The conventional bevel was firm, wedge‐shaped and with a leading edge at the side. The modified bevel was soft, hemispherical and with a leading edge in the midline. The intubating laryngeal mask position was adjusted until optimal ventilation was obtained and intubation was attempted using the randomised device. If tactile resistance was felt, a predetermined sequence of adjusting manoeuvres were utilised before a subsequent attempt. The first‐attempt successful intubation rate with the conventional bevel was 23/37 (62%) and with the modified bevel was 28/33 (85%). The second‐attempt successful intubation rate for the conventional bevel was 12/37 (32%) and for the modified bevel was 4/33 (12%). Intubation failed after three attempts for one patient in each group. Fewer overall intubation attempts were required with the modified bevel (p = 0.033). We conclude that intubation success rates through the intubating laryngeal mask with a straight silicone‐reinforced tube are higher with a soft, hemispherical bevel with a leading edge in the midline compared with the firm, wedge‐shaped bevel with a leading edge at the side.
Awake tracheal intubation with the intubating laryngeal mask in a patient with diffuse idiopathic skeletal hyperostosis
Authors: Palmer J. H. MacG. , Ball D. R.
Published: March 2003

Diffuse idiopathic skeletal hyperostosis, otherwise known as Forestier's disease or ankylosing hyperostosis, is a relatively common condition that is distinguished from ankylosing spondylitis by the relative preservation of spinal function and the characteristic ‘candle flame’ lipping of the vertebrae. We report a patient with this condition and a well‐recorded history of impossible intubation who presented for emergency laparotomy. The patient was intubated awake using the intubating laryngeal mask and sedation and anaesthesia were provided by a target‐controlled infusion of propofol.
Towards a pain‐free venepuncture
Authors: Ong E. L. , Lim N. L. , Koay C. K.
Published: March 2003

A randomised, prospective trial was conducted to assess the efficacy of various means of alleviating the pain of subcutaneous lidocaine infiltration. One hundred and twenty‐two patients were randomly allocated to different groups to receive buffered lidocaine 1%, warmed lidocaine 1% or infiltration by the counter‐irritation technique. A visual analogue pain score was recorded at different stages of cannulation and results showed that pain scores were significantly lower in the group receiving buffered lidocaine 1% (p < 0.02) and in the counter‐irritation group (p < 0.05). Thus buffering lidocaine 1% and administration of lidocaine 1% by the counter‐irritation technique is effective in relieving the pain of lidocaine infiltration.
Effects of intrathecal ketamine added to bupivacaine for spinal anaesthesia
Authors: Kathirvel S. , Sadhasivam S. , Saxena A. , Kannan T. R. , Ganjoo P.
Published: March 2003

We prospectively studied 30 healthy female patients undergoing intracavitory brachytherapy applicator insertion for carcinoma of the cervix under spinal anaesthesia. Patients were randomly allocated to receive either intrathecal bupivacaine 10 mg alone or bupivacaine 7.5 mg combined with preservative‐free ketamine 25 mg. Spinal block onset, maximum sensory level, duration of blockade, haemodynamic variables, postoperative analgesic requirements and adverse events were recorded. Onset of sensory and motor block and duration of spinal analgesia were comparable between groups. Duration of motor blockade was shorter (p = 0.0416) and requirement for intravenous fluids in the peri‐operative period was less (p = 0.0159) in the ketamine group. Significantly more patients in the ketamine group had adverse events, such as sedation, dizziness, nystagmus, ‘strange feelings’ and postoperative nausea and vomiting. Although the addition of ketamine to spinal bupivacaine had local anaesthetic sparing effects, it did not provide extended postoperative analgesia or decrease the postoperative analgesic requirements. Moreover, the central adverse effects of ketamine limit its spinal application.
Comparison of a new video‐optical intubation stylet versus the conventional malleable stylet in simulated difficult tracheal intubation
Authors: Biro P. , Weiss M. , Gerber A. , Pasch T.
Published: March 2003

Handling and efficacy of a new video‐optical intubation stylet were assessed in a simulated difficult tracheal intubation setting and compared with a conventional malleable stylet. Forty‐five anaesthetists performed 10 tracheal intubations using both techniques. Laryngoscopy was performed by the observer, who created a grade 3 view according the classification by Cormack and Lehane. The time taken to place the tracheal tube and the final tracheal tube positions were documented. Mean (SD) intubation time for the video‐optical stylet was 20.4 (7.7) s and for the malleable stylet 10.2 (3.3) s (p < 0.01). With the video‐optical stylet the trachea was correctly intubated in all 225 attempts; with the malleable stylet 44 (19.6%) oesophageal and 44 (19.6%) endobronchial intubations occurred (p < 0.01). The video‐optical intubation stylet enabled us to recognise inappropriate tracheal tube positions and to correct them immediately. This equipment can be considered a reliable and effective tool for management of the difficult airway.
Anaesthesia and saccadic eye movements
Authors: Khan O. A. , Taylor S. R. J. , Jones J. G.
Published: March 2003

During the last 10 years, there has been a vast increase in day‐case surgery under general anaesthesia, but this has not been accompanied by research into the residual cognitive and motor effects during recovery from anaesthesia. Part of the explanation for this phenomenon is the lack of a suitable biophysical monitor of anaesthetic sedation. This review discusses one of the most commonly used of these biophysical monitors – namely saccadic eye movements. In particular, the efficacy of peak saccadic velocity as a monitor of sedation will be evaluated. In addition, the physiology and pharmacology of saccadic eye movements will be discussed within the context of developing other parameters of saccadic eye movements as novel biophysical monitors of anaesthetic sedation.
Ability of anaesthetists to identify a marked lumbar interspace
Authors: Broadbent C. R. , Maxwell W. B. , Ferrie R. , Wilson D. J. , Gawne‐Cain M. , Russell R.
Published: March 2003

Anaesthetists' ability to identify correctly a marked lumbar interspace was assessed in 100 patients undergoing spinal magnetic resonance imaging scans. Using ink, one anaesthetist marked an interspace on the lower spine and attempted to identify its level with the patient in the sitting position. A second anaesthetist attempted to identify the level with the patient in the flexed lateral position. A marker capsule was taped over the ink mark and a routine scan performed. The actual level of markers ranged from one space below to four spaces above the level at which the anaesthetist believed it to be. The marker was one space higher than assumed in 51% of cases and was identified correctly in only 29%. Accuracy was unaffected by patient position (sitting or lateral), although it was impaired by obesity (p = 0.001) and positioning of the markers high on the lower back (p < 0.001). The spinal cord terminated below L1 in 19% of patients. This, together with the risk of accidentally selecting a higher interspace than intended for intrathecal injection, implies that spinal cord trauma is more likely when higher interspaces are selected.
Costing anaesthetic practice
Authors: Kendell J. , Wildsmith J. A. W. , Gray I. G.
Published: March 2003

A computerised database of operating theatre activity was used to estimate the costs of regional and general anaesthesia for varicose vein and inguinal hernia surgery. Data retrieved for each procedure included the anaesthetic technique and drugs used, and the duration of anaesthesia, surgery and recovery. The costs of anaesthetic drugs and disposables, salary costs of the anaesthetic personnel and maintenance costs for anaesthetic equipment were considered. Drugs and disposables accounted for ≈ 25% of the total cost of an anaesthetic. Anaesthetic times were 5 min longer for regional anaesthesia, but recovery times were 10 min shorter following regional anaesthesia for varicose vein surgery. Staff costs were dependent on the length of time each staff member spent with the patient. Although the number of cases was small, provision of a field block and sedation for inguinal hernia repair was considerably cheaper than other anaesthetic techniques.
National obstetric anaesthetic practice in the UK 1997/1998
Authors: Khor L. J. H. , Jeskins G. , Cooper G. M. , Paterson‐Brown S.
Published: March 2003

In the United Kingdom, the Royal College of Obstetricians and Gynaecologists requires maternity units recognised for training to complete annual statistical returns. Analysis of these data revealed that anaesthetists were directly involved in more than 251 000 procedures in the peripartum period in 1997/1998. There had been an increase in the number of women delivered by Caesarean section (18.5% of all deliveries) compared with previous reports. The proportion of Caesarean sections performed under regional anaesthesia had increased for both elective and emergency Caesarean section deliveries (85.5% and 70.2%, respectively). For pain relief in labour, there had been neither an increase nor a decrease in the uptake of regional analgesia (23.6%). There were limited training opportunities for anaesthetists in general anaesthesia for Caesarean section and for obstetricians in vaginal breech delivery. The known admissions to intensive care units equated to over 100 women per month in the United Kingdom requiring intensive care as a result of childbirth.
Effectiveness of continuous positive airway pressure to enhance pre‐oxygenation in morbidly obese women
Authors: Cressey D. M. , Berthoud M. C. , Reilly C. S.
Published: March 2003

Morbid obesity is associated with a reduction in time to desaturate during apnoea following standard pre‐oxygenation and induction of anaesthesia. We have compared the effects of using 7.5 cmH2O of continuous positive airway pressure (CPAP) for pre‐oxygenation with a standard technique using a Mapleson A breathing system, in 20 morbidly obese women. In a prospective, open, randomised trial, we measured the time taken to desaturate to 90% from time of giving a succinylcholine bolus as part of a rapid induction of anaesthesia. All patients received 3 min pre‐oxygenation prior to induction. Tracheal intubation was confirmed and all patients kept apnoeic until oxygen saturation decreased to 90%. No statistically significant difference in mean time to desaturate to 90% could be demonstrated in the CPAP group compared to the Mapleson A group (240 s and 203 s, respectively). A brief period of lower mean heart rate in the CPAP group was the only statistically significant difference in cardiovascular parameters. There was no significant difference in the volume of gastric gas after induction between groups.
Jugular bulb oximetry during cardiac surgery
Authors: Shaaban Ali M. , Harmer M. , Latto I. P.
Published: March 2003

Imbalance between cerebral oxygen supply and demand is thought to play an important role in the development of cerebral injury during cardiac surgery. This article presents an overview of cerebral oxygenation monitored by jugular bulb oximetry during cardiac surgery with cardiopulmonary bypass. The general principles of jugular bulb oximetry including physiology, intermittent and continuous monitoring, technical considerations, limitations and potential complications are discussed. Different applications of jugular bulb oximetry during bypass surgery and the possible therapeutic approaches to impaired cerebral oxygenation are described.
Information and consent for anaesthesia: a postal survey of current practice in Great Britain
Authors: Watkins E. J. , Milligan L. J. , O'Beirne H. A.
Published: March 2003

A postal questionnaire survey was sent to Royal College of Anaesthetists' tutors in Great Britain and Northern Ireland to gain insight into current practice with regard to information and consent for anaesthesia. Details of consent practice in three specific areas were requested: anaesthesia in general, teaching medical students during anaesthesia and obstetric anaesthesia. Replies were received from 218 tutors (77%). Of these, 72% of departments had a policy on consent for anaesthesia that was in accordance with The Association of Anaesthetists of Great Britain and Ireland guidelines on ‘Information and Consent for Anaesthesia’. We identified three areas of concern. Firstly, almost a third of departments (27%) had no policy on consent for anaesthesia. Second, only 18% of relevant departments obtain specific consent for the teaching of medical students on anaesthetised patients. Third, 1 year after publication of the guidelines, 17% of obstetric anaesthetic units, despite stating an intention to alter their departmental policy based on the Association's recommendations, had not yet implemented any changes.
Pyogenic cervical epidural abscess and discitis following stellate ganglion block
Authors: Vadodaria B. , Bridgens J. , Richmond M.
Published: March 2003

We report a case of epidural abscess and pyogenic cervical discitis, following a stellate ganglion block performed for pain relief. The patient presented with quadriplegia 12 days following the stellate ganglion block. Magnetic resonance imaging confirmed the diagnosis of an epidural abscess. The patient recovered full limb function after surgical drainage. This is the first report of cervical epidural abscess as a direct complication of this procedure.
Does sevoflurane inhibit serum cholinesterase in children?
Authors: Lejus C. , Delaroche O. , Le Roux C. , Legendre E. , Rivault O. , Floch H. , Renaudin M. , Pinaud M.
Published: March 2003

Serum cholinesterase activity was measured at induction, and following anaesthesia in 41 children aged between 4 and 30 months. The median exposure to sevoflurane was 273%.min. The results did not demonstrate any significant difference in cholinesterase activity, when expressed by gram of serum proteins following inhalation anaesthesia using sevoflurane or intravenous anaesthesia using propofol. The values (SD) obtained were 175 (42) UI.g−1 before anaesthesia and 177 (43) UI.g−1 following anaesthesia. The only change in cholinesterase activity detected was related to heamodilution. We conclude that plasma fluoride concentration following sevoflurane administration [13.8 (4.2) µm.l−1] is too low to exert an inhibiting effect on in vivo cholinesterase activity and that the previously reported decrease in mivacurium requirements during sevoflurane anaesthesia is unlikely to be due to inhibition by fluoride ions.
Isoflurane and coronary heart disease
Authors: Agnew N. M. , Pennefather S. H. , Russell G. N.
Published: March 2003

Summary Early studies indicated that isoflurane caused coronary steal and should therefore be avoided in patients with coronary heart disease. Subsequently, more detailed trials have disputed this and ␣␣have shown that as long as coronary perfusion pressure is maintained, isoflurane does not cause coronary steal or myocardial ischaemia. There is now growing evidence, initially in animal work but more recently in human studies, that isoflurane has myocardial protective properties, limiting infarct size and improving functional recovery from myocardial ischaemia. The mechanism for ␣␣this protection mimics ischaemic preconditioning and involves the opening of adenosine triphosphate‐dependent potassium channels. The few studies comparing the myocardial protection offered by individual anaesthetic agents indicate that isoflurane represents the anaesthetic agent of choice for patients with coronary heart disease.
Measurement of liver tissue oxygenation after orthotopic liver transplantation using a multiparameter sensor
Authors: Leary T. S. , Klinck J. R. , Hayman G. , Friend P. , Jamieson N. V. , Gupta A. K.
Published: March 2003

Summary The currently used methods of monitoring liver perfusion and oxygenation after liver transplantation have major limitations in clinical use. We describe the use of a multiparameter sensor to enable continuous monitoring of liver tissue oxygen tension, carbon dioxide tension and hydrogen ion concentration in the early postoperative period in 12 patients after liver transplantation. The sensor was inserted under direct vision via the falciform ligament into the liver before skin closure. Tissue oxygen tension values decreased in the first 24 h and subsequently increased to a mean (SD) = 7.3 (2.8) kPa at 48 h after surgery. This was associated with a decrease in the degree of acidosis. There were no complications attributable to the sensor. This study demonstrates that continuous measurement of liver oxygen tension, carbon dioxide tension and pH is possible. This technique may be useful as a continuous monitor to help identify grafts at risk of ischaemia.
Plasma paracetamol concentrations after different doses of rectal paracetamol in older children A comparison of 1 g vs. 40 mg.kg−1
Authors: Howell T. K. , Patel D.
Published: March 2003

Summary We compared the plasma paracetamol levels attained after the administration of different doses of rectal paracetamol in healthy children to see if they attained therapeutic levels (> 10 µg.ml−1). We recruited 24 children (ASA I–III) over 25 kg undergoing elective surgery. They were randomly assigned to receive rectal paracetamol at a dose of 1 g or 40 mg.kg−1. Blood samples were taken for analysis at 2, 3, 4 and 5 h post dose. Most children in the 1 g group failed to attain therapeutic plasma levels, whereas those in the 40 mg kg−1 group did achieve therapeutic levels (mean maximum concentration = 7.8 vs. 15.9 µg.ml−1, p = 0.009).
A model of relief forming by tectonic uplift and valley incision in orogenesis
Authors: Sugai  , Ohmori
Published: March 2003

A model for the change in shape of interfluves by concurrent tectonics and denudation was developed based on the morphometric attributes of landforms. The tributaries flowing down valley side slopes and dissecting low‐relief surfaces on the interfluves are one of the most important elements for relief‐forming processes. They were named as β‐tributaries. The valleyhead altitude (H ), the junction altitude (L) and the valley length (l ) of the β‐tributary were measured. The altitudinal difference (h=H−L), which indicates the local relief, and the average slope of tributary (tan θ=h/L) were calculated. The regression analyses among H, L, l, h and tan θ indicate that the valley length, relief and slope increase with an increase in valleyhead altitude.

Based on the functional relations above, the shape of interfluve is a function of uplift, altitude and erosion. This model is used to illustrate the change in cross‐section of interfluves during a period of sustained rock uplift.

Successive changes in shape of interfluve can be divided into two substages: (1) the early substage, characterized by trapezoidal cross‐sections with the original low‐relief surfaces and residual, shallow stream networks on the ridges; and (2) the later substage, characterized by a triangular cross‐section, with the original low‐relief surfaces removed and with the interfluves lowered by headward erosion of β‐tributaries. In central Japan, the transitional relief from the trapezoidal to the triangular cross‐section appears when the ridges of interfluves attain elevations about 1600–2000 m above sea level.
Modelling quartz cementation of quartzose sandstones
Authors: Wangen
Published: March 2003

Cementation of quartzose sandstones is modelled assuming that the main source of silica is quartz dissolved at stylolites. The cementation process is shown to operate in one of two different regimes depending on the Damköhler number for diffusion. The regime, where diffusion of silica from the stylolites is a faster process than precipitation, is characterized by a nearly constant supersaturation between the stylolites. This regime, which spans the depth interval of quartz cementation for close stylolites, allows for approximate analytical expressions for the porosity evolution as a function of time and temperature. An expression is derived for the temperature where half the initial porosity is lost during constant burial along a constant thermal gradient. This expression is used to study the sensitivity of all parameters which enter the cementation process. The cementation process is shown to be particularly sensitive to the activation energy for quartz dissolution. The expression for the porosity decrease under constant burial is generalized to any piecewise linear burial and temperature history. The influence of the burial histories on the cementation process is then studied.
Drainage on evolving fold‐thrust belts: a study of transverse canyons in the Apennines
Authors: Alvarez
Published: March 2003

Anticlinal ridges of the actively deforming Umbria–Marche Apennines fold‐thrust belt are transected by deep gorges, accommodating a drainage pattern which almost completely ignores the presence of pronounced anticlinal mountains. Because the region was below sea level until the folds began to form, simple antecedence cannot explain these transverse canyons. In addition, the fold belt is too young for there to have been a flat‐lying cover from which the rivers could have been superposed.

In 1978, Mazzanti & Trevisan proposed an explanation for these gorges which deserves wider recognition. They suggested that the Apennine fold ridges emerged from the sea in sequence, with the erosional debris from each ridge piling up against the next incipient ridge to emerge, gradually extending the coastal plain seaward. The new coastal plain adjacent to each incipient anticline provided a flat surface on which a newly elongated river could cross the fold, positioning it to cut a gorge as the fold grew. Their mechanism is thus a combination of antecedence and superposition in which folds, overlying sedimentary cover and downstream elongations of the rivers all form at the same time.

A study of Apennine drainage, using the sequence of older‐to‐younger transected Apennine folds as a proxy for the historical evolution of drainage cutting through a single fold, shows that transverse drainage forms when sedimentation dominates at the advancing coastline. Longitudinal drainage forms when uplift dominates, the folds first emerge as offshore islands and the Mazzanti–Trevisan mechanism is suppressed.

Complicating factors include several departures from steady‐state growth of the fold‐thrust belt, a possible case of precursory submarine drainage, early emergence of anticlinal culminations and the location of several transverse canyons at the structurally highest point along anticlinal axes.
Depositional and tectonic evolution of a supradetachment basin:40Ar/39Ar geochronology of the Nova Formation, Panamint Range, California
Authors: Snyder N. P. , Hodges K. V.
Published: March 2003

The Nova Basin contains an upper Miocene to Pliocene supradetachment sedimentary succession that records the unroofing of the Panamint metamorphic core complex, west of Death Valley, California. Basin stratigraphy reflects the evolution of sedimentation processes from landslide emplacement during basin initiation to the development of alluvial fans composed of reworked, uplifted sections of the basin fill.40Ar/39Ar geochronology of volcanic units in middle and lower parts of the sequence provide age control on the tectonic and depositional evolution of the basin and, more generally, insights regarding the rate of change of depositional environments in supradetachment basins. Our work, along with earlier research, indicate basin deposition from 11.38 Ma to 3.35 Ma. The data imply sedimentation rates, uncorrected for compaction, of ~100 m Myr−1in the lower, high‐energy part to ~1000 m Myr−1in the middle part characterized by debris‐flow fan deposition. The observed variation in sediment flux rate during basin evolution suggests that supradetachment basins have complex depositional histories involving rapid transitions in both the style and rate of sedimentation.
The Late Cenozoic Eridanos delta system in the Southern North Sea Basin: a climate signal in sediment supply?
Authors: Overeem I. , Weltje G. J. , Bishop‐Kay C. , Kroonenberg S. B.
Published: March 2003

ABSTRACT The Eridanos fluvio‐deltaic system, draining most of north‐western Europe, developed during the Late Cenozoic as a result of simultaneous uplift of the Fennoscandian shield and accelerated subsidence in the North Sea Basin. This seismo‐stratigraphic study aims to reconstruct the large‐scale depositional architecture of the deltaic portion of the basin fill and relate it to external controls. A total of 27 units have been recognized. They comprise over 62×103 km3 in the Southern North Sea Basin alone, and have an average delta surface area of 28×103 km2, which suggests that the size of the drainage area was about 1.1×106 km2. Water depth in the depocentre is seen to decrease systematically over time. This trend is interrupted by a deepening phase between 6.5 and 4.5 Ma that can be correlated with the simultaneous occurrence of increased uplift of the Fennoscandian shield, increased subsidence of the Southern North Sea Basin, and a long‐term eustatic highstand. All these observations point to a tectonic control on long‐term average rates of accommodation and supply. Controls on short‐term variations are inferred from variations in rates of sediment supply and bifurcation of the delta channel network. Both rates were initially low under warm, moist, relatively stable climate conditions. The straight wave‐dominated delta front gradually developed into a lobate fluvial‐dominated delta front. Two high‐amplitude sea‐level falls affected the Pliocene units, which are characterized by widespread delta‐front failures. Changes in relative sea level and climate became more frequent from the late Pliocene onward, as the system experienced the effects of glacial–interglacial transitions. Peaks in sedimentation and bifurcation rates were coeval with cold (glacial) conditions. The positive correlation between rates of supply and bifurcation on the one hand, and climate proxies (pollen and δ18O records) on the other hand is highly significant. The evidence presented in this study convincingly demonstrates the control of climate on time‐averaged sediment supply and channel‐network characteristics, despite the expected nonuniformity and time lags in system response. The presence of a clearly discernible climate signal in time‐averaged sediment supply illustrates the usefulness of integrated seismo‐stratigraphic studies for basin‐wide analysis of delta evolution on geological time scales.
Supersequences, superbasins, supercontinents – evidence from the Neoproterozoic–Early Palaeozoic basins of central Australia
Authors: Lindsay John F.
Published: March 2003

Neoproterozoic sedimentary basins cover a large area of central Australia. They rest upon rigid continental crust that varies from c. 40–50 km in thickness. Whilst the crust was in part formed during the Archaean and early Palaeoproterozoic, its final assembly occurred at approximately 1.1 Ga as the Neoproterozoic supercontinent, Rodinia, came into being. The assembly process left an indelible imprint on the region producing a strong crustal fabric in the form of a series of north dipping thrusts that pervade much of the thick craton and extend almost to the Moho. Following a period of stability (1.1–0.8 Ga), a large area of central Australia, in excess of 2.5 × 106 km2, began to subside in synchroneity. This major event was due to mantle instability resulting from the insulating effect of Rodinia. Initially, beginning c. 900 Ma, a rising superplume uplifted much of central Australia leading to peneplanation of the uplifted region and the generation of large volumes of sand‐sized clastic materials. Ultimately, the decline of the superplume led to thermal recovery and the development of a sag basin (beginning at c. 800 Ma), which in turn resulted in the redistribution of the clastic sediments and the development of a vast sand sheet at the base of the Neoproterozoic succession.

The superbasin generated by the thermal recovery was short lived (c. 20 M.y.) but, in conjunction with the crustal fabric developed during supercontinent assembly, it set the stage for further long‐term basin development that extended for half a billion years well into the Late Palaeozoic. Following the sag phase at least five major tectonic episodes influenced the central Australian region. Compressional tectonics reactivated earlier thrust faults that had remained dormant within the crust, disrupting the superbasin, causing uplift of basement blocks and breaking the superbasin into the four basins now identified within the central Australian Neoproterozoic succession (Officer, Amadeus, Ngalia and Georgina Basin). These subsequent tectonic events produced the distinctive foreland architecture associated with the basins and were perhaps the trigger for the Neoproterozoic ice ages. The reactivated basins became asymmetric with major thrust faults along one margin paralleled by deep narrow troughs that formed the main depocentres for the remaining life of the basins. The final major tectonic event to influence the central Australian basins, the Alice Springs Orogeny, effectively terminated sedimentation in the region in the Late Palaeozoic (c. 290 Ma). Of the six tectonic episodes recorded in the basinal succession only one provides evidence of extension, suggesting the breakup of east Gondwana at the end of the Rodinian supercontinent cycle may have occurred at close to the time of the Precambrian–Cambrian boundary. The central Australian basins are thus the products of events surrounding the assembly and dispersal of Rodinia.
Frontal accretion and thrust wedge evolution under very oblique plate convergence: Fiordland Basin, New Zealand
Authors: Barnes P. M. , Davy B. , Sutherland R. , Delteil J.
Published: March 2003

A thrust wedge with unusual geometry has developed under very oblique (50–60°) convergence between the Pacific and Australian Plates, along the 240‐km length of the Fiordland margin, New Zealand. The narrow (25 km‐wide) wedge comprises three overlapping components, lying west of the offshore section of the Alpine Fault, and straddles a change of > 30° in the regional strike of the plate boundary. Swath bathymetry, marine seismic reflection profiles, and dated samples together reveal the stratigraphy, structure, and evolution of the wedge and the underthrusting, continental, Caswell High (Australian Plate).

 Lateral variations in the composition and structure of the accretionary wedge, and the depth of the décollement thrust, result partly from variations in crustal structure and basement relief of the underthrust plate, and from associated variations in the thickness of turbidites available for frontal accretion. In the southern Fiordland Basin the underthrust plate is undergoing flexural uplift and extension, and a thick turbidite section is available for accretion. Along‐strike, a structurally elevated portion of the underthrust plate is very obliquely colliding with the central part of the accretionary wedge, the turbidite section available for accretion is condensed, and structural inversion occurs in the underthrust plate.

  Growth of the thrust wedge is inferred to have commenced in the Pliocene prior to 3 ± 1 Ma, but much of the wedge developed in the Quaternary. The spatial distribution of thrusting has varied through time, with most late Quaternary shortening occurring on structures within 10 km of the right‐stepping deformation front. Estimates of the magnitude and rates of deformation indicate that the wedge accommodates a significant component of the oblique convergence between the Pacific and Australian Plates. Shortening of up to 7.3 ± 1.4 km and 9.1 ± 1.8 km within the southern and central parts of the wedge, respectively, represent about 5–15% of the total 70–140 km of shortening predicted across the plate boundary since 6.4 Ma, and about 10–30% since 3 Ma. Late Quaternary shortening rates of the order of 1–5 mm yr−1, estimated across both the northern and southern parts of the wedge, represent about 10–50 and 5–21% of the total NUVEL‐1 A shortening across the plate boundary at these respective latitudes, implying that most shortening is occurring onshore. Furthermore, possible oblique‐slip thrusting within the wedge may be accommodating boundary‐parallel displacement of 0–6 mm yr−1, representing 0–17% of the total predicted within the plate boundary.
Quantifying the sequence stratigraphy and drowning mechanisms of atolls using a new 3‐D forward stratigraphic modelling program (CARBONATE 3D)
Authors: Warrlich G. M. D. , Waltham D. A. , Bosence D. W. J.
Published: March 2003

This paper describes a new 3‐D forward numerical model (CARBONATE 3D) that simulates the stratigraphic and sedimentological development of carbonate platforms and mixed carbonate–siliciclastic shelves by simulating the following sedimentary processes: (1) Carbonate shallow, open‐marine production, dependent on water depth, restriction and sediment input; (2) Carbonate shallow, restricted‐marine production, dependent on water restriction; (3) Pelagic sediment production and deposition; (4) Coarse and fine siliciclastic input; (5) Erosion, transport and redeposition of sediment, dependent on currents, slope, depth and restriction as well as sediment grain‐size and composition; (6) Dissolution of subaerially exposed carbonate. In this paper the model is used to investigate the controlling mechanisms on the sequence stratigraphy of isolated carbonate platforms and atolls and to predict distinctive architectural signatures from different drowning mechanisms. Investigation of the mechanisms controlling atoll strata shows that although relative sea‐level is the major control, antecedent topography, environmental setting and early diagenesis have profound influence on what stratigraphic geometries and facies develop. Hence care must be taken if sea‐level curves are interpreted from real stratigraphies. Atoll drowning by fast sea‐level rise, by lowered production and by repeated exposure and fast subsequent sea‐level rises are investigated and different stratigraphic signatures for the respective mechanisms predicted. A fast relative sea‐level rise results in a bucket‐shaped morphology developed prior to drowning and a sharp transition from the platform margin facies to a pelagic cover. Drowning caused by lowered platform margin production is predicted to result in the development of a dome‐shaped, shallow‐water shoal over the whole platform top prior to drowning. Fourth order amplitudes of several tens of metres, typical of ‘icehouse’ settings, cause atoll drowning at subsidence rates where atolls subject to fourth order amplitude of only a few metres, typical of ‘greenhouse’ settings, can keep up with the rising sea‐level. In the resultant strata, vertical facies belts are less well developed but horizontally extensive facies bands are more prominent. High fourth order amplitudes (up to 80 m) without sufficient third order scale subsidence will not lead to drowning, however, as the platform can recover in each fourth order lowstand. These results suggest that atolls might be easier to drown in ‘icehouse’ rather than in ‘greenhouse’ conditions but only in situations with suitably high rates of longer‐term relative sea‐level rise or sufficient lag times.
Assembling the stratigraphic record: depositional patterns and time‐scales in an experimental alluvial basin
Authors: Sheets B. A. , Hickson T. A. , Paola C.
Published: March 2003

Our understanding of sedimentation in alluvial basins is best for very short and very long time‐scales (those of bedforms to bars and basinwide deposition, respectively). Between these end members, the intermediate time‐scales of stratigraphic assembly are especially hard to constrain with field data. We address these ‘mesoscale’ fluvial dynamics with data from an experimental alluvial system in a basin with a subsiding floor. Observations of experimental deposition over a range of time‐scales illustrate two important properties of alluvial systems. First, ephemeral flows are disproportionately important in basin filling. Lack of correlation between flow occupation and sedimentation indicates that channelized flows serve mainly as conduits for sediment, while most deposition occurs via short‐lived unchannelized flow events. Second, there is a characteristic time required for individual depositional events to average to basin‐scale stratal patterns. This time can be scaled in terms of the time required for a single channel‐depth of aggradation, and in this form is constant through a four‐fold variation of experimental subsidence rate.
The stratigraphic and structural evolution of the Dzereg Basin, western Mongolia: clastic sedimentation, transpressional faulting and basin destruction in an intraplate, intracontinental setting
Authors: Howard J. P. , Cunningham W. D. , Davies S. J. , Dijkstra A. H. , Badarch G.
Published: March 2003

The Dzereg Basin is an actively evolving intracontinental basin in the Altai region of western Mongolia. The basin is sandwiched between two transpressional ranges, which occur at the termination zones of two regional‐scale dextral strike‐slip fault systems. The basin contains distinct Upper Mesozoic and Cenozoic stratigraphic sequences that are separated by an angular unconformity, which represents a regionally correlative peneplanation surface. Mesozoic strata are characterized by northwest and south–southeast‐derived thick clast‐supported conglomerates (Jurassic) overlain by fine‐grained lacustrine and alluvial deposits containing few fluvial channels (Cretaceous). Cenozoic deposits consist of dominantly alluvial fan and fluvial sediments shed from adjacent mountain ranges during the Oligocene–Holocene. The basin is still receiving sediment today, but is actively deforming and closing. Outwardly propagating thrust faults bound the ranges, whereas within the basin, active folding and thrusting occurs within two marginal deforming belts. Consequently, active fan deposition has shifted towards the basin centre with time, and previously deposited sediment has been uplifted, eroded and redeposited, leading to complex facies architecture. The geometry of folds and faults within the basin and the distribution of Mesozoic sediments suggest that the basin formed as a series of extensional half‐grabens in the Jurassic–Cretaceous which have been transpressionally reactivated by normal fault inversion in the Tertiary. Other clastic basins in the region may therefore also be inherited Mesozoic depocentres. The Dzereg Basin is a world class laboratory for studying competing processes of uplift, deformation, erosion, sedimentation and depocentre migration in an actively forming intracontinental transpressional basin.
Pharmacokinetics and pharmacodynamics of the leukotriene B4 receptor antagonist CP‐105,696 in man following single oral administration
Authors: Liston Theodore E. , Conklyn Maryrose J. , Houser Janet , Wilner Keith D. , Johnson Arlene , Apseloff Glen , Whitacre Caroline , Showell Henry J.
Published: March 2003

Aims
 CP‐105,696, (+)‐1‐(3S,4R)‐[3‐(4‐phenylbenzyl)‐4‐hydroxy‐chroman‐7‐yl] cyclopropane carboxylic acid is a potent, novel LTB4 receptor antagonist advanced to clinical trials to determine its efficacy in inflammatory diseases. The pharmacokinetics and pharmacodynamics of CP‐105,696 were investigated in healthy male volunteers following oral administration of single doses of 5 to 640 mg.

Methods
 Forty‐eight subjects participated in a randomized, double‐blind, parallel group study. Plasma and urine concentrations of CP‐105,696 were determined at intervals after drug administration. As an indication of LTB4 receptor antagonism following oral administration of CP‐105,696, the inhibiton of LTB4‐induced upregulation of the neutrophil cell surface complement receptor (CR3), CD11b/CD18, was monitored at 4 h following drug administration using an ex vivo whole blood flow cytometry assay.

Results

 C
max and AUC(0,∞) increased in a dose‐related manner. Respective mean Cmax values were 0.54 to 30.41 μg ml−1 following doses of 5 to 640 mg. Respective mean AUC(0,∞) values were 1337 to 16819 μg ml−1 h for the 40 to 640 mg dose groups. Plasma concentrations declined in a monoexponential manner, with terminal elimination half‐lives ranging from 289 to 495 h. Group mean terminal elimination half‐lives were dose‐independent. Urinary excretion of unchanged drug accounted for <1% of the administered dose. A linear relationship was observed between CP‐105,696 plasma concentrations and inhibition of LTB4‐mediated CD11b upregulation on human neutrophils in whole blood. CP‐105,696 plasma concentrations of 5–6 μg ml−1 were necessary to elicit a two‐fold shift to the right of the LTB4 concentration response curve for CD11b upregulation.

Conclusions
 These studies demonstrate pharmacologically significant LTB4‐receptor antagonism following a single dose of CP‐105,696 and pharmacokinetics consistent with once‐daily dosing.
Effect of protease inhibitors on nucleoside analogue phosphorylation in vitro
Authors: Hoggard P. G. , Manion V. , Barry M. G. , Back D. J.
Published: March 2003

Aims
 Combination antiretroviral therapy for human immunodeficiency virus (HIV) infection now involves both nucleoside analogues and protease inhibitors. Since intracellular phosphorylation is essential for the activity of all the nucleoside analogues this study was designed to investigate interactions with protease inhibitors at the intracellular level which may alter antiviral efficacy.

Methods
 PHA‐stimulated PBMCs (3×106 cell/plate) and U937 cells (4×106 cells/plate) were incubated with either radiolabelled zidovudine (ZDV), stavudine (d4T), zalcitabine (ddC), lamivudine (3TC) or didanosine (ddI) in the presence and absence of the protease inhibitors, indinavir, ritonavir, and saquinavir (0.1−10 μm ) for 24 h. Cells were extracted overnight prior to analysis by radiometric h.p.l.c. Intracellular phosphates were standardised to pmol per million cells.

Results
 None of the three protease inhibitors tested had any significant effect on the intracellular phosphorylation of the five nucleoside analogues. It is particularly important to focus on the active triphosphate anabolites and data for control vs ritonavir (10 μm ) incubations in U937 cells were as follows: ZDVTP, 0.19±0.02 vs 0.21±0.02 pmol/106 cells (mean±s.d.; n=5); d4TTP, 0.30±0.13 vs 0.27±0.26; 3TCTP, 0.32±0.12 vs 0.26±0.19; ddCTP, 0.07±0.04 vs 0.06±0.02; ddATP, 0.014±0.003 vs 0.018±0.006 pmol/106 cells.

Conclusions
 The protease inhibitors, indinavir, ritonavir and saquinavir have no effect on the enzymes responsible for phosphorylation. Combining protease inhibitors and nucleoside analogues should not lead to any intracellular interactions in vivo.