Peripartum anaesthetic management of a patient with Brugada syndrome and myoadenylate deaminase deficiency.

Brugada syndrome is a rare electrophysiological cardiac disease which can result in serious arrhythmias and sudden cardiac death. Peripartum management is centred around avoiding arrhythmogenic drugs, including high doses of sodium channel blocking drugs such as bupivacaine. Myoadenylate deaminase deficiency, also known as adenosine monophosphate deaminase deficiency, is the commonest cause of myopathy in Caucasians. There is evidence that myoadenylate deaminase deficiency can predispose patients to developing malignant hyperthermia when exposed to specific anaesthetic agents. We present a case of a pregnant patient with both Brugada syndrome and myoadenylate deaminase deficiency, in which analgesic and general anaesthetic options for each condition presented potentially conflicting dilemmas for the delivery of intrapartum care.

Sciatic nerve ischaemia after iliac artery occlusion balloon catheter placement for placenta percreta.

Placenta percreta is a complex obstetric condition and a cause of life-threatening peripartum haemorrhage. National guidelines advise preoperative placement of internal iliac artery occlusion balloon catheters in such cases to reduce haemorrhage, avoid caesarean hysterectomy and preserve fertility. Maternal complications of prophylactic occlusion balloon catheter insertion include puncture-site complications and arterial thrombosis, the signs of which are usually immediately clinically evident. Presentation of ischaemic nerve injury attributable to iliac artery thrombosis secondary to the presence of an occlusion balloon catheter is as yet unreported. Awareness of this possible complication and local unit guidelines may allow early detection and treatment.

Downward migration of radiocaesium in organic soils across a transect in Scotland.

Following the accident at the Chernobyl nuclear power plant in 1986, radioactive materials including (137)Cs were distributed over large parts of the former Soviet Union and Europe. Due to the relatively long physical half-life of (137)Cs (30.1 y) measurable activity concentrations can still be observed in the natural environment. We have determined the depth distribution of (137)Cs from the testing of nuclear weapons in the atmosphere and Chernobyl, in eight highly-organic soils along an approximately east to west transect across the Central Highlands of Scotland. The (137)Cs activity concentrations in the soil profiles, corrected for radioactive decay to May 1986, were between 2.8 and 14.4 kBq m(-2). There were differences in the pattern of distribution of (137)Cs in the soil profiles. The mean migration depth of (137)Cs in the soil profiles was 12.2 cm with a range between 8.2 and 17.4 cm. Quantitative mineralogical analysis of the ash obtained after heating the soil to 400 °C indicated that clay minerals alone did not have a prime role in controlling the migration of (137)Cs down the profile.

Type A aortic dissection in pregnancy.

Type A aortic dissection is a life-threatening event to both mother and baby, and accounted for 14% of maternal cardiac deaths in the 2006-2008 UK Confidential Enquiries into Maternal Deaths. Difficulty exists in the diagnosis of this rare but potentially curable condition, the mortality of which increases with delay in diagnosis. We present a case of acute type A aortic dissection in a previously well multiparous woman, treated successfully by aortic root repair immediately following caesarean section. The acute presentation of aortic dissection and diagnostic clues that may have expedited the diagnosis are discussed. A brief literature review is presented of the perioperative management of patients undergoing cardiothoracic surgery post-caesarean section and the modifications to standard techniques that are required.

Caesarean section for twin pregnancy in a parturient with Brugada syndrome.

Brugada syndrome is a common cause of sudden cardiac death. We report the anaesthetic management of a woman with Brugada syndrome for elective caesarean section of twins. There are few reports of this disease in pregnancy and we believe this is the first of elective caesarean section in a parturient with the syndrome. The characteristic electrocardiographic changes of the syndrome are linked to sodium channel blockers including local anaesthetics such as bupivacaine. The use of bupivacaine for intrathecal central neuraxial blockade as well as other drugs commonly used in obstetric anaesthesia is discussed.

Determining the role of N remobilization for growth of apple (Malus domestica Borkh) trees by measuring xylem-sap N flux.

The contribution of N remobilization to the seasonal growth of field-grown Malus domestica (apple) trees was measured using two different techniques. 'Fuji' trees grafted on M.9 apple rootstocks were planted in the field and fertilized and irrigated for two growing seasons. During the second year, the trees received 15N-labelled fertilizer and destructive harvests were taken during the spring and summer to determine the pattern of N remobilization and uptake. At the same time, patterns of N translocation in the xylem were measured by sampling saps at each harvest and analysing them for their constituent amino acids and amides. Total water flux through the trunk xylem was also measured throughout the sampling period using the heat balance technique. The flux of amino compounds in the xylem was then calculated to see if this approach could quantify remobilization. Most of the N for leaf growth was provided by remobilization, which lasted for some 40 d following bud-burst. The labelled N was not taken up until 14 d after remobilization had started. The predominant amino compounds recovered in the xylem were Asn, Asp, Arg, and Gln, whose concentration peaked during remobilization, except for Arg whose concentration was highest at bud-break and declined thereafter. The amount of N translocated in the xylem as Asn, Asp and Gln correlated well with the amount of N remobilized (as measured by the recovery of unlabelled N in the new above-ground growth). The data suggest that Arg is translocated predominantly as a consequence of root uptake and they are discussed in relation to measuring N remobilization in field-grown trees.

Translocation of amino acids in the xylem of apple (Malus domestica Borkh.) trees in spring as a consequence of both N remobilization and root uptake.

Nitrogen is remobilized from storage for the growth of Malus domestica leaves each spring. Seasonal patterns of N translocation in the xylem sap as a consequence of remobilization were determined in 2-year-old 'Golden delicious' trees grafted on M9 rootstocks. The trees were grown in sand culture and (15)NH(4)(15)NO(3) at 10.4 atom% abundance supplied during August-September. The following year no further N was supplied and destructive harvests were taken during bud burst and leaf growth to determine the patterns of N remobilization together with the isolation of xylem sap for an analysis of their amino acid profiles and (15)N enrichments by GC-MS. The concentration of amino acids in the xylem sap rose following bud burst, peaked at full bloom and then fell again during petal fall and fruit set. The peak in amino acid concentration corresponded with the period when the rate of N remobilization was the fastest. The majority of labelled N was recovered in Asn, Gln + Glu and Asp demonstrating that they were being translocated as a consequence of remobilization. In a second experiment, 8-year-old trees growing in an orchard were fertilized with N either in the autumn or spring. Xylem sap samples were collected in the spring and early summer and, by comparison with the amino acid profiles recovered in trees from both treatments, Asn was identified as the main compound translocated as a consequence of both remobilization and root uptake of N, although there was evidence that root uptake of N occurred later. The data are discussed in relation to quantifying the internal cycling of N in trees.

Echocardiographic monitoring of minimally invasive mitral valve surgery using an endoaortic clamp.

BACKGROUND AND AIMS OF THE STUDY: Twenty-four patients underwent minimally invasive mitral valve repair (n = 16) or mitral valve replacement (n = 8) using the Port-Access system. Intraoperative transesophageal echocardiography (TEE) was used in these patients to: (i) reassess valve pathology preoperatively; (ii) guide and continuously assess placement and position of the aortic endoclamp; (iii) measure aortic root diameters, aortic distensibility and aortic wall appearance prior to and after aortic endoclamping; (iv) evaluate the de-airing procedure; (v) evaluate the results of mitral valve repair; and (vi) guide weaning from cardiopulmonary bypass (CPB). METHODS AND RESULTS: Placement and positioning of the endoclamp was guided effectively in all but one patient who had acute retrograde aortic dissection with the onset of femoro-femoral bypass. The mean position of the tip of the endoclamp was 2.8 +/- 0.5 cm from the aortic valve annulus. The position was stable in all but five patients in whom repositioning and additional clamp volume were required. There was only a poor relationship between balloon volume and sinotubular junction diameter. The dynamic movement of the aorta was well preserved after clamping and the elasticity module did not change significantly (1.6 +/- 0.71 vs. 1.5 +/- 0.75 dynes x 10(6)/cm2). No intimal tears or wall edema was observed after clamp release. De-airing was incomplete in five patients, two of whom had transient ST-elevations with regional wall motion abnormalities. Weaning of CPB was therefore postponed until the ECG had normalized. All mitral valve repairs but one were successful (equal to or less than grade I residual mitral insufficiency). One patient with persistent grade II mitral insufficiency underwent valve replacement using the same approach. CONCLUSIONS: TEE can effectively guide minimally invasive mitral valve surgery using the Port-Access system. Placement and positioning of the endoclamp and its effects on the aortic wall can be evaluated. De-airing, weaning from CPB and the results of the procedure were effectively monitored using TEE.

Role of nitrogen remobilization from old leaves for new leaf growth of Eucalyptus globulus seedlings.

Six-month-old Eucalyptus globulus Labill. seedlings were grown in sand culture irrigated with a nutrient solution containing 6.0 mol N m(-3) for 3 months (November-January). Before rapid growth began in February, seedlings were repotted and irrigated with either 6.0 mol N m(-3) (High-N treatment) or 1.0 mol N m(-3) (Low-N treatment). Seedlings were analyzed during the subsequent flush of growth to determine the role of old leaves, and in particular the leaf protein Rubsico, as a source of N for new leaf growth. During spring growth, the N content of old leaves of High-N seedlings decreased with decreasing leaf dry weight, although there was no change in leaf number. In High-N seedlings, the net loss of N from old leaves provided less than 10% of the N used for new leaf growth, and the new leaves quickly became the dominant sink for N. In contrast, in Low-N seedlings, the net loss of N from old leaves provided 44% of the N used for new leaf growth. During the period of spring growth, the amount of soluble proteins recovered from old leaves of Low-N seedlings dropped, but there was no change in the content of either Rubisco or chlorophyll. The photosynthetic capacity of old leaves remained constant throughout the study period, and there was no evidence that N was remobilized from Rubisco.

Decreased ribulose-1,5-bisphosphate carboxylase-oxygenase in transgenic tobacco transformed with "antisense" rbcS : IV. Impact on photosynthesis in conditions of altered nitrogen supply.

The effect of nitrogen supply during growth on the contribution of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco; EC 4.1.1.39) to the control of photosynthesis was examined in tobacco (Nicotiana tabacum L.). Transgenic plants transformed with antisense rbcS to produce a series of plants with a progressive decrease in the amount of Rubisco were used to allow the calculation of the flux-control coefficient of Rubisco for photosynthesis (CR). Several points emerged from the data: (i) The strength of Rubisco control of photosynthesis, as measured by CR, was altered by changes in the short-term environmental conditions. Generally, CR was increased in conditions of increased irradiance or decreased CO2. (ii) The amount of Rubisco in wild-type plants was reduced as the nitrogen supply during growth was reduced and this was associated with an increase in CR. This implied that there was a specific reduction in the amount of Rubisco compared with other components of the photosynthetic machinery. (iii) Plants grown with low nitrogen and which had genetically reduced levels of Rubisco had a higher chlorophyll content and a lower chlorophyll a/b ratio than wild-type plants. This indicated that the nitrogen made available by genetically reducing the amount of Rubisco had been re-allocated to other cellular components including light-harvesting and electron-transport proteins. It is argued that there is a "luxury" additional investment of nitrogen into Rubisco in tobacco plants grown in high nitrogen, and that Rubisco can also be considered a nitrogen-store, all be it one where the opportunity cost of the nitrogen storage is higher than in a non-functional storage protein (i.e. it allows for a slightly higher water-use efficiency and for photosynthesis to respond to temporarily high irradiance).

Sucrose storage in cell suspension cultures of Saccharum sp. (sugarcane) is regulated by a cycle of synthesis and degradation.

We have investigated the regulation of sucrose storage in cell-suspension cultures of sugarcane. When grown in batch culture, sucrose accumulation commences after about 5 d, when the nitrogen supply is exhausted. Sucrose storage is also induced by decreasing the nitrogen supply to cells growing in a chemostat. The measured activity of sucrose-phosphate synthase is high enough to account for the rate of sucrose accumulation, provided precautions are taken to avoid the hydrolysis of UDP during the assay. The cells contained high sucrose-synthase activity but pulsing experiments with [(14)C]glucose and unlabelled fructose indicated that this enzyme did not contribute substantially to the synthesis of sucrose, because the glucosyl and fructosyl moieties of sucrose were equally labelled. Several lines of evidence demonstrate the presence of a cycle in which sucrose is synthesized and degraded simultaneously; sucrosephosphate-synthase activity doubles during the phase when the cells are actively storing sucrose but activity is also high after storage has ceased, or when the sucrose is being remobilised; pulse experiments with [(14)C]fructose also showed that sucrose synthesis occurs not only during the storage phase, but also after storage has stopped and during the rapid mobilisation of sucrose; the cells contain high activities of sucrose synthase and alkaline invertase and these are both at a maximum when sucrose storage is occurring; even during the storage phase. [(14)C]fructose pulses lead to labelling of free glucose which is evidence for rapid synthesis and degradation of sucrose. It is proposed that the rate and extent of sucrose storage is regulated by this cycle of synthesis and degradation. Measurements of enzyme activities and metabolite levels are presented, and it is discussed which factors could contribute to the regulation of these two opposing fluxes and, hence, the rate of net sucrose storage and mobilisation.