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•Negative emotion can affect memory for items and associations differentially.•Strengthened item memory reflected in increased amygdala activity.•Weakened contextual/associative memory reflected in reduced hippocampal activity.•Imbalance between strong negative items and weak contextual associations predicts intrusions.

Abstract: Background: This study aimed to determine whether the morbidity and outcome rates for laparoscopic transperitoneal dismembered pyeloplasty are different from those for dismembered pyeloplasty, to analyze the learning curve of laparoscopic pyeloplasty, and to determine whether preoperative stent placement affects outcome. Methods: For this study, 49 laparoscopic pyeloplasties (period 2000–2005) and 51 open pyeloplasties (period 1992–2003) were reviewed. Results: Compared with open procedures, laparoscopic procedures were associated with a longer mean operating time (159 vs 91 min; p < 0.001), a shorter mean time to normal diet (38 vs 72 h; p < 0.001), and a similar mean hospital stay (5 days; p = 0.6). The operative complication rates were 17% for primary laparoscopic pyeloplasties and 24% for primary open pyeloplasties. The rates were higher for secondary procedures. The success rates for primary and secondary procedures were, respectively, 98% (41/42) and 57% (4/7) for laparoscopy and 96% (46/48) and 67% (2/3) for open surgery. Failed procedures showed no improvement in loin pain or obstruction. At the 6-month follow-up evaluation, 29% of the open surgery patients but none of the laparoscopic surgery patients reported wound pain. Conclusions: The efficacy of laparoscopic pyeloplasty is equivalent to that of open pyeloplasty, with less wound pain at 6 months. The outcome for secondary procedures is inferior. There was a trend toward a reduction in complications and the conversion rates with time, suggesting that there may be a learning curve of approximately 30 laparoscopic pyeloplasty cases. Preoperative stent insertion did not seem to affect any objective measures of outcome for laparoscopic pyeloplasty.

For many years, London Underground's Northern Line tunnels just south of Old Street station had suffered from attack by sulphuric acid. These tunnels were constructed between 1899 and 1901, and were enlarged between 1922 and 1924. Acid began to seep into the tunnels in 1945 and cracks appeared in the tunnel linings in 1960. Over the years, to ensure safety, London Underground Limited (LUL) monitored the increasing levels of distortion and cracking of the tunnel linings and installed temporary strengthening until the need for innovative long-term solutions became evident. This paper describes various investigations into the problem, the formation of a solution and the consequent construction works, which had to be carried out with minimal disruption to services within the complex operating environment of the two Northern Line branches. The solution was to replace the grey cast-iron linings with larger diameter acid resistant linings made from cast duplex stainless steel. The works were carried out at night using a special shield, through which the trains passed during the day. The project took six years from initial concept to completion, including more than four years of research and design, a precasting contract for the linings and finally nine months of installation works. In total, the project cost approximately £15 million.For many years, London Underground's Northern Line tunnels just south of Old Street station had suffered from attack by sulphuric acid. These tunnels were constructed between 1899 and 1901, and were enlarged between 1922 and 1924. Acid began to seep into the tunnels in 1945 and cracks appeared in the tunnel linings in 1960. Over the years, to ensure safety, London Underground Limited (LUL) monitored the increasing levels of distortion and cracking of the tunnel linings and installed temporary strengthening until the need for innovative long-term solutions became evident. This paper describes various investigations into the problem, the formation of a solution and the consequent construction works, which had to be carried out with minimal disruption to services within the complex operating environment of the two Northern Line branches. The solution was to replace the grey cast-iron linings with larger diameter acid resistant linings made from cast duplex stainless steel. The works were carried out at night using a special shield, through which the trains passed during the day. The project took six years from initial concept to completion, including more than four years of research and design, a precasting contract for the linings and finally nine months of installation works. In total, the project cost approximately £15 million.

A large-scale virtual reality town was used to test the topographical and episodic memory of patients with unilateral temporal lobe damage. Seventeen right and 13 left temporal lobectomy patients were compared with 16 healthy matched control subjects. After they had explored the town, subjects' topographical memory was tested by requiring them to navigate to specific locations in the town. The ability to recognize scenes from and draw maps of the virtual town was also assessed. Following the topographical memory tests, subjects followed a route around the same town but now collected objects from two different characters in two different locations. Episodic memory for various aspects of these events was then assessed by paired forced-choice recognition tests. The results showed an interaction between laterality and test type such that the right temporal lobectomy (RTL) patients were worse on tests of topographical memory, and the left temporal lobectomy (LTL) patients worse on tests of context-dependent episodic memory. Specifically, the RTL group was impaired on navigation, scene recognition and map drawing relative to control subjects. They were also impaired on recognition of objects in the episodic memory task. The LTL group was impaired relative to control subjects on their memory for contextual aspects of the events, such as who gave them the objects, the order in which objects were received and the locations in which they received them. They were also mildly impaired on topographical memory, but less so than the RTL group. These results suggest that topographical memory is predominately mediated by structures in the right medial temporal lobe, whereas the context-dependent aspects of episodic memory in this non-verbal test are more dependent on the left medial temporal lobe.

The anaesthetic management of a 38-year-old woman having excision of a meningioma involving the superior sagittal sinus is described. The procedure was performed using low flow moderate hypothermic cardiopulmonary bypass with central cannulation. Relevant literature is reviewed.

A new Chinese remainder theorem (CRT)-based technique for the conversion of numbers in residue number system (RNS) format to binary representation is proposed that employs a high-radix SRT division-like architecture. The major benefit of the new technique is that it permits the efficient conversion of residue numbers with many moduli. A k-modulus RNS converter returning a w-bit result employs a (⌈log2 4;k⌉+1)-bit carry–propagate adder, a ROM with ⌈log2 4;k⌉+3 address bits, a (w+⌈log2 4;k⌉)-bit borrow–save subtractor, and a w-bit carry–propagate adder. This comprises less hardware than any other reported general modulus CRT-based converter.

A model of place-cell firing is presented that makes quantitative predictions about specific place cells' spatial receptive fields following changes to the rat's environment. A place cell's firing rate is modeled as a function of the rat's location by the thresholded sum of the firing rates of a number of putative cortical inputs. These inputs are tuned to respond whenever an environmental boundary is at a particular distance and allocentric direction from the rat. The initial behavior of a place cell in any environment is simply determined by its set of inputs and its threshold; learning is not necessary. The model is shown to produce a good fit to the firing of individual place cells, and populations of place cells across environments of differing shape. The cells' behavior can be predicted for novel environments of arbitrary size and shape, or for manipulations such as introducing a barrier. The model can be extended to make behavioral predictions regarding spatial memory. Hippocampus 10:369–379, 2000 © 2000 Wiley-Liss, Inc.

A model of place‐cell firing is presented that makes quantitative predictions about specific place cells' spatial receptive fields following changes to the rat's environment. A place cell's firing rate is modeled as a function of the rat's location by the thresholded sum of the firing rates of a number of putative cortical inputs. These inputs are tuned to respond whenever an environmental boundary is at a particular distance and allocentric direction from the rat. The initial behavior of a place cell in any environment is simply determined by its set of inputs and its threshold; learning is not necessary. The model is shown to produce a good fit to the firing of individual place cells, and populations of place cells across environments of differing shape. The cells' behavior can be predicted for novel environments of arbitrary size and shape, or for manipulations such as introducing a barrier. The model can be extended to make behavioral predictions regarding spatial memory. Hippocampus 10:369–379, 2000 © 2000 Wiley‐Liss, Inc.

Gastrin-releasing peptide (GRP) and its amphibian homolog, bombesin, are potent secretogogues in mammals. We determined the roles of intracellular free Ca2+([Ca2+]i), protein kinase C (PKC), and mitogen-activated protein kinases (MAPK) in GRP receptor (GRP-R)-regulated secretion. Bombesin induced either [Ca2+]ioscillations or a biphasic elevation in [Ca2+]i. The biphasic response was associated with peptide secretion. Receptor-activated secretion was blocked by removal of extracellular Ca2+, by chelation of [Ca2+]i, and by treatment with inhibitors of phospholipase C, conventional PKC isozymes, and MAPK kinase (MEK). Agonist-induced increases in [Ca2+]iwere also inhibited by dominant negative MEK-1 and the MEK inhibitor, PD89059, but not by an inhibitor of PKC. Direct activation of PKC by a phorbol ester activated MAPK and stimulated peptide secretion without a concomitant increase in [Ca2+]i. Inhibition of MEK blocked both bombesin- and phorbol 12-myristate 13-acetate-induced secretion. GRP-R-regulated secretion is initiated by an increase in [Ca2+]i; however, elevated [Ca2+]iis insufficient to stimulate secretion in the absence of activation of PKC and the downstream MEK/MAPK pathways. We demonstrated that the activity of MEK is important for maintaining elevated [Ca2+]ilevels induced by GRP-R activation, suggesting that MEK may affect receptor-regulated secretion by modulating the activity of Ca2+-sensitive PKC.

Summary Microelectrodes filled with horseradish peroxidase (HRP) were used to label single identified giant axons in the isolated lamprey spinal cord. Subsequent to the iontophoretic injection of HRP, the spinal cord was stimulated at repetition rates of 20–30/s and the activity in labelled axons monitored. Immediately following failure of the action potential, the spinal cord was fixed by immersion and processed for light and electron microscopy. Electron micrographs were taken of synaptic contacts made by the labelled axons. Several quantitative measures were made from each synapse using a digitizing tablet interfaced with a digital computer. These measures included vesicle number (VN), vesicle area (VA), length of differentiated membrane (DM), vesicle density (VD=VN/VA), vesicle frequency (VF = VN/DM), and a relative measure of the amount of vesicle membrane added to the axolemma during the stimulation period, the curvature ratio (CR). Measures from 106 stimulated synapses were compared with 134 synapses from injected but unstimulated giant axons. The results from these experiments suggest that measurable ultrastructural changes occur during transmitter release at identified C.N.S. synapses, which are consistent with the hypothesis of synaptic vesicle recycling.

Summary Synaptic junctions located on the dendrites of lamprey (Petromyzon marinus) reticulospinal neurons labelled with intracellularly-injected horseradish peroxidase were studied. The normal ultrastructure of the synaptic junctions was defined and several quantitative measures made from each junction in order to test the hypothesis that distally-located synapses are ultrastructurally different from those located at proximal dendritic sites. A total of 820 contacts from one neuron and 279 from a second neuron ranging from 20 to 340 µm from the soma were quantified. The vast majority of the presynaptic endings contained round, clear-cored vesicles and formed an asymmetrical membrane differentiation with the postsynaptic dendrite. A small fraction of the population contained flattened or pleomorphic vesicles and these synapses were equally distributed with respect to distance from the soma. Many of the terminals contained a few large dark- and clear-cored vesicles. Four quantitative measures of each synaptic contact were made. These included vesicle number, length of differentiated membrane, vesicle area and terminal area. Four ratios relating the different quantitative measures were also calculated. Each ratio or measurement from the synaptic junctions was plotted as a function of distance from the soma to determine if differences existed at any distance. It was found that synaptic junctions are uniformly similar and that distal junctions did not differ significantly (P > 0.05) from those at proximal dendritic sites. It is concluded that if distal synapses do compensate for their remote location they do this in some other way, possibly by increasing the number of synaptic contacts made by each presynaptic axon.

ß-Oxidation enzymes were detected both in the mitochondria and microbodies of pea cotyledons. Intact mitochondria did not show ß-oxidation enzyme activity but in ruptured mitochondria this activity was high. It is apparent that the mitochondrial membrane barrier prevents rapid access of acyl-CoA substrates to matrix ß-oxidation sites. Removal of the membrane barrier permits rapid access of acyl-CoAs and these enzyme activities may then be measured.

Purified pea cotyledon mitochondria did not oxidise acetyl-CoA in the presence of carnitine. However, acetylcarnitine was oxidised. It was concluded that acetylcarnitine passed through the mitochondrial membrane barrier but acetyl-CoA did not. Only a sensitive radioactive assay detected carnitine acetyltransferase in intact mitochondrion or intact mitoplast preparations. When the mitochondria or mitoplasts were burst, acetyl-CoA substrate was available to the matrix carnitine acetyltransferase and a high activity of the enzyme was measured. The inner mitochondrial membrane is there-fore the membrane barrier to acetyl-CoA but acetylcarnitine is suggested to be transported through this membrane via an integral carnitine: acylcarnitine translocator. Evidence is presented to indicate that when the cotyledons from 48-h-grown peas are oxidising pyruvate, acetylcarnitine formed in the mitochondrial matrix by the action of matrix carnitine acetyltransferase may be transported to extra-mitochondrial sites via the membrane translocator.

A method is described for separating mitochondria from microbodies in cotyledon preparations of Pisum sativum L. cv. Alaska. Pure and intact mitochondria were obtained on a continuous: discontinuous sucrose density gradient as shown by marke-enzyme assay and electron microscopy. Manipulation of sucrose-gradient construction to widen the distance between organelles provided a quick method for the separation of the mitochondria from the microbodies. The shorter time of exposure of mitochondria to centrifugation and osmotic stress produces mitochondria free of contamination.

Firstly, to determine a satisfactory animal model for induction of intrarenal calcification, a study of four previously described animal models of intrarenal calcification was carried out which showed that intraperitoneal injection of 10% calcium gluconate into female Sprague-Dawley rats was most effective. We then investigated the hypothesis that dietary supplementation with essential fatty acids could reduce the intrarenal calcification developing as a result of intraperitoneal calcium injection. Using a combination of fish oil and evening primrose, oil, we demonstrated a significant difference in renal parenchymal calcification, which was 940±240 µg Ca/g dry weight renal parenchyma in unsupplemented animals and 320–370 ±55–65 µg Ca/g dry weight renal parenchyma in supplemented animals (means±SEM, P<0.005). It was also demonstrated that there was synergism between eicosapentaenoic acid (EPA) and ?-linolenic acid (GLA): dietary supplementation with a combined oil preparation containing 27 mg/ml EPA and 67 mg/ml GLA mixed as 2% with food was as effective as oils containing either 400 mg/ml EPA or 80 mg/ml GLA mixed as 4% of food.

Tidal forcing of the shallow water equations is typical of a class of problems where an approximate equilibrium solution is sought by long time integration of a differential equation system. A combination of the angled-derivative scheme with a staggered leap-frog scheme is sometimes used to discretise this problem. It is shown here why great care then needs to be taken with the boundary conditions to ensure that spurious solution modes do not lead to numerical instabilities. Various techniques are employed to analyse two simple model problems and display instabilities met in practical computations; these are then used to deduce a set of stable boundary conditions.

The effect of H+ on the N-methyl-d-aspartate-induced (NMDA) membrane current in enzymatically isolated catfish cone horizontal cells was investigated. Extracellular acidification to pH 5.5 blocked nearly completely the NMDA-induced current and reduced desensitization. The pK for the H+ effect was 6.5, near that for the free amino acid histidine. Protons did not alter the receptor affinity for NMDA and the inhibition was insensitive to the membrane potential and surface charge screening. However, extracellular H+ increased the IC50 for Zn2+. These results indicate that protons can modulate the NMDA-induced membrane current by a mechanism that may include interaction with histidine residues.

Neurones isolated from embryonic cockroach brains were maintained in culture for up to 8 weeks. A single patch electrode was used to record voltage changes in response to injected current, membrane ionic currents under whole-cell voltageclamp conditions or single-channel currents from isolated membrane patches. The voltage changes in response to injected current that depolarized the cell indicated increases in membrane permeability to calcium and potassium. These observations were confirmed using a voltage clamp. The potassium current observed in the youngest cultures turned on with a delay and was blocked by tetraethylammonium (TEA) and 4-aminopyridine (4-AP). Two kinds of decrease in the outward potassium current were observed. One may be associated with extracellular potassium accumulation, inactivation of the potassium channel or inactivation of a calcium channel. The other appears to be a voltage-dependent inactivation. The magnitude of the calcium permeability appeared to increase as the cultures developed, being most prominent in cultures more than 2 weeks old. Single-channel conductance measured from an analysis of records from six isolated membrane patches ranged from 15 to 110pS. Except for one channel, the probability of the channels being open did not change appreciably with membrane potential. Our results suggest that much of the increase in potassium permeability may be due an increase in intracellular calcium level.

Eastern African coastal forests are located within the Swahili regional centre of endemism and Swahili‐Maputaland regional transition zone in eastern Africa, between 1d̀ North and 25d̀ South, and 34—41d̀ East. Approximately 3167 km2coastal forest remains: 2 km2in Somalia, 660 km2in Kenya, 697 km2in Tanzania, 16 km2in Malawi, 3 km2in Zimbabwe and perhaps 1790 km2in Mozambique. Most forests are small (≤ 20 km2), and all but 19 are under 30 km2in area. Over 80% of coastal forest is located on government land, principally Forest Reserves; only 8.3 km2is found in National Parks (6.2 km2in Kenya (Arabuko‐Sokoke), 2 km2in Tanzania (Mafia Island) and tiny patches in Zimbabwe). Coastal forests are an important and highly threatened centre of endemism for plants (c550 endemic species), mammals (6 species), birds (9 species), reptiles (26 species), frogs (2 species), butterflies (79 species), snails (>86 species) and millipedes (>20 species). Endemic species are concentrated in the forests of the Tana River, between Malindi in Kenya to Tanga in northern Tanzania, and in southern Tanzania. Forests with highest numbers of endemics are: lower Tana River, Arabuko‐Sokoke, Shimba Hills (Kenya); lowland East Usambara, Pugu Hills, Matumbi Hills, Rondo and Litipo and other plateaux near Lindi (Tanzania); the Tanzanian offshore island of Pemba; Bazaruto archipelago (Mozambique), and tiny forest remnants of southern Malawi, eastern Zimbabwe and Mozambique. Most coastal forest endemics have a narrow distributional range, often exhibiting single‐site endemism or with scattered or disjunct distributional patterns. They are best interpreted as relicts and not the result of recent evolution. Relictualization probably started with the separation of the ancient Pan African rainforest into two parts during the Miocene. The coastal forests are interpreted as a ‘vanishing refuge’ with the endemic species gradually becoming more and more relict (and presumably extinct) due historically to climatic desiccation and more recently to human destruction.

East African coastal forests possess considerable botanical importance as an area of high plant endemicity, but are little known ecologically. Quantitative botanical sampling techniques have been used to determine vegetation communities in Pande and Kiono coastal forests, Tanzania. Data from 76 quadrats established in six transects (three in each forest) and containing a total of 146 plant species have been classified using TWINSPAN. Seven species-associations and four sample-associations are recognised. Undisturbed forest supports six species-associations which are rich in plant species of restricted distribution, and these differ between the sites studied. Forest heavily disturbed by man supports one species-association composed of more generalist forest species and this association is similar between sites. Variation in vegetation types of undisturbed forests appears to be caused by edaphic conditions, rainfall and degree of exposure. Variation in the vegetation of disturbed forests appears to be controlled by the intensity of forest disturbance. Heavy human disturbance of coastal forests reduces their biodiversity values as plant-diversity and the habitats of rare plant species are lost.

Several letters to the editor are presented in response to articles in previous issues including "Sunny outlook," by Nigel Lawson in the December 15, 2007 issue, "Desperate ambition," by Jane Clifton in the December 8, 2007 issue, and "The Black Page," by Joanne Black in the December 15, 2007 issue.

Urethral melanoma is very rare and pathological diagnosis is important. The prognosis remains poor irrespective of the treatment modality. Rare cases of long-term survival have been reported, one of them following conservative management. An initial attempt at conservative resection is worth considering to offer a better quality of life to the patient for as long as possible. We describe a technique of organ-sparing resection in the management of urethral melanoma along with the follow-up protocol that we adapted. Copyright 2001 The British Association of Plastic Surgeons

The signed sliding window (SSW) number system for accelerating long-wordlength modulo multiplication is introduced. Compared with the previously published unsigned sliding window (USW) number system, SSW reduces the average number of nonzero digits in a number or reduces the amount of pre-computation required. In addition, how USW and SSW can be combined advantageously with Montgomery's algorithm for modulo reduction is described.

A technique for converting the partial products in a modified Booth's algorithm multiplier from two's complement form to unsigned form, therefore eliminating the need for sign-extension circuitry is described. A proof is provided and an example of a multiply–accumulator given.

It is shown that operand prescaling doubles the speed of the maximally-redundant radix-4 SRT division iteration through design simplification.

A new and fast algorithm for SRT division that combines a modified version of the Svoboda algorithm with the radix-2 signed-digit number system is presented. The quotient bit selection is a simple function of the two most significant digits of the current partial remainder, and the two operands are each prescaled by a single subtraction.

SUMMARYPyoderma gangrenosum is an uncommon skin disorder characterised by deep ulcers surrounded by a violaceous over‐hanging edge. Although in many instances there is no clear association with any underlying disease, pyoderma gangrenosum has been described in ulcerative colitis, Crohn's disease, polyarthritis, diabetes mellitus and myeloma. Pyoderma gangrenosum may also be seen as a rare manifestation of myeloproliferative disease including leukaemia. In children, as in our case, it may be the presenting feature.

Extradural haematomas in children are rare, but they may occur following a trivial head injury. We report a case where, following an unrecognised head injury to a three‐year‐old child, the insidious non‐specific presentation of the extradural haematoma led to delay in the diagnosis and treatment.

Pancreatico-pleural fistula is a rare condition in which pancreatic enzymes drain directly in to the pleural cavity, most commonly from an enlarging pseudocyst. We review the literature on the causes, investigations and treatment of pancreatico-pleural fistulae and compare this with our own experience of the case of a 41 year old man with a left sided pancreatico-pleural fistula associated with pancreatic duct obstruction. The fistula could not be demonstrated by USS, CT or ERCP, and after these investigations the patient was managed conservatively. However, deterioration in the patients' condition led to an urgent but not emergency laparotomy and operative pancreatogram. This demonstrated the distally obstructed pancreatic duct, with associated pleural fistula for which aggressive surgical intervention was indicated. The patient subsequently completely recovered.

Extradural abscess is a rare but recognized complication of extradural anaesthesia. Previous reports have been associated with a short time interval between extradural catheterization and presentation. We report a patient with rheumatoid arthritis, receiving steroid therapy, in whom an extradural abscess did not present until 23 days after the insertion of a thoracic extradural catheter to provide postoperative analgesia.