Antegrade continence enema (ACE): predictors of outcome in 111 patients

PURPOSE

The antegrade continence enema (ACE) is used as a means of managing faecal incontinence and constipation with varying outcomes. We aim to evaluate our outcomes of ACEs and identify predictors of outcome.

METHODS

A retrospective case-note review of patients ≤16 years of age undergoing an ACE (March 2000-September 2013) was carried out. Data collected included: patient demographics, functional outcomes and complications. Data are quoted as median (range) and compared using Mann-Whitney and Fisher's exact test. Univariate analysis was performed to identify predictors of successful outcomes. P < 0.05 is significant. Successful outcome = total continence/occasional leakage and failed outcome = regular soiling and/or constipation.

RESULTS

111 patients with complete data sets underwent an ACE [59% male, median age = 9.5 years (3.4-16 years)] and median follow-up = 48 months (4 months-11 years 4 months). Underlying diagnoses were idiopathic constipation (n = 68), anorectal malformation (n = 27), neuropathic bowel (n = 7), Hirschsprung disease (n = 5) and gastrointestinal dysmotility (n = 4). Social continence was achieved in 87/111 (78%). Fifteen percent of patients underwent reversal of ACE due to resolution of symptoms. There was no difference in outcomes related to diagnosis, gender, age or follow-up duration. Complication rate was 20.7% (23/111).

CONCLUSIONS

The ACE is safe and effective in the management of intractable constipation and soiling. No predictors of outcome were identified.

Botulinum toxin use in paediatric colorectal surgery

PURPOSE

To evaluate outcomes of intrasphincteric botulinum toxin injection (ISBTI) in children with intractable constipation.

METHODS

Retrospective case-note review of patients ≤ 16 years of age undergoing ISBTI between January 2010 and February 2014. Data collected included patient demographics, diagnosis, complications, follow-up duration and functional outcomes. Successful outcome was defined as resolution/improvement in symptoms and failed when there was no change in symptoms. Statistical analyses were performed using PRISM (GraphPad, CA, USA). p values <0.05 were considered as significant.

RESULTS

43 patients [male 29, median age 5 years 9 months (range 13 months-13 years 5 months)] underwent 86 ISBTIs. Underlying diagnoses were idiopathic constipation (67 %), Hirschsprung disease (26 %), anorectal malformation (5 %), gastrointestinal dysmotility (2 %). 72 % (31/43) reported improvement in symptoms after the first ISBTI. 39 % of patients had recurrence of symptoms at 12-month median follow-up. 10 patients non-responsive to ISBTI required an antegrade continence enema or stoma. There was no correlation between age (p = 0.3), gender (p = 0.7), diagnosis (p  = 0.84), or number of ISBTIs (p = 0.17) with successful outcome.

CONCLUSION

Successful outcomes occurred in 72 % patients after the first ISBTI. 25 % required further surgical management of their symptoms. Further work is required to help predict which patients will benefit from ISBTI.

Exomphalos major: the Northern Ireland experience

PURPOSE

In exomphalos major (EM), closure of the defect in the abdominal wall presents a challenge. The aim of this study is to evaluate a single centre experience of EM.

MATERIALS

A 15-year retrospective case-note review; data presented as median (range).

RESULTS

Fourteen infants (7 female) were born with EM: birth weight 2.9 (1.2-3.8) kg, gestational age 38 (31-39) weeks. One infant died in utero and one within the first hour of life. Severe pulmonary hypoplasia was present in 7/13 (54%), and there was a mortality of 6/13 (46%) live births. Infants were treated non-operatively primarily. Two infants underwent early surgery: one infant, born with a ruptured sac, had a surgical silo constructed on day 1 and closure on day 8, while a second infant had partial closure (skin only) on day 11. Ten infants had application of silver sulphadiazine to the sac 2-3 times per week. Enteral feeds were established soon after birth. They were discharged from hospital to allow granulation. Ventral hernia closure was performed on a subsequent admission.

CONCLUSIONS

Exomphalos major can be successfully treated non-operatively, allowing immediate enteral feeding and early discharge while granulation takes place. In this series, exomphalos major has an incidence of 1 in 26,000, mortality is 46% and severe pulmonary hypoplasia is present in 54% of infants.

Benefit of preformed silos in the management of gastroschisis

Gastroschisis is traditionally managed by primary closure (PC) or delayed closure after surgical silo placement. Bedside insertion of preformed silos (PFS) and delayed closure has become more widespread, although its benefits remain unclear. To identify differences in outcome of infants managed with PFS compared with traditional closure (TC) techniques. Single-centre retrospective review of 53 consecutive neonates admitted between February 2000 and January 2006. Data expressed as median (range). Non-parametric statistical analysis used with P < 0.05 regarded as significant. Forty infants underwent TC and 13 had PFS and delayed closure. Median ventilation time in both groups was 4 days (P = 0.19) however this was achieved with higher mean airway pressures (MAPs) (day 0, 10 (5-16) versus 8 (5-10) cmH(2)O; P = 0.02) and inspired oxygen (40 (21-100) versus 30 (21-60)%; P = 0.03) in TC group. Urine output on day-1 of life was significantly higher in PFS group (1.1 (0.16-3.07) versus 0.45 (0-2.8) ml/kg/h; P = 0.02). Inotrope support was required in 17/40 (43%) of TC versus 0/13 (0%) in PFS (P < 0.01). After exclusion of infants with short bowel syndrome and/or intestinal atresia (n = 9), there was a shorter time to full enteral feeds in the TC group (22 (12-36) versus 27 (17-45); P = 0.07), although there was no difference in the period of parenteral nutrition (PN) (P = 0.1) or overall hospital stay (P = 0.34). No deaths or episodes of necrotizing enterocolitis occurred. The use of PFS for gastroschisis closure is associated with a reduction in pulmonary barotrauma, better tissue perfusion and improved early renal function, consistent with a reduction in abdominal compartment syndrome.

Homozygous mutation of focal adhesion kinase in embryonic stem cell derived neurons: normal electrophysiological and morphological properties in vitro

Background

Genetically manipulated embryonic stem (ES) cell derived neurons (ESNs) provide a powerful system with which to study the consequences of gene manipulation in mature, synaptically connected neurons in vitro. Here we report a study of focal adhesion kinase (FAK), which has been implicated in synapse formation and regulation of ion channels, using the ESN system to circumvent the embryonic lethality of homozygous FAK mutant mice.

Results

Mouse ES cells carrying homozygous null mutations (FAK^-/-) were generated and differentiated in vitro into neurons. FAK^-/- ESNs extended axons and dendrites and formed morphologically and electrophysiologically intact synapses. A detailed study of NMDA receptor gated currents and voltage sensitive calcium currents revealed no difference in their magnitude, or modulation by tyrosine kinases.

Conclusion

FAK does not have an obligatory role in neuronal differentiation, synapse formation or the expression of NMDA receptor or voltage-gated calcium currents under the conditions used in this study. The use of genetically modified ESNs has great potential for rapidly and effectively examining the consequences of neuronal gene manipulation and is complementary to mouse studies.

Aortic root replacement in patients with Marfan's syndrome: the Southampton experience

BACKGROUND

The purpose of this study was to evaluate the early and late clinical outcome after aortic root replacement (ARR) in patients with Marfan's syndrome.

METHODS

A total of 65 consecutive patients with Marfan's syndrome (mean age 41.7 +/- 10.7 years, range 15 to 76 years) undergoing ARR between 1972 and 1998 in Southampton were studied. Of the patients, 45 had a chronic aneurysm of the ascending aorta and 20 had a type A dissection (16 acute and 4 chronic). The operations were elective in 38 and nonelective in 27 cases (emergency in 22 and urgent in 5). Mean size of the ascending aorta was 6.3 +/- 1.4 cm (3.8 to 12 cm). A Bentall procedure was performed in 62 and a homograft root replacement in 3 patients. Mean follow-up was 8 +/- 4.1 years (0 to 22.9 years).

RESULTS

Operative mortality was 6.1% (4 deaths) (for the elective vs nonelective procedures it was 2.6% vs 11%, p = 0.2). The 10-year freedom from thromboembolism, hemorrhage, and endocarditis was 88%, 89.8%, and 98.4% (0.9%, 0.9%, and 0.2% per patient-year) and from late aortic events it was 86.3% (1.3% per patient-year). Aortic root replacement for dissection was an independent predictor of occurrence of late aortic events (p = 0.01). Five patients had a reoperation with one early death. The 10-year freedom from reoperation was 89.2% (1.1% per patient year) (for elective and nonelective procedures, 90.8% vs 84.6%, p = 0.6). The 10-year survival, including operative mortality, was 72.7% (for elective and nonelective procedures, 78% vs 66.5%, p = 0.6). Late aortic events was an independent adverse predictor of survival (p = 0.02).

CONCLUSIONS

In patients with Marfan's syndrome, elective ARR, usually for chronic aneurysm, is associated with a low mortality, low rate of aortic complications, and good late survival. Nonelective ARR, mostly for dissection, has a greater operative risk and a significantly higher incidence of late catastrophic aortic events. Early prophylactic surgery in these patients is therefore recommended. Long-term clinical and radiologic follow-up to prevent or to treat late aortic events is highly desirable.

Enhanced long-term potentiation and impaired learning in mice with mutant postsynaptic density-95 protein

Specific patterns of neuronal firing induce changes in synaptic strength that may contribute to learning and memory. If the postsynaptic NMDA (N-methyl-D-aspartate) receptors are blocked, long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission and the learning of spatial information are prevented. The NMDA receptor can bind a protein known as postsynaptic density-95 (PSD-95), which may regulate the localization of and/or signalling by the receptor. In mutant mice lacking PSD-95, the frequency function of NMDA-dependent LTP and LTD is shifted to produce strikingly enhanced LTP at different frequencies of synaptic stimulation. In keeping with neural-network models that incorporate bidirectional learning rules, this frequency shift is accompanied by severely impaired spatial learning. Synaptic NMDA-receptor currents, subunit expression, localization and synaptic morphology are all unaffected in the mutant mice. PSD-95 thus appears to be important in coupling the NMDA receptor to pathways that control bidirectional synaptic plasticity and learning.

Influence of rhodamine 123 on the photosensitizing properties of porphyrins

The photophysical and photochemical properties of porphyrins were profoundly changed upon addition of rhodamine 123. The Soret band of the porphyrins shifted to higher wavelengths, the fluorescence yield of the porphyrins decreased with unaltered decay rates, and their triplet state was quenched. These observations indicate a strong interaction between porphyrins and rhodamine 123 and formation of 1:1 nonfluorescent complexes, of which the binding constants were determined. Illumination of a porphyrin in the presence of rhodamine 123 resulted in the formation of a porphyrin radical cation, which could be detected with ESR spectroscopy. Quenching of the triplet state of the porphyrins by rhodamine 123 resulted in a decreased singlet oxygen yield and a decrease of the photooxidation of histidine, methionine, tyrosine, and tryptophan. However, the oxidation of thiol compounds was increased and the stoichiometry of the reaction between cysteine and oxygen changed from 2 to 3.8 mol cysteine/ mol oxygen. These results show that the presence of rhodamine 123 converted the for porphyrins prevalent energy transfer (type II) reaction to an electron transfer (type I) reaction.

Bilirubin phototoxicity to human cells by green light phototherapy in vitro

Phototherapy of newborn infants with blue or green light is the most common treatment of neonatal hyperbilirubinemia. Using bilirubin bound to human lymphoid and basal skin cells we obtained the green light dose dependency of the bilirubin phototoxicity to these cell types. Cells (3-5 x 10(6)/mL) were incubated with bilirubin complexed to human serum albumin (final concentrations 340 microM bilirubin, 150 microM albumin). Under these conditions all cells showed maximum binding of bilirubin. Irradiation with broadband green light (lambda max = 512 nm) over 24 h led to a light dose-dependent population of cells, which contained no bilirubin on the cell membrane as determined by Nomarski interference microscopy. The light-induced mechanism of the disappearance of bilirubin caused lethal membrane damage to the cells (trypan blue exclusion test). The cell kill rate increased with the irradiation dose and with the fraction of cells with no bilirubin. When 90% of lymphoid cells were bilirubin free, 46% of them were dead (using 480 J cm-1 green light). Similar results were obtained with basal skin cells. In addition, bilirubin-induced damage of cell membrane and nuclear membrane was also shown by transmission electron microscopy. Bilirubin (340 microM) in the dark led to 5% of the cells being killed. Basal skin cells bind 2.5 times more bilirubin molecules than lymphoid cells and showed a different bilirubin disappearance. Irradiation of bilirubin in carbon tetrachloride with 514.5 nm laser light showed generation of singlet oxygen via its luminescence at 1270 nm. These results demonstrate that green light phototherapy of hyperbilirubinemia may cause both skin and immune system damage.

Pentobarbitone modulation of NMDA receptors in neurones isolated from the rat olfactory brain

1. The action of pentobarbitone on the N-methyl-D-aspartate (NMDA) receptors of neurones freshly dissociated from the olfactory bulb and olfactory tubercle has been studied using patch-clamp techniques. 2. Pentobarbitone produced a concentration-dependent depression of the currents evoked by NMDA with an IC50 value of c. 250 microM. 3. Analysis of the NMDA-evoked noise produced power spectra that could be fitted by the sum of two Lorentzians with corner frequencies of 17 and 82 Hz. Pentobarbitone increased the corner frequency of the high frequency component but did not alter the apparent single channel conductance estimated from the noise. 4. Single channel recordings in either the cell-attached or outside-out patch configurations revealed that NMDA (20 or 50 microM) opened channels with a main conductance level around 55 pS and a principal subconductance around 44 pS. The uncorrected mean open time of the channels was 3.4 ms and mean burst length was 6.0 ms. Mean cluster length was about 12 ms. 5. Pentobarbitone produced a concentration-dependent reduction in both mean open time and burst length. Mean cluster length was much less affected. Pentobarbitone did not decrease unitary current amplitude or bias the open-state current amplitude distribution in favour of a particular substate. 6. From these data it appears that pentobarbitone depresses the inward current evoked by NMDA by reducing the probability of channel opening and this results from a shortening of the lifetime of the channel open state and by decreasing burst length.

Singlet oxygen luminescence spectra: a comparison of interferometer- and grating-based spectrometers

The current trend in methodology for determining IR and near-IR absorption spectra is to employ interferometer-based instruments to replace the monochromator-based devices used heretofore. As a dispersion element, the interferometer offers major improvements in spectral resolution (Connes advantage), light throughput (Jacquinot advantage) and data acquisition through multiplexing (Felgett advantage). We have compared signal-to-noise (S/N) ratios of grating-based and interferometer-based instruments for making spectral determinations of near-IR luminescence. Our results show that under identical excitation and detector conditions the interferometer instrument easily outperforms the grating, giving a 10-fold improvement in S/N at high signal amplitude (A488nm = 0.97) and a 20-fold improvement when the signal amplitude is low (A488nm = 0.06). Although some spectral resolution is sacrificed when scan times on the Fourier transform (FT)IR are significantly shortened, the S/N ratio was found only to decrease by a factor of 2 for a 10-fold decrease in scan time. This adds to the advantages of the FTIR technique because the S/N will thus improve for the same total acquisition time.

Anaesthetic modulation of nicotinic ion channel kinetics in bovine chromaffin cells

1. We have investigated the action of the anaesthetics methoxyflurane, methohexitone and etomidate on the nicotinic acetylcholine receptor channel of bovine adrenal chromaffin cells using the whole cell patch clamp technique. 2. Spectral analysis of macroscopic currents evoked by 25 microM carbachol revealed that each of the agents tested reduced the lifetime of the channel open state in a dose-dependent manner. The whole cell current was inhibited in a concentration-dependent fashion by each agent. 3. Channel gating parameters were calculated from single channel studies and the results used to test models explaining the modulation of nicotinic acetylcholine receptor channels by anaesthetics. 4. Each of the agents studied reduced the mean channel open time in a concentration-dependent manner. Anaesthetic concentrations reducing mean open time by 50% were: 370 microM methoxyflurane, 30 microM methohexitone or 23 microM etomidate. 5. Methohexitone and etomidate produced an increase in the number of brief closures within bursts, while no such increase was observed with methoxyflurane. Despite these inter-burst gaps, mean burst length was reduced by each of the agents tested. 6. It is concluded that a simple sequential blocking model fails to account for the action of these anaesthetics. An extended model, in which blocked channels can close, may be applicable.

Calcium channel currents in bovine adrenal chromaffin cells and their modulation by anaesthetic agents

1. The calcium channel currents of bovine adrenal chromaffin cells were characterized using a variety of voltage pulse protocols and selective channel blockers before examination of their modulation by anaesthetic agents. 2. All the anaesthetics studied (halothane, methoxyflurane, etomidate and methohexitone) inhibited the calcium channel currents in a concentration-dependent manner and increased the rate of current decay. 3. The anaesthetics did not shift the current-voltage relation nor did they change the voltage for half-maximal channel activation derived from analysis of the voltage dependence of the tail currents. None of the anaesthetics appeared to alter the time constant of tail current decay. 4. To complement earlier studies of the inhibitory actions of anaesthetics on K(+)-evoked catecholamine secretion and the associated Ca2+ uptake, the IC50 values for etomidate and methohexitone were determined using a biochemical assay. The IC50 values for anaesthetic inhibition of calcium channel currents corresponded closely with those for inhibition of K(+)-evoked calcium uptake and catecholamine secretion. 5. The inhibitory effect of the volatile anaesthetics and etomidate is best explained by dual action: a reduction in the probability of channel opening coupled with an increase in the rate of channel inactivation. Methohexitone appeared to inhibit the currents by a use-dependent slow block.

Effects of the micro-environment on the photophysical properties of hematoporphyrin

The photochemical degradation of histidine, cysteine and tyrosine with hematoporphyrin as sensitizer was potentiated by the presence of Sephadex, BioGel or Percoll particles. This effect could only partly be explained by binding of the sensitizer to the gel particles, leading a.o. to monomerization of aggregated sensitizer molecules in the aqueous environment. The hematoporphyrin triplet state life time increased from 250 microseconds in phosphate buffer to 1992 microseconds in the presence of 50% Percoll. Most likely the effect of the gel particles on the sensitizer triplet state is, at least partly, mediated by the solvent. A plausible explanation seems to be that the vicinal water structure at the particle interface stabilizes the sensitizer triplet.

The action of anaesthetics on stimulus-secretion coupling and synaptic activity

1. Anaesthetics are known to depress excitatory synaptic transmission and the mechanism of this inhibition has been investigated using bovine adrenal chromaffin cells as an experimental model. 2. These cells are homologous with post-ganglionic sympathetic neurons and have well characterized receptor and secretory mechanisms. They are amenable both to the direct measurement of evoked secretion with its associated ion fluxes, and to electrophysiological investigation using the patch clamp technique. 3. These approaches have been used to study the influence of anaesthetics on pre- and post-synaptic mechanisms involved in stimulus-secretion coupling. 4. A variety of agents inhibited secretion evoked by direct depolarization, and this was shown to be due to a reduction in calcium influx. 5. Direct inhibition of voltage-gated calcium currents was confirmed by whole-cell patch clamp measurements. 6. In addition, anaesthetics powerfully modulated nicotinic receptor mediated events: carbachol-evoked secretion was more sensitive to anaesthetics than that stimulated by high potassium. 7. The mechanism of anaesthetic action on the nAChR was examined in more detail with patch-clamp experiments. 8. These showed that anaesthetics reduced the probability of channels being in the open state, largely as a result of reduction in mean channel open time. 9. The data are discussed in relation to excitatory synaptic transmission.

The mechanism by which procaine inhibits catecholamine secretion from bovine chromaffin cells

1. We have investigated the action of procaine on stimulus-secretion coupling in bovine adrenal chromaffin cells. 2. Procaine inhibited the catecholamine secretion evoked by 500 microM carbachol (CCh) with an IC50 of 35 microM and the associated calcium influx (IC50 60 microM). It inhibited the catecholamine secretion evoked by depolarization with high potassium by less than 20% even at the highest concentrations tested (3.2 mM). 3. The secretion evoked by CCh was associated with an increase in sodium influx. This evoked influx was also inhibited by procaine (IC50 80 microM). 4. This selective action of procaine on the CCh-evoked catecholamine secretion was investigated further by patch-clamp techniques. 5. In agreement with the ion flux studies, procaine inhibited the inward current evoked by CCh. Procaine also altered the spectral characteristics of the noise associated with the agonist-induced current by adding an additional high frequency component. The amplitude of this component showed an e-fold increase for a 55 mV membrane hyperpolarization. 6. Data from cell-attached patches showed that increasing concentrations of procaine produced a progressive fall in the mean channel open time and an increase in mean blocked time. This combination led to a decrease in mean burst length. In addition, Popen was reduced by 50 microM procaine. These changes in channel conducting time were sufficient to account for the reduction in inward current. A limited study of the action of procaine on nicotinic channels in outside-out patches gave similar results. 7. The data were considered in relation to various schemes of anaesthetic-channel interactions. The data did not fit the sequential blocking model or the extended channel block model but could be fitted to a modified sequential blocking model in which the rate constant for channel reopening after block was itself subject to modulation by the anaesthetic and the blocked channel could close without passing through the open state.

Diagnostic peritoneal lavage: integration with clinical information to improve diagnostic performance

Management of abdominal trauma requires both the detection of injuries sustained and an ability to distinguish patients who require operative repair from those who do not. In this prospective study of 200 patients receiving diagnostic peritoneal lavage (DPL) following blunt trauma, relationships among DPL result, clinical features (information from initial patient assessment), and laparotomy outcome were investigated. The DPL result alone predicted requirement for laparotomy with an accuracy of 93%, a specificity of 96%, a sensitivity of 85%, a positive predictive value (PV-Positive) of 87%, and a negative predictive value (PV-Negative) of 95%. Combining clinical features with the DPL result reduced the number of unnecessary laparotomies (increased PV-Positive and specificity), but increased the number of missed necessary laparotomies (decreased PV-Negative and sensitivity). The best diagnostic performance was found by combining the DPL result with circulatory status, which, in this series of patients, predicted necessary laparotomy with an accuracy of 95%, a specificity of 99%, a sensitivity of 81%, a PV-Positive of 98%, and a PV-Negative of 94%.