Ex vivo normothermic perfusion for quality assessment of marginal donor kidney transplants.

BACKGROUND: A significant proportion of kidneys procured for transplantation are discarded because of concerns about their suitability. In this study ex vivo normothermic perfusion (EVNP) was used as a quality assessment device before renal transplantation. METHODS: Seventy-four human kidneys deemed unsuitable for transplantation following retrieval underwent 60 min of EVNP with an oxygenated red cell-based solution at 36°C. Receiver operating characteristic (ROC) curves were used to identify thresholds of renal blood flow and urine output. These thresholds and a grading of macroscopic appearance were incorporated into an EVNP assessment score (highest quality, 1; lowest, 5). This was applied to a series of 36 kidneys transplanted after EVNP. RESULTS: In the discarded kidney series, 60 (81 per cent) scored 1-4 and 14 (19 per cent) scored 5. Although none of these kidneys was transplanted, those with a score from 1 to 4 were considered suitable for transplantation. In the 36 transplanted kidneys, the score ranged between 1 and 3 (score 1, 17; score 2, 11; score 3, 8). All of these kidneys were transplanted without any complications or primary non-function. The delayed graft function rate was 6 per cent (1 of 17) in kidneys scoring 1, 0 per cent (0 of 11) in those scoring 2 and 38 per cent (3 of 8) in those scoring 3 (P = 0·024). The mean(s.d.) estimated glomerular filtration rate at 12 months was 51(16), 63(15) and 38(21) ml in kidneys scoring 1, 2 and 3 respectively (P = 0·015). CONCLUSION: EVNP combined with a simple scoring system is an innovative technology for pretransplant assessment of kidney quality and acceptability for transplantation. This study suggests that a high percentage of retrieved kidneys are being discarded unnecessarily.

Ischaemic conditioning reduces kidney injury in an experimental large-animal model of warm renal ischaemia.

BACKGROUND: Ischaemic conditioning, using short repeated sequences of intermittent ischaemia, is a strategy that may ameliorate ischaemia-reperfusion injury. The aim of the study was to assess the effects of direct and remote ischaemic conditioning in a porcine model of renal warm ischaemia-reperfusion injury. METHODS: Pigs (50 kg) underwent laparotomy and 60-min occlusion of the left renal pedicle followed by right nephrectomy. Animals were divided into three groups: untreated controls (n = 8); direct postconditioning involving six 15-s cycles of clamping then releasing of the left renal artery (n = 7); or remote periconditioning involving four 5-min cycles of clamping then releasing of the left common iliac artery (n = 8). After 7 days kidney tissue was harvested, and blood and urine samples were collected on postoperative days 1, 3 and 7. RESULTS: The direct postconditioning group had a lower area under the serum creatinine curve (mean(s.d.) 1378(157) versus 2001(1022) µmol/l · day respectively; P = 0.036) and peak creatinine level (316(46) versus 501(253) µmol/l respectively; P = 0.033) compared with values in control animals. There was a significant increase in serum levels of tumour necrosis factor α on day 1 in control animals but not in the conditioning groups (P = 0.013). Urinary levels of neutrophil gelatinase-associated lipocalin increased over the study period in both the control and remote groups (P = 0.001 for both), but not in the direct group (P = 0.176). There was no mortality and no complications related to either conditioning technique. CONCLUSION: In this in vivo large-animal model, direct renal artery ischaemic postconditioning protected kidneys against warm ischaemia injury. This straightforward technique could readily be translated into clinical practice. Surgical relevance Ischaemic conditioning has been shown to improve outcomes in both experimental studies and clinical trials in cardiac surgery. Evidence from small-animal and human studies assessing ischaemic conditioning techniques in renal transplantation have not yet established the optimal technique and timing of conditioning. In this study, a large-animal model of renal warm ischaemia was used to compare different conditioning techniques. Postconditioning applied directly to the renal artery was shown to reduce renal injury. Furthermore, new evidence is provided that shorter cycles of ischaemic postconditioning than previously described can protect against renal injury. Evidence from a large-animal model is provided for different conditioning techniques. The beneficial postconditioning technique described is straightforward to perform and provides an alternative method of conditioning following renal transplantation, with potential for application in clinical practice.

Midterm experience of ipsilateral axillary-axillary arteriovenous loop graft as tertiary access for haemodialysis.

Objectives. To present a series of ipsilateral axillary artery to axillary vein loop arm grafts as an alternative vascular access procedure for haemodialysis in patients with difficult access. Design. Retrospective case series. Methods. Patients who underwent an axillary loop arteriovenous graft from September 2009 to September 2012 were included. Preoperative venous imaging to exclude central venous stenosis and to image arm/axillary veins was performed. A cuffed PTFE graft was anastomosed to the distal axillary artery and axillary vein and looped on the arm. Results. 25 procedures were performed on 22 patients. Median age was 51 years, with 9 males and 13 females. Median number of previous access procedures was 3 (range 0-7). Median followup was 16.4 months (range 1-35). At 3 months and 1 year, the primary and secondary patency rates were 70% and 72% and 36% and 37%, respectively. There were 11 radiological interventions in 6 grafts including 5 angioplasties and 6 thrombectomies. There were 19 surgical procedures in 10 grafts, including thrombectomy, revision, repair for bleeding, and excision. Conclusions. Our series demonstrates that the axillary loop arm graft yields acceptable early patency rates in a complex group of patients but to maintain graft patency required high rates of surgical and radiological intervention, in particular graft thrombectomy.

Spontaneous, isolated caecal necrosis: report of a case, review of the literature, and updated classification.

Isolated necrosis of the caecum is a rare cause of abdominal pain. In the absence of occlusive vascular disease it has a number of well documented associations, the commonest of which is patients' receiving haemodialysis for endstage renal failure. It has also been associated with shock states, cardiac failure, ischaemic heart disease, diabetes and drugs such as cocaine, thiopentone and cytotoxic agents. However, there are few reported cases in the literature without the aforementioned associations and the majority of cases, regardless of aetiology, were treated with either hemicolectomy or wedge resection and ileocolic anastamosis. This report describes a case of isolated caecal necrosis, mimicking acute appendicitis, successfully treated by local excision of the necrotic segment. It also provides a systematic review of the literature and proposes an updated classification of associations in isolated caecal necrosis.

Effects of hydrogen sulphide in an experimental model of renal ischaemia-reperfusion injury.

BACKGROUND: Renal ischaemia-reperfusion injury (IRI) is a major cause of acute renal failure and renal transplant dysfunction. The aim of this study was to investigate the efficacy of the endogenous gaseous signalling molecule hydrogen sulphide in protecting against renal IRI. METHODS: Large White female pigs underwent laparotomy and cross-clamping of the left renal pedicle for 60 min. Animals were allocated randomly to treatment with either intravenous hydrogen sulphide (n = 6) or saline control (n = 6) 10 min before clamp release, and then underwent a right nephrectomy. Staff were blinded to treatment allocation and animals were recovered for 7 days. RESULTS: Hydrogen sulphide therapy resulted in a marked reduction in kidney injury with reduced serum creatinine levels on days 1-5, in a reduced area under the creatinine-time curve, and a halving of the time to achieve a creatinine level of less than 250 µmol/l, compared with the control. Hydrogen sulphide also preserved glomerular function, as shown by the urinary protein/creatinine ratio, which, compared with baseline, increased on days 1 and 3 in the control group (mean(s.e.m.) 3·22(1·43), P = 0·016 and 2·59(1·27), P = 0·031), but not in the treatment group (0·99(0·23), P = 0·190 and 1·06(0·44), P = 0·110, respectively). Mean(s.e.m.) tumour necrosis factor α levels at 6 h postreperfusion increased in the control animals (56(6) versus 115(21) pg/ml; P = 0·026), but not in the hydrogen sulphide-treated animals (61(7) versus 74(11) pg/ml; P = 0·460). Renal neutrophil infiltration at 30 min (myeloperoxidase staining) was also significantly reduced by treatment with hydrogen sulphide (P = 0·016). CONCLUSION: Hydrogen sulphide offers a promising new approach to ameliorating renal IRI with potential translation into a number of clinical settings, including renal transplantation.

Effect of season and ambient temperature on outcome of guaiac-based faecal occult blood tests performed for colorectal cancer screening.

AIM: Guaiac-based faecal occult blood tests (gFOBTs) are used in the colorectal cancer screening programme. Recent data suggested that the immunological faecal occult blood test illustrated a variation in positivity according to season and ambient temperature. Our aim was to assess the effect of season and ambient temperature on the positivity rates of the gFOBT during pilot screening for colorectal cancer. METHOD: Data from the first year of round 1 of the pilot screening programme in Coventry and Warwickshire were analysed. Patients with positive and negative gFOBT samples were included. Patients with spoilt samples or incomplete data were excluded. Of the total of 59513 patients, 30311 were men and 29202 women. Mean age was 56 years. Daily temperature data were provided by the meteorological office. RESULTS: Median exposure of the gFOBT test card was 6 days (range 1-17). Median daily maximum temperature was 14°C. Spring and summer illustrated significantly decreased positivity rates compared with autumn and winter (Pearson's chi-squared test, P<0.001). Mean daily maximum temperature for the test card exposure showed no significant difference in positivity rates (P=0.53). Subgroup analysis revealed a significant reduction in positive samples in the >25°C subgroup (P=0.045). CONCLUSIONS: There is a seasonal variation in positivity rates of gFOBTs with increased positivity in spring and summer months. There is no difference in positivity rates in relation to ambient temperature except in subgroup analysis where there is a significant reduction in positivity rates above 25°C.

Stability of phantom limb phenomena after upper limb amputation: a longitudinal study.

Amputees may experience stump pain (SP), phantom limb (PL) sensations, pain, and/or a general awareness of the missing limb. The mechanisms underlying these perceptions could involve nervous system neuroplasticity and be reflected in altered sensory function of the residual limb. Since little is known about the progression of post-amputation sensory phenomena over time, we longitudinally evaluated the stability of, and relationships among: 1) subjective reports of PL sensations, pain, awareness, and SP, 2) stump tactile and tactile spatial acuity thresholds, and 3) use of a functional vs. a cosmetic prosthesis in 11 otherwise healthy individuals with recent unilateral, traumatic upper-extremity amputation. Subjects were evaluated within 6 months and at 1-3 years after amputation. Processing of tactile sensory information from the stump remained stable over the study time period. PL awareness was frequent, stable over time, intense, and occurred with or without PL sensations. Functional prosthetic use correlated with stable vividness of PL awareness whereas subjects who used a cosmetic prosthesis had less vivid PL awareness at follow-up. Initial SP correlated with follow-up SP, the initial PL pain correlated with follow-up PL pain but neither initial nor follow-up SP appear to be related to follow-up PL pain after accounting for initial PL pain intensity. Neither limb temperature nor prosthesis-use correlated with the initial vs. follow-up change in PL pain intensity. These data provide evidence that PL pain described 1-3 years after an amputation is not related in any simple way to peripheral sensory function, SP, or limb temperature; and PL awareness but not PL pain may be influenced by the frequent use of a functional prosthesis.

The 2-minute walk test as a measure of functional improvement in persons with lower limb amputation.

OBJECTIVE: To determine the construct validity and responsiveness of the 2-minute walk test as a measure of function in individuals with lower extremity amputation. DESIGN: The distances walked in 2 minutes were compared with the results on the physical functioning subscale of the Medical Outcomes Study Short-Form 36-Item Health Survey (SF-36) and the Houghton Scale. SETTING: Regional amputee rehabilitation program. PATIENTS: Retrospective data from 290 patients (mean age, 66yr) with unilateral transtibial, unilateral transfemoral, or bilateral amputations. INTERVENTION: Repeated testing. MAIN OUTCOME MEASURES: Distance walked in 2 minutes, SF-36 (aggregated into physical and mental composite scores), and the Houghton score. We also examined the change in the distance before and after a rehabilitation program. RESULTS: The distance walked in 2 minutes showed a weak correlation with the physical functioning subscale of the SF-36 (r = .22, p = .008) and a moderate correlation with the total Houghton score at discharge from rehabilitation (r = .493, p

Evolutionary and preservational constraints on origins of biologic groups: divergence times of eutherian mammals.

Some molecular clock estimates of divergence times of taxonomic groups undergoing evolutionary radiation are much older than the groups' first observed fossil record. Mathematical models of branching evolution are used to estimate the maximal rate of fossil preservation consistent with a postulated missing history, given the sum of species durations implied by early origins under a range of species origination and extinction rates. The plausibility of postulated divergence times depends on origination, extinction, and preservation rates estimated from the fossil record. For eutherian mammals, this approach suggests that it is unlikely that many modern orders arose much earlier than their oldest fossil records.

Key innovations and the ecology of macroevolution.

The origin or evolutionary `success' of taxa is often attributed to key innovations-aspects of organismal phenotype that promote diversification. Different ways of delimiting taxa and measuring `success' (i.e. number or longevity of species, morphological variety or differential control of energy) give rise to different ideas of how key innovations might operate. Key innovations may enhance competitive ability, relax adaptive trade-offs or permit exploitation of a new productive resource base. Recent key innovation studies comparing species richness in extant sister clades may miss important observations possible only with consideration of the fossil record, traditional higher taxa and phenotypic diversity.

Molar tooth diversity, disparity, and ecology in Cenozoic ungulate radiations.

A classic example of adaptive radiation is the diversification of Cenozoic ungulates into herbivore adaptive zones. Their taxonomic diversification has been associated with changes in molar tooth morphology. Analysis of molar crown types of the Artiodactyla, Perissodactyla, and archaic ungulates ("Condylarthra") shows that the diversity of genera and crown types was high in the Eocene. Post-Eocene molars of intermediate crown types are rare, and thus the ungulate fauna contained more taxa having fewer but more disparate crown types. Taxonomic diversity trends alone give incomplete descriptions of adaptive radiations.

The hypocone as a key innovation in mammalian evolution.

The hypocone, a cusp added to the primitively triangular upper molar teeth of therian mammals, has evolved convergently > 20 times among mammals during the Cenozoic. Acquisition of the hypocone itself involves little phenotypic change, but subsequent diversification of groups possessing the hypocone may be greatly enhanced. Our analysis of the Cenozoic mammalian radiations, including the Recent fauna, shows that high species diversity of mammals with hypocones and association of the hypocone with herbivory strongly support recognition of the hypocone as a key innovation that has allowed invasion of, and diversification within, herbivorous adaptive zones. In contrast, mammals lacking hypocones show no marked increase in species diversity during the Cenozoic.

Egr-1 activation of rat adrenal phenylethanolamine N-methyltransferase gene.

The immediate early gene transcription factor Egr-1 increases luciferase reporter gene activity 3-4-fold when a rat phenylethanolamine N-methyltransferase (PNMT) promoter-luciferase construct and an Egr-1 expression construct are cotransfected into transformed PC12 cells (RS1). Egr-1 also stimulates endogenous PNMT mRNA expression in the RS1 cells. Furthermore, when transfected RS1 cells are treated with dexamethasone, both luciferase and endogenous PNMT mRNA rise an additional 2-fold although dexamethasone does not independently activate transcription from the PNMT promoter. While both Egr-1 sites (-45 and -165 base pairs) in the PNMT promoter appear necessary for maximum luciferase reporter gene expression, the -165 site appears to be the more important for mediating the Egr-1 response. When the upstream site is deleted or either or both sites are mutated in PNMT-reporter gene constructs, Egr-1-induced luciferase activity from the PNMT promoter is significantly reduced. In addition, the incremental activation by dexamethasone is lost when sequences containing the glucocorticoid response element are deleted or when the Egr-1 sites are mutated. In the transfected RS1 cells, a rise in nuclear Egr-1 protein accompanies the rise in endogenous PNMT mRNA. Similarly, reserpine-treated rats (10 mg/kg, intraperitoneally), which show an 8-fold elevation in adrenal PNMT mRNA at 6 h postdrug administration, also show a marked rise in Egr-1 protein in adrenal medullary cell nuclei. These studies provide the first direct evidence that a transcription factor, Egr-1, can activate PNMT gene expression and identify PNMT as a novel target gene for Egr-1. Finally, the incremental enhancement of the Egr-1 response by glucocorticoids suggests a potential interaction between Egr-1 and another transcription factor, the glucocorticoid receptor.

Segmental effects of epidural spinal cord stimulation in humans.

1. The segmental effects of spinal cord stimulation (SCS) were studied in twenty-four human subjects who had spinal cord stimulators implanted for the treatment of pain. The cathode was in the epidural space over the dorsum of the thoracic cord. 2. SCS generated action potentials in sensory, motor and mixed nerves which could be recorded with near-nerve electrodes. These action potentials could follow high frequencies of stimulation and appeared to be due to the antidromic activation of primary afferents in the dorsal columns. 3. Synaptic actions on single lumbosacral motoneurons were derived from peristimulus time histograms (PSTHs) of single motor units. SCS produced a brief short-latency period of increased firing probability (PIF) in motoneurons of all of the muscles examined, probably representing monosynaptic activation. It is argued that the facilitation arises from the antidromic activation of Ia afferents in the dorsal columns. This is the probable explanation for the muscle contractions that can be induced by SCS. 4. SCS inhibited short-latency group I homonymous facilitation and reciprocal inhibition. The mechanism appears to be presynaptic to the motoneurons and may represent collision in Ia afferents, presynaptic inhibition or homosynaptic depression. 5. It was difficult to demonstrate consistent effects of SCS on reflex pathways from cutaneous afferents to flexor motoneurons because the effects of stimulation of cutaneous nerves on these motoneurons were themselves variable. 6. It is concluded that SCS applied with epidural electrodes over the dorsal cord activates primary afferents in the dorsal columns. Antidromic activation of these afferents results in strong monosynaptic facilitation of motoneurons as well as reduction in transmission in some reflex pathways to motoneurons.

Acyloxyacyl hydrolase, a leukocyte enzyme that deacylates bacterial lipopolysaccharides, has phospholipase, lysophospholipase, diacylglycerollipase, and acyltransferase activities in vitro.

Human acyloxyacyl hydrolase (AOAH) is a leukocyte enzyme that hydrolyzes acyloxyacyl bonds in the lipid A region of bacterial lipopolysaccharide (LPS), thereby detoxifying the LPS. We report here that the enzyme also acts in vitro on glycerophospholipids, lysophospholipids, and diacylglycerol. While AOAH preferentially removes palmitate or stearate from the sn-1 position of phospholipid and diacylglycerol substrates that have unsaturated acyl chains in the sn-2 position, it is able to cleave both palmitates from sn-1,2-dipalmitoylphosphatidylcholine and sn-1,2-dipalmitoylglycerol. This apparent preference for removing saturated (or shorter) acyl chains from glycerolipids is consistent with its ability to cleave laurate more rapidly than palmitoleate from lipopolysaccharide (Erwin, A. L., and Munford, R. S. (1990) J. Biol. Chem. 265, 16444-16449). AOAH also catalyzes acyl transfer from LPS and phosphatidylethanolamine to acceptor lipids; approximately equal amounts of laurate and myristate are transferred from LPS to monooleoylglyceryl ether, forming acyloleoylglyceryl ether. The demonstration that AOAH has phospholipase, lysophospholipase, diacylglycerol lipase, and acyltransferase activities in vitro suggests that the enzyme may have roles in addition to LPS deacylation (detoxification) in phagocytic cells.

Afferents contributing to the exaggerated long latency reflex response to electrical stimulation in Parkinson's disease.

Reflex pathways to tibialis anterior motoneurons from low threshold afferents of the common peroneal nerve were examined in 13 Parkinsonian subjects and 12 age-matched normals. Post-synaptic events occurring in single motoneurons were derived from changes in the firing probability of single voluntarily activated motor units during afferent stimulation. A period of increased firing probability of "monosynaptic" latency (about 33 ms) occurred in all subjects in both groups. A second, later, period of increased firing probability (latency about 64 ms) was seen in 2/12 normals and 8/13 Parkinsonian subjects. Neither of these responses could be produced by cutaneous stimulation. The electrical threshold of the afferents mediating the later effect was 0.82 of the threshold of alpha motoneuron axons which is similar to that of the afferents mediating the shorter latency response. Thus, large non cutaneous afferents contribute to this long latency response in man presumably through polysynaptic pathways. Transmission in these pathways is enhanced in Parkinson's disease.

Further observations on the depression of group Ia facilitation of motoneurons by vibration in man.

Stimulation of low threshold afferents in the peroneal nerve causes a short latency facilitation of individual tibialis anterior motor units considered to be due to the composite Ia EPSP. This facilitation is depressed by vibration 20 to 128 Hz applied over the tibialis anterior. The depression occurs without any change in the firing rate of the motor unit or in the facilitation from cutaneous afferents and so is unlikely to be due to postsynaptic inhibition. The depression can occur with vibration frequencies as low as 40 Hz and is therefore unlikely to be due to occlusion in Ia afferents. There is no evidence that vibration alters the electrical threshold of large afferents. A similar facilitation of soleus motor units resulting from stimulation of low threshold afferents in the tibial nerve is depressed for up to 75 ms following a 40 ms burst of 50 Hz vibration applied to the tendon of the tibialis anterior. The burst of vibration itself did not facilitate soleus motor units so there is no evidence to suggest that the vibration spread to soleus spindles. Homosynaptic depression is, therefore, unlikely. These findings provide further evidence that presynaptic inhibition of Ia afferents occurs in man.