The HPB Clinic: Do Patients Want a Copy of Their Clinic Letter?

The NHS plan published by the Department of Health (DH) in 2000 recommended that patients should receive copies of all clinician-generated correspondence written about them. Concerns from many groups delayed widespread implementation of the policy and a committee set up under the NHS Modernisation Board recommended that further research was required in this area prior to rolling out the policy fully. Good practice guidelines on copying letters to patients were subsequently produced by the DH in 2001.

Surgical adjuncts to laparoscopic distal pancreatectomy

Abstract Laparoscopic distal pancreatectomy (LDP) has emerged as an alternative approach to traditional open surgery for managing isolated pathology in the body and tail of the pancreas. Experience with this technique to date is limited with only small series reported in the literature. Common difficulties with this operation are related to dissection of the pancreas from the portal vein and management of the pancreatic stump. In this paper we describe our single centre experience to date and describe strategies we have developed which we believe facilitate safe and effective laparoscopic distal pancreatectomy.

Successful management of necrotizing pancreatitis by percutaneous necrosectomy after orthotopic liver transplant for paracetamol induced acute liver failure: a case report

OBJECTIVES

Acute pancreatitis, which can develop after any whole-organ transplant, is often associated with immunosuppression. Pancreatitis that complicates a liver transplant can be a significant problem that results in a high mortality rate.

MATERIALS AND METHODS

We describe the successful use of minimally invasive techniques to treat severe acute pancreatitis. To our knowledge, this is the first reported case in which major laparotomy was precluded by the use of percutaneous necrosectomy to manage necrotizing pancreatitis in a liver transplant recipient. We also briefly review the published literature on severe acute pancreatitis in liver transplant recipients.

RESULTS

Our patient, who had a Model for End- Stage Liver Disease score of 39 when transplanted and an Acute Physiology and Chronic Health Evaluation II score of 19 when infected necrosis in his pancreas was diagnosed, recovered completely after 92 days of hospitalization. He underwent 2 percutaneous drainage procedures and 3 percutaneous necrosectomies to treat his pancreatic complication. A review of the literature revealed that severe acute pancreatitis significantly increases morbidity and mortality in liver transplant recipients. Unlike necrotizing pancreatitis, which develops outside the context of liver transplant where there is a distinct shift towards minimally invasive procedures, infected necrosis associated with fulminant liver failure or a liver transplant is usually treated with open necrosectomy.

CONCLUSIONS

Severe acute pancreatitis in liver transplant recipients should be managed exactly as it is in patients who have not received a liver transplant. Anatomically guided minimally invasive necrosectomy appears to be beneficial, especially when patients are critically unwell, as they are following a liver transplant.

Pancreas transplantation

Since the introduction of pancreas transplantation more than 40 years ago, efforts to develop more minimally invasive techniques for endocrine replacement therapy have been in progress, yet this surgical procedure still remains the treatment of choice for diabetic patients with end-stage renal failure. Many improvements have been made in the surgical techniques and immunosuppressive regimens, both of which have contributed to an increasing number of indications for pancreas transplantation. This operation can be justified on the basis that patients replace daily injections of insulin with an improved quality of life but at the expense of a major surgical procedure and lifelong immunosuppression. The various indications, categories, and outcomes of patients having a pancreas transplant are discussed, particularly with reference to the effect on long-term diabetic complications.

Survival rates of tropical and temperate passerines: a Trinidadian perspective

Mark-recapture data collected using mist nets over a 10-yr period in Trinidad were used to estimate adult survival rates for 17 species of forest passerines. Trinidadian survival rates (mean 65%, range 45%-85%) were significantly higher than published estimates for European (mean survival 52%, range 32%-71%) and North American (mean survival 53%, range 29%-63%) passerines of similar body size (equivalent to 45% higher mean life expectancy in Trinidad). These findings were confirmed after controlling for phylogeny using a method of independent contrasts. Transient and/or young birds were an important feature of the Trinidad data, and studies that fail to allow for the presence of such birds risk underestimating adult survival. This study lends support to the hypothesis that avian survival rates are higher in the humid tropics, although the magnitude of the difference may be smaller than previously suggested.

Pancreas transplantation

Over the last 5 years, there has been a resumed interest in treating diabetes by transplantation, particularly islet transplantation. However, despite advances being reported in Canada and the US, replication in the UK has been much more difficult. At present there is still only one treatment that can consistently reverse insulin independence in the long-term and that is whole pancreas transplantation. Long-term normoglycaemia has beneficial effects on preventing and ameliorating the secondary complications of diabetes and will be discussed.

Pancreas graft salvage using pancreatico-duodenectomy with enteric drainage

As demand for donor pancreases increases, attempts are being made to utilize even marginal grafts for transplantation. Injury during pancreas recovery can predispose to posttransplant complications and graft loss. Early recognition and correction can salvage these grafts. The authors report an instance of poor segmental perfusion of the pancreas graft that was salvaged by pancreas head resection and enteric drainage through a Roux-en-Y pancreatico-jejunostomy.

Liver resection for colorectal liver metastasis

At some point in the natural course of colorectal cancer up to 50% of patients will develop metastasis to the liver. Historically only 20% of these patients would have to be deemed resectable, with an intent to cure, at the time of presentation. But with recent improvements in cross-sectional imaging, chemotherapeutic agents and advances in the techniques of surgical resection the emphasis of resection has now changed to 'who is not resectable' as opposed to 'who is resectable'. There are few contraindications to liver resection on the proviso that the patient is fit enough. As a result of this paradigm shift, 5 year survival rates are approaching 60%. Historically liver resection was perceived as a formidable operation but now liver resection for CRLM is safe and specialist centres are reporting mortality rates of less than 1%. This review briefly covers the standard techniques currently employed and some of the recent innovations being developed to improve resectability.

Singing, but not seizure, induces synaptotagmin IV in zebra finch song circuit nuclei

Synaptotagmins are a family of proteins that function in membrane fusion events, including synaptic vesicle exocytosis. Within this family, synaptotagmin IV (Syt IV) is unique in being a depolarization-induced immediate early gene (IEG). Experimental perturbation of Syt IV modulates neurotransmitter release in mice, flies, and PC12 cells, and modulates learning in mice. Despite these features, induction of Syt IV expression by a natural behavior has not been previously reported. We used the zebra finch, a songbird species, to investigate Syt IV because song is a naturally learned behavior whose neuroanatomical basis is largely identified. We observed that, similar to rodents, Syt IV is inducible in songbirds. This induction was selective and depended on the nature of neuronal depolarization. Generalized seizures caused by the GABA(A) receptor antagonist, metrazole, induced the IEG, ZENK, in zebra finch brain. However, these same seizures failed to induce Syt IV in song control areas. In contrast, when nontreated birds sang, three song control areas showed striking Syt IV induction. Further, this induction appeared sensitive to the social context in which song was sung. Together, these data suggest that neural activity during singing can drive Syt IV expression within song circuitry whereas generalized seizure activity fails to do so even though song control areas are depolarized. Our findings indicate that, within this neural circuit for a procedurally learned sensorimotor behavior, Syt IV is selective and requires precisely patterned neural activity and/or neuromodulation associated with singing.

Primary endoluminal stenting of transplant renal artery stenosis from cadaver and non-heart-beating donor kidneys

This study evaluated the efficacy of primary endovascular stenting in cases of transplant renal artery stenosis (TRAS) from cadaver and non-heart-beating donor kidneys. Patients with TRAS (n = 13) from a single-centre transplant population (n = 476) were treated by primary percutaneous angioplasty and endovascular stenting. The short-term efficacy of this intervention is demonstrated in terms of serum creatinine, glomerular filtration rate (GFR) biochemical, anti-hypertensive medications and mean arterial blood pressure control. Stenting for TRAS was performed in male (n = 10) and female (n = 3) recipients. The median age at transplantation was 55 yr (range 10-67 yr). Stenting occurred at a median duration of 410 d post-transplantation (range 84-5799 d). Mean serum creatinine (pre, 247 micromol/L; post, 214 micromol/L; p = 0.002), GFR (pre, 82.6 mL/min; post, 100.9 mL/min; p < 0.001), arterial blood pressure (pre, 104 mmHg; post, 97 mmHg; p = 0.036) and the number of anti-hypertensive medications required (pre, 3.4; post, 3.0; p = 0.002) showed significant improvement after post-endovascular therapy. There were no serious complications encountered. Primary endovascular stenting of TRAS produces a significant improvement in biochemical parameters of renal graft function and in blood pressure stability, with the benefit of low patient morbidity and single arterial puncture. Primary endoluminal stenting of TRAS is a safe and effective procedure for the treatment of TRAS.

Randomised trial of vitamin A supplementation in pregnant women in rural Malawi found to be anaemic on screening by HemoCue

OBJECTIVE

To assess the effects of vitamin A supplementation in women with anaemia during pregnancy.

DESIGN

Single-centre randomised controlled trial.

SETTING

Rural community in southern Malawi, central Africa.

POPULATION

Seven hundred women with singleton pregnancies at 12-24 weeks measured by ultrasound scan and with haemoglobin <11.0 g/dl by HemoCue screening method. Analysis was by intention to treat. All received iron and folate, and sulphadoxine/pyrimethamine for antimalarial prophylaxis.

METHODS

Women were randomised to receive oral supplementation with daily 5000 or 10,000 iu vitamin A, or placebo.

MAIN OUTCOME MEASURES

Anaemia, as assessed by Coulter counter, severe anaemia, iron status and indices of infection.

RESULTS

Vitamin A deficiency was, in this rural population, less common than predicted. Vitamin A supplementation had no significant impact on anaemia, severe anaemia, iron status and indices of infection. Vitamin A stores were less likely to be depleted at the end of pregnancy in supplemented groups.

CONCLUSIONS

Vitamin A supplementation programmes to reduce anaemia should not be implemented in similar antenatal populations in rural sub-Saharan Africa unless evidence emerges of positive benefit on substantive clinical outcomes. Introducing public health interventions of unknown benefit and with unclear biological mechanisms can divert scarce resources from clinical and social interventions more likely to impact maternal mortality.

Combined Laparoscopic and Percutaneous Treatment of a Type II Endoleak Following Endovascular Abdominal Aortic Aneurysm Repair

We describe a novel approach in treating a persistent type II endoleak related to the inferior mesenteric artery (IMA) and the lower lumbar arteries. The endoleak failed to thrombose following percutaneous IMA coil embolization. We proceeded to one-stage laparoscopic IMA division and intra-sac thrombin injection under direct laparoscopic vision and fluroscopy. A CT scan at 1 and 7 months post-intervention showed no evidence of endoleak and the growth of the aneurysm was arrested. This combined laparoscopic and percutaneous approach may be a useful treatment option in the management of persistent complex type II endoleak. Its durability, however has yet to be defined.

Ischaemic preconditioning in transplantation and major resection of the liver

BACKGROUND

Ischaemia-reperfusion injury (IRI) contributes significantly to the morbidity and mortality of transplantation and major resection of the liver. Its severity is reduced by ischaemic preconditioning (IP), the precise mechanisms of which are not completely understood. This review discusses the pathophysiology and role of IP in this clinical setting.

METHODS

A Medline search was performed using the keywords 'ischaemic preconditioning', 'ischaemia-reperfusion injury', 'transplantation' and 'hepatic resection'. Additional articles were obtained from references within the papers identified by the Medline search.

RESULTS AND CONCLUSION

The mechanisms underlying hepatic IRI are complex, but IP reduces the severity of such injury in several animal models and in recent human trials. Increased understanding of the cellular processes involved in IP is of importance in the development of treatment strategies aimed at improving outcome after liver transplantation and major hepatic resection.

Progress in living donor liver transplantation

Living donor liver transplantation (LDLT) has the capacity to reduce the current discrepancy between the number of patients on the transplant waiting list and the number of available organ donors. For pediatric patients, LDLT has clearly reduced the number of waiting list deaths, providing compelling evidence for an increase in LDLT programs. This review discusses many of the recent advances in LDLT.

Reproductive health in rural Malawi: a population-based survey

OBJECTIVES

To assess pregnancy outcome, maternal mortality and health-seeking behaviour in a rural African population and to assess the effects on these of women's education, distance from a health centre and household type.

DESIGN

Descriptive population-based study.

SETTING

A rural community in southern Malawi.

POPULATION

All women living in the catchment area of a rural health centre.

METHODS

Interviews with women in 20,649 households using structured questionnaires.

MAIN OUTCOME MEASURES

Pregnancy outcome, the effect of women's education, distance from a health centre and household type on pregnancy outcome, maternal morbidity and estimates of maternal and perinatal mortality.

RESULTS

Educational level was lower for women than for men. A significant association was found between educational level and fertility. Women aged 45-49 reported an average of six pregnancies with four resulting in currently living children. Successful pregnancy outcome was more likely with increased education and if the woman lived closer to the health centre. Despite living an average of 5 km from the health centre, over 90% of women attended antenatal clinic with a mean of five visits. Assistance at delivery by a trained health care worker was more likely as education increased and was less likely as distance from the health centre increased. Maternal mortality was reported at 413 per 100,000 deliveries (95% CI 144-682). The perinatal mortality rate in this population was estimated at 30 per 1000. An increased perinatal mortality was noted for women who were delivered by a female relative. Perinatal mortality rates were similar for delivery by a traditional birth attendant or a trained nurse-midwife. Education and proximity to the health centre were both associated with improved outcome.

CONCLUSIONS

Many women in this rural community suffer the consequences of high pregnancy loss. Maternal and perinatal mortality are high. Improved education and skilled assistance at delivery can result in improved pregnancy outcome. Proximity of any household to a health centre has an effect on outcomes.

Fibrosis-associated gene expression in renal transplant glomeruli after acute renal allograft rejection

BACKGROUND

Acute allograft rejection is thought to be a risk factor for chronic allograft nephropathy, the cardinal features of which are vasculopathy, interstitial fibrosis and glomerulosclerosis. Fibrosis-associated genes might act as ad interim surrogate markers for chronic allograft nephropathy. The aim of this study was to determine mRNA expression of fibrosis-associated genes in glomeruli plucked from protocol renal transplant biopsies, in patients with or without a history of acute rejection.

METHODS

A consecutive series of 52 patients (31 male, 21 female) was assessed. Donor categories were cadaveric, living related or asystolic. Transplant recipients received either cyclosporin- or tacrolimus-based immunosuppression. Patients routinely underwent percutaneous needle-core renal transplant biopsy at 1 week, and 3 and 6 months. Acute rejection episodes were confirmed histologically and treated with intravenous methylprednisolone, or antithymocyte globulin if steroid resistant. Individual glomeruli were plucked and total mRNA was extracted. Fibrosis-associated genes were amplified by reverse transcriptase-polymerase chain reaction (PCR) and quantified by enzyme-linked immunosorbent assay.

RESULTS

The expression of both collagen type III (mean 0.42 versus 0.31 arbitrary units of PCR products corrected for a housekeeping gene) and collagen IV (mean 0.46 versus 0.42 arbitrary units) at 6 months did not differ between recipients who experienced acute rejection episodes and those who were free from rejection. There was also no significant difference between groups in terms of mRNA expression of collagen IValpha2, matrix metalloproteinase 2, tissue inhibitor of matrix metalloproteinases 1 and 2, transforming growth factor beta or tenascin.

CONCLUSION

These results suggest that acute rejection episodes do not increase the expression of fibrosis-associated genes in glomeruli from renal transplant biopsies.

Pancreatectomy with islet autotransplantation for the treatment of severe chronic pancreatitis: the first 40 patients at the leicester general hospital

BACKGROUND

Surgical resection of the pancreas is considered a final resort in the treatment of chronic pancreatitis. However, the opportunity to perform an islet autotransplant at the same time provides the potential to prevent the onset of diabetes.

METHODS

Pancreatectomy together with islet autotransplantation has been offered in our center since 1994. A total of 40 patients have now undergone this procedure. The follow-up times range from 6 months to 7 years. The data presented here include the annual postoperative oral glucose tolerance test and glycosylated hemoglobin (HbA(1c)) results, together with insulin and opiate requirements.

RESULTS

Nineteen male and 21 female patients (median age 44, range 21-65) have been transplanted. Pancreatitis was related to alcohol in 45% and was idiopathic in 40%. A median of 130108 (24332-1, 165538) islet equivalent (IEQ) were transplanted, which related to 2020 (320-23311) IEQ per kilogram of body weight. At 2 years posttransplant, 18 patients had a median HbA(1c) of 6.6% (5.2-19.3%), fasting C-peptide of 0.66 ng/mL (0.26-2.65 ng/mL), and required a median of 12 (0-45) units of insulin per day. At 6 years, these figures were 8% (6.1-11.1%), 1.68 ng/mL (0.9-2.78 ng/ml) and 43 U/day (6-86 U/day), respectively. The majority of patients no longer require opiate analgesia, 68% have been able to return to work, and one patient has had a baby.

CONCLUSIONS

Islet autotransplantation offers a valuable addition to surgical resection of the pancreas, as a treatment for chronic pancreatitis; and even in cases in which insulin independence is not achieved, the potential beneficial effects of C-peptide make the procedure worthwhile.

Idiopathic chronic ulcerative enteritis--the role of radical surgical resection

Idiopathic chronic ulcerative enteritis is uncommon. It is a term that describes ulceration of the small bowel in the absence of a recognisable cause. Patients mainly present with a surgical abdomen and their management often proves to be a therapeutic challenge. Our series describes three such cases: the first patient presented with a tender left iliac fossa mass and rectal bleeding, the second with peritonitis and pneumoperitoneum, the third with severe acute colitis. All three patients needed urgent surgical intervention with further laparotomies due to recurrent ulceration, perforation and fistula formation in addition to intensive supportive measures such as inotropes and total parenteral nutrition. The importance and challenges of idiopathic chronic ulcerative enteritis are therefore discussed.

Unexplained fitting in three parturients suffering from postdural puncture headache

We present the cases of three women who, within a 6-month period, suffered post-partum generalized tonic-clonic seizures. All had received an epidural in labour for analgesia and were subsequently diagnosed as suffering from postdural puncture headache. All were treated for that headache with Synacthen and one also received sumatriptan before her seizures. All made satisfactory recoveries and were discharged home. None displayed classical patterns suggestive of pre-eclampsia, meningitis, cortical venous thrombosis or any other pathological process that might explain these events adequately, and the specific precipitating factors were left unidentified.

NMR analysis of helix I from the 5S RNA of Escherichia coli

The structure of helix I of the 5S rRNA from Escherichia coli has been determined using a nucleolytic digest fragment of the intact molecule. The fragment analyzed, which corresponds to bases (-1)-11 and 108-120 of intact 5S rRNA, contains a G-U pair and has unpaired bases at its termini. Its proton resonances were assigned by two-dimensional NMR methods, and both NOE distance and coupling constant information have been used to calculate structural models for it using the full relaxation matrix algorithm of the molecular dynamics program XPLOR. Helix I has A-type helical geometry, as expected. Its most striking departure from regular helical geometry occurs at its G-U, which stacks on the base pair to the 5' side of its G but not on the base pair to its 3' side. This stacking pattern maximizes interstrand guanine-guanine interactions and explains why the G-U in question fails to give imino proton NOE's to the base pair to 5' side of its G. These results are consistent with the crystal structures that have been obtained for wobble base pairs in tRNAPhe [Mizuno, H., & Sundaralingam, M. (1978) Nucleic Acids Res. 5, 4451-4461] and A-form DNA [Rabbinovich, D., Haran, T., Eisenstein, M., & Shakked, Z. (1988) J. Mol. Biol. 200, 151-161]. The conformations of the terminal residues of helix I, which corresponds to bases (-1)-11 and 108-120 of native 5S RNA, are less well-determined, and their sugar puckers are intermediate between C2' and C3'-endo, on average.

Two-stage subtotal hepatectomy for metastatic adrenal adenocarcinoma, a case report

Adrenal adenocarcinoma is a rare tumor with a poor prognosis. We present a case of recurrent adrenal adenocarcinoma with synchronous bilobar liver metastases that was treated by a two-stage subtotal hepatectomy. A formal right hemihepatectomy was performed with cryotherapy to a left lobe metastasis that was subsequently resected after a period of hepatic regeneration.

Ten-year experience of endoscopic transanal resection

OBJECTIVE

To audit the results of endoscopic transanal resection of tumor (ETAR) performed by a single surgeon at a specialized colorectal unit during a 10- year period.

SUMMARY BACKGROUND DATA

A minimally invasive surgical technique, ETAR has enabled much progress to be made in the development of local treatment strategies for rectal neoplasia. It can be used in both the curative and palliative management of rectal lesions and is a treatment option for patients who would be unable to tolerate major surgery.

METHODS

The surgical outcome of 104 patients (43 women, 61 men) undergoing ETAR under the care of a single surgeon between 1989 and 1999 was reviewed. Patients were identified from the consultant's personal records and cross-referenced with operating room logs. Data were collected retrospectively and no patients were lost to follow-up.

RESULTS

One hundred four patients underwent 163 procedures during the study period. Follow-up ranged from 6 months to 10 years. Seventy-five patients with a pre-ETAR diagnosis of benign rectal adenoma underwent resection. In 60 patients, the diagnosis was confirmed to be benign; 30 of these were treated with a single resection and 28 with multiple resections. There were two technical failures, both a result of high mobility of the lesion. In no patients did carcinoma subsequently develop. In the remaining 15 patients the final histology demonstrated a malignancy; 9 patients underwent an open surgical rectal resection and 5 had complete endoscopic resection of their lesion. No carcinomas that were fully resected endoscopically have recurred (follow-up 13 months to 8years). The final patient had an extensive rectal cancer and was palliated for 2 months by ETAR. Twelve patients (8 men, 4 women) underwent ETAR for anastomotic strictures; successful treatment was achieved in 11. The one failure was in a Park's pouch that was subsequently refashioned. Seventeen patients underwent 30 ETARs for palliation of nonresectable rectal adenocarcinoma. Successful palliation of symptoms was achieved in 13 patients and the remainder underwent colostomy formation. One patient died of a myocardial infarction. There were two further complications (blood transfusion for postoperative bleeding, postoperative cerebrovascular accident).

CONCLUSIONS

Endoscopic transanal resection of tumor is safe and effective and offers successful palliation or definitive treatment of rectal lesions with low rates of death and complications when performed by a dedicated surgeon.

Endoscopic-assisted intrathoracic oesophagogastrostomy without thoracotomy for tumours of the lower oesophagus and cardia

AIMS

This study aimed to evaluate the efficacy of a novel technique enabling a trans-hiatal oesophagectomy with intrathoracic anastomosis under direct vision, without thoracotomy.

METHODS

Trans-hiatal dissection of the oesophagus was performed using direct and laparoscopic visualization. The oesophagus was transected above the tumour with a linear endo-GIA-2 60 mum stapler. The stomach was transected and a gastric tube fashioned. The anvil of an appropriately sized CEEA circular stapler was modified enabling it to flatten. It was attached to a novel delivery system introduced under direct vision along a guidewire into the stapled oesophagus. The anvil was realigned to its original position in the distal oesophagus, docked with the body of the stapler and an intrathoracic anastomosis performed.

RESULTS

Ten patients (female n=3, male n=7) aged from 39--77 years (mean age 65 years), ASA 2--3 with distal third tumours were treated. Duration of procedure ranged from 2--5 hours (mean 4 hours). One patient suffered a post-operative chest infection and an anastomotic leak treated successfully with a self-expanding metal stent. Hospital stay ranged from 6--28 days (mean 17 days). There was no mortality.

CONCLUSION

This technique allows a safe intrathoracic anastomosis to be performed trans-hiatally under direct vision, avoiding the need for thoracotomy in patients with high comorbidity.

The "open" and "closed" structures of the type-C inorganic pyrophosphatases from Bacillus subtilis and Streptococcus gordonii

Recently, a new class of soluble inorganic pyrophosphatase (type-C PPase) has been described that is not homologous in amino acid sequence or kinetic properties to the well-studied PPases (types A and B) found in many organisms from bacteria to humans and thought to be essential to the cell. Structural studies of the type-C PPases from Streptococcus gordonii and Bacillus subtilis reveal a homodimeric structure, with each polypeptide folding into two domains joined by a flexible hinge. The active site, formed at the interface between the N and C-terminal domains, binds two manganese ions approximately 3.6 A apart in a conformation resembling binuclear metal centres found in other hydrolytic enzymes. An activated water molecule bridging the two metal ions is likely poised for nucleophilic attack of the substrate. Importantly, the S. gordonii and B. subtilis enzymes have crystallised in strikingly different conformations. In both subunits of the S. gordonii crystal structure (1.5 A resolution) the C-terminal domain is positioned such that the active site is occluded, with a sulphate ion bound in the active site. In contrast, in the B. subtilis structure (3.0 A resolution) the C-terminal domain is rotated by about 90 degrees, leaving the active site wide open and accessible for substrate binding.

Use of non-heart-beating donors in renal transplantation

The rate of renal transplantation has plateaued and is now limited by the number of donor organs available. In the past all donor kidneys came from living donors or controlled non-heart beating donors. It was not until the introduction of brainstem death criteria that cadaveric heart beating donors became the main source. Recently, there has been renewed interest in non-heart beating donors, who have already suffered cardiorespiratory arrest. Kidneys from these donors have a unique set of problems associated with increased duration of warm ischaemia. To minimise this, the kidneys are cooled in situ using an intra-aortic balloon catheter and are perfused with cold hyperosmolar citrate. Retrieval can then proceed in the normal fashion. Despite a higher level of delayed graft function, the results from non-heart beating renal transplantation are good, with long term function comparable to cadaveric organs. If used safely, they enable significant expansion of the donor pool. Techniques in the future, such as machine perfusion preservation, may further improve the results from non-heart beating programmes.

The heterotrimer of the membrane-peripheral components of transhydrogenase and the alternating-site mechanism of proton translocation

Transhydrogenase undergoes conformational changes to couple the redox reaction between NAD(H) and NADP(H) to proton translocation across a membrane. The protein comprises three components: dI, which binds NAD(H); dIII, which binds NADP(H); and dII, which spans the membrane. Experiments using isothermal titration calorimetry, analytical ultracentrifugation, and small angle x-ray scattering show that, as in the crystalline state, a mixture of recombinant dI and dIII from Rhodospirillum rubrum transhydrogenase readily forms a dI(2)dIII(1) heterotrimer in solution, but we could find no evidence for the formation of a dI(2)dIII(2) tetramer using these techniques. The asymmetry of the complex suggests that there is an alternation of conformations at the nucleotide-binding sites during proton translocation by the complete enzyme. The characteristics of nucleotide interaction with the isolated dI and dIII components and with the dI(2)dIII(1) heterotrimer were investigated. (a) The rate of release of NADP(+) from dIII was decreased 5-fold when the component was incorporated into the heterotrimer. (b) The binding affinity of one of the two nucleotide-binding sites for NADH on the dI dimer was decreased about 17-fold in the dI(2)dIII(1) complex; the other binding site was unaffected. These observations lend strong support to the alternating-site mechanism.

Learning to communicate

Of the few animal groups that learn their vocalizations, songbirds are uniquely amenable to molecular, physiological, and behavioral analyses of the neural features responsible for vocal learning. In order to communicate effectively as an adult, a young songbird recognizes and memorizes a model of his species-specific song during a developmentally critical period called sensory acquisition. Factors are now emerging that contribute to the length and strength of this learning phase. In a second critical period, known as sensorimotor learning, the young bird uses auditory feedback to perfect his motor performance, creating a match to the memorized model. New studies show that motor matching can persist beyond sensorimotor learning, and thus a role for the acquired model might also persist into adulthood. Fascinating in their own right, songbirds also provide optimism that mature brains have recourse to plasticity.

A case-control comparison of the results of renal transplantation from heart-beating and non-heart-beating donors

INTRODUCTION

The decline in heart-beating brainstem dead organ donors has necessitated the search for other organ sources. In the field of renal transplantation one alternative source currently available, but little used, is that of kidneys from non-heart-beating donors (NHBD). Reticence to use NHBD kidneys is in part due to concerns over the effect that warm ischemic may have subsequent graft function. Presented here are the results of the NHBD renal transplants at the Leicester transplant unit, and compared with matched heart-beating donor transplants as a case control analysis.

METHODS

In order to analyze any differences in graft performance between the two organ sources, the confounding effect of other variables known to influence the outcome of renal transplantation was minimized by matching NHBD and HBD transplants for the following criteria: donor age and sex, first or re-transplant, anastomosis and cold times, tissue match and PRA sensitisation. Transplant performance was assessed primarily by graft survival, the statistical evaluation of which was by log rank analysis of Kaplan-Meier curves.

RESULTS

72 NHBD and 192 HBD transplants were performed over an eight year period. Of the 192 HBD transplants, 105 matched one or more of the NHBD by the criteria outlined above, and thus constituted the control group for comparison. There was no significant difference in overall graft survival between the two groups. The 5 year survival for the NHBD was 73% compared with 65% for HBD kidneys. When death with a functioning graft is treated as censored data, then these figures become 75% and 81% respectively, again without statistical significance.

CONCLUSION

NHBD kidneys are a valuable additional source of organs for transplantation, with long-term survival, comparable to transplants from HBD.

Sub-clinical acute rejection detected using protocol biopsies in patients with delayed graft function

Acute rejection in renal transplants is difficult to diagnose when patients have delayed graft function (DGF) in the early post-transplant period. In this study protocol, renal transplant biopsies were performed in an attempt to detect sub-clinical acute rejection episodes. Eighty-three patients were eligible for the study, of whom 33 had DGE All had protocol renal transplant biopsies performed under ultrasound control at 7 days post-transplant, and those with DGF had further biopsies weekly until the graft functioned. All histologically confirmed acute rejection episodes were treated. Sub-clinical acute rejection was detected in 6/33 (18%) patients with DGF compared to 2/50 (4%) in the other patients (P < 0.05). Borderline rejection was present in 4/33 (12%) and 4/50 (8%) patients, respectively. Because of the high detection rate of sub-clinical acute rejection and the low morbidity of renal transplant biopsies, their use is recommended in patients with DGF.

The structure of Escherichia coli nitroreductase complexed with nicotinic acid: three crystal forms at 1.7 A, 1.8 A and 2.4 A resolution

Escherichia coli nitroreductase is a flavoprotein that reduces a variety of quinone and nitroaromatic substrates. Its ability to convert relatively non-toxic prodrugs such as CB1954 (5-[aziridin-1-yl]-2,4-dinitrobenzamide) into highly cytotoxic derivatives has led to interest in its potential for cancer gene therapy. We have determined the structure of the enzyme bound to a substrate analogue, nicotinic acid, from three crystal forms at resolutions of 1.7 A, 1.8 A and 2.4 A, representing ten non-crystallographically related monomers. The enzyme is dimeric, and has a large hydrophobic core; each half of the molecule consists of a five-stranded beta-sheet surrounded by alpha-helices. Helices F and F protrude from the core region of each monomer. There is an extensive dimer interface, and the 15 C-terminal residues extend around the opposing monomer, contributing the fifth beta-strand. The active sites lie on opposite sides of the molecule, in solvent-exposed clefts at the dimer interface. The FMN forms hydrogen bonds to one monomer and hydrophobic contacts to both; its si face is buried. The nicotinic acid stacks between the re face of the FMN and Phe124 in helix F, with only one hydrogen bond to the protein. If the nicotinamide ring of the coenzyme NAD(P)H were in the same position as that of the nicotinic acid ligand, its C4 atom would be optimally positioned for direct hydride transfer to flavin N5. Comparison of the structure with unliganded flavin reductase and NTR suggests reduced mobility of helices E and F upon ligand binding. Analysis of the structure explains the broad substrate specificity of the enzyme, and provides the basis for rational design of novel prodrugs and for site-directed mutagenesis for improved enzyme activity.

Human islet autotransplantation to prevent diabetes after pancreas resection

In severe cases of chronic pancreatitis pain relief can often only be achieved by pancreas resection, however this may render the patient diabetic. In an effort to prevent diabetes some patients may be suitable for a simultaneous islet autotransplant. The last report from the International Islet Transplant Registry has reported 222 cases. This review discusses the current progress in human islet autotransplantation.

Pancreas resection and islet autotransplantation for end-stage chronic pancreatitis

OBJECTIVE

To assess the safety and efficacy of islet autotransplantation (IAT) combined with total pancreatectomy (TP) to prevent diabetes.

SUMMARY BACKGROUND DATA

There have been recent concerns regarding the safety of TP and IAT. This is thought to be related to the infusion of large volumes of unpurified pancreatic digest into the portal vein. Minimizing the volume of islet tissue by purifying the pancreatic digest has not been previously evaluated in terms of the postoperative rate of death and complications, pain relief, and insulin independence.

METHOD

During a 54-month period, 24 patients underwent pancreas resection with IAT. Islets were isolated using collagenase and a semiautomated method of pancreas digestion. Where possible, islets were purified on a density gradient and COBE processor. Islets were embolized into the portal vein, within the spleen and portal vein, or within the spleen alone. The total median volume of digest was 9.9 mL.

RESULTS

The median number of islets transplanted was 140,419 international islet equivalents per kilogram. The median increase in portal pressure was 8 mmHg. Early complications included duodenal ischemia, a wedge splenic infarct, partial portal vein thrombosis, and splenic vein thrombosis. Intraabdominal adhesions were the main source of long-term problems. Eight patients developed transient insulin independence. Three patients were insulin-independent as of this writing. Patients had significantly decreased insulin requirements and glycosylated hemoglobin levels compared with patients undergoing TP alone. Of the patients alive and well as of this writing, four had failed to gain relief of their abdominal pain and were still opiate-dependent.

CONCLUSION

Combined TP and IAT can be a safe surgical procedure. Unfortunately, almost all patients were still insulin-dependent, but they had decreased daily insulin requirements and glycosylated hemoglobin levels compared with patients undergoing TP alone. A prospective randomized study is therefore needed to assess the long-term benefit of TP and IAT on diabetic complications.

The crystal structure of an asymmetric complex of the two nucleotide binding components of proton-translocating transhydrogenase

BACKGROUND

Membrane-bound ion translocators have important functions in biology, but their mechanisms of action are often poorly understood. Transhydrogenase, found in animal mitochondria and bacteria, links the redox reaction between NAD(H) and NADP(H) to proton translocation across a membrane. Linkage is achieved through changes in protein conformation at the nucleotide binding sites. The redox reaction takes place between two protein components located on the membrane surface: dI, which binds NAD(H), and dIII, which binds NADP(H). A third component, dII, provides a proton channel through the membrane. Intact membrane-located transhydrogenase is probably a dimer (two copies each of dI, dII, and dIII).

RESULTS

We have solved the high-resolution crystal structure of a dI:dIII complex of transhydrogenase from Rhodospirillum rubrum-the first from a transhydrogenase of any species. It is a heterotrimer, having two polypeptides of dI and one of dIII. The dI polypeptides fold into a dimer. The loop on dIII, which binds the nicotinamide ring of NADP(H), is inserted into the NAD(H) binding cleft of one of the dI polypeptides. The cleft of the other dI is not occupied by a corresponding dIII component.

CONCLUSIONS

The redox step in the transhydrogenase reaction is readily visualized; the NC4 atoms of the nicotinamide rings of the bound nucleotides are brought together to facilitate direct hydride transfer with A-B stereochemistry. The asymmetry of the dI:dIII complex suggests that in the intact enzyme there is an alternation of conformation at the catalytic sites associated with changes in nucleotide binding during proton translocation.

Human islet cell transplantation--future prospects

BACKGROUND

Islet transplantation has the potential to cure diabetes mellitus. Nevertheless despite successful reversal of diabetes in many small animal models, the clinical situation has been far more challenging. The aim of this review is to discuss why insulin-independence after islet allotransplantation has been so difficult to achieve.

METHODS

A literature review was undertaken using Medline from 1975 to July 2000. Results reported to the International Islet Transplant Registry (ITR) up to December 1998 were also analysed.

RESULTS

Up to December 1998, 405 islet allotransplants have been reported the ITR. Of those accurately documented between 1990 and 1998 (n = 267) only 12% have achieved insulin-independence (greater than 7 days). However with refined peri-transplant protocols insulin independence at 1 year can reach 20%.

CONCLUSIONS

There are many factors which can explain the failure of achieving insulin-independence after islet allotransplantation. These include the use of diabetogenic immunosuppressive agents to abrogate both islet allo-immunity and auto-immunity, the critical islet mass to achieve insulin-independence and the detrimental effects of transplanting islets in an ectopic site. However recent evidence most notably from the Edmonton group demonstrates that islet allotransplantation still has great potential to become an established treatment option for diabetic patients.