High resolution structure of BipD: an invasion protein associated with the type III secretion system of Burkholderia pseudomallei

Burkoldheria pseudomallei is a Gram-negative bacterium that possesses a protein secretion system similar to those found in Salmonella and Shigella. Recent work has indicated that the protein encoded by the BipD gene of B. pseudomallei is an important secreted virulence factor. BipD is similar in sequence to IpaD from Shigella and SipD from Salmonella and is therefore likely to be a translocator protein in the type-III secretion system of B. pseudomallei. The crystal structure of BipD has been solved at a resolution of 2.1 A revealing the detailed tertiary fold of the molecule. The overall structure is appreciably extended and consists of a bundle of antiparallel alpha-helical segments with two small beta-sheet regions. The longest helices of the molecule form a four-helix bundle and most of the remaining secondary structure elements (three helices and two three-stranded beta-sheets) are formed by the region linking the last two helices of the four-helix bundle. The structure suggests that the biologically active form of the molecule may be a dimer formed by contacts involving the C-terminal alpha-helix, which is the most strongly conserved part of the protein. Comparison of the structure of BipD with immunological and other data for IpaD indicates that the C-terminal alpha-helix is also involved in contacts with other proteins that form the translocon.

Caspase 8 is absent or low in many ex vivo gliomas

BACKGROUND

Better treatments are required urgently for patients with malignant glioma, which currently is incurable. Death ligands, such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), may offer promise for the treatment high-grade glioma if such ligands induce apoptotic signaling in vivo in glioma cells. Caspase 8 is required for death ligand signaling, and its levels may influence the sensitivity of glioma cells to death ligands. It also may act as a tumor suppressor protein. The authors analyzed caspase 8 expression levels in ex vivo glioma specimens and explored potential mechanisms of its regulation.

METHODS

Eleven glioblastomas, 5 anaplastic astrocytomas, and 3 low-grade astrocytomas were studied. The levels of caspase 8, caspase 10, cellular FLICE inhibitory protein (c-FLIP), and signal transducer and activator of transcription (STAT)-1 were assayed using quantitative immunoblotting. Caspase 8 mRNA was measured by Northern blot analysis. The methylation status of the caspase 8 gene was determined by bisulfate modification of genomic DNA, cloning, and sequencing. Statistical analyses were performed using nonparametric (Spearman) correlations.

RESULTS

Some ex vivo glioma samples lacked detectable caspase 8, with many expressing barely detectable levels. No tumors expressed significant amounts of caspase 10 or c-FLIP. A strong association was found between caspase 8 mRNA and protein levels. Neither expression of the transcription factor STAT-1 nor caspase 8 gene methylation correlated with caspase 8 levels.

CONCLUSIONS

The absence of caspase 8 protein in many resected glioma samples implied that many patients with glioma may not benefit from death ligand-based treatments, unless caspase 8 (or caspase 10) protein expression can be elevated. Demethylating agents are unlikely to boost caspase 8 levels in glioma cells, but treatments that increase caspase 8 mRNA levels may up-regulate expression of the protein.

Caspase-8 levels affect necessity for mitochondrial amplification in death ligand-induced glioma cell apoptosis

Fifty percent of high-grade glioma patients die within a year of diagnosis and less than two percent survive five years postdiagnosis. Elucidating apoptosis signaling pathways may assist in designing better adjuvant therapies. Preliminary characterizations suggested that glioma cells may either employ mitochondrial-independent or -dependent death receptor-induced apoptotic pathways, characteristic of cells termed type I and type II, respectively. In the present study, we generated panels of clonal transfectants overexpressing various levels of Bcl-2, in two parental glioma cell lines. These cells were used to explore molecular factors determining the necessity for mitochondrial amplification of death receptor signaling. Moderate Bcl-2 expression was sufficient to render one glioma cell line (D270) resistant to apoptosis induced by Fas ligand or TRAIL, consistent with these cells being type II. However, expression of even very high levels of Bcl-2 in a second line (D645) did not affect death ligand sensitivity, indicative of a type I phenotype. D270 cells expressed much less caspase-8 protein than D645 cells. Enforced overexpression of caspase-8 (or cytoplasmic Diablo/Smac) in D270 cells overcame Bcl-2 inhibition of death ligand-induced apoptosis, converting them from type II to type I. This indicates that caspase-8 levels can influence the requirement for mitochondrial involvement in death receptor apoptotic signaling in glioma cells.

Single-centre audit of endoscopic common bile duct stone retrieval

Background

Endoscopic extraction of stones in the bile duct is not without risk, with complications occurring in up to 10 per cent of patients. The aim of this study was to determine the success and complications of stone retrieval by endoscopic retrograde cholangiopancreatography (ERCP) in this institution.

Methods

This was a retrospective analysis of a prospective database for all ERCPs (single operator, single institution) between 1990 and 1995. Some 271 consecutive patients with a strong suspicion of bile duct stones, from history or investigations, were studied. All patients underwent ERCP and attempted retrieval of bile duct stones if detected. Treatment success was strictly defined as a stone-free postprocedure radiograph. All patients were followed to identify complications occurring within 30 days of the procedure.

Results

The median age of the 271 patients was 73 (range 17–96) years; 62 per cent were women. Some 139 patients had 162 significant other medical conditions (61 per cent cardiopulmonary) that required specialist treatment. The presenting symptoms included painful jaundice (34 per cent), acute pancreatitis (25 per cent), cholangitis (17 per cent), painless jaundice (14 per cent) and abdominal pain alone (9 per cent). Stones were seen at ERCP in 192 patients (71 per cent); the median number of stones was 1 (range 0–20). Successful endoscopic stone retrieval was achieved in 136 patients (71 per cent) at the first attempt, with an overall success rate of 90 per cent. The median number of ERCPs per patient was 1 (range 1–4). There were five false-negative ERCPs (2 per cent) and 19 retrieval failures (10 per cent), which included requirement for percutaneous cholangiography or endoscopic stenting for successful treatment. Complications occurred in eight␣patients (3 per cent), and included cholangitis (1␣per cent), pancreatitis (less than 1 per cent) and haemorrhage (less than 1 per cent). There were two procedure-related deaths (1 per cent), from myocardial infarction and cholangitis.

Conclusion

Endoscopic stone retrieval can be achieved successfully with low morbidity and mortality rates, even in patients with significant co-morbidity. These data provide further support for dedicated units offering a regional ERCP service.

Laparoscopic bile duct injuries: a single-institution experience spanning 8 years

Background

This audit represents the authors' experience in the management of 42 bile duct injuries following laparoscopic cholecystectomy and is the largest series reported so far in the UK.

Methods

Between November 1990 and May 1998, 42 patients were referred for management of bile duct injury following laparoscopic cholecystectomy. The case notes of all patients were reviewed and follow-up information was obtained to provide a 100 per cent follow-up rate. Aspects of the cholecystectomy, presentation, investigation, definitive treatment and follow-up are discussed.

Results

The referral source was 25 surgeons from 17 different hospitals. The incidence peaked in 1992 (ten cases) and has been stable at four referrals per year over the past 4 years. The median age was 56 years and the M: F ratio 10: 32. Thirty-five laparoscopic operations were performed by consultants and seven by trainees. Intraoperative cholangiography was performed in three. Seventeen operations were converted to an open procedure because of intraoperative difficulty. Injury was noted at operation in nine and an immediate restorative procedure was attempted. Twelve patients had had a reconstructive procedure before referral to this unit and the remainder were referred with a fresh injury. Patients in whom the bile duct was transected (n = 34) presented mostly with jaundice; those with minor injuries not involving the common duct (n = 8) presented with peritonitis. Thirty patients required operation; 25 underwent hepaticojejunostomy reconstruction, two needed revision of a previous biliary–enteric anastomosis, two had primary bile duct repair over a T tube and one required relaparoscopy to clip a leaking cystic duct. At a median of 12 months four patients who had had a reconstruction were symptomatic for cholangitis. Percutaneous transhepatic dilatation was successful in two and a further two required revision of the anastomosis. Another four patients had asymptomatic stenosis and were treated successfully by a single episode of dilatation. Follow-up showed all patients to be asymptomatic at a median follow-up of 42 months; however, six had a raised level of alkaline phosphatase. The remaining patients were managed successfully by therapeutic endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography. The overall median hospital stay was 18 days. Perioperative complications were seen in nine patients with no procedure-related deaths.

Conclusion

Although the initial learning curve seems to have been overcome, a steady state of problems now exists and seems likely to continue. Best results were obtained by hepaticojejunostomy. Most postrepair strictures were dealt with without operation.

The p35 relative, p49, inhibits mammalian and Drosophila caspases including DRONC and protects against apoptosis

This study characterized the ability of a new member of the p35 family, p49, to inhibit a number of mammalian and insect caspases. p49 blocked apoptosis triggered by treatment with Fas ligand (FasL), Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or ultraviolet (UV) radiation but provided negligible protection against apoptosis induced by the chemotherapeutic drug cisplatin. The caspase cleavage site in p49 was determined, and mutation of the P1 residue of this site abolished the ability of p49 to inhibit caspases, implying that p49 inhibits caspases through an analogous suicide-substrate mechanism to p35. Unlike p35, p49 inhibited the upstream insect caspase DRONC.

Analysis of FasL and TRAIL induced apoptosis pathways in glioma cells

FasL and TNF-related apoptosis-inducing ligand (TRAIL) belong to a subgroup of the TNF superfamily which induce apoptosis by binding to their death domain containing receptors. In the present study we have utilized a panel of seven cell lines derived from human malignant gliomas to characterize molecular pathways through which FasL and TRAIL induce apoptosis in sensitive glioma cells and the mechanisms of resistance in cell lines which survive the death stimuli. Our findings indicate that FADD and Caspase-8 are essential for FasL and TRAIL mediated apoptosis in glioma cells. One sensitive cell line (D270) can be protected from FasL and TRAIL induced death by anti-apoptotic Bcl-2 family members while another (D645) cannot, implying that these lines may represent glioma examples of type II and type I cells respectively. For the first time we demonstrate resistance to FasL but not to TRAIL within the one glioma cell line. Furthermore, we report distinct mechanisms of resistance within different glioma lines, including downregulation of Caspase-8 in U373MG. Cycloheximide sensitized four of the resistant cell lines suggesting the presence of labile inhibitors. None of the known apoptosis inhibitors examined accounted for the observed resistance, suggesting novel inhibitors may exist in glioma cells.

A novel, rapid, computerized method for quantitation of neuronal damage in a rat model of stroke

Determination of extent of infarction in animal models of cerebral ischemia is most commonly achieved by either classical histology (thionin staining) and light microscopy or staining with 2,3, 5-triphenyltetrazolium chloride (TTC). These techniques have limitations and we now describe a novel technique and its validation for assessment of the neuroprotective activity of AM-36, a novel arylalkypiperazine compound with combined antioxidant and sodium channel blocking activity. AM-36 (1.8 mg/kg i.p.) or vehicle, was administered 30 min, 24 and 48 h after endothelin-1-induced middle cerebral artery occlusion in conscious rats. Rats were killed at 72 h, brains removed and frozen in liquid nitrogen prior to coronal sectioning. Using a simple apparatus relying on basic principles of light propagation and a computerised image analysis system, ischemic damage in unstained slide-mounted sections was clearly visualised and measured. AM-36 significantly reduced the area of infarct in both cortex and striatum. The method was verified by thionin staining, and light microscopy. Linear regression analysis showed a highly significant correlation between methods at 72 h for infarct area in the cortex and striatum. Highly significant correlations between methods were found at 3 and 24 h after ischemia. Our method quickly and clearly delineates areas of damage in a manner superior to conventional staining methods.

Delayed treatment with AM-36, a novel neuroprotective agent, reduces neuronal damage after endothelin-1-induced middle cerebral artery occlusion in conscious rats

BACKGROUND AND PURPOSE

AM-36 is a novel arylalkylpiperazine with combined antioxidant and Na(+) channel blocking actions. Individually, these properties have been shown to confer neuroprotection in a variety of in vitro and in vivo animal models of stroke. Preliminary studies have shown that AM-36 is neuroprotective in vivo. The purpose of the present study was to assess the neuroprotective and behavioral outcome after delayed administration of AM-36 in an endothelin-1-induced, middle cerebral artery model of cerebral ischemia in conscious rats.

METHODS

Conscious male hooded Wistar rats were subjected to middle cerebral artery occlusion by perivascular microinjection of endothelin-1 via a previously implanted cannula. AM-36 (6 mg/kg IP) or vehicle was administered intraperitoneally 30, 60, or 180 minutes after middle cerebral artery occlusion. Functional outcome was determined 24, 48, and 72 hours after stroke by neurological deficit score, motor performance, and sensory hemineglect tests. Rats were killed at 72 hours, and infarct area and volume were determined by histology and computerized image analysis.

RESULTS

Endothelin-1-induced middle cerebral artery occlusion resulted in marked functional deficits and neuronal damage. AM-36 significantly reduced cortical damage when administration was delayed until 30, 60, or 180 minutes after stroke. Interestingly, neuronal damage was time-dependently reduced, with the greatest protection found when AM-36 was administered 180 minutes after stroke. Striatal damage was significantly reduced after treatment with AM-36 at 180 minutes after stroke. Functional outcome paralleled histopathology. Rota-rod performance, sensory hemineglect, and neurological deficit scores returned to preischemia levels in AM-36-treated rats by 72 hours after stroke when administration was delayed by 180 minutes after stroke.

CONCLUSIONS

AM-36 potently protects against both neuronal damage and functional deficits even when administered up to 180 minutes after induction of stroke. In fact, the greatest protection was found when administration was delayed by 180 minutes after stroke. The possible mechanisms of action of AM-36 are discussed. The present findings suggest that AM-36 may have great promise in the acute treatment of human stroke.

Umbilical port metastasis from gallbladder carcinoma after laparoscopic cholecystectomy

A case of gallbladder carcinoma is presented where metastatic tumour developed at the abdominal wall port site following laparoscopic cholecystectomy.

Bile duct stents: is there an increased rate of complications in patients receiving chemotherapy?

The aim of this study was to determine whether palliative chemotherapy accelerates the rate of biliary stent occlusion, in patients with a malignant biliary obstruction. Such treatment can induce neutropenia and increase the risk of bacterial sepsis. Overgrowth of bacteria within the bile of patients receiving chemotherapy could accelerate the rate of stent occlusion. Retrospective analysis of treatment records for 80 consecutive patients with a diagnosis of adenocarcinoma arising from the pancreas, bile ducts or gall bladder was conducted. Two groups were identified, those with a biliary stent in situ (primary stent group: 47/80; 59%) at the time of referral and those without (no stent group: 33/80; 41%). The majority of patients went on to receive chemotherapy, 64% and 70% in the primary stent group and no stent group, respectively. The rate of febrile neutropenia was similar in the two groups (5% versus 7% of all chemotherapy cycles in the primary stent group and no stent group, respectively). The rate of stent occlusion was not significantly different between those exposed to chemotherapy (37%; 95% CI 20-54%) and those unexposed (39%; 95% CI 19-59%). Similarly, the mean duration of patency was not shortened by chemotherapy (105 days in the chemotherapy group versus 119 days in the non-chemotherapy group; P = 0.97, Mann-Whitney U-test). We conclude that there is no evidence of increased rate of bile duct-related complications in patients receiving chemotherapy. In particular, we find no indication for the use of prophylactic antibiotics.

A phase II study of continuous-infusion 5-fluorouracil with cisplatin and epirubicin in inoperable pancreatic cancer

Carcinomas of the exocrine pancreas respond poorly to most chemotherapy regimens. Recently continuous infusional 5-fluorouracil (200 mg m-(2)day-1) with 3 weekly cisplatin (60 mg m-2) and epirubicin (50 mg m-2) (the ECF regimen) has proven to be an active regimen in gastric and breast cancer and consequently worthy of further study in pancreatic cancer. Thirty-five patients were treated with the ECF regimen as above, of whom 29 were evaluable for response and 32 were evaluable for toxicity. The mean age was 59 years (range 37-75). Sixteen patients had locally advanced disease at presentation and 19 had metastases. Objective tumour responses were documented in five (17.3%) patients who achieved a partial response; in 18 (62%) patients there were no change and six (20.7%) patients progressed on therapy. Patients with either stable disease or partial response had a significantly improved overall survival (median = 253 days) compared with patients who progressed (median = 170 days; P = 0.01). Grade 3/4 (WHO) toxicity (all cycles) included alopecia in 18 (56%) patients, nausea/vomiting in eight (25%) stomatitis in three (9%) and diarrhoea in seven (22%) patients, with rhinorrhoea and excessive lacrimation in one patient each. Neutropenic sepsis occurred in 13 cycles in ten patients, and there was one toxic death due to sepsis. There were eight other episodes of non-neutropenic sepsis requiring hospital admission. Fourteen patients (40%) experienced complications with their Hickman lines, including thrombotic episodes (six patients) or their line falling out (five patients). ECF can prolong survival in patients with locally advanced or metastatic pancreatic cancer who demonstrate a response or stabilisation of their disease. However, this is associated with considerable toxicity.

Toxicity of melaleuca oil and related essential oils applied topically on dogs and cats

Cases of melaleuca oil toxicosis have been reported by veterinarians to the National Animal Poison Control Center when the oil was applied dermally to dogs and cats. In most cases, the oil was used to treat dermatologic conditions at inappropriate high doses. The typical signs observed were depression, weakness, incoordination and muscle tremors. The active ingredients of commercial melaleuca oil are predominantly cyclic terpenes. Treatment of clinical signs and supportive care has been sufficient to achieve recovery without sequelae within 2-3 d.

Pancreaticogastrostomy: the preferred operation for pain relief in chronic pancreatitis

We present the results of surgery in 53 patients with intractable pain due to chronic pancreatitis associated with pancreatic duct dilatation. Using a limited mucosal to mucosal anastomosis over a silastic T tube the main pancreatic duct was drained in 33 patients into a Roux-en-Y jejunal loop (pancreaticojejunostomy, PJ) and in 20 patients into the stomach (pancreaticogastrostomy, PG). There was one postoperative death in the PJ group and none in the PG group. All patients were followed up for a minimum of four years. There was significantly greater pain relief in the PG group both at 1 (P less than 0.01) and 4 years (P less than 0.05) after surgery. We argue that PG is the operation of choice to relieve intractable pain in most patients with chronic pancreatitis associated with duct dilatation.

Exercise testing in children before and after surgical treatment of aortic stenosis

Twenty-three children with valvar or discrete subvalvar aortic stenosis underwent a controlled, progressive bicycle exercise test within 6 months before and 3-30 months after surgery for left ventricular outflow tract obstruction. The patients were divided into three groups according to the preoperative resting gradient of left ventricular to aortic peak systolic pressure: 30-69 mm Hg (group A), 70-99 mm Hg (group B), and greater than or equal to 100 mm Hg (group C). Preoperatively, 19 of 23 patients (83%) developed significant ST depression (greater than or equal to 1.0 mm) during exercise, whereas only seven (30%) had abnormal ST depression at rest. Postoperatively, mean exercise-induced ST depression regressed to less than 1 mm in all three groups. In the total population the frequency of ST depression greater than 1 mm was significantly reduced after surgical treatment and mean total work and peak exercise systolic blood pressure were significantly increased within 12 months after surgery. Total work increased significantly in group B within 12 months and in group C within 13-24 months after surgery, but remained unchanged on group A. Peak exercise heart rates were similar before and after surgery in each group. Peak exercise systolic pressures increased after surgery in all three groups, but the mean differences were statistically significant only in group C patients tested 13-24 months after surgery. The results of this study show that exercise testing is useful for quantifying the severity of aortic stenosis and documenting the clinical improvement (or lack thereof) after surgical treatment, and that properly supervised exercise testing can be performed at minimal risk to children with significant aortic stenosis.

Responses of normal children and young adults to controlled bicycle exercise

Exercise responses were obtained from 149 children and young adults (average age 14.5 years) and divided by sex and body surface area (BSA): children with BSA less than 1 m2; children with BSA 1--1.19 m2; males with BSA greater than or equal to 1.2 m2; and females with BSA greater than or equal to 1.2 m2. Total work, mean and maximal power outputs were more affected by body size (height) than age in children with BSA less than 1 m2 and in males and females with BSA greater than or equal to 1.2 m2. Mean systolic pressure increased up to 64% above the preexercise supine value at peak effort, with the level of mean maximal systolic pressure having a positive relationship with body size (height), power output and preexercise sitting systolic pressure in all subgroups except children with BSA 1--1.19 m2. Mean diastolic pressure increased up to 24% above the preexercise supine value at peak effort. ST-segment depression of 1--2 mm was recorded in 12.1% (18 of 149) of the population at peak exercise. These changes occurred in 8.9% of all males and in 16.9% of all females (p greater than 0.1). The data from this study reveal the importance of sex and body size in the clinical interpretation of exercise responses in growing subjects, provide a reference for objective evaluation of subjects with or without cardiac abnormalities and provide a guide for careful monitoring of subjects during an exercise study.

The aetiology of hypocalcaemia in acute pancreatitis

Plasma calcitonin, glucagon and parathyroid hormone were measured in patients with acute pancreatitis. Plasma calcitonin was not detectable in 6 specimens obtained from the hypocalcaemic patients. Plasma glucagon values were similar in patients with acute pancreatitis and control subjects and were unrelated to hypocalcaemia, which was not even induced by glucagon infusion. High or rising parathyroid hormone levels were noted in association with hypo-and normocalcaemia, suggesting that parathyroid hormone rises and maintains plasma calcium within normal limits. Plasma parathyroid hormone was, however, undetectable in 8 patients with prolonged hypocalcaemia. Deficiency of parathyroid hormone due to its destruction by proteolytic enzymes or because of parathyroid gland exhaustion is suggested as the major factor inducing persistent hypocalcaemia in acute pancreatitis. Administration of parathyroid hormone should, therefore, be considered in patients with acute pancreatitis when hypocalcaemia does not respond to intravenous calcium therapy.

Possible use of glucagon in the treatment of pancreatitis

Four patients with pancreatic disease received glucagon intravenously. In two a definite decrease in the volume of pancreatic exocrine secretion was shown, and in one of these pancreatic juice protein and bicarbonate levels also fell. Two patients with acute pancreatitis had pronounced relief of epigastric pain associated with falls in plasma amylase after intravenous glucagon.Several mechanisms could account for the possible beneficial effect of glucagon in pancreatitis, and further studies of its use in this disease are justified.