The PKC-ß selective inhibitor, Enzastaurin, impairs memory in middle-aged rats.

Enzastaurin is a Protein Kinase C-ß selective inhibitor that was developed to treat cancers. Protein Kinase C-ß is an important enzyme for a variety of neuronal functions; in particular, previous rodent studies have reported deficits in spatial and fear-conditioned learning and memory with lower levels of Protein Kinase C-ß. Due to Enzastaurin's mechanism of action, the present study investigated the consequences of Enzastaurin exposure on learning and memory in 12-month-old Fischer-344 male rats. Rats were treated daily with subcutaneous injections of either vehicle or Enzastaurin, and behaviorally tested using the spatial reference memory Morris Water Maze. Rats treated with Enzastaurin exhibited decreased overnight retention and poorer performance on the latter testing day, indicating a mild, but significant, memory impairment. There were no differences during the probe trial indicating that all animals were able to spatially localize the platform to the proper quadrant by the end of testing. RNA isolated from the hippocampus was analyzed using Next Generation Sequencing (Illumina). No statistically significant transcriptional differences were noted. Our findings suggest that acute Enzastaurin treatment can impair hippocampal-based learning and memory performance, with no effects on transcription in the hippocampus. We propose that care should be taken in future clinical trials that utilize Protein Kinase C-ß inhibitors, to monitor for possible cognitive effects, future research should examine if these effects are fully reversible.

Pragmatic staging of oesophageal cancer using decision theory involving selective endoscopic ultrasonography, PET and laparoscopy.

BACKGROUND: Following CT, guidelines for staging oesophageal and gastro-oesophageal junction (GOJ) cancer recommend endoscopic ultrasonography (EUS), PET-CT and laparoscopy for T3-T4 GOJ tumours. These recommendations are based on generic utilities, but it is unclear whether the test risk outweighs the potential benefit for some patients. This study sought to quantify investigation risks, benefits and utilities, in order to develop pragmatic, personalized staging recommendations. METHODS: All patients with a histological diagnosis of oesophageal or GOJ cancer staged between May 2006 and July 2013 comprised a development set; those staged from July 2013 to July 2014 formed the prospective validation set. Probability thresholds of altering management were calculated and predictive factors identified. Algorithms and models (decision tree analysis, logistic regression, artificial neural networks) were validated internally and independently. RESULTS: Some 953 patients were staged following CT, by [(18) F]fluorodeoxyglucose PET-CT (918), EUS (798) and laparoscopy (458). Of these patients, 829 comprised the development set (800 PET-CT, 698 EUS, 397 laparoscopy) and 124 the validation set (118 PET-CT, 100 EUS, 61 laparoscopy). EUS utility in the 71.8 per cent of patients with T2-T4a disease on CT was minimal (0.4 per cent), its risk exceeding benefit. EUS was moderately accurate for pT1 N0 disease. A number of factors predicted metastases on PET-CT and laparoscopy, although none could inform an algorithm. PET-CT altered management in 23.0 per cent, and laparoscopy in 7.1 per cent, including those with T2 and distal oesophageal tumours. CONCLUSION: Although EUS provided additional information on T and N category, its risk outweighed potential benefit in patients with T2-T4a disease on CT. Laparoscopy seemed justified for distal oesophageal tumours of T2 or greater.

Indications, stains and techniques in chromoendoscopy.

Early detection of malignancies within the gastrointestinal tract is essential to improve the prognosis and outcome of affected patients. However, conventional white light endoscopy has a miss rate of up to 25% for gastrointestinal pathology, specifically in the context of small and flat lesions within the colon. Chromoendoscopy and other advanced imaging techniques aim at facilitating the visualization and detection of neoplastic lesions and have been applied throughout the gastrointestinal tract. Chromoendoscopy, particularly in combination with magnifying endoscopy has significantly improved means to detect neoplastic lesions in the gastrointestinal mucosa, particularly in ulcerative colitis and Crohn's colitis. In addition, chromoendoscopy is beneficial in the upper gastrointestinal tract, especially when evaluating Barrett's oesophagus (BO) for the presence of dysplasia. Furthermore, it also improves characterization, differentiation and diagnosis of endoscopically detected suspicious lesions, and helps to delineate the extent of neoplastic lesions that may be amenable to endoscopic resection. This review discusses the dyes, indications and advanced endoscopic imaging methods used in various chromoendoscopic techniques, and presents a critical overview of the existing evidence supporting their use in current practice with a particular emphasis on the role in inflammatory bowel disease and BO.

An odd lump in the oesophagus - diagnostic and therapeutic approach?

A 60-year-old woman initially presented with a history of mild haematemesis. The patient denied any dysphagia, weight loss, or fever, intake of non-steroidal anti-inflammatory drugs or excessive alcohol consumption. She did not have abdominal pain and had not observed blood in her stools or melaena. At upper endoscopy, a potential source of bleeding could not be detected, but a subepithelial mass in the mid-oesophagus was revealed. The diagnostic and therapeutic approach to subepithelial oesophageal lesions is discussed.

Broad-based nutritional supplementation in 3xTg mice corrects mitochondrial function and indicates sex-specificity in response to Alzheimer's disease intervention.

Nutrition has been highlighted as a potential factor in Alzheimer's disease (AD) risk and decline and has been investigated as a therapeutic target. Broad-based combination diet therapies have the potential to simultaneously effect numerous protective and corrective processes, both directly (e.g., neuroprotection) and indirectly (e.g., improved vascular health). Here we administered either normal mouse chow with a broad-based nutritional supplement or mouse chow alone to aged male and female 3xTg mice and wildtype (WT) controls. After approximately 4 months of feeding, mice were given a battery of cognitive tasks and then injected with a radiolabeled glucose analog. Brains were assessed for differences in regional glucose uptake and mitochondrial cytochrome oxidase activity, AD pathology, and inflammatory markers. Supplementation induced behavioral changes in the 3xTg, but not WT, mice, and the mode of these changes was influenced by sex. Subsequent analyses indicated that differential response to supplementation by male and female 3xTg mice highlighted brain regional strategies for the preservation of function. Several regions involved have been shown to mediate responses to steroid hormones, indicating a mechanism for sex-based vulnerability. Thus, these findings may have broad implications for the human response to future therapeutics.

Continuous estrone treatment impairs spatial memory and does not impact number of basal forebrain cholinergic neurons in the surgically menopausal middle-aged rat.

CEE (conjugated equine estrogens) is the most widely prescribed estrogen-only menopausal hormone therapy in the United States, and is comprised of over 50% estrone (E1) sulfate. Following CEE administration, E1 is the principal circulating estrogen. However, the cognitive and neurobiological effects of E1 in a middle-aged rodent model have not yet been evaluated. We assessed cognitive effects of continuous E1 treatment in middle-aged surgically menopausal rats using a maze battery. We also quantified number of choline acetyltransferase-immunoreactive (ChAT-IR) neurons in distinct basal forebrain regions known in earlier studies in to be impacted by the most potent naturally-circulating estrogen in rodents and women, 17ß-estradiol (17ß-E2), as well as CEE. On the spatial working memory delayed-match-to-sample water maze, the highest E1 dose impaired memory performance during acquisition and after delay challenge. E1 did not impact ChAT-IR neuron number in the medial septum (MS) or horizontal/vertical diagonal bands. In a comparison study, 17ß-E2 increased MS ChAT-IR neuron number. Findings indicate that E1 negatively impacts spatial working memory and memory retention, and does not increase ChAT-IR neuron number in basal forebrain, as does 17ß-E2. Thus, data from prior studies suggest that 17ß-E2 and CEE can enhance cognition and increase number of ChAT-IR basal forebrain neurons, while here we show that E1 does not induce these effects. Findings from preclinical basic science studies can inform the design of specific combinations of estrogens that could be beneficial to the brain and cognition. Accumulating data suggest that E1 is not likely to be among these key beneficial estrogens.

Biliary papillomatosis and new ultrasound imaging modalities.

Biliary papillomatosis (BP) is a rare disorder of the biliary tract with a significant risk of malignant transformation and a high recurrence rate after operation due to the diffuse distribution of the disease. Preoperative diagnosis is difficult also by reason of the low sensitivity and specificity of conventional ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), endoscopic retrograde cholangiography (ERC) and positron emission tomography (PET). Therefore, the introduction of new diagnostic imaging methods is of importance to improve the preoperative diagnosis of this originally as benign described disease which is reflected in the term of "benign papillomatosis of the biliary tree". The present review summarizes the literature and discusses new sonographic imaging techniques including contrast-enhanced ultrasound (CEUS), contrast-enhanced low mechanical endoscopic ultrasound (CELMI-EUS) and endoscopic ultrasound elastography.

A unique clinical phenotype of primary sclerosing cholangitis associated with Crohn's disease.

BACKGROUND AND AIMS: A distinct clinical phenotype has been demonstrated for ulcerative colitis with concomitant primary sclerosing cholangitis (PSC). The course and behaviour of Crohn's disease (CD) with PSC has, in contrast, never been defined. We aimed to define the characteristics of patients with concomitant PSC and CD. METHODS: The Oxford PSC and IBD databases were abstracted for: PSC subtype, date of diagnosis, symptom onset, smoking history, Mayo Clinic PSC score and outcomes (hepatic failure, liver transplantation, Montréal CD classification, treatment, cancer and death). Patients with PSC/CD were matched 1:2 to two control groups: one with PSC/UC and one with isolated CD. RESULTS: 240 patients with PSC were identified; 32 (13%) with CD, 129 (54%) with co-existing UC, and 79 had PSC without IBD. For PSC/CD vs. CD controls, isolated ileal CD was less common (6% vs. 31%, p=0.03). Smoking was less common in PSC/CD (13% vs. 34%, p=0.045). No difference in the distribution of CD, or treatment required was observed. For PSC/CD vs. PSC/UC controls, more patients with PSC/CD were female (50% vs. 28%, p=0.021). 22% of PSC/CD patients had small duct PSC compared with 6% with PSC/UC, (p=0.038). Major event-free survival was prolonged in the PSC/CD group compared with PSC/UC, (Cox regression p=0.04). CONCLUSION: Unlike PSC/UC, patients with PSC/CD were as likely to be female as male, more commonly had small duct PSC and less commonly progressed to cancer, liver transplantation, or death. Compared to patients with isolated CD, patients with PSC/CD were less likely to smoke or have ileal disease.

The cognitive effects of conjugated equine estrogens depend on whether menopause etiology is transitional or surgical.

The question of whether to take hormone therapy (HT) will impact every woman as she enters reproductive senescence. In women, studies suggest that ovarian hormone loss associated with menopause has deleterious cognitive effects. Results from clinical studies evaluating whether estrogen-containing HT mitigates these effects, and benefits cognition, are discrepant. Type of menopause, surgical vs. transitional, impacts cognitive outcome in women. However, whether type of menopause impacts cognitive effects of HT has not been methodically tested in women or an animal model. We used the 4-vinylcyclohexene diepoxide rodent model of ovarian follicle depletion, which mimics transitional menopause, and the traditional rat model of menopause, ovariectomy, to cognitively test the most commonly prescribed estrogen therapy in the United States, conjugated equine estrogens (Premarin). Here we show conjugated equine estrogens benefited cognition in surgically menopausal rats, but, in contrast, impaired cognition in transitionally menopausal rats. Androstenedione, released from the residual transitional menopausal ovary, was positively associated with impaired performance, replicating our previous findings in 4-vinylcyclohexene diepoxide animals. The current findings are especially salient given that no clinical study testing cognition has methodically separated these two populations of menopausal women for analysis. That we now show surgical vs. transitional modes of menopause result in disparate cognitive effects of HT has implications for future research and treatments optimizing HT for menopausal women.

Contrast-enhanced ultrasound for imaging of adrenal masses.

PURPOSE: The number of incidentally discovered adrenal masses is growing due to the increased use of modern high-resolution imaging techniques. However, the characterization and differentiation of benign and malignant adrenal lesions is challenging. This study aimed to evaluate contrast-enhanced ultrasound for the characterization of adrenal masses. MATERIALS AND METHODS: We studied 58 patients with adrenal masses detected with computed tomography, magnetic resonance imaging, or ultrasound. 7 patients had bilateral adrenal lesions. Contrast-enhanced ultrasound was performed using high-resolution ultrasound (3.5 - 7 MHz) and intravenous injection of 2.4 ml SonoVue. The contrast enhancement pattern of all adrenal lesions was documented. RESULTS: The 18 malignant adrenal tumors were significantly larger at the time of diagnosis compared to the 40 benign lesions (p < 0.03). The majority of benign adrenal lesions (37 / 40) had a nonspecific type of contrast enhancement (24 / 40) or a peripheral to central contrast filling (13 / 40) described as the iris phenomenon. Similar findings were observed in malignant adrenal tumors: most malignant lesions also showed nonspecific (6 / 18) or peripheral to central contrast filling (9 / 18). Peripheral to central contrast filling had 50 % sensitivity (26 - 74 %) and 68 % specificity (51 - 81 %) for indicating malignancy. CONCLUSION: Contrast-enhanced ultrasound facilitates the visualization of vascularization even in small adrenal masses, but it does not help to distinguish malignant and benign lesions.

13C-methacetin-breath test compared to also noninvasive biochemical blood tests in predicting hepatic fibrosis and cirrhosis in chronic hepatitis C.

BACKGROUND: The (13)C-methacetin-breath test and also several noninvasive blood tests comprising routine laboratory parameters have been proposed to predict fibrosis and cirrhosis in chronic hepatitis C. The aim of the study was to compare the diagnostic accuracy between these tests referring to hepatic histology as gold standard. METHODS: 96 patients with chronic hepatitis C virus infection underwent percutaneous liver biopsy and the (13)C-methacetin-breath test. The Fibroindex, the aspartate aminotransferase to platelet ratio index , and the aspartate aminotransferase to alanine aminotransferase ratio were used as parameters for the staging of fibrosis. The main endpoint was the area under the characteristic curves for the diagnosis of advanced fibrosis (F3-F4) and cirrhosis (F4) according to the Batts Ludwig criteria. RESULTS: ROC analysis revealed a cut-off <14.6 per thousand best with 92.6% sensitivity and 84.1% specificity for the (13)C-methacetin-breath test, for the Fibroindex >1.82 70.4% sensitivity and 91.3% specificity, for the aspartate aminotransferase to platelet ratio >1.0 a 66.7% sensitivity and 75.4% specificity, and for the aspartate aminotransferase to alanine aminotransferase ratio >1.0 63.0% sensitivity and 59.4% specificity in predicting liver cirrhosis. The areas under the curve for the breath test, the Fibroindex, aspartate aminotransferase to platelet ratio and the aspartate aminotransferase to alanine aminotransferase ratio were 0.958, 0.845, 0.799, and 0.688, respectively, when predicting cirrhosis. For identifying patients with advanced fibrosis, the areas under the curve were 0.827, 0.804, 0.779, and 0.561, respectively. Discordances between Fibroindex (21%), aspartate aminotransferase to platelet ratio (29%) or aspartate aminotransferase to alanine aminotransferase ratio (37.6%) and liver biopsy were significantly more frequent than between (13)C-breath test (11.6%) and liver biopsy (P<0.05). CONCLUSION: The (13)C-methacetin-breath test is more reliable in predicting advanced fibrosis and cirrhosis than simple biochemical parameters (aspartate aminotransferase to platelet ratio; aspartate aminotransferase to alanine aminotransferase ratio).

Improved characterisation of solitary solid pancreatic tumours using contrast enhanced transabdominal ultrasound.

BACKGROUND: Contrast enhanced ultrasound (CEUS) is a new imaging method for detection and characterisation of liver tumours. The role of CEUS in pancreatic disease is less obvious. We prospectively evaluated CEUS for characterization of undetermined solid pancreatic lesions (gold standard histology). PATIENTS AND METHODS: A total of 112 solitary undetermined pancreatic masses (70 ductal adenocarcinoma and 42 neoplastic nodules of other origin) were prospectively examined in patients without metastatic disease using transabdominal ultrasound. Tumour enhancing features were analyzed in comparison to the surrounding pancreatic parenchyma in patients with adequate visualisation. RESULTS: The sign of iso-hypervascularity as a sign of non-ductal adenocarcinoma showed a sensitivity of 100%, specifity of 90% and accuracy of 93.8%. The sign of hypovascularity as a sign of ductal adenocarcinoma showed a sensitivity of 90%, specifity of 100% and an accuracy of 93.8%. CONCLUSION: CEUS allows differential diagnosis of ductal adenocarcinoma and non-ductal adenocarcinoma (mainly neuroendocrine tumours and (microcystic) serous pancreatic adenoma) in the most of cases.

13C-methacetin breath test as liver function test in patients with chronic hepatitis C virus infection.

BACKGROUND: The 13C-methacetin breath test enables the quantitative evaluation of the cytochrome P450-dependent liver function. AIM: To find out whether this breath test is sensitive in noncirrhotic patients also with chronic hepatitis C in early stages of fibrosis. METHODS: Sixty-one healthy controls and 81 patients with chronic hepatitis C underwent a 13C-methacetin breath test. In all patients, a liver biopsy was performed. The liver histology was classified according to the histology activity index-Knodell score. RESULTS: Delta over baseline values of the patients at 15 min significantly differed from controls (19.2 +/- 9.2 per thousand vs. 24.1 +/- 5.7 per thousand; P < 0.003). The cumulative recovery after 30 min in patients was 11.4 +/- 4.8% and in healthy controls 13.8 +/- 2.8% (P < 0.002). However, patients with early fibrosis (histology activity index IVB) did not differ in delta over baseline values of the patients at 15 min (23.2 +/- 7.9 per thousand vs. 22.6 +/- 7.2 per thousand; P = 0.61) or cumulative recovery (13.6 +/- 3.7% vs. 13.2 +/- 3.8%; P = 0.45) from patients with more advanced fibrosis (histology activity index IVC). Patients with clinically nonsymptomatic cirrhosis (histology activity index IVD; Child A) metabolized 13C-methacetin to a significantly lesser extent (delta over baseline values of the patients at 15 min: 8.3 +/- 4.9 per thousand; P < 0.005 and cumulative recovery after 30 min: 5.6 +/- 3.2%; P < 0.003). The 13C-methacetin breath test identified cirrhotic patients with 95.0% sensitivity and 96.7% specificity. CONCLUSION: The non-invasive 13C-methacetin breath test reliably distinguishes between early cirrhotic (Child A) and noncirrhotic patients, but fails to detect early stages of fibrosis in patients with chronic hepatitis C.

The new DR-70 immunoassay detects cancer of the gastrointestinal tract: a validation study.

BACKGROUND: Malignant cells characteristically possess high levels of plasminogen activator, which induce local fibrinolysis. The DR-70 immunoassay is a newly developed test, which quantifies fibrin degradation products in serum by a proprietary antibody. AIM: To evaluate the DR-70 immunoassay as a detection assay for the presence of gastrointestinal cancers. METHODS: We prospectively collected blood sera of 85 patients with histologically proven tumour and 100 healthy blood donors. Ten microlitres of the sera was used for the DR-70 immunoassay. Nineteen patients had a hepatocellular and 10 cholangiocellular carcinoma, 13 cancer of the pancreas, 30 colorectal cancer, 10 stomach cancer and three cancer of the oesophagus. RESULTS: Receiver-operator curve analysis revealed <0.7 microg/mL as the best cut-off value to distinguish between patients with cancer and healthy controls. Using this cut-off value, the DR-70 immunoassay showed a good clinical performance with a sensitivity of 91% and a specificity of 93%. Patients with advanced tumour spread showed significantly higher DR-70 values than those with early-stage tumours (P < 0.0003). CONCLUSION: The DR-70 immunoassay reliably differs between cancer patients and healthy controls. Therefore, it promises to become a useful test for the detection of cancer in clinical practice.

[Acute lower gastrointestinal hemorrhage. Diagnosis and management]. / Akute untere Gastrointestinalblutung. Diagnostik und Management.

In most cases (80%), acute lower gastrointestinal bleeding stops spontaneously, but rebleeding is frequent (25%). The intensity and quality of the bleeding--hematochezia, melena, or occult bleeding--determines the diagnostic and therapeutic strategy (endoscopic evaluation of the upper and lower gastrointestinal tract, mesenteric angiography, scintigraphy, enteroscopy, capsule endoscopy) and its urgency. Acute lower gastrointestinal bleeding can mostly be treated conservatively or by endoscopic interventions (injection therapy, clip application, coagulation and ligation methods). Severe hemorrhage can render colonoscopy and the identification of the bleeding source technically difficult. Emergency operations are only indicated when patients with severe hemorrhage cannot be stabilized by interventional endoscopy or angiography with selective embolization.

[Imaging of the abdomen.

In the last decade, innovative ultrasound technology has become the primary imaging method in Gastroenterology. Compared to other imaging techniques (e. g., computed tomography and magnetic resonance imaging), conventional ultrasound images have the disadvantage of a restricted field-of-view (width), thus producing images that are not always easy to read. During the examination, the many mosaic-like single images obtained in real-time sonography must be mentally pieced together by the user, in order to obtain a complex 3-dimensional picture of the anatomical structure and its surrounding tissue. The extended field-of-view of the Panoramic Imaging technique is a useful addition to conventional diagnostic ultrasound since it provides the enhanced overview required for exact topography of surrounding structures. This is especially true for the Power Mode Panoramic Imaging technique that allows the trading of vessels over greater distances, e.g., in the extremities. Thus, accuracy and reproducibility of measurements in the examination of larger structures and organs has improved. A clearer representation of these anatomical structures increases understanding and acceptance by referring clinicians. An exact diagnosis based on ultrasound imaging will certainly result in cost savings in health-care, since the use of further imaging methods (and therefore the total examination time) may be reduced.

Detection of Helicobacter pylori infection: when to perform which test?

This paper reviews current diagnostic techniques for Helicobacter pylori infection and critically questions their value under different diagnostic circumstances. As long as we do not have general treatment recommendations for H. pylori infection, endoscopy is still the basis for primary diagnosis because it assesses therapy indications. In addition, histology characterizes the gastroduodenal lesions observed and may reveal malignant diseases. New rapid urease tests from the biopsies are inexpensive, simple, and quick giving results reliably within 1 h. Culturing H. pylori from gastric samples after therapy failure and testing the strains for antimicrobial susceptibility is becoming increasingly important with higher prevalence of drug resistances. Nonendoscopic tests are more convenient to the patient. Serological tests inexpensively detect circulating IgG or IgA antibodies. However, inspite of the cost attractiveness, serology might be problematic in indicating present H. pylori infection. The tests of choice for noninvasive monitoring therapy success or failure are the 13C-urea breath test and the faecal antigen immunoassay. Both tests are also of value for first diagnosis in children when endoscopy is not indicated. In the future, serological detection of virulence factors and polymerase chain reaction with molecular fingerprinting might help to identify H. pylori strains with high pathogenicity or antibiotic resistance.

[Bacillary angiomatosis of the liver, a suspected ultrasound diagnosis?]. / Bazilläre Angiomatose der Leber, eine sonographische Verdachtsdiagnose?

Infections with Bartonella henselae or Bartonella quintana present with vasoproliferative lesions in skin and parenchymatous organs in immunocompromised patients. A case report of a 38-year-old patient with HIV infection and hepatitis B surface antigen status is described. The dominant clinical symptoms in our patient were fever and icterus. Ultrasonography of the abdomen showed a picture similar to that of liver cirrhosis. Irregular (echorich) nodes with hyper-vascularization were suspected to be hepatocellular carcinoma. Ultrasound guided puncture of one of these lesions and histological examination revealed the diagnosis of bartonella infection. Under antibiotic treatment with clarithromycin and doxycycline the fever and the hyperbilirubinemia decreased. The sonographically detectable lesions reduced in size. Vasoproliferative lesions in immunodeficient patients caused by bartonella infection show a characteristic slightly hyperechogenic irregular pattern at ultrasound. Typically, circumscribed hypervascularization might be shown by color Doppler imaging. Liver cirrhosis and diffuse tumor infiltration should be excluded.

Structural, functional and immunological studies on a polymeric bacterial protein

The characterization of proteins from Brucella spp, the causative agent of brucellosis, has been the subject of intensive research. We have described an 18-kDa cytoplasmic protein of Brucella abortus and shown the potential usefulness of this protein as an antigen for the serologic diagnosis of brucellosis. The amino acid sequence of the protein showed a low but significant homology with that of lumazine synthases. Lumazine is an intermediate product in bacterial riboflavin biosynthesis. The recombinant form of the 18-kDa protein (expressed in E. coli) folds like the native Brucella protein and has lumazine-synthase enzymatic activity. Three-dimensional analysis by X-ray crystallography of the homolog Bacillus subtilis lumazine synthase has revealed that the enzyme forms an icosahedral capsid. Recombinant lumazine synthase from B. abortus was crystallized, diffracted X rays to 2.7-A resolution at room temperature, and the structure successfully solved by molecular replacement procedures. The macromolecular assembly of the enzyme differs from that of the enzyme from B. subtilis. The Brucella enzyme remains pentameric (90 kDa) in its crystallographic form. Nonetheless, the active sites of the two enzymes are virtually identical at the structural level, indicating that inhibitors of these enzymes could be viable pharmaceuticals across a broad species range. We describe the structural reasons for the differences in their quaternary arrangement and also discuss the potential use of this protein as a target for the development of acellular vaccines.