Avelumab in unresectable/metastatic, progressive, grade 2-3 neuroendocrine neoplasms (NENs): Combined results from NET-001 and NET-002 trials.

BACKGROUND: Higher grade neuroendocrine neoplasm (NENs) continues to pose a treatment dilemma, with the optimal treatment undefined. Although immunotherapy has revolutionised the treatment of many cancers, its role in NENs remains unclear. We aimed to investigate the efficacy and safety of avelumab, a PD-L1-directed antibody, in patients with advanced unresectable/metastatic higher grade NENs. METHODS: NET001 and NET002 are phase II studies investigating avelumab (NCT03278405 and NCT03278379). Eligible patients had unresectable and/or metastatic WHO G2-3 NENs from a gastroenteropancreatic (GEP) source or a bronchial primary (excluding typical carcinoid) and 0-2 prior lines of systemic therapy (excluding SSAs). Patients were treated with avelumab 10 mg/kg intravenously every two weeks for 26 cycles. NET001 investigated G3 poorly differentiated GEP neuroendocrine carcinomas (NECs) and bronchial small/large cell NEC, whereas NET002 investigated G2-3 well-differentiated GEPNETs and bronchial atypical carcinoids. The primary endpoint in both trials was overall response rate (ORR) by RECIST v1.1; secondary endpoints included progression-free survival, overall survival, disease control rate at six months and toxicity. RESULTS: Twenty-seven patients were enrolled (21 GEP, 6 lung; 10 in NET-001, 17 in NET-002); median age 64 (range 37-80), 30% ECOG PS 1-2 and 78% received 1+ lines of prior therapy. The median Ki-67 index was 35% (range 10-100). Twelve of the twenty-seven patients had died at the time of data lock. The median time on treatment was 85 days (seven cycles). No objective responses were observed. Stable disease was achieved in 33% of patients, and the disease control rate at 6 mo was 21%. The median PFS was 3.3 months (range 1.2-24.6), and the median OS was 14.2 months. Treatment-related adverse events (all grades) occurred in 58% of patients. Three patients had treatment-related grade 3-4 AEs leading to treatment discontinuation (immune-related hepatitis n = 2 and infusion-related reaction n = 1). CONCLUSION: Single-agent PD-L1 blockade with avelumab showed limited antitumour activity in patients with G2-3 NENs. Correlative studies are underway. Further studies are needed to explore the role of dual immunotherapy and other combinations in this population with few treatment alternatives.

Strategies for the delay of surgery in the management of resectable hepatobiliary malignancies during the COVID-19 pandemic.

Objective: We aimed to review data about delaying strategies for the management of hepatobiliary cancers requiring surgery during the covid-19 pandemic. Background: Given the covid-19 pandemic, many jurisdictions, to spare resources, have limited access to operating rooms for elective surgical activity, including cancer, thus forcing deferral or cancellation of cancer surgeries. Surgery for hepatobiliary cancer is high-risk and particularly resource-intensive. Surgeons must critically appraise which patients will benefit most from surgery and which ones have other therapeutic options to delay surgery. Little guidance is currently available about potential delaying strategies for hepatobiliary cancers when surgery is not possible. Methods: An international multidisciplinary panel reviewed the available literature to summarize data relating to standard-of-care surgical management and possible mitigating strategies to be used as a bridge to surgery for colorectal liver metastases, hepatocellular carcinoma, gallbladder cancer, intrahepatic cholangiocarcinoma, and hilar cholangiocarcinoma. Results: Outcomes of surgery during the covid-19 pandemic are reviewed. Resource requirements are summarized, including logistics and adverse effects profiles for hepatectomy and delaying strategies using systemic, percutaneous and radiation ablative, and liver embolic therapies. For each cancer type, the long-term oncologic outcomes of hepatectomy and the clinical tools that can be used to prognosticate for individual patients are detailed. Conclusions: There are a variety of delaying strategies to consider if availability of operating rooms decreases. This review summarizes available data to provide guidance about possible delaying strategies depending on patient, resource, institution, and systems factors. Multidisciplinary team discussions should be leveraged to consider patient- and tumour-specific information for each individual case.

Immediate and long-term impact of the COVID-19 pandemic on delivery of surgical services.

BACKGROUND: The ongoing pandemic is having a collateral health effect on delivery of surgical care to millions of patients. Very little is known about pandemic management and effects on other services, including delivery of surgery. METHODS: This was a scoping review of all available literature pertaining to COVID-19 and surgery, using electronic databases, society websites, webinars and preprint repositories. RESULTS: Several perioperative guidelines have been issued within a short time. Many suggestions are contradictory and based on anecdotal data at best. As regions with the highest volume of operations per capita are being hit, an unprecedented number of operations are being cancelled or deferred. No major stakeholder seems to have considered how a pandemic deprives patients with a surgical condition of resources, with patients disproportionally affected owing to the nature of treatment (use of anaesthesia, operating rooms, protective equipment, physical invasion and need for perioperative care). No recommendations exist regarding how to reopen surgical delivery. The postpandemic evaluation and future planning should involve surgical services as an essential part to maintain appropriate surgical care for the population during an outbreak. Surgical delivery, owing to its cross-cutting nature and synergistic effects on health systems at large, needs to be built into the WHO agenda for national health planning. CONCLUSION: Patients are being deprived of surgical access, with uncertain loss of function and risk of adverse prognosis as a collateral effect of the pandemic. Surgical services need a contingency plan for maintaining surgical care in an ongoing or postpandemic phase.

ANTECEDENTES: La pandemia en curso tiene un efecto colateral sobre la salud en la prestación de atención quirúrgica a millones de pacientes. Se sabe muy poco sobre el manejo de la pandemia y sus efectos colaterales en otros servicios, incluida la prestación de servicios quirúrgicos. MÉTODOS: Se ha realizado una revisión de alcance de toda la literatura disponible relacionada con COVID-19 y cirugía utilizando bases de datos electrónicas, páginas web de sociedades, seminarios online y repositorios de pre-publicaciones. RESULTADOS: Se han publicado varias guías perioperatorias en un corto período de tiempo. Muchas recomendaciones son contradictorias y, en el mejor de los casos, se basan en datos anecdóticos. A medida que las regiones con el mayor volumen de operaciones per cápita se ven afectadas, se cancela o difiere un número sin precedentes de operaciones. Ninguna de las principales partes interesadas parece haber considerado cómo una pandemia priva de recursos a los pacientes que necesitan una intervención quirúrgica, con pacientes afectados de manera desproporcionada debido a la naturaleza del tratamiento (uso de anestesia, quirófanos, equipo de protección, contacto físico y necesidad de atención perioperatoria). No existen recomendaciones sobre cómo reanudar la actividad quirúrgica. La evaluación tras la pandemia y la planificación futura deben incluir a los servicios quirúrgicos como una parte esencial para mantener la atención quirúrgica adecuada para la población también durante un brote epidémico. La prestación de servicios quirúrgicos, debido a su naturaleza transversal y a sus efectos sinérgicos en los sistemas de salud en general, debe incorporarse a la agenda de la OMS para la planificación nacional de la salud. CONCLUSIÓN: Los pacientes se ven privados de acceso a la cirugía con una pérdida de función incierta y riesgo de un pronóstico adverso como efecto colateral de la pandemia. Los servicios quirúrgicos necesitan un plan de contingencia para mantener la atención quirúrgica durante la pandemia y en la fase post-pandemia.

Population-based study of the prevalence and management of self-reported high pain scores in patients with non-resected pancreatic adenocarcinoma.

BACKGROUND: Pain is a common debilitating symptom in pancreatic adenocarcinoma. This cohort study examined the use of, and factors associated with, pain-directed interventions for a high pain score in patients with non-curable pancreatic adenocarcinoma. METHODS: Administrative databases were linked and patients with non-resected pancreatic adenocarcinoma diagnosed between 2010 and 2016, who reported one or more Edmonton Symptom Assessment System (ESAS) score, were identified. A high pain score was defined as an ESAS score of at least 4. Outcomes were pain-directed interventions: opiates (in patients aged 65 years or more with universal drug coverage), nerve block and radiation therapy for a high pain score. Reduction in pain score of at least 1 point after pain-directed intervention was also evaluated. Modified Poisson regression was used to examine factors associated with pain-directed intervention. RESULTS: Among 2623 patients with a median age of 67 years, 1223 (46·6 per cent) were women, and 1621 (61·8 per cent) reported a high pain score at a median of 38 days after diagnosis. Of those with a high pain score, 75·6 per cent (688 of 910) received opiates, 13·5 per cent (219 of 1621) radiation and 1·2 per cent (19 of 1621) nerve block. The pain score decreased in 62·1 per cent of patients after administration of opiates, 73·4 per cent after radiation and all patients after nerve block. In multivariable analysis, no patient factor (age, sex, co-morbidity burden, rurality, income quintile) was associated with receipt of non-opiate pain-directed intervention for a high pain score. In patients aged at least 65 years, advanced age was associated with lower odds of opiate use. CONCLUSION: Opiates are the most common pain-directed intervention for non-curable pancreatic adenocarcinoma, whereas radiation therapy and nerve blocks are seldom used. The lack of association between pain-directed interventions and patient factors points toward practice-driven patterns.

ANTECEDENTES: El dolor es un síntoma debilitante frecuente en el adenocarcinoma de páncreas. Este estudio de cohortes examinó el uso de las intervenciones dirigidas para el tratamiento del dolor y los factores asociados a las mismas en pacientes con adenocarcinoma pancreático incurable que presentaban puntuaciones altas de dolor. MÉTODOS: Se revisaron las bases de datos administrativas y se identificaron los pacientes con adenocarcinoma pancreático no resecado diagnosticados entre 2010-2016 con puntuaciones > 1 del Sistema de Evaluación de Síntomas de Edmonton (Edmonton Symptom Assessment System, ESAS). La puntuación alta de dolor se definió como ESAS > 4. Los resultados evaluados fueron las intervenciones dirigidas contra el dolor: opiáceos (en pacientes mayores de 65 años con cobertura universal de medicamentos), bloqueo nervioso y radioterapia en el caso de puntuación alta del dolor. También se evaluó la reducción en la puntuación del dolor (> 1 punto) después de la intervención dirigida contra el dolor. Los factores asociados a la intervención contra el dolor se analizaron mediante una regresión de Poisson modificada. RESULTADOS: De los 2.623 pacientes con una mediana de edad de 67 años, 1.223 (46,6%) eran mujeres, y 1.621 (61.8%) presentaron una puntuación alta de dolor con una mediana de 38 días desde el momento del diagnóstico. De aquellos con puntuación alta de dolor, el 75,6% recibió opiáceos (n = 688/910), el 13,5% radiación (n = 219/1.621) y el 1,2% bloqueo nervioso (n = 19/1.621). La puntuación del dolor disminuyó en el 62,2% después del tratamiento con los opiáceos, en el 73,8% después de la radiación y en el 100% después del bloqueo nervioso. En el análisis multivariable, ningún factor relacionado con el paciente (edad, sexo, comorbilidades, vivir en una zona rural, quintil de ingresos) se asoció con una intervención dirigida contra dolor sin opiáceos en los casos de puntuación alta del dolor. En pacientes mayores de 65 años, la edad avanzada se asoció con menor probabilidad de uso de opiáceos. CONCLUSIÓN: Mientras que los opiáceos son la intervención dirigida contra dolor más común para el adenocarcinoma pancreático no resecable, la radioterapia y el bloqueo nervioso rara vez se usan. La falta de asociación de las intervenciones dirigidas contra el dolor con los factores del paciente apunta hacia el uso de patrones terapéuticos basados ​​en la práctica clínica.

Predictors of Post-operative Pain and Opioid Consumption in Patients Undergoing Liver Surgery.

BACKGROUND: Post-operative pain management is a critical component of perioperative care. Patients at risk of poorly controlled post-operative pain may benefit from early measures to optimize pain management. We sought to identify risk factors for post-operative pain and opioid consumption in patients undergoing liver resection. METHODS: This is a multi-institutional prospective nested cohort study of patients undergoing open liver resection. Opioid consumption and pain scores were collected following surgery. To estimate the effects of patient factors on opioid consumption (oral morphine equivalents-OME) and on pain scores (NRS-11), we used generalized linear models and multivariable linear regression model, respectively. RESULTS: One hundred and fifty-three patients who underwent open liver resection between 2013 and 2016 were included in the study. The mean patient age was 62.2 years, and 43.3% were female. Younger patients were significantly more likely to use more opioids in the early post-operative period (16.7 OME/10 years, p < 0.001). Patient factors that were significantly associated with increased NRS-11 pain scores also included younger patient age (difference in pain score of 0.3/10 years with cough and 0.2/10 years at rest, p < 0.01 for both) as well as a history of analgesic use (difference in pain score of 0.9 with cough and 0.6 at rest, p < 0.01 and p = 0.07, respectively). CONCLUSION: Younger patients and those with a history of analgesic use are more likely to report higher post-operative pain and require higher doses of opioids. Early identification of these patients, and measures to better manage their pain, may contribute to optimal perioperative care.

Population-based study of the impact of surgical and adjuvant therapy at the same or a different institution on survival of patients with pancreatic adenocarcinoma.

Background: Pancreatic cancer surgery is increasingly regionalized in high-volume centres. Provision of adjuvant chemotherapy in the same institution can place a burden on patients, whereas receiving adjuvant chemotherapy at a different institution closer to home may create disparities in care. This study compared long-term outcomes of patients with pancreatic adenocarcinoma receiving adjuvant chemotherapy at the institution where they had undergone surgery with outcomes for those receiving chemotherapy at a different institution. Methods: This was a population-based study of patients receiving adjuvant chemotherapy after resection of pancreatic adenocarcinoma performed at ten designated hepatopancreatobiliary centres in Ontario, Canada, between 2004 and 2014. Patients were divided into those receiving chemotherapy at the same institution as surgery or a different institution from where surgery was performed. The primary outcome was overall survival (OS). Multivariable Cox regression assessed the association between OS and each chemotherapy group, adjusted for potential confounders. Results: Of 589 patients, 374 (63·5 per cent) received adjuvant chemotherapy at the same institution as surgery. After adjusting for age, sex, co-morbidity, socioeconomic status, rural living, tumour stage, margin positivity and year of surgery, the location of adjuvant chemotherapy was not independently associated with OS (hazard ratio 1·03, 95 per cent c.i. 0·85 to 1·24). For patients who underwent chemotherapy at a different institution, mean travel distance to receive chemotherapy was less (22·9 km) than that needed for surgery (106·7 km). Conclusion: After pancreatectomy for pancreatic adenocarcinoma at specialized hepatopancreatobiliary surgery centres, OS was not affected by the location of the centre delivering adjuvant chemotherapy. Receiving this treatment in a local centre reduced patients' travel burden.

Access to care and outcomes for neuroendocrine tumours: does socioeconomic status matter?

Introduction: Neuroendocrine tumours (nets) are a poorly understood malignancy lacking standardized care. Differences in socioeconomic status (ses) might worsen the effect of non-standardized care. We examined the effect of ses on net peri-diagnostic care patterns and outcomes. Methods: In this population-based cohort study, net cases identified from a provincial cancer registry (1994-2009) were divided into low (1st and 2nd income quintiles) and high (3rd, 4th, and 5th quintiles) ses groups. We compared peri-diagnostic health care utilization (-2 years to +6 months), metastatic recurrence, and overall survival (os) between the groups. Results: Of 4966 net patients, 38.3% had a low ses. Neither the primary net sites (p = 0.15), nor the metastatic presentation (p = 0.31) differed. Patients with low ses had a higher mean number of physician visits (20.1 ± 19.9 vs. 18.1 ± 16.5, p = 0.001) and imaging studies (56 ± 50 vs. 52 ± 44, p = 0.009) leading to the net diagnosis. Rates of primary tumour resection (p = 0.14), hepatectomy (p = 0.45), systemic therapy (p = 0.38), and liver embolization (p = 0.13) did not differ with ses. In the low-ses group, metastatic recurrence was more likely (41.1% vs. 37.6%, p = 0.01) during a median follow-up of 61.7 months, and the 10-year os was inferior (47.1% vs. 52.2%, p < 0.01). Low ses was associated with worse os (hazard ratio: 1.16; 95% confidence interval: 1.06 to 1.26) after adjustment for age, sex, comorbidity burden, primary net site, and rural living. Conclusions: Low ses was associated with more physician visits and imaging before a net diagnosis, but not with more advanced stage at presentation nor with an effect on the pattern of therapy. Long-term outcomes were inferior in the low-ses group. These data can help to inform the design of health care delivery for nets.

External Beam Radiotherapy in the Treatment of Gastroenteropancreatic Neuroendocrine Tumours: A Systematic Review.

AIMS: External beam radiotherapy (EBRT) is infrequently used to treat gastroenteropancreatic neuroendocrine tumours (GEPNETS), with little published data to date. We carried out a systematic review to assess the activity of EBRT for GEPNETS. MATERIALS AND METHODS: Major databases were searched for papers including at least five patients treated with contemporary EBRT techniques. Eligible studies underwent dual independent review. The primary end points were response rate for lesions treated with definitive intent and recurrence-free survival for primary lesions treated with neoadjuvant or adjuvant intent. RESULTS: Of 11 included studies (all retrospective), seven investigated pancreatic neuroendocrine tumours (PNETs, 100 patients, 14% grade 3) and four studies investigated extra-pancreatic neuroendocrine tumours (84 patients, 14% grade 3). Trials investigating PNETs administered a median of 50.4 Gy via three-dimensional conformal radiotherapy and intensity-modulated radiotherapy. EBRT was given with neoadjuvant or adjuvant intent in 56 patients, with a recurrence rate of 15%. For the 44 patients not undergoing surgery, the radiological response rate was 46%. Grade 3 + toxicity rates were 11% (acute) and 4% (late). Twelve patients with anorectal neuroendocrine carcinoma received 58 Gy to the primary tumour. Seventy-two patients were treated to sites of metastatic disease (34 bone, 27 brain, 11 soft tissue). Local and distant control were poorly reported. Overall survival ranged from 9 to 19 months. No studies in this group reported toxicity outcomes. CONCLUSIONS: There are limited, retrospective data on the overall activity and safety of EBRT in GEPNETS. EBRT generally seems to be well tolerated in selected PNET patients with encouraging activity. Well-designed prospective studies in clearly defined populations are required to clarify the role of EBRT in neuroendocrine tumours.

Factors influencing recurrence following initial hepatectomy for colorectal liver metastases.

BACKGROUND: Data on recurrence patterns following hepatectomy for colorectal liver metastases (CRLMs) and their impact on long-term outcomes are limited in the setting of modern multimodal management. This study sought to characterize the patterns of, factors associated with, and survival impact of recurrence following initial hepatectomy for CRLMs. METHODS: A retrospective cohort study of patients undergoing initial hepatectomy for CRLMs at 39 institutions (2006-2013) was conducted. Kaplan-Meier methods were used for survival analyses. Overall survival landmark analysis at 12 months after hepatectomy was performed to compare groups based on recurrence. Multivariable Cox and regression models were used to determine factors associated with recurrence. RESULTS: Among 2320 patients, tumours recurred in 47·4 per cent at median of 10·1 (range 0-88) months; 89·1 per cent of recurrences developed within 3 years. Recurrence was intrahepatic in 46·2 per cent, extrahepatic in 31·8 per cent and combined intra/extrahepatic in 22·0 per cent. The 5-year overall survival rate decreased from 74·3 (95 per cent c.i. 72·2 to 76·4) per cent without recurrence to 57·5 (55·0 to 60·0) per cent with recurrence (adjusted hazard ratio (HR) 3·08, 95 per cent c.i. 2·31 to 4·09). After adjusting for clinicopathological variables, prehepatectomy factors associated with increased risk of recurrence were node-positive primary tumour (HR 1·27, 1·09 to 1·49), more than three liver metastases (HR 1·27, 1·06 to 1·52) and largest metastasis greater than 4 cm (HR 1·19; 1·01 to 1·43). CONCLUSION: Recurrence after CRLM resection remains common. Although overall survival is inferior with recurrence, excellent survival rates can still be achieved.

Variability of Ki67 labeling index in multiple neuroendocrine tumors specimens over the course of the disease.

BACKGROUND: The Ki67-LI is a valid surrogate for biologic behavior of neuroendocrine tumors (NETs), with higher levels associated with aggressive behavior. The World Health Organization (WHO) classifies NETs according to Ki67-LI (G1: <3%; G2 : 3-20%; G3: >20%). Little is known about the evolution of NETs histologic characteristics over the disease course. We sought to evaluate variations in Ki67-LI throughout NETs disease course. METHODS: We retrospectively reviewed the Sunnybrook Odette Cancer Center NET database for patients with multiple pathology specimens. Primary outcome was the WHO NET class based on Ki67-LI for each specimen. We assessed change in WHO class between specimens. RESULTS: Forty-three patients were retrieved, of which 39 had specimens from the primary tumor and a metastatic focus, and 4 had specimens from multiple metastatic foci. Sixteen (37.0%) were identified with Ki67-LI falling in different WHO classes on distinct biopsies. For 12 (75.0%) of those 16 patients, Ki67-LI showed enough variability for WHO class to be upstaged: 5 (31%) from G1 to G2, 2 (13%) from G2 to G3, and 5 (31%) from G1 to G3. CONCLUSION: When multiple pathology specimens were available, Ki67-LI varied throughout NETs disease course, with a majority of cases upgraded to a higher WHO class. If confirmed, this finding may have implications in how neuroendocrine tumors are monitored and treated. Further research is warranted to confirm these findings, understand better the underlying mechanisms of Ki67 variability, and define its relationship to prognosis.

The clinical results of the Turnbull-Cutait delayed coloanal anastomosis: a systematic review.

Turnbull and Cutait described abdominoperineal pull-through followed by delayed coloanal anastomosis (DCA) in 1961. DCA could reduce anastomotic leaks, pelvic morbidity and use of stomas. Strong evidence about its clinical benefits is still lacking. This systematic review examined the clinical outcomes of DCA for the treatment of malignant or benign colorectal conditions. A systematic search of electronic medical databases was conducted. Two independent reviewers selected studies, extracted data and assessed risk of bias. The primary outcome was pelvic morbidity (anastomotic leak, pelvic abscess or sepsis, use of stoma). Fecal continence and survival data were also analyzed. From 1,251 citations, we included seven observational studies including 1,124 patients. All included studies were considered at high risk of bias. Two studies comparing DCA with immediate anastomosis reported a significant decrease in anastomotic leak, and pelvic abscess or sepsis. Low rates of pelvic morbidity were reported in the other five studies: anastomotic leak 0-7 %, pelvic abscess 0-11.8 % and pelvic sepsis 6.8-10 %. Rates of permanent stoma after DCA were low in six studies (1-6 %), with one study reporting an incidence of 25 %. Fecal continence was reported as satisfying in all studies. No differences were observed in a comparative setting. Survival data were reported in four studies. Clinical heterogeneity and methodological issues precluded meta-analysis. Based on retrospective evidence, DCA offers a low rate of anastomotic leak, pelvic morbidity and use of stoma, with reasonable fecal continence. Results are encouraging, but prospective studies are needed for comparison with standard of care.

Neo-adjuvant chemoradiotherapy and multivisceral resection to optimize R0 resection of locally recurrent adherent colon cancer.

BACKGROUND: Neo-adjuvant chemoradiotherapy reduces local recurrence in rectal cancer, but there is a paucity of evidence regarding its role for colon cancer. The aim of this study was to evaluate the feasibility and outcomes of a neo-adjuvant chemoradiotherapy (NCRT) approach for locally recurrent adherent colon cancer (LRACC). METHODS: All patients with non-metastatic LRACC treated with NCRT and multi-visceral resection (MVR) from January 2000 to July 2010 were included. The primary outcome was the rate of R0 resection (negative microscopic margins). Secondary outcomes were toxicities, post-operative morbidity and mortality, local recurrence, overall survival (OS) and disease-free survival (DFS). RESULTS: Fifteen patients were identified. Nine primary cancers were located in the sigmoid and 4 in the left colon. Patients were treated with 45-50 Gy in 25 daily fractions and concurrent 5-FU infusion (225 mg/m(2)/day). En-bloc MVR included between 2 and 5 adjacent organs/structures. All but two resulted in R0 resection. One patient had a complete pathologic response and one had minimal residual tumour cells in the resected specimen. Post-operative major morbidity was 33.3%. No mortality occurred. At a median follow-up of 54 months, there were 2 local, 1 regional, and 2 distant lung recurrences. No grade 3 or 4 acute or late toxicities were observed. 5-year OS and DFS were 90.0% and 63.5% respectively. CONCLUSIONS: NCRT followed by MVR is a feasible option for the treatment of highly selected LRACC to achieve R0 resection, while maintaining acceptable treatment toxicity. Short-term oncological results appear satisfactory, including good local control.

Cloning and expression of a beta-glycosidase gene from Thermus thermophilus. Sequence and biochemical characterization of the encoded enzyme.

A 3.2 kilobase pair DNA fragment from Thermus thermophilus HB27 coding for a beta-galactosidase activity was cloned and sequenced. A gene and a truncated open reading frame orf1 encoding respectively a beta-glycosidase (ttbeta-gly) and probably a sugar permease were located directly adjacent to each other. The deduced aminoacid sequence of the enzyme Ttbeta-gly showed strong identity with those of beta-glycosidases belonging to the glycosyl hydrolase family 1. The enzyme was overexpressed in Escherichia coli and was purified by a two-step purification procedure. The recombinant enzyme is monomeric with a molecular mass of 49-kDa. It catalyzes the hydrolysis of beta-D-galactoside, beta-D-glucoside and beta-D-fucoside derivatives. However, the kcat/Km ratio is much higher for p-nitrophenyl-beta-D-glucoside and p-nitrophenyl-beta-D-fucoside than for p-nitrophenyl-beta-D-galactoside. The specificity towards linkage positions of the disaccharides tested decreased in the following order: beta1-3 (100%) > beta1-2 (71%) > beta1-4 (40%) > beta1-6 (10%). Ttbeta-gly is a thermostable enzyme displaying an optimum temperature of 88 degrees C and a half life of 10 min at 90 degrees C. It performs transglycosylation reactions at high temperature with a yield exceeding 63% for transfucosylation reactions. On the basis of this work, the enzyme appears to be an attractive tool in the synthesis of fucosyl adducts and fucosyl sugars.

Mutational analysis of the thermostable arginine repressor from Bacillus stearothermophilus: dissecting residues involved in DNA binding properties.

Recently the crystal structure of the DNA-unbound form of the full-length hexameric Bacillus stearothermophilus arginine repressor (ArgR) has been resolved, providing a possible explanation for the mechanism of arginine-mediated repressor-operator DNA recognition. In this study we tested some of these functional predictions by performing site-directed mutagenesis of distinct amino acid residues located in two regions, the N-terminal DNA-binding domain and the C-terminal oligomerization domain of ArgR. A total of 15 mutants were probed for their capacity to repress the expression of the reporter argC - lacZ gene fusion in Escherichia coli cells. Substitutions of highly conserved amino acid residues in the alpha2 and alpha3 helices, located in the winged helix-turn-helix DNA-binding motif, reduced repression. Loss of DNA-binding capacity was confirmed in vitro for the Ser42Pro mutant which showed the most pronounced effect in vivo. In E. coli, the wild-type B. stearothermophilus ArgR molecule behaves as a super-repressor, since recombinant E. coli host cells bearing B. stearothermophilusargR on a multicopy vector did not grow in selective minimal medium devoid of arginine and grew, albeit weakly, when l -arginine was supplied. All mutants affected in the DNA-binding domain lost this super-repressor behaviour. Replacements of conserved leucine residues at positions 87 and/or 94 in the C-terminal domain by other hydrophobic amino acid residues proved neutral or caused either derepression or stronger super-repression. Substitution of Leu87 by phenylalanine was found to increase the DNA-binding affinity and the protein solubility in the context of a double Leu87Phe/Leu94Val mutant. Structural modifications occasioned by the various amino acid substitutions were confirmed by circular dichroism analysis and structure modelling.

Synthetic genes specifying periodic polymers modelled on the repetitive domain of wheat gliadins: conception and expression.

In order to optimise new polypeptide based biomaterials, we developed a procedure for producing homoblock polypeptides using recombinant DNA technology. Synthetic genes encoding periodic polypeptides modelled on the consensus sequence of wheat gliadins (a family of wheat storage proteins) were devised to be expressed in Escherichia coli. The construction strategy followed allows the construction of three genes encoding 8, 16, and 32 copies of the PQQPY module. The optimal expression conditions in the enterobacteria were established and a convenient purification procedure was shown to be useful in recovery of sizable amounts of strictly periodic polypeptides. The identities of the synthesized polypeptides were assessed using positive cross reactions to antibodies raised against a synthetic decapeptide (PQQPYPQQPA) and amino acid composition was determined as well.

The highly thermostable arginine repressor of Bacillus stearothermophilus: gene cloning and repressor-operator interactions.

We report here the cloning of the arginine repressor gene argR of Bacillus stearothermophilus and the characterization and purification to homogeneity of its product. The deduced amino acid sequence of the 16.8-kDa ArgR subunit shares 72% identity with its mesophilic homologue AhrC of Bacilus subtilis. Sequence analysis of B. stearothermophilus ArgR and comparisons with mesophilic arginine repressors suggest that the thermostable repressor comprises an N-terminal DNA-binding and a C-terminal oligomerization and arginine-binding region. B. stearothermophilus ArgR has been overexpressed in E. coli and purified as a 48.0-kDa trimeric protein. The repressor inhibits the expression of a B. stearothermophilus argC-lacZ fusion in E. coli cells. In the presence of arginine, the purified protein binds tightly and specifically to the argC operator, which largely overlaps the argC promoter. The purified B. stearothermophilus repressor proved to be very thermostable with a half-life of approximately 30 min at 90 degrees C, whereas B. subtilis AhrC was largely inactivated at 65 degrees C. Moreover, ArgR operator complexes were found to be remarkably thermostable and could be formed efficiently at up to 85 degrees C, well above the optimal growth temperature of the moderate thermophile B. stearothermophilus. This pronounced resistance of the repressor-operator complexes to heat treatment suggests that the same type of regulatory mechanism could operate in extreme thermophiles.

The arginine operon of Bacillus stearothermophilus: characterization of the control region and its interaction with the heterologous B. subtilis arginine repressor.

Mechanisms of gene regulation have not yet been extensively studied in thermophilic bacteria. In previous studies we showed that the Bacillus stearothermophilus argCJBD gene cluster is subject to specific repression by arginine. Here we report the cloning by colony hybridization, and characterization of the proximal part of the argC gene together with the adjacent control region of the cluster. The promoter was identified by primer extension mapping of the argC transcription startpoint: a sequence overlapping it was found to be similar to the arginine operators of B. subtilis and to a smaller extent of E. coli. Use of an argC-lacZ gene fusion revealed that the argC promoter is strongly repressed by the heterologous B. subtilis arginine repressor/activator AhrC in E. coli cells. Mobility shift and DNase I footprinting experiments revealed tight, specific and arginine-dependent binding of this operator-like sequence to purified AhrC. It is therefore very likely that in B. stearothermophilus the expression of the argCJBD operon is modulated by a repressor that is the thermophilic homologue of AhrC.

Genetic diversity and geographical distribution of wild Saccharomyces cerevisiae strains from the wine-producing area of Charentes, France.

Electrophoretic karyotyping, mitochondrial DNA restriction fragment length polymorphism analysis, and PCR amplification of interspersed repeats were used to study the variability, phylogenetic affinities, and biogeographic distribution of wild Saccharomyces cerevisiae enological yeasts. The survey concentrated on 42 individual wine cellars in the Charentes area (Cognac region, France). A limited number (35) of predominant S. cerevisiae strains responsible for the fermentation process have been identified by the above molecular methods of differentiation. One strain (ACI) was found to be distributed over the entire area surveyed. There seemed to be little correlation between geographic location and genetic affinity.