Gemcitabine-based adjuvant chemotherapy in subtypes of ampullary adenocarcinoma: international propensity score-matched cohort study.

BACKGROUND: Whether patients who undergo resection of ampullary adenocarcinoma have a survival benefit from adjuvant chemotherapy is currently unknown. The aim of this study was to compare survival between patients with and without adjuvant chemotherapy after resection of ampullary adenocarcinoma in a propensity score-matched analysis. METHODS: An international multicentre cohort study was conducted, including patients who underwent pancreatoduodenectomy for ampullary adenocarcinoma between 2006 and 2017, in 13 centres in six countries. Propensity scores were used to match patients who received adjuvant chemotherapy with those who did not, in the entire cohort and in two subgroups (pancreatobiliary/mixed and intestinal subtypes). Survival was assessed using the Kaplan-Meier method and Cox regression analyses. RESULTS: Overall, 1163 patients underwent pancreatoduodenectomy for ampullary adenocarcinoma. After excluding 187 patients, median survival in the remaining 976 patients was 67 (95 per cent c.i. 56 to 78) months. A total of 520 patients (53·3 per cent) received adjuvant chemotherapy. In a propensity score-matched cohort (194 patients in each group), survival was better among patients who received adjuvant chemotherapy than in those who did not (median survival not reached versus 60 months respectively; P = 0·051). A survival benefit was seen in patients with the pancreatobiliary/mixed subtype; median survival was not reached in patients receiving adjuvant chemotherapy and 32 months in the group without chemotherapy (P = 0·020). Patients with the intestinal subtype did not show any survival benefit from adjuvant chemotherapy. CONCLUSION: Patients with resected ampullary adenocarcinoma may benefit from gemcitabine-based adjuvant chemotherapy, but this effect may be reserved for those with the pancreatobiliary and/or mixed subtype.

ANTECEDENTES: Actualmente se desconoce si la quimioterapia adyuvante ofrece un beneficio en la supervivencia de los pacientes que se someten a resección de un adenocarcinoma ampular. El objetivo de este estudio fue comparar la supervivencia mediante la concordancia estimada por emparejamiento por puntaje de propensión, entre pacientes con y sin quimioterapia adyuvante después de la resección de un adenocarcinoma ampular. MÉTODOS: Se realizó un estudio internacional de cohortes multicéntrico, que incluyó a los pacientes que se sometieron a una duodenopancreatectomía por adenocarcinoma ampular (2006-2017) en 13 centros de seis países. Los puntajes de propensión se usaron para emparejar a los pacientes que recibieron quimioterapia adyuvante con los que no; tanto en la cohorte completa como en dos subgrupos (subtipo pancreaticobiliar / mixto e intestinal). La supervivencia se evaluó utilizando el método de Kaplan-Meier y las regresiones de Cox. RESULTADOS: En total, 1.163 pacientes fueron sometidos a una duodenopancreatectomía por adenocarcinoma ampular. Después de excluir a 179 pacientes, la mediana de supervivencia de los 976 pacientes restantes fue de 67 meses (i.c. del 95%, 56-78), de los cuales un total de 520 pacientes (53%) recibieron quimioterapia adyuvante. En una cohorte de emparejamiento por puntaje de propensión (194 versus 194 pacientes), la mediana de supervivencia fue mejor en los pacientes tratados con quimioterapia adyuvante en comparación con aquellos sin quimioterapia adyuvante (no se alcanzó la mediana de supervivencia versus 60 meses, respectivamente; P = 0,051). En el subtipo pancreaticobiliar/mixto se observó un beneficio en la supervivencia; no se alcanzó la mediana de supervivencia en pacientes que recibieron quimioterapia adyuvante versus 32 meses en el grupo sin quimioterapia, P = 0,020. El subtipo intestinal no mostró beneficio en la supervivencia de la quimioterapia adyuvante. CONCLUSIÓN: Los pacientes con adenocarcinoma ampular resecado pueden beneficiarse de la quimioterapia adyuvante basada en gemcitabina, pero este efecto podría reservarse para aquellos pacientes con subtipo de tumor pancreaticobiliar y/o mixto.

L-Sorbose phosphorylation in Escherichia coli K-12.

L-Sorbose is phosphorylated by Escherichia coli by two distinct Enzymes II of the phosphoenolpyruvate-dependent phosphotransferase system. The glucose Enzyme II (specified by the gene ptsG) phosphorylates L-sorbose with an apparent Km of 0.08 +/- 0.03 mM and V of 31.8 +/- 3.5 nmol . mg-1 . min-1 whilst the fructose Enzyme II (specified by the gene ptsF) phosphorylates it with an apparent Km of 28.9 +/- 2.7 mM and V of 20.2 +/- 0.8 nmol . mg-1 . min-1. L-Sorbose induces neither of these Enzymes II, but sorbose inhibits the growth of strains expressing either of these functions constitutively. Mutants that have lost their sensitivity to L-sorbose are found to have lost either the glucose or the fructose phosphotransferase Enzyme II.U

Positive control of sulphate reduction in Escherichia coli. Isolation, characterization and mapping oc cysteineless mutants of E. coli K12.

To determine to what extent the biosynthesis of cysteine in Escherichia coli resembles that in Salmonella typhimurium, the following experiments were performed. (1) Mutants of E. coli K 12 deficient in the biosynthesis of cysteine were isolated. (2) These mutants were classified by nutritional and biochemical criteria; some mutants lacked a single enzyme of sulphate reduction, other mutants appeared to lack two or more enzymes. (3) The genetic map predicted from the biochemical data alone is shown to be incorrect, and an alternative map, consistent with the genetic data, is proposed for the cys mutants of E. coli.

Positive control of sulphate reduction in Escherichia coli. The nature of the pleiotropic cysteineless mutants of E. coli K12.

1. The function of the wild-type alleles of the pleiotropic mutants cysB and cysE of Escherichia coli was investigated. 2. The wild-type allele cysB(+) is dominant to the mutant allele cysB in stable and transient heterozygotes. 3. The wild-type allele cysE(+) is dominant to the mutant allele cysE, as predicted. 4. Sulphur-starved cultures of cysB or cysE strains contain less than 0.2nmole of free cysteine/mg. dry wt. 5. Complementation in vitro is not observed between extracts of cysB mutants and mutants lacking sulphite reductase only. 6. A scheme, involving positive control of the enzymes of sulphate activation and reduction, is suggested to account for the control of cysteine biosynthesis.

A specialized transducing phage, lambda psrlA, for the sorbitol phosphotransferase of Escherichia coli K12.

A specialized transducing phage for the srlA gene, specifying the sorbitol-specific Enzyme II of the phosphoenolpyruvate:sugar phosphotransferase system, was constructed and its DNA was analysed by restriction endonuclease digestion. Phage construction involved four steps: (1) integration of lambda into the srlA gene; (2) selection of phage carrying (a) the left and (b) the right end of the srlA gene by means independent of the function of the new DNA acquired; (3) reconstitution of the srlA gene in a dilysogen of these two phage; and (4) the excision, using the heteroimmune lambdoid phage 21, of a plaque-forming srlA+ phage from the dilysogenic chromosome. Comparison of the DNA restriction digests of the transducing phage with those of its parents and of wild-type lambda revealed fragments consisting partly of lambda and partly of Escherichia coli DNA. The junction points in the intermediate phage define a site that must lie within the reconstituted gene of the final phage. This technique should be of general application in relating genes, cloned by our method, to DNA sequences.

Amino-sugar transport systems of Escherichia coli K12.

Glucosamine, mannose and 2-deoxyglucose enter Escherichia coli by the phosphotransferase system coded for by the gene ptsM. The glucosamine- and mannose-negative, deoxyglucose-resistant phenotype of ptsM mutants can be suppressed by a mutation mapping near ptsG that allows constitutive expression of the glucose phosphotransferase coded for by the gene ptsG. N-Acetylglucosamine enters E. coli by two distinct phosphotransferase systems (White, 1970). One of these is the PtsM system, the other is coded for by a gene which maps near the nagA,B genes at about min 15 on the E. coli chromosome. We propose that this gene be designated ptsN. Strains with either of these components of the phosphotransferase system will utilize N-acetylglucosamine as sole carbon source.

Phosphotransferase-mediated regulation of carbohydrate utilization in Escherichia coli K12: the nature of the iex (crr) and gsr (tgs) mutations.

Mutants of Escherichia coli K12 defective in the gene iex (crr) no longer utilize glucose or N-acetylglucosamine in preference to lactose, but competition between either of these sugars and another that also enters by a phosphotransferase (PT) mechanism is not affected. In this they differ from gsr (tgs) mutants. In gsr mutants, glucose does not exclude any other sugar, though N-acetylglucosamine still does so. In gsr mutants that are also ptsM the phosphoenolpyruvate-dependent phosphorylation of glucose or methyl alpha-glucoside is reduced by 90%: N-acetylglucosamine phosphorylation is not affected. The iex mutation does not affect the phosphorylation of either of these compounds. The wild-type alleles iex+ and gsr+ are dominant in lambda heterozygotes. Glucose inhibits the lactose permease of wild-type cells, but only when the permease is present in low amounts. The inhibition is also relieved (1) by induction of another transport system that is subject to regulation by the iex system or (2) by an iex mutation. We suggest that the iex gene specifies a protein that, in cells transporting certain sugars by a PT mechanism, acts to inhibit active transport systems. The protein is present in limiting concentration in the cell, sufficient only to inhibit the basal, uninduced, level of the active transport systems. In consequence the inducer (or its precursor) may be excluded from the cell and induction thus prevented.

Uptake of fructose by the sorbitol phosphotransferase of Escherichia coli K12.

Strains of Escherichia coli that are unable to grow on fructose because they lack the phosphoenolpyruvate: fructose phosphotransferases specified by ptsF and ptsX mutate to grow on media containing fructose as sole carbon source, but do not regain the function of either of the missing phosphotransferases. Instead, fructose is taken up and phosphorylated to fructose 6-phosphate by a phosphoenolpyruvate: sorbitol phosphotransferase which, in wild-type cells, is induced by sorbitol but not by fructose, but which is constitutively expressed in these mutants. The regulatory gene srlC controlling enzymes of sorbitol uptake and catabolism has been located on the E. coli genome as part of the linkage group cysI srlC attI86 pheA.

The cloning, DNA sequence, and overexpression of the gene araE coding for arabinose-proton symport in Escherichia coli K12.

A lambda placMu1 insertion was made into araE, the gene for arabinose-proton symport in Escherichia coli. A phage containing an araE'-'lacZ fusion was recovered from the lysogen and its restriction map compared with that of the 61-min region of the E. coli genome to establish the gene order thyA araE orf lysR lysA galR; araE was transcribed toward orf. A 4.8-kilobase SalI-EcoRI DNA fragment containing araE was subcloned from the phage lambda d(lysA+ galR+ araE+) into the plasmid vector pBR322. From this plasmid a 2.8-kilobase HincII-PvuII DNA fragment including araE was sequenced and also subcloned into the expression vector pAD284. The araE gene was 1416-base pairs long, encoding a hydrophobic protein of 472 amino acids with a calculated Mr of 51,683. The amino acid sequence was homologous with the xylose-proton symporter of E. coli and the glucose transporters from a human hepatoma HepG2 cell line, human erythrocytes, and rat brain. The overexpressed araE gene product was identified in Coomassie-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels of cell membranes as a protein of apparent Mr 35,000 +/- 1,150. Arabinose protected this protein against reaction with N-ethylmaleimide.

Identification of the GalP galactose transport protein of Escherichia coli.

Escherichia coli strains have been isolated with a transposon 10 insertion or an amber mutation inactivating the galP gene, which specifies the galactose-H+ (GalP) transport system. Comparison of the membrane proteins between these strains and their GalP+ parents by dual isotope analysis showed that a component of Mr = 34-39,000 was consistently absent from the GalP- mutants. Galactose, methyl-beta-D-galactoside, and talose protected the GalP transport system from inactivation by N-ethylmaleimide. A membrane protein of Mr = 34-38,000 was modified by N-([2-3H]ethyl)maleimide at the binding site of these sugars. Two-dimensional gel electrophoresis of the membrane proteins has resolved a component of Mr = 35-38,000 (average apparent pI = 5.7) present in parent strains (GalP+) but not in the GalP- mutants. These observations identified a protein of apparent Mr = 37,000 as the product of the galP gene of E. coli.

Location of a structural gene for xylose-H+ symport at 91 min on the linkage map of Escherichia coli K12.

Mutations in the xylose-H+ transport activity of Escherichia coli K12 were isolated using Mud(ApRlac). The initial selection was for simultaneous acquisition of ampicillin and xylose resistance in an fda background. Colonies were then screened for xylose-inducible beta-galactosidase and for growth on xylose of their fda+ derivatives. Two of the xylose-positive derivatives were shown to be impaired in xylose-H+ symport in whole cells and in xylose transport into subcellular vesicles. Their xylose transport in whole cells showed increased sensitivity to arsenate. The site of prophage insertion was mapped to 91.4 min on the E. coli genome between pgi and malB. It is proposed that the gene for the xylose-H+ symport system be called xylE.

Two genes affecting glucarate utilization in Escherichia coli K12.

D-Glucarate is transported into Escherichia coli K12 by an inducible system at an apparent rate of 7 to 15 nmol min-1 (mg dry mass)-1. The apparent Km for uptake is 16 muM. The system is induced by growth on glucarate or glycollate. Galactarate competes with glucarate for the uptake system. A mutation (gar A) was isolated in which activities of glucarate transport and glucarate dehydratase and the ability to grow on glucarate or galactarate are all impaired. The mutation maps at min 16. Another mutation of indistinguishable phenotype is probably a deletion of the genes garB and tonA at min 3.5.

Proton-linked D-xylose transport in Escherichia coli.

The addition of xylose to energy-depleted cells of Escherichia coli elicited an alkaline pH change which failed to appear in the presence of uncoupling agents. Accumulation of [14C]xylose by energy-replete cells was also inhibited by uncoupling agents, but not by fluoride or arsenate. Subcellular vesicles of E. coli accumulated [14C]xylose provided that ascorbate plus phenazine methosulfate were present for respiration, and this accumulation was inhibited by uncoupling agents or valinomycin. Therefore, the transport of xylose into E. coli appears to be energized by a proton-motive force, rather than by a phosphotransferase or directly energized mechanism. Its specificity for xylose as inducer and substrate and the genetic location of a xylose-H+ transport-negative mutation near mtl showed that the xylose-H+ system is distinct from other proton-linked sugar transport systems of E. coli.

The control of sulphate reduction in Escherichia coli by O-acetyl-L-serine.

1. Extracts of Escherichia coli A.T.C.C. 9723 and K(12)703 contain serine transacetylase and O-acetylserine sulphhydrase. Synthesis of the latter enzyme is repressed by growth on l-cyst(e)ine and other sulphur compounds. 2. O-Acetyl-l-serine added to cells growing on glutathione or sulphate as source of sulphur induces the enzymes that catalyse (a) the activation of sulphate to adenosine 3'-phosphate 5'-sulphatophosphate (EC 2.7.7.4 and 2.7.1.25), (b) the reduction of adenosine 3'-phosphate 5'-sulphatophosphate to sulphite and (c) the reduction of sulphite to sulphide (EC 1.8.1.2). Hydrogen sulphide is liberated from cultures growing on sulphate as source of sulphur and in the presence of O-acetylserine. 3. The cysE mutants of E. coli K(12) lack serine transacetylase. Addition of O-acetylserine permits growth on sulphate as source of sulphur; at the same time the enzymes of sulphate reduction, previously absent, are synthesized. Such mutants have no detectable intracellular cyst(e)ine when starved of sulphur. 4. These results suggest that O-acetylserine is necessary for synthesizing the enzymes of sulphate reduction in E. coli. Its action does not appear to be by interference with the repressive control exerted over these enzymes by cyst(e)ine.

Isolation and mapping of glutathione reductase-negative mutants of Escherichia coli K12.

Two independent mutants defective in glutathione reductase (EC 1.6.4.2) were isolated in an Escherichia coli K12 strain lysogenized with bacteriophage Mu. The prophage was lost (and the ability to reduce glutathione regained) by 32% of the xylose-positive transductants when T4GT7 was used as the vector, but the markers were not cotransduced by P1. Similarly, the prophage site and malA were cotransduced by T4GT7 but not by P1. The gor gene maps between min 77 and 78 on the E. coli genome, and the mutation causes no growth defect.