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Background: Cancer cachexia is not purely an end-stage phenomenon and can influence the outcomes of patients with potentially curable disease. This review examines the effect of pre-treatment cachexia on overall survival, in patients undergoing surgical resection of oesophagogastric cancer., Methods: A systematic literature search of MEDLINE, EMBASE and Cochrane Library databases was conducted, from January 2000 to May 2022, to identify studies reporting the influence of cachexia on patients undergoing an oesophagogastric resection for cancer with curative intent. Meta-analyses of the primary (overall survival) and secondary (disease-free survival and postoperative mortality) outcomes were performed using random-effects modelling. Meta-regression was used to examine disease stage as a potential confounder., Results: Ten non-randomized studies, comprising 7186 patients, were eligible for inclusion. The prevalence of pre-treatment cachexia was 35 per cent (95 per cent c.i.: 24-47 per cent). Pooled adjusted hazard ratios showed that cachexia was adversely associated with overall survival (HR 1.46, 95 per cent c.i.: 1.31-1.60, P < 0.001). Meta-analysis of proportions identified decreased overall survival at 1-, 3- and 5-years in cachectic cohorts. Pre-treatment cachexia was not a predictor of disease-free survival and further data are required to establish its influence on postoperative mortality. The proportion of patients with stage III/IV disease was a significant moderator of between-study heterogeneity. Cachexia may have a greater influence on overall survival in studies where more patients have a locally advanced malignancy., Conclusion: Pre-treatment cachexia adversely influences overall survival following resection of an oesophagogastric malignancy., (© The Author(s) 2023. Published by Oxford University Press on behalf of BJS Society Ltd.)

Mutations in CYP24A1, encoding the vitamin D 24-hydroxlase enzyme, are known to cause a range of clinical phenotypes and presentations including idiopathic infantile hypercalcaemia and adult-onset nephrocalcinosis and nephrolithiasis. In the context of raised or borderline high serum calcium levels, suppressed PTH and persistently elevated 1,25 dihydroxy vitamin D levels, this rare condition should be considered. We present a case where this biochemical pattern was seen and mutations in CYP24A1 were confirmed. We were able to successfully control serum calcium levels and reduce urinary calcium excretion by treatment with low-dose fluconazole, which inhibits vitamin D-synthesizing enzymes (including 25-hydroxylases and 1-α-hydroxylase) thereby reducing levels of 1,25-dihydroxy vitamin D.

Background: We assessed whether medication safety improved when a medication profiling program was added to a computerized provider order entry system., Design: Between June 2001 and January 2002 we profiled outpatients with potential prescribing errors using computerized retrospective drug utilization software. We focused primarily on drug interactions. Patients were randomly assigned either to Provider Feedback or to Usual Care. Subsequent adverse drug event (ADE) incidence and other outcomes, including ADE preventability and severity, occurring up to 1 year following the last profiling date were evaluated retrospectively by a pharmacist blinded to patient assignment., Measurements: Data were abstracted using a study-designed instrument. An ADE was defined by an Adverse Drug Reaction Probability scale score of 1 or more. Statistical analyses included negative binomial regression for comparing ADE incidence., Results: Of 913 patients in the analytic sample, 371 patients (41%) had one or more ADEs. Incidence, by individual, was not significantly different between Usual Care and Provider Feedback groups (37% vs. 45%; p = 0.06; Coefficient, 0.19; 95% CI: -0.008, 0.390). ADE severity was also similar. For example, 51% of ADEs in the Usual Care and 58% in the Provider Feedback groups involved symptoms that were not serious (95% CI for the difference, -15%, 2%). Finally, ADE preventability did not differ. For example, 16% in the Usual Care group and 17% in the Provider Feedback group had an associated warning (95% CI for the difference, -7 to 5%; p = 0.79)., Conclusion: Medications safety did not improve with the addition of a medication profiling program to an electronic prescribing system.

T5 5'-3' exonuclease is a member of a homologous group of 5' nucleases which require divalent metal co-factors. Structural and biochemical studies suggest that single-stranded DNA substrates thread through a helical arch or hole in the protein, thus bringing the phosphodiester backbone into close proximity with the active site metal co-factors. In addition to the expected use of Mg(2+), Mn(2+) and Co(2+) as co-factors, we found that divalent zinc, iron, nickel and copper ions also supported catalysis. Such a range of co-factor utilisation is unusual in a single enzyme. Some co-factors such as Mn(2+) stimulated the cleavage of double-stranded closed-circular plasmid DNA. Such endonucleolytic cleavage of circular double-stranded DNA cannot be readily explained by the threading model proposed for the cleavage of substrates with free 5'-ends as the hole observed in the crystal structure of T5 exonuclease is too small to permit the passage of double-stranded DNA. We suggest that such a substrate may gain access to the active site of the enzyme by a process which does not involve threading.

Bacteriophage T5 5'-->3' exonuclease is a member of a family of sequence related 5'-nucleases which play an essential role in DNA replication. The 5'-nucleases have both exonucleolytic and structure-specific endo-nucleolytic DNA cleavage activity and are conserved in organisms as diverse as bacteriophage and mammals. Here, we report the development of a structure-specific single cleavage assay for this enzyme which uses a 5'-overhanging hairpin substrate. The products of DNA hydrolysis are characterised by mass spectrometry. The steady-state catalytic parameters of the enzyme are reported and it is concluded that T5 5'-->3' exonuclease accelerates the cleavage of a specific phosphodiester bond by a factor of at least 10(15). The catalytic assay has been extended to three mutants of T5 5'-->3' exonuclease, K83A, K196A and K215A. Mutation of any of these three lysine residues to alanine is detrimental to catalytic efficiency. All three lysines contribute to ground state binding of the substrate. In addition, K83 plays a significant role in the chemical reaction catalysed by this enzyme. Possible roles for mutated lysine residues are discussed.

The three dimensional crystal structure of T5 5'-3' exonuclease was compared with that of two other members of the 5'-3' exonuclease family: T4 ribonuclease H and the N-terminal domain of Thermus aquaticus DNA polymerase I. Though these structures were largely similar, some regions of these enzymes show evidence of significant molecular flexibility. Previous sequence analysis had suggested the existence of a helix-hairpin-helix motif in T5 exonuclease, but a distinct, though related structure is actually found to occur. The entire T5 exonuclease structure was then compared with all the structures in the complete Protein Data Bank and an unexpected similarity with gamma-delta (gamma delta) resolvase was observed. 5'-3' exonucleases and gamma delta resolvase are enzymes involved in carrying out quite different manipulations on nucleic acids. They appear to be unrelated at the primary sequence level, yet the fold of the entire catalytic domain of gamma delta resolvase is contained within that of the 5'-3'exonuclease. Different large-scale helical structures are used by both families to form DNA binding sites.

Phage T5 exonuclease is a 5'-->3'exodeoxyribonuclease that also exhibits endonucleolytic activity on flap structures (branched duplex DNA containing a free single-stranded 5'-end). Oligonucleotides were used to construct duplexes with either blunt ends, 5'-overhangs, 3'-overhangs, a flap or a forked end (pseudo-Y). The binding of T5 exonuclease to various structures was investigated using native electrophoretic mobility shift assays (EMSA) in the absence of the essential divalent metal cofactor. Binding of T5 exonuclease to either blunt-ended duplexes or single-stranded oligonucleotides could not be detected by EMSA. However, duplexes with 5'-overhangs, flaps and pseudo-Y structures showed decreased mobility with added T5 exonuclease. On binding to DNA the wild-type enzyme was rendered partially resistant to proteolysis, yielding a biologically active 31.5 kDa fragment. However, the protein-DNA complex remained susceptible to inactivation by p-hydroxymercuribenzoate (PHMB, a cysteine-specific modifying agent), suggesting that neither cysteine is intimately associated with substrate binding. Replacement of both cysteine residues of the molecule with serine did not greatly alter the catalytic or binding characteristics of the protein but did render it highly resistant to inhibition by PHMB.

Background and Methods: Icodextrin 7.5% is an iso-osmolar, glucose polymer-containing peritoneal dialysis solution with an ultrafiltration potential similar to glucose 3.86%. We compared in an open, randomized, prospective study the ultrafiltration potential of icodextrin with that of glucose during the daytime dwell of 23 patients treated with automated peritoneal dialysis (CCPD)., Results: Daytime ultrafiltration volume and 24-h ultrafiltration volume increased significantly in icodextrin-treated patients (n = 11) at 3 and 6 months, allowing patients a less rigid fluid restriction or an adapted treatment schedule. This improved the patients' subjective well-being. Although ultrafiltration at 9 and 12 months also increased it did not reach statistical significance. Similar to the gain in ultrafiltration volume, 24-h dialysate creatinine clearance per 1.73 m2 (DCl/1.73 m2) and DCl/1.73 m2 per litre used dialysate (DCl/1.73 m2/l) increased in icodextrin-treated patients. DCl/1.73 m2/l per litre ultrafiltrate (DCl/1.73 m2/l/UF) did not increase. No side-effects of icodextrin were encountered, although serum disaccharide levels increased., Conclusion: Icodextrin enhances ultrafiltration during the daytime dwell in CCPD patients. As a result of an increased 24-h ultrafiltration volume, DCl/1.73 m2 and DCl/1.73 m2/l improve. DCl/1.73 m2/l/UF does not rise, which suggests that the increase in DCl/1.73 m2 and DCl/1.73 m2/l is caused by convective transport.

There is conflict by evidence as to whether therapy with vancomycin plus an aminoglycoside is more nephrotoxic than therapy with either agent alone. Here we report the results of a prospective, non-randomized, open-label study of the incidence of nephrotoxicity in elderly patients who received vancomycin alone (32 patients) or an aminoglycoside alone (67 patients) or in combination (37 patients). The mean (95% confidence limits) incidence of nephrotoxicity, defined as an increase of > or = 44.2 mumol/L in the serum creatinine, was 19% (5-32%) in patients receiving vancomycin alone, 24% (10-38%) in patients receiving vancomycin plus an aminoglycoside, and 12% (4-20%) in patients receiving an aminoglycoside alone (P > 0.05 for all comparisons). The corresponding absolute increases of the serum creatine were 20.3 +/- 23.0 mumol/L (-24.8 to +65.4 mumol/L), 37.1 +/- 53.0 mumol/L (-67.2 to +140.4 mumol/L), and 22.1 +/- 31.8 mumol/L (-40.7 to +94.6 mumol/L). The absolute increase was significantly greater (P < 0.05) in patients receiving vancomycin plus an aminoglycoside than in patients receiving an aminoglycoside alone. A meta-analysis of seven previously published studies combined with our data revealed that the incidence of nephrotoxicity associated with combination therapy is 13.3 +/- 3.1% (7.3-19.4%) greater than therapy with vancomycin alone (P < 0.01) and 4.3 +/- 1.4% (1.6-7.0%) greater than therapy with an aminoglycoside alone (P < 0.05). The clinical relevance of this finding may be limited in that the mean duration of antimicrobial therapy in three of the studies was greater than 21 days.

The T5 D15 exonuclease purified from an overproducing strain of E. coli was shown to possess a low level of endonucleolytic activity specific for single-stranded DNA when assayed with 1-10 mM Mg2+ as co-factor. Endonuclease activity on double-stranded circular DNA could not be detected under these conditions. Nicked circular DNA was first gapped by the enzyme's exonucleolytic activity, creating a single-stranded region. This gapped substrate was then endonucleolytically cleaved and rapidly degraded. We show that a gapped and not a nicked substrate is required for this activity as previously suggested (Moyer, R. W. and Roth, C. T. 1977, J. Virol. 24, 177-193). The single-strand endonuclease activity could be selectively suppressed by using low concentrations of Mg2+ as co-factor (less than 1 mM), thus allowing nicked double-stranded circular DNA to be gapped to a single-stranded circular species. We also report on sequence similarities between the T5 exonuclease and several prokaryotic DNA polymerases.

A method for achieving strand specific nicking of DNA has been developed. Phosphorothioate groups were incorporated enzymatically into the (-)strand of M13 RF IV DNA. When such DNA is reacted with restriction endonucleases in the presence of ethidium bromide nicked DNA (RF II) is produced. All of the restriction enzymes tested linearised phosphorothioate-containing DNA in the absence of this dye. The strand specificity of the reaction was investigated by employing the ethidium bromide mediated nicking reaction in the phosphorothioate-based oligonucleotide-directed mutagenesis method. The mutational efficiencies obtained were in the region of 64-89%, indicating that these restriction enzymes hydrolyse the phosphodiester bond at the cleavage site of the unsubstituted (+)strand.

The application of T7 and lambda exonuclease to phosphorothioate-based oligonucleotide-directed mutagenesis was investigated. Oligonucleotide primers designed to introduce single or double base mismatches, an insertion or a deletion (each of 16 bases) were annealed to M13 phage derivatives. Double stranded closed circular DNA (RF IV) containing phosphorothioate internucleotidic linkages in the (-)strand was prepared enzymatically from these templates. A nick was introduced into the (+)strand of the hetroduplex DNA. This nicked DNA (RF II) was subjected to treatment with T7 or lambda exonuclease. Both of these enzymes were able to degrade almost all of the viral (+)strand when presented with DNA containing one or two base mismatches. Repolymerisation of the DNA after the gapping reaction, followed by transfection into E. coli cells gave mutational efficiencies of up to 95%. In the case of RF II DNA prepared with insertion or deletion primers these exonucleases could only partially degrade the viral (+)strand but were nevertheless highly efficient in such mutagenesis experiments.