Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

A simple method to overcome the inhibitory effect of heparin on DNA amplification

BACKGROUND

Genetic material from large patient cohorts is increasingly central to translational genetic research. However, patient blood samples are a finite resource and their supply and storage are often dictated by clinical and not research protocols. Our experience supports difficulty in amplifying DNA from blood stored in herparin; a scenario that other researchers may have or will encounter. This technical note describes a number of simple steps that enable successful PCR amplification.

METHODS

DNA was extracted using the Illustra Nucleon Genomic DNA Extraction Kit. PCR amplification was attempted using a number of commercially available PCR mastermixes.

RESULTS

PCR DNA amplification failed using ReddyMix™ PCR Master Mix, Thermo-Start® (Thermo Scientific Inc. US) and ZymoTaq™ (Zymo research, US) PCR mastermixes, as demonstrated absence of products on gel electrophoresis. However, using the Invitrogen™ (Thermo Scientific Inc., US) Platinum® Taq DNA Polymerase, PCR products were identified on a 1% agarose gel for all samples. PCR products were cleaned with ExoSAP-IT® (Affymetrix Inc., US) and a sequencing reaction undertaken using a standard Big Dye protocol. Subsequent genotyping was successful for all samples for alleles at the CDH1 locus.

CONCLUSION

From our experience a standard phenol/chloroform purification and using the Invitrogen™ Platinum® Taq has enabled the amplification of whole blood samples taken into lithium heparin and stored frozen for up to a month. This simple method may enable investigators to utilise blood taken in lithium heparin for DNA extraction and amplification.

Hepatic expression of UGT enzymes and implications in pharmacokinetic variations in Asians during chemotherapy

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Background: The objective of this study was to screen the promoter and relevant coding regions in the UGT1A1 and UGT1A9 genes and genotypically quantitate expression of these genes in hepatic tissues obtained from Asian cancer patients undergoing hepatectomy. Methods: Non-cancerous Asian hepatic tissues (Chinese: N=36; Malay: N=1; Indian: N=3) were obtained from the institution’s central tissue repository bank. Messenger RNA was isolated from each tissue sample and reverse transcribed to cDNA followed by real time PCR experiments. Results from these gene expression experiments were normalized against GAPDH transcripts. DNA was also extracted from the hepatocytes, screened for variations in the promoter regions (UGT1A1*60, g.3140G>A and UGT1A1*28) and exon 1 (UGT1A1*6) of the UGT1A1 and UGT1A9 (UGT1A9*22, I399C>T) genes. Results: Large interindividual variations were observed in the hepatic expression pattern of UGT1A1 and UGT1A9 mRNA with respect to the different polymorphic variants. There was no significant association between hepatic expression of UGT1A1 mRNA and UGT1A1*60, g-3140G>A and *6 genotypes (P>0.05 in each case). The median expression level of UGT1A1 mRNA was approximately 2-fold higher in liver tissues harboring UGT1A1 6/6 (reference) genotype (N=27, median = 0.478; range: 0.065 to 3.125) compared to the heterozygous 6/7 genotype (N=9, median = 0.254; range: 0.042 to 1.894; P=0.77). The median expression levels of UGT1A9 mRNA were approximately 3-fold higher in liver tissues harboring I399CC genotype (N=3, median = 2.735; range: 0.702 to 3.375) when compared with the homozygous variant TT genotype (N=8, median = 0.973; range: 0.652 to 4.155; P=0.88). Conclusions: The results showed that polymorphisms in the UGT1A genes may influence the expression pattern of the respective proteins and could contribute to the high degree of interpatient variability in the glucuronidation dependent metabolism and elimination of chemotherapeutic agents in Asian cancer patients.

No significant financial relationships to disclose.

Multiple chromatin modifications important for gene expression changes in cardiac hypertrophy

Cardiac hypertrophy is an increase in the size of cardiac myocytes to generate increased muscle mass, usually driven by increased workload for the heart. Although important during postnatal development and an adaptive response to physical exercise, excessive hypertrophy can result in heart failure. One characteristic of hypertrophy is the re-expression of genes that are normally only expressed during foetal heart development. Although the involvement of these changes in gene expression in hypertrophy has been known for some years, the mechanisms involved in this re-expression are only now being elucidated and the transcription factor REST (repressor element 1-silencing transcription factor) has been identified as an important repressor of hypertrophic gene expression.

Comparison of effects of anandamide at recombinant and endogenous rat vanilloid receptors

BACKGROUND

Anandamide, an endogenous lipid, activates both cannabinoid (CB(1)) and vanilloid (VR1) receptors, both of which are co-expressed in rat dorsal root ganglion (DRG) cells. Activation of either receptor results in analgesia but the relative contribution of CB(1) and VR1 in anandamide-induced analgesia remains controversial. Here we compare the in vitro pharmacology of recombinant and endogenous VR1 receptors using calcium imaging, in clonal and DRG cells, respectively. We also consider the contribution of CB(1) and VR1 receptors to anandamide-induced analgesia.

METHODS

Using a Flurometric Imaging Plate Reader (FLIPR), calcium imaging has been used to study the effects of several vanilloid and cannabinoid ligands in rat VR1-transfected HEK293 (rVR1-HEK) cells and in DRG cells. The effect of pre-exposure of several vanilloid and cannabinoids has also been compared in DRG cells.

RESULTS

The VR1 agonists capsaicin, olvanil, (N-(4-hydroxyphenyl-arachinoylamide) (AM404) and anandamide caused a concentration-dependent increase in intracellular calcium concentration ([Ca(2+)](i)), with similar temporal profiles in both rVR1-HEK and DRG cells, and potency (pEC(50)) values of 8.25 (SEM 0.11), 8.37 (0.04), 6.96 (0.06), 5.85 (0.01) and 7.45 (0.10), 7.55 (0.07), 6.10 (0.13), approximately 5.5, respectively. These responses were inhibited by the VR1 antagonist capsazepine (1 micro M). In contrast, application of synthetic cannabinoid antagonists failed to inhibit the anandamide-induced increase in [Ca(2+)](i). Reapplication of VR1 agonists significantly inhibited a subsequent challenge to either capsaicin or anandamide in either cell type, whilst pre-exposure to cannabinoid agonists were without effect.

CONCLUSION

Here we provide evidence that the pharmacology of recombinant rVR1 receptors is similar to those endogenously expressed in DRG cells. Moreover, we have shown that VR1, but not CB(1), receptors are involved in anandamide-induced responses in dorsal root primary neurones in vitro. Therefore, the analgesic properties of anandamide are likely to be mediated, at least in part, by VR1 activation in DRG cells in vivo.

TRPV3 is a temperature-sensitive vanilloid receptor-like protein

Vanilloid receptor-1 (VR1, also known as TRPV1) is a thermosensitive, nonselective cation channel that is expressed by capsaicin-sensitive sensory afferents and is activated by noxious heat, acidic pH and the alkaloid irritant capsaicin. Although VR1 gene disruption results in a loss of capsaicin responses, it has minimal effects on thermal nociception. This and other experiments--such as those showing the existence of capsaicin-insensitive heat sensors in sensory neurons--suggest the existence of thermosensitive receptors distinct from VR1. Here we identify a member of the vanilloid receptor/TRP gene family, vanilloid receptor-like protein 3 (VRL3, also known as TRPV3), which is heat-sensitive but capsaicin-insensitive. VRL3 is coded for by a 2,370-base-pair open reading frame, transcribed from a gene adjacent to VR1, and is structurally homologous to VR1. VRL3 responds to noxious heat with a threshold of about 39 degrees C and is co-expressed in dorsal root ganglion neurons with VR1. Furthermore, when heterologously expressed, VRL3 is able to associate with VR1 and may modulate its responses. Hence, not only is VRL3 a thermosensitive ion channel but it may represent an additional vanilloid receptor subunit involved in the formation of heteromeric vanilloid receptor channels.

Molecular cloning and the cDNA-derived amino acid sequence of Narcissus tazetta isolectins

Recently several complete cDNAs encoding the Narcissus tazetta lectins (NTL) were cloned. The sequence analyses of the cloned DNAs reveal that there are at least three unidentical positive clones for NTLs. The primary structure of the three NTL clones contains a mature polypeptide consisting of 105 amino acids and a C-terminal peptide extension beyond the C-terminal amino acids Thr-Gly. There are two fixed-position cysteines within the protein domain (amino acids 29 and 52), which are probably involved in the disulfide-bond linkage within the molecules to confer the secondary structure of the mature lectin. One third of the deduced amino acid composition consisted of glycine, leucine, and asparagine. From the cDNA-derived amino acid sequences the three NTL clones are not identical and are suggested to be isolectins present in N. tazetta var. chinensis. This study further confirms the previous isolation of mannose-specific isolectins from Chinese daffodil leaves.

Lectins from bulbs of the Chinese daffodil Narcissus tazetta (family Amaryllidaceae)

The isolation of three lectins with similar N-terminal amino acid sequences from the bulbs of the Chinese daffodil Narcissus tazetta was achieved. The isolation protocol involved ion exchange chromatography on DEAE-cellulose, affinity chromatography on mannose-agarose, and fast protein liquid chromatography-gel filtration on Superose 12. The lectins were all adsorbed on mannose-agarose and demonstrated a single band with a molecular weight of 13 kDa in SDS-polyacrylamide gel electrophoresis and a single 26 kDa peak in gel filtration, indicating that they were mannose-binding, dimeric proteins. The lectins differed in hemagglutinating activity, with the magnitude of the activity correlating with the ionic strength of the buffer required to elute the lectin from the DEAE-cellulose column. The bulb lectin did not exert potent cytotoxicity against cancer cell lines or fetal bovine lung cells but inhibited syncytium formation in, and reinstated viability of, fetal bovine lung cells infected with bovine immunodeficiency virus.

Mannose-specific isolectins with different hemagglutinating potencies isolated from Chinese daffodil (Narcissus tazetta var. chinensis) leaves

Three mannose-specific lectins exhibiting considerable similarities in NH2-terminal amino acid sequence were isolated from leaves of the Chinese daffodil Narcissus tazetta (Family Amaryllidaceae). The purification protocol involved extraction with an aqueous buffer, anion exchange chromatography on DEAE-cellulose using stepwise elution with increasing salt concentrations, affinity chromatography on mannose-agarose, and FPLC-gel filtration on Superose 12. From the peak unadsorbed on DEAE-cellulose, and two peaks adsorbed on the ion exchanger and eluted respectively with 0.2 M Tris-HCl buffer and 0.5 M NaCl, were prepared fractions which yielded isolectins 1, 2, and 3 after adsorption on mannose-agarose and FPLC-gel filtration. All three isolectins were homodimers with a molecular weight of 26 kDa. The lectin unadsorbed on DEAE-cellulose had the lowest, while the most strongly adsorbed lectin had the highest hemagglutinating activity.

Isolation and characterization of a mannose-binding lectin from leaves of the Chinese daffodil Narcissus tazetta

A mannose-binding lectin was isolated from leaves of the Chinese daffodil Narcissus tazetta (family Amaryllidaceae) using a procedure that comprised extraction with aqueous buffer, ammonium sulfate precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel Blue gel and mannose-agarose, and FPLC-gel filtration on Superose 12. The lectin was adsorbed on mannose-agarose and unadsorbed on DEAE-cellulose and Affi-gel Blue gel. It was an unglycosylated homodimer with a molecular mass of 26 kDa. Analysis of the N-terminal sequence of the N. tazetta lectin revealed considerable homology to lectins from the daffodil Narcissus pseudonarcissus, the snowdrop Galanthus nivalis (family Amaryllidaceae), the tulip Tulipa, and Kidachi aloe Aloe arborescens (family Liliaceae), and the orchid lectins (family Orchidaceae). The most striking likeness exists among the Amaryllidaceae lectins. The N. tazetta lectin exhibits hemagglutinating activity toward rabbit erythrocytes.

Isolation and Characterization of a Type 1 Ribosome-Inactivating Protein from Fruiting Bodies of the Edible Mushroom (Volvariella volvacea)

A novel single-chained ribosome-inactivating protein (RIP) with a molecular weight of approximately 29 000 was purified from fruiting bodies of the edible mushroom Volvariellavolvacea with a procedure involving ammonium sulfate precipitation, ion-exchange chromatography on DEAE-cellulose, and gel filtration on Superdex 75. The mushroom RIP, designated volvarin, exhibited a potent inhibitory action on protein synthesis in the rabbit reticulocyte lysate system with an IC(50) value of 0.5 nM. Like most plant RIPs, volvarin acted as an N-glycosidase that depurinated rRNA from rabbit reticulocyte lysate, releasing a characteristic RNA fragment after treatment with aniline. It also exerted a deoxyribonuclease activity on supercoiled SV-40 DNA and demonstrated a strong abortifacient effect in mice.

Urinary excretion of testosterone and estradiol in Chinese men and relationships with serum lipoprotein concentrations

Urinary excretion of total and free testosterone and estradiol was measured in 46 healthy Chinese men, along with serum concentrations of total testosterone and estradiol and the calculated free (unbound) concentrations. Associations with serum concentrations of total, low-density lipoprotein (LDL), high-density lipoprotein-2 (HDL2), and HDL3 cholesterol, apolipoproteins (apos) A-I and B, lipoprotein(a) [Lp(a)] were studied. Serum total and free testosterone concentrations were positively correlated with HDL and HDL2 cholesterol and apo A-I. Serum total and free estradiol levels showed borderline-significant negative associations with total and LDL cholesterol levels. Among urinary variables, total estradiol excretion was negatively associated with apo B levels and showed borderline-significant associations with total and LDL cholesterol. Adjustment for potential confounders, including age, body mass index (BMI), and waist to hip ratio (WHR), strengthened the associations between urinary total estradiol and serum total cholesterol, LDL cholesterol, and apo B. Urinary free estradiol showed a significant correlation with HDL3 cholesterol. Urinary excretion of total testosterone was significantly negatively associated with serum cholesterol and LDL cholesterol levels only after controlling for confounding variables. There were no significant associations between hormone variables and Lp(a) values. This study suggests that variation in sex hormone production accounts for some of the variation in serum lipid levels.

Prevalence and clinical significance of antibodies to ribonucleoproteins in systemic lupus erythematosus in Malaysia

One hundred and seventy patients with systemic lupus erythematosus (SLE) were studied for the prevalence of antibodies to the small RNA-associated proteins Ro/SSA, La/SSB, Sm, U1RNP and Sm. The relationship of these autoantibodies to different races, sexes and clinical manifestations of SLE was evaluated. Passive immunodiffusion was employed using human spleen extract as antigen source for Ro and rabbit thymus extract for La, Sm and U1RNP. We found the prevalence of antibodies to be as follows: anti-Ro/SSA, 36%; anti-La/SSB, 8%; anti-Sm, 15% ; anti-U1RNP, 21%. Except for a low prevalence of anti-La, the prevalence of these antibodies was similar to that in Western studies, The prevalence of anti-Ro/SSA is similar to that reported in the Western studies, but lower than that reported in the Oriental patients from Singapore and Hong Kong. Linkages of anti-Ro with anti-La antibodies were usual; however, although anti-Sm antibodies were usually associated with anti-U1RNP, they were more frequently associated with anti-Ro antibodies. The Malay patients had a high prevalence of anti U1RNP compared to other races. No gender difference was detected. Anti-Sm antibody was associated with serositis and anti-U1RNP antibodies with Raynaud's phenomenon. No association was found between the presence of skin renal or cerebral manifestations and any specific antibodies or combination of antibodies.