James R. Lawrence

Salicylic Acid sans Aspirin in Animals and Man : Persistence in Fasting and Biosynthesis from Benzoic Acid

Salicylic acid (SA), which is central to defense mechanisms in plants and the principal metabolite of aspirin, occurs naturally in man with higher levels of SA and its urinary metabolite salicyluric acid (SU) in vegetarians overlapping with levels in patients on low-dose aspirin regimens. SA is widely distributed in animal blood. Fasting for major colorectal surgery did not cause disappearance of SA from plasma, even in patients following total proctocolectomy. A 13C6 benzoic acid load ingested by six volunteers led, between 8 and 16 h, to a median 33.9% labeling of urinary salicyluric acid. The overall contribution of benzoic acid (and its salts) to the turnover of circulating SA thus requires further assessment. However, that SA appears to be, at least partially, an endogenous compound should lead to reassessment of its role in human (and animal) pathophysiology.

Urinary excretion of salicyluric and salicylic acids by non-vegetarians, vegetarians, and patients taking low dose aspirin

Aim: To compare amounts of salicyluric acid (SU) and salicylic acid (SA) excreted daily in the urine of non-vegetarians and vegetarians not taking salicylate drugs, and patients taking 75 or 150 mg aspirin/day. Methods: Urine excreted over 24 hours was collected from volunteers in the four groups. The volumes were recorded and the concentrations of SU and SA were determined electrochemically after separation by high performance liquid chromatography. Results: Significantly more SU was excreted daily by vegetarians (median, 11.01; range, 4.98–26.60 μmol/24 hours) than by non-vegetarians (median, 3.91; range, 0.87–12.23 μmol/24 hours), although amounts were significantly lower than those excreted by patients taking aspirin. Median amounts of SU excreted by patients taking 75 and 150 mg/day of low dose aspirin were 170.69 (range, 13.15–377.18) μmol/24 hours and 165.17 (range, 5.61–429.12) μmol/24 hours, respectively. The amount of SU excreted by patients taking either 75 or 150 mg of aspirin/day was not significantly different. Significantly more SA was excreted by vegetarians (median, 1.19; range, 0.02–3.55 μmol/24 hours) than by non-vegetarians (median, 0.31; range, 0.01–2.01 μmol/24 hours). The median amounts of SA excreted by vegetarians and the patients taking aspirin were not significantly different. Conclusions: More SU and SA is excreted in the urine of vegetarians than in non-vegetarians, consistent with the observation that fruits and vegetables are important sources of dietary salicylates. However, significantly less SU was excreted by vegetarians than patients taking aspirin, indicating that the daily intake of bioavailable salicylates by vegetarians is considerably lower than that supplied by a single 75 or 150 mg dose of aspirin.

The identification of salicylates as normal constituents of serum: a link between diet and health?

AIM: To examine sera for the presence of salicylic acid and 2,3- and 2,5-dihydroxybenzoic acids (2,3- and 2,5-DHBA), in individuals not taking salicylate drugs. METHODS: Extracts of acidified serum samples were analysed by high performance liquid chromatography with electro-chemical detection. The chromatographic conditions were altered, and the retention times of the unknown compounds compared against authentic salicylic acid, 2,3-DHBA, and 2,5-DHBA. Serum samples (some spiked with salicylic acid) were incubated with salicylate hydroxylase and analyses undertaken. An extract of acidified serum was derivatised using N-methyl-N-trimethylsilyltrifluoroacetamide and the salicylic acid derivative identified by gas chromatography-mass spectrometry. RESULTS: Salicylic acid, 2,3-DHBA, and 2,5-DHBA were identified as being normal constituents of serum. CONCLUSIONS: Salicylic acid, 2,3-DHBA, and 2,5-DHBA possess anti-inflammatory properties. The finding that these compounds are present as normal constituents of serum, possibly arising from diet, raises important questions as to their role in the promotion of health.

Is there a role for dietary salicylates in health

Acetylsalicylic acid (aspirin; 2-acetoxybenzoic acid) has been used for >100 years for pain relief and to treat inflammatory conditions and fevers. More recently, regular intake has been associated with decreased incidence of certain cancers, particularly colon cancer. After absorption aspirin is very rapidly hydrolysed to salicylic acid (2-hydroxybenzoic acid). The anti-cancer effects of aspirin may be a result of salicylic acid reducing the transcription of prostaglandin H(2)-synthase and thereby the synthesis of pro-inflammatory and potentially-neoplastic prostaglandins. Salicylic acid is widely present in plants and functions as a hormonal mediator of the systemic acquired resistance response to pathogen attack and environmental stress. Thus, it is present in a large range of fruit, vegetables, herbs and spices of dietary relevance. Consequently, the recognised effect of consuming fruit and vegetables on lowering risk of colon cancer may be partly attributable to salicylates in plant-based foods. The present review discusses which types of fruit and vegetables are the richest source of salicylates and whether they are sufficiently released from the food matrix to modify the key cellular events associated with the pathogenesis of colon cancer.

Clinical validation of hrHPV testing on vaginal and urine self-samples in primary cervical screening (cross-sectional results from the Papillomavirus Dumfries and Galloway—PaVDaG study)

Objectives Papillomavirus Dumfries and Galloway (PaVDaG) assessed the performance of a high-risk human papillomavirus (hrHPV) PCR-based assay to detect high-grade cervical intraepithelial neoplasia (CIN2+) in self-collected vaginal and urine samples. Setting Women attending routine cervical screening in primary care. Participants 5318 women aged 20–60u2005years provided self-collected random urine and vaginal samples for hrHPV testing and a clinician-collected liquid-based cytology (LBC) sample for cytology and hrHPV testing. Interventions HrHPV testing. All samples were tested for hrHPV using the PCR-based cobas 4800 assay. Colposcopy was offered to women with high-grade or repeated borderline/low-grade cytological abnormalities; also to those who were LBC negative but hrHPV 16/18 positive. Primary and secondary outcome measures The self-tests absolute sensitivity and specificity for CIN2+ were assessed on all biospecimens; also, their relative sensitivity and specificity compared with clinician-taken samples. Interlaboratory and intralaboratory performance of the hrHPV assay in self-collected samples was also established. Results HrHPV prevalence was 14.7%, 16.6% and 11.6% in cervical, vaginal and urine samples, respectively. Sensitivity for detecting CIN2+ was 97.7% (95% to 100%), 94.6% (90.7% to 98.5%) and 63.1% (54.6% to 71.7%) for cervical, vaginal and urine hrHPV detection, respectively. The corresponding specificities were 87.3% (86.4% to 88.2%), 85.4% (84.4% to 86.3%) and 89.8% (89.0% to 90.7%). There was a 38% (24% to 57%) higher HPV detection rate in vaginal self-samples from women over 50u2005years compared with those ≤29u2005years. Relative sensitivity and specificity of hrHPV positivity for the detection of CIN2+ in vaginal versus cervical samples were 0.97 (0.94 to 1.00) and 0.98 (0.97 to 0.99); urine versus cervical comparisons were 0.53 (0.42 to 0.67) and 1.03 (1.02 to 1.04). The intralaboratory and interlaboratory agreement for hrHPV positivity in self-samples was high (κ values 0.98 (0.96 to 0.99) and 0.94 (0.92 to 0.97) for vaginal samples and 0.95 (0.93 to 0.98) and 0.90 (0.87 to 0.94) for urine samples). Conclusions The sensitivity of self-collected vaginal samples for the detection of CIN2+ was similar to that of cervical samples and justifies consideration of this sample for primary screening.

Guidelines: is bigger better? A review of SIGN guidelines

Objectives To quantify and analyse the quality of evidence that is presented in national guidelines. Setting Levels of evidence used in all the current valid recommendations in the Scottish Intercollegiate Guideline Network (SIGN) guidelines were reviewed and statistically analysed. Outcome measures The proportion of level D evidence used in each guideline and a statistical analysis. Method Data were collected from published guidelines available online to the public. SIGN methodology entails a professional group selected by a national organisation to develop each of these guidelines. Statistical analysis of the relationship between the number of guideline recommendations and the quality of evidence used in its recommendations was performed. Result The proportion of level D evidence increases with the number of recommendations made. This correlation is significant with Kendalls τ=0.22 (approximate 95% CI 0.008 to 0.45), pu2009=u20090.04; and Spearman ρ=0.22 (approximate 95% CI 0.02 to 0.57), p=0.04. Conclusions Practice guidelines should be brief and based on scientific evidence. Paradoxically the longest guidelines have the highest proportion of recommendations based on the lowest level of evidence. Guideline developers should be more aware of the need for brevity and a stricter application of evidence-based principles could achieve this. The findings support calls for a review of how evidence is used and presented in guidelines.

Identification and determination of salicylic acid and salicyluric acid in urine of people not taking salicylate drugs

Background Salicylic acid (SA) is present in the serum of people who have not taken salicylate drugs. Now we have examined the urine of these subjects and found that it contains SA and salicyluric acid (SU). We have established the identities of these phenolic acids and determined their concentrations. Methods and Results The acidic hydrophobic compounds of urine were separated using high-performance liquid chromatography (HPLC) and were detected and quantified electrochemically. Two approaches were used to establish the identity of SA and SU. First, the retention times (Rt) of the substances extracted and those of SA and SU were compared under two sets of chromatographic conditions; the Rt of the compounds suspected to be SA and SU and those of the authentic substances were very similar under both sets of conditions. Second, the unknown substances, isolated by HPLC, were treated with acetyl chloride in methanol and compared with the methyl esters of SA and SU by using gas chromatography-mass spectrometry; the unknown compounds after esterification had very similar mass spectra and gas chromatographic Rt to those of methyl salicylate and methyl salicylurate. The median (n = 10) urinary concentration of SA was 0·56 μmol/L (range 0·07-0·89 μmol/L) and that of SU was 3·20 μmol/L (range 1·32-6·54 μmol/L). SA and its major urinary metabolite, SU, were found in the urine of all of the 10 people examined.

Clinical and Biochemical Determinants of Plasma Lipid Peroxide Levels in Type 2 Diabetes

The enhanced risk and increased severity of atheroma in diabetes is well recognized but, as yet, incompletely explained. A cross-sectional study of vascular disease risk factors in a group of type 2 diabetic patients from South West Scotland has revealed an association between glycaemic control, assessed by HbA1 level and plasma lipid peroxides measured by a specific high-performance liquid chromatography method. Duration of diabetes appeared to be a subsidiary contributor to lipid peroxidation. We suggest this evidence supports the importance of glycaemic control in modulating glyco-oxidative mechanisms probably crucial to production of diabetic complications. Atherosclerosis prevention in diabetes may hinge on exemplary simultaneous control of both hyperglycaemia and hyperlipidaemia.

Defining optimal triage strategies for hrHPV screen positive women - an evaluation of HPV 16/18 genotyping, cytology and p16/Ki-67 cyto-immunochemistry.

Background: Several options for the triage of high-risk HPV screen–positive (hrHPV+) women were assessed. Methods: This study incorporated CIN2+ cases and controls, all of whom tested hrHPV+ and whose results of liquid-based cytology (LBC), HPV16/18 genotyping, and p16/Ki67 cytoimmunochemistry were available. Sensitivity and specificity for the CIN2+ of these triage tests were evaluated. Results: Absolute sensitivities of HPV 16/18 typing, LBC, and p16/Ki-67 cytoimmunochemistry for CIN2+ detection were 61.7%, 68.3%, and 85.0% for women with hrHPV+ clinician-taken samples. Respective specificities were 70.5%, 89.1%, and 76.7%. The absolute accuracy of the triage tests was similar for women with a hrHPV+ self-sample. P16/Ki-67 cyto-immunochemistry was significantly more sensitive than LBC although significantly less specific. Conclusions: All three single-test triage options, if positive, exceed the threshold of 20% risk at which colposcopy would be indicated. However, none of them conferred a post-test probability of CIN2+ <2%; which would permit routine recall. P16/Ki-67 cytoimmunochemistry on HPV16/18 negative women had a post-test probability of CIN2+ of 1.7% and 0.6% if also LBC negative. Impact: This is one of the few studies to directly compare the performance of triage strategies of hrHPV+ women, in isolation and combinations. It is the only study assessing triage strategies in women who test hrHPV+ in self-taken vaginal samples. A combined triage option that incorporated HPV 16/18 typing prior to p16/ki-67 cytoimmunochemistry in HPV 16/18–negative women yielded a post-test probability of CIN2+ of >20%, whereas women who tested negative had a probability of CIN2+ of <2%. Cancer Epidemiol Biomarkers Prev; 26(11); 1629–35. ©2017 AACR.

Aspirin for cancer is no mere antiplatelet prototype. There is potential in its ancient roots

Aspirin (ASA), increasingly accepted as predominantly a cyclooxygenase (COX)-1 inhibitor, is a prodrug for salicylic acid (SA) which has no such activity. SA is widespread in nature, vital in plants, and present in drug free serum from animals and man. Evolutionary conserved SA receptors are found in human tissues. Very low doses of ASA will, on repeat dosing, produce near maximal platelet COX-1 inhibition. Evidence for cancer prophylaxis is based on ASA doses of at least 75mg/day. Pleiotropic mechanisms underlie low dose ASAs undoubted efficacy in preventive medicine but the key barrier to its more widespread use is gastrointestinal toxicity. ASA/SA combination formulations may improve the current risk/benefit ratio of chemo-prophylactic preparations. There is well established methodology for, and should be few regulatory barriers to, their evaluation.