The role of breast reconstruction choice on body image patient-reported outcomes at four years post-mastectomy for breast cancer: A longitudinal prospective cohort study.

OBJECTIVES: To examine the impact of breast reconstruction on women's perceptions of body image over time and to assess the influence of sociodemographic variables on body image. METHODS: A prospective, longitudinal cohort study, using validated breast cancer-specific questionnaires, to compare patient-reported outcomes in women choosing immediate (n = 61), delayed (n = 16) or no (n = 23) breast reconstruction. RESULTS: One hundred women completed baseline questionnaires that included items on body image; 30 women completed all four annual follow-up sets, while 20 women completed baseline only. The three groups were well matched at baseline and similar trajectories in body image measures were identified over 48 months in all groups. At 12 months post-mastectomy, significant changes were seen in eight of the 10 subscales; this reduced to seven subscales at 24 months and four at 36 months. By 48 months, only three subscales remained significantly different to baseline scores: women remained less vulnerable and had fewer limitations (improved outcomes); the one worse outcome was persistently higher levels of arm concern. Three of the sociodemographic variables (health insurance, age and employment status) showed significant inter-group differences at some time points. CONCLUSION: These findings suggest women recover from the negative impact of mastectomy on body image within four years of surgery, whether they have immediate, delayed or no reconstruction. Our results provide some indirect evidence that having a choice of BR options is important, regardless of the choice made. Four years appears to be a suitable follow-up period for future studies in this area.

THE PREVALENCE OF PROBABLE FAMILIAL CHYLOMICRONEMIA SYNDROME IN A SOUTHERN CALIFORNIA POPULATION.

OBJECTIVE: To estimate the prevalence of probable familial chylomicronemia syndrome (FCS) in a major Southern California Academic Center as well as to provide a systematic review of past FCS studies and management recommendations. METHODS: Electronic medical records were queried based on single fasting plasma triglyceride (TG) levels of ≥880 mg/dL and at least 1 episode of acute pancreatitis. After the exclusion of secondary causes (diabetes, alcohol misuse, gallbladder disease, chronic kidney disease, uncontrolled hypothyroidism, estrogen, and drug use) and responses to lipid-lowering treatment, probable patients with FCS were identified. A systematic review of all published literature on the prevalence and management guidelines for FCS was then presented and discussed. RESULTS: Out of 7 699 288 charts queried, 138 patients with TG levels of ≥880 mg/dL and documented evidence of at least 1 episode of acute pancreatitis were identified. Nine patients did not have any documented secondary causes of chylomicronemia. Four of the 9 patients had >20% decrease in TG levels after lipid-lowering treatment, 2 patients were not responsive to lipid-lowering medication, and data on lipid-lowering medications were missing in 3 patients. CONCLUSION: Our study estimates the prevalence of probable FCS at a range of 0.26 to 0.66 per million. Using the recommended criteria, probable FCS cases can be identified to allow early diagnosis and management.

Hepatitis due to Reactivation of Hepatitis B Virus in Endemic Areas Among Patients With Hepatitis C Treated With Direct-acting Antiviral Agents.

Hepatitis due to reactivation of hepatitis B virus (HBV) has been reported in patients treated with direct-acting antiviral (DAA) agents for chronic hepatitis C virus infection. We performed an observational study to determine the incidence of and factors associated with hepatitis in 327 patients receiving pan-oral DAA agents for HCV infections in areas endemic for HBV in China. Ten patients were positive for hepatitis B surface antigen (HBsAg), and 124 patients had occult HBV infection. HBV reactivation was determined by measuring HBV DNA and HBsAg status in serial serum samples collected every 2 weeks during DAA treatment and then every 4 weeks after treatment until week 12. In the total study population, 10 patients (3.1%) had hepatitis; 3 cases were associated with HBV reactivation (1 case not in the icteric phase, 1 case in the icteric phase, and 1 case with liver failure) and 7 from other causes. Testing positive for HBsAg before DAA treatment was a strong risk factor for developing hepatitis during treatment (hazard ratio, 15.0; P < .001).

An evaluation of factors affecting preference for immediate, delayed or no breast reconstruction in women with high-risk breast cancer.

OBJECTIVE: Women with locally advanced breast cancer face many conflicting issues affecting their choice of immediate versus delayed versus no breast reconstruction (BR). This single-centre pilot study assessed high-risk women's reasons and priorities in choosing the timing and type of BR in a setting where all clinically feasible options were discussed with all women. METHODS: Fifty-one women from a metropolitan breast oncology practice, who were likely to require post-mastectomy radiotherapy (PMRT), were recruited after making their decision about BR. Participants completed a questionnaire (69% preoperatively), adapted from Reaby (1998), evaluating the factors affecting their decision. Responses were subsequently classified into eight issue-based domains (feeling normal, feeling good, being practical, influence of others, expectations, fear, timing and unnecessary). Demographic and clinical data were also collected. RESULTS: There were 32 immediate BR (IBR = 63%), seven delayed BR (DBR = 13%) and 12 no BR (NBR = 23%). Analysis using the chi square test showed women over 60 were more likely to choose NBR (p = 0.005), while women living with a partner were more likely to choose IBR (p = 0.032). The most relevant domains for both IBR and DBR were 'feeling good' and 'feeling normal'; and for NBR were 'unnecessary' and 'being practical'. Although all women understood pre-operatively the potential aesthetic limitations of PMRT, 63% still chose IBR. CONCLUSIONS: These data will enable clinicians, researchers and women with breast cancer to gain a clearer understanding of the factors that impact on the choice and timing of BR in women requiring PMRT, a major breast cancer survivorship decision. Copyright © 2016 John Wiley & Sons, Ltd.

Identification of erythropoietin mimetic peptide 1 linear form in a sealed vial and its administration study in horses for doping control purpose.

The erythropoietin mimetic peptide 1 linear form (EMP1-linear), GGTYSCHFGPLTWVCKPQGG-NH2 , was identified in an unknown preparation consisting of white crystalline powder contained in sealed glass vials using ultrahigh performance liquid chromatography-high-resolution mass spectrometry (UPLC-HRMS). The white crystalline powder, allegedly used for doping racehorses, was found to contain around 2% (w/w) of EMP1-linear. EMP1-linear can be cyclised in equine plasma at physiological temperature of 37°C by forming an intramolecular disulfide bond to give EMP1, which is a well-known erythropoiesis stimulating agent that can bind to and activate the receptor for cytokine erythropoietin (EPO). Thus, EMP1-linear is a prodrug of EMP1, which is a performance-enhancing doping agent that can be misused in equine sports. In order to identify potential target(s) for detecting the misuse of EMP1-linear in horses, an in vitro metabolic study using horse liver S9 fraction was performed. After incubation, EMP1-linear mainly existed in its cyclic form as EMP1, and four N-terminus truncated in vitro metabolites TYSCHFGPLTWVCKPQGG-NH2 (M1), SCHFGPLTWVCKPQGG-NH2 (M2), WVCKPQGG-NH2 (M3) and VCKPQGG-NH2 (M4) were identified. An intravenous administration study with the preparation of white crystalline powder containing EMP1-linear was also conducted using three retired thoroughbred geldings. EMP1 was detectable only in the postadministration plasma samples, whereas the four identified in vitro metabolites were detected in both postadministration plasma and urine samples. For controlling the misuse of EMP1-linear in horse, its metabolite M3 gave the longest detection time in both plasma and urine and could be detected for up to 4 and 27 h postadministration, respectively.

Doping control analysis of myo-inositol trispyrophosphate and 10 bisphosphonates in equine plasma by ion chromatography-mass spectrometry and its application to clodronic acid horse administration.

Bisphosphonates and myo-inositol trispyrophosphate (ITPP) are two classes of difficult-to-detect polar drugs that are prohibited under the rules of racing. ITPP is a drug capable of increasing the amount of oxygen in hypoxic tissues, and studies have shown that administration of ITPP increases the maximal exercise capacity in mice. The properties of ITPP make it an ideal candidate as a doping agent to enhance performance in racehorses. In recent years, ITPP had indeed been detected in racehorses and confiscated items. As for bisphosphonates, it is especially critical to control their use as since February 2019, the International Agreement on Breeding, Racing and Wagering (IABRW) by the International Federation of Horseracing Authorities (IFHA) had identified specific conditions on which bisphosphonates should not be administered to a racehorse. A recent review of literature shows that there is yet a simultaneous screening method for detecting ITPP and bisphosphonates in equine samples. This paper describes an efficient ion chromatography high-resolution mass spectrometry (IC-HRMS) method for the simultaneous detection of ITPP and 10 bisphosphonates at sub-parts-per-billion (ppb) to low-ppb levels in equine plasma after solid-phase extraction (SPE) and its application to an administration study of clodronic acid in horses.

Doping control analysis of seven bioactive peptides in horse plasma by liquid chromatography-mass spectrometry.

In recent years, there has been an ongoing focus for both human and equine doping control laboratories on developing detection methods to control the misuse of peptide therapeutics. Immunoaffinity purification is a common extraction method to isolate peptides from biological matrices and obtain sufficient detectability in subsequent instrumental analysis. However, monoclonal or polyclonal antibodies for immunoaffinity purification may not be commercially available, and even if available, such antibodies are usually very costly. In our study, a simple mixed-mode anion exchange solid-phase extraction cartridge was employed for the extraction of seven target peptides (GHRP-1, GHRP-2, GHRP-6, ipamorelin, hexarelin, CJC-1295, and N-acetylated LKKTETQ (active ingredient of TB-500)) and their in vitro metabolites from horse plasma. The final extract was subject to ultra-high-performance liquid chromatographic separation and analysed with a hybrid high-resolution mass spectrometer. The limits of detection for all seven peptides were estimated to be less than 50 pg/mL. Method validation was performed with respect to specificity, precision, and recovery. The applicability of this multi-analyte method was demonstrated by the detection of N-acetylated LKKTETQ and its metabolite N-acetylated LK from plasma samples obtained after subcutaneous administration of TB-500 (10 mg N-acetylated LKKTETQ) to two thoroughbred geldings. This method could easily be modified to cover more bioactive peptides, such as dermorphin, ß-casomorphin, and desmopressin. With the use of high-resolution mass spectrometry, the full-scan data acquired can also be re-processed retrospectively to search for peptides and their metabolites that have not been targeted at the time of analysis. To our knowledge, this is the first identification of in vitro metabolites of all the studied peptides other than TB-500 in horses.

Patient-reported health-related quality of life outcomes following mastectomy for breast cancer, with immediate, delayed or no breast reconstruction: Four-year follow-up from a prospective cohort study.

BACKGROUND: Breast reconstruction (BR) improves women's health-related quality of life (HRQOL) following mastectomy for breast cancer, yet factors contributing to improved HRQOL remain unclear. This study aimed to explore the overall impact of mastectomy with or without BR on participants' perceptions of HRQOL over time in a cohort of women with high-risk breast cancer; to examine differences in mean HRQOL scores between immediate BR, delayed BR and no BR groups; to assess the influence of patient characteristics potentially associated with HRQOL scores; and to determine the feasibility of long-term collection of patient-reported outcome measures in clinical settings. METHODS: A prospective, longitudinal study of 100 women with high-risk breast cancer who underwent mastectomy with or without breast reconstruction and were likely to require post-mastectomy radiotherapy. Four validated patient-reported questionnaires, comprising 21 outcome measures relating to HRQOL, administered at baseline and up to 4 years post-mastectomy. Demographic, clinical and surgical data extracted from patient medical records. RESULTS: Consistently significant declines in perceptions of future health and arm symptoms, consistently significant improvements in treatment side effects, breast symptoms and fatigue, as well as significant improvements, compared to baseline, in social functioning and financial difficulties at 48 months. No significant differences in mean HRQOL scores between women given a choice of reconstructive options. CONCLUSION: Similar trajectories of HRQOL scores were found in women with high-risk breast cancer who were offered a choice of BR. Informed choice may be an independent contributing factor in long-term maintenance of most HRQOL indicators at their pre-mastectomy levels.

Nanolitre-scale crystallization using acoustic liquid-transfer technology.

Focused acoustic energy allows accurate and precise liquid transfer on scales from picolitre to microlitre volumes. This technology was applied in protein crystallization, successfully transferring a diverse set of proteins as well as hundreds of precipitant solutions from custom and commercial crystallization screens and achieving crystallization in drop volumes as small as 20 nl. Only higher concentrations (>50%) of 2-methyl-2,4-pentanediol (MPD) appeared to be systematically problematic in delivery. The acoustic technology was implemented in a workflow, successfully reproducing active crystallization systems and leading to the discovery of crystallization conditions for previously uncharacterized proteins. The technology offers compelling advantages in low-nanolitre crystallization trials by providing significant reagent savings and presenting seamless scalability for those crystals that require larger volume optimization experiments using the same vapor-diffusion format.

Synchronous femoral hernias diagnosed during endoscopic inguinal hernia repair.

BACKGROUND: During totally extraperitoneal (TEP) endoscopic repair of inguinal hernias, it is possible to see the internal opening of the femoral canal. The aim of our study was to determine the incidence of synchronous femoral hernias found in patients undergoing TEP endoscopic inguinal hernia repair. METHOD: This was a retrospective review of prospectively collected data on 362 consecutive patients who underwent 484 TEP endoscopic inguinal hernia repairs during a 5-year period, May 2005 to May 2010. During surgery, both inguinal and femoral canal orifices were routinely inspected. The presence of unilateral or bilateral inguinal and femoral hernias was recorded and repaired accordingly. RESULTS: There were a total of 362 patients. More males (343, 95%) underwent a TEP hernia repair than females (19, 5%). There were more cases of unilateral (240/362, 66%) than bilateral (122/362, 34%) inguinal hernias. A total of 18 cases of synchronous femoral hernias were found during operation. There was a higher incidence of femoral hernia in females (7/19, 37%) compared to males (11/343, 3%) (P < 0.001). None of the femoral hernias were clinically detectable preoperatively. CONCLUSION: Females undergoing elective inguinal hernia repair are more likely to have a synchronous femoral hernia than males. We suggest that all women presenting with an inguinal hernia also have a formal assessment of the femoral canal. TEP endoscopic inguinal hernia repair is an ideal approach as both inguinal and femoral orifices can be assessed and hernias repaired simultaneously during surgery.

Application of a non-target variable data independent workflow (vDIA) for the screening of prohibited substances in doping control testing.

A non-target variable Data Independent Acquisition (vDIA) workflow based on accurate mass measurements using a Q Exactive OrbiTrap is presented for the first time for equine doping control testing. The vDIA workflow uses a combination of MS1 events (1 to 2) and multiple vDIA events to cover the analytes of interest. The workflow basically captures a digital image of a sample allowing all relevant MS1 and MS2 data to be recorded. In theory, the workflow can accommodate an unlimited number of analytes as long as they are amenable to the sample extraction protocol and fall within the mass limits of the workflow. Additional targets fulfilling the above requirements can be added without changing any settings. The performance of the vDIA workflow was illustrated by applying it to two screening methods in horse urine, with one workflow covering 331 basic drugs and the other covering 45 quaternary ammonium drugs (QADs). Both screening methods have good detection sensitivity with 84% of the basic drugs having Limits of Detection (LoDs) of ≤ 1 ng/mL and 84% of the QADs having LoDs of ≤ 0.4 ng/mL. Other method characteristics including retention reproducibility, method precision and false hit rate will also be presented.

Acoustic matrix microseeding: improving protein crystal growth with minimal chemical bias.

A crystal seeding technique is introduced that uses acoustic waves to deliver nanolitre volumes of seed suspension into protein drops. The reduction in delivery volume enables enhanced crystal growth in matrix-seeding experiments without concern for bias from chemical components in the seed-carrying buffer suspension. Using this technique, it was found that while buffer components alone without seed can marginally promote crystal growth in some cases, crystal seeding is far more effective in boosting the number of sparse-matrix conditions that yield protein crystals.

Doping control analysis of recombinant human erythropoietin, darbepoetin alfa and methoxy polyethylene glycol-epoetin beta in equine plasma by nano-liquid chromatography-tandem mass spectrometry.

Recombinant human erythropoietin (rhEPO), darbepoetin alfa (DPO) and methoxy polyethylene glycol-epoetin beta (PEG-EPO) are synthetic analogues of the endogenous hormone erythropoietin (EPO). These erythropoiesis-stimulating agents have the ability to stimulate the production of red blood cells and are commercially available for the treatment of anaemia in humans. These drugs are understood to have performance-enhancing effects on human athletes due to their stimulation of red blood cell production, thereby improving delivery of oxygen to the muscle tissues. Although their effect on horses has not been proven, these substances were thought to be similarly performance enhancing and have indeed been applied covertly to horses. As such, these protein-based drugs are prohibited by authorities in both human and equine sports. The method officially adopted by the International Olympic Committee (IOC) and World Anti Doping Agency (WADA) for the confirmation of rhEPO and/or DPO (rhEPO/DPO) in human urine is based on electrophoresis in combination with Western blotting. A shortcoming of the WADA method is the lack of definitive mass spectral data for the confirmation of a positive finding. Recently, a liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for the detection and confirmation of rhEPO/DPO in equine plasma was reported. However, we have not been successful in achieving the reported sensitivity. This paper presents a method for the detection and confirmation of rhEPO/DPO, as well as the newly released PEG-EPO, in equine plasma. The procedures involve immunoaffinity extraction using anti-rhEPO antibody-coated Dynabeads followed by trypsin digestion. The injected extract was further purified and concentrated using an on-line trap column in the nano-LC system. Detection and confirmation were achieved by monitoring a unique peptide segment of rhEPO/DPO/PEG-EPO using nano-liquid chromatography-tandem mass spectrometry equipped with a nanospray ionisation source operated in the selected reaction monitoring mode. rhEPO, DPO and PEG-EPO can be confirmed at 0.1, 0.2 and 1.0 ng/mL, respectively, in equine plasma.

Doping control analysis of antipsychotics and other prohibited substances in equine plasma by liquid chromatography/tandem mass spectrometry.

Antipsychotics are banned substances and considered by the Fédération Equestrian Internationale (FEI) to have no legitimate use in equine medicine and/or have a high potential for abuse. These substances are also prohibited in horseracing according to Article 6 of the International Agreement on Breeding, Racing and Wagering (published by the International Federation of Horseracing Authorities). Over the years, antipsychotics have been abused or misused in equestrian sports and horseracing. A recent review of literature shows that there is yet a comprehensive screening method for antipsychotics in equine samples. This paper describes an efficient liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous detection of over 80 antipsychotics and other prohibited substances at sub-parts-per-billion (ppb) to low-ppb levels in equine plasma after solid-phase extraction (SPE).

Administration study of recombinant human relaxin-2 in horse for doping control purpose.

The insulin-like peptide relaxin (RLX), an endogenous peptide hormone produced in human for pregnancy and reproduction, is also known to exert a range of physiological and pathological effects. Its use is banned in human sports, horseracing, and equestrian competitions due to its potential performance enhancing effect through vasodilation resulting in the increase of blood and oxygen supplies to muscles. Little is known about the biotransformation and elimination of RLX in horses. This paper describes an administration study of rhRLX-2 and its elimination in horses, and the development of sensitive methods for the detection and confirmation of rhRLX-2 in both horse plasma and urine by nano-liquid chromatography/high resolution mass spectrometry (nano-LC/HRMS) after immunoaffinity extraction with the objective of controlling the abuse of rhRLX-2 in horses. The limits of detection in plasma and urine are 2 pg/mL and 5 pg/mL, respectively. Two thoroughbred geldings were each administered one dose of 10 mg rhRLX-2 subcutaneously daily for 3 consecutive days. The rhRLX-2 could be detected and confirmed in the plasma and urine samples collected 105 h and 80 h, respectively, after the last dose of administration. For doping control purposes, rhRLX-2 ELISA could be used as a screening test to identify potential positive samples for further investigation using the nano-LC/HRMS methods.

Non-nucleoside inhibitors of HCV polymerase NS5B. Part 4: structure-based design, synthesis, and biological evaluation of benzo[d]isothiazole-1,1-dioxides.

A series of benzo[d]isothiazole-1,1-dioxides were designed and evaluated as inhibitors of HCV polymerase NS5B. Structure-based design led to the incorporation of a high affinity methyl sulfonamide group. Structure-activity relationship (SAR) studies of this series revealed analogues with submicromolar potencies in the HCV replicon assay and moderate pharmacokinetic properties. SAR studies combined with structure based drug design focused on the sulfonamide region led to a novel and potent cyclic analogue.

Doping control analysis of insulin and its analogues in equine plasma by liquid chromatography-tandem mass spectrometry.

Insulin administration can increase muscle glycogen by utilising hyperinsulinaemic clamps prior to sports events or during the recovery phases, and increase muscle size by its chalonic action to inhibit protein breakdown. In order to control insulin abuse in equine sports, a method to detect effectively the use of insulins in horses would be required. Besides the readily available human insulin and its synthetic analogues, structurally similar insulins from other species can also be used as doping agents. This study describes a method for the simultaneous detection of bovine, porcine and human insulins, as well as the synthetic analogues Humalog (Lilly) and Novolog (Novo Nordisk) in equine plasma. Insulins were isolated from equine plasma by immunoaffinity purification, followed by centrifugal filtration, and analysed by nano-liquid chromatography-tandem mass spectrometry (LC/MS/MS). Insulin and analogues were detected and confirmed by comparing their retention times and major product ions. All five insulins (human insulin, Humalog, Novolog, bovine insulin and porcine insulin), which are exogenous in the horse, could be detected and confirmed at 0.05ng/mL. This method was successful in confirming the presence of human insulin in plasma collected from horses up to 4h after having been administered a single low dose of recombinant human insulin (Humulin R, Eli Lilly). To our knowledge, this is the first identification of exogenous insulin from post-administration horse plasma samples.

Comprehensive screening of acidic and neutral drugs in equine plasma by liquid chromatography-tandem mass spectrometry.

A multi-target high-throughput liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for the detection of low ppt to low ppb levels of anabolic steroids, corticosteroids, anti-diabetics, and non-steroidal anti-inflammatory drugs (NSAIDs) in equine plasma was developed for the purpose of doping control. Plasma samples were first deproteinated by addition of trichloroacetic acid. Drugs were then extracted by solid-phase extraction (SPE) using Bond Elut Certify cartridges, and the extracts were analysed by a triple-quadrupole/linear ion trap LC-MS-MS instrument in positive electrospray ionization (+ESI) mode with selected reaction monitoring (SRM) scan function. Chromatographic separation of the targeted drugs was achieved using a reverse phase 3.3 cm L x 2.1 mm ID, 3 microm particle size LC column with gradient elution. Plasma samples fortified with 66 targeted drugs including betamethasone, boldione, capsaicin, flunisolide, gestrinone, gliclazide, 17alpha-hydroxyprogesterone hexanoate, isoflupredone and triamcinolone acetonide, etc. at low ppt to low ppb levels could be consistently detected. No significant matrix interference was observed at the retention time of the targeted ion transitions when blank plasma samples were analysed. The method has been validated for its extraction recoveries, precision and sensitivity, and is used regularly in the authors' laboratory to screen for the presence of these drugs in plasma samples from racehorses.

The adsorption of vancomycin by polyacrylonitrile, polyamide, and polysulfone hemofilters.

The aim of this study was to characterize vancomycin adsorption by polyacrylonitrile (PAN), polyamide, and polysulfone hemofilters using an in vitro model of hemofiltration. Vancomycin (36 mg) was added to a blood-crystalloid mixture of known volume (target concentration of 50 mg/L) and pumped around a closed circuit. Adsorption, which was calculated from the fall in concentration over 120 min, was significantly greater by 0.6-m(2) PAN filters (10.08 +/- 2.26 mg) than by 0.6-m(2) polyamide (5.20 +/- 1.82 mg) or 0.7-m(2) polysulfone (4.80 +/- 2.40 mg) filters (P < 0.05). Cumulative adsorption was not changed by the addition of 500-mL lactated Ringer's solution (to reduce the circulating vancomycin concentration). These data show that although adsorption of vancomycin by PAN, polyamide, and polysulfone hemofilters occurs, the absolute adsorption is small. Adsorption is dependent on filter material and is not reversed by a decrease in circulating concentration.

A bottom-up approach in estimating the measurement uncertainty and other important considerations for quantitative analyses in drug testing for horses.

Quantitative determination, particularly for threshold substances in biological samples, is much more demanding than qualitative identification. A proper assessment of any quantitative determination is the measurement uncertainty (MU) associated with the determined value. The International Standard ISO/IEC 17025, "General requirements for the competence of testing and calibration laboratories", has more prescriptive requirements on the MU than its superseded document, ISO/IEC Guide 25. Under the 2005 or 1999 versions of the new standard, an estimation of the MU is mandatory for all quantitative determinations. To comply with the new requirement, a protocol was established in the authors' laboratory in 2001. The protocol has since evolved based on our practical experience, and a refined version was adopted in 2004. This paper describes our approach in establishing the MU, as well as some other important considerations, for the quantification of threshold substances in biological samples as applied in the area of doping control for horses. The testing of threshold substances can be viewed as a compliance test (or testing to a specified limit). As such, it should only be necessary to establish the MU at the threshold level. The steps in a "Bottom-Up" approach adopted by us are similar to those described in the EURACHEM/CITAC guide, "Quantifying Uncertainty in Analytical Measurement". They involve first specifying the measurand, including the relationship between the measurand and the input quantities upon which it depends. This is followed by identifying all applicable uncertainty contributions using a "cause and effect" diagram. The magnitude of each uncertainty component is then calculated and converted to a standard uncertainty. A recovery study is also conducted to determine if the method bias is significant and whether a recovery (or correction) factor needs to be applied. All standard uncertainties with values greater than 30% of the largest one are then used to derive the combined standard uncertainty. Finally, an expanded uncertainty is calculated at 99% one-tailed confidence level by multiplying the standard uncertainty with an appropriate coverage factor (k). A sample is considered positive if the determined concentration of the threshold substance exceeds its threshold by the expanded uncertainty. In addition, other important considerations, which can have a significant impact on quantitative analyses, will be presented.