Cholecystectomy: does subspecialization alter workload?

AIMS: Cholecystectomy is a common operation. This study reviewed the changes in workload and practice in a teaching hospital over a 4-year period, during which a hepatobiliary subspecialist unit was developed. METHODS: Computerized demographic data, and details of operations and inpatient events were reviewed for all patients undergoing cholecystectomy in a single teaching hospital from 1993 to 1997. For statistical analysis the consultants were grouped into those with a hepatobiliary interest (n = 3) and those with other primary interests (n = 6); and the workload for the first 12 months of the study was compared with that of the last 12-month period. RESULTS: Between April 1993 and April 1997, 1121 cholecystectomies were performed, of which 75 were excluded because they were performed with other simultaneous procedures. Of the remaining operations, 911 involved cholecystectomy alone (mean patient age 52. 9 years), and 135 (12.9 per cent) comprised cholecystectomy with exploration of the common bile duct (ECBD) (mean age 60.1 years). Between the first and last years studied, the rate of ECBD rose significantly from 7.4 to 14.9 per cent (P < 0.01, chi2 test), and the proportion of ECBD procedures being performed by hepatobiliary specialists rose from 31.6 to 52.7 per cent, but this was not statistically significant (P = 0.13). However, for cholecystectomy in the same period the proportion performed by hepatobiliary surgeons rose from 40.4 to 58.5 per cent, representing a highly significant trend (P < 0.001). Following cholecystectomy alone there was a significantly shorter stay associated with patients treated by hepatobiliary surgeons (P = 0.002, F test), although the median postoperative hospital stay was 2 days for both groups of surgeons (interquartile range 1-3 days for hepatobiliary and 1-4 days for non-hepatobiliary surgeons). CONCLUSIONS: Although cholecystectomy is not viewed as a specialist procedure, the trend in this teaching hospital reveals a steady increase in the proportion of cholecystectomies being performed by teams with a biliary interest. The data indicate that this practice is associated with a shorter hospital stay.

Current practice in the management of acute cholecystitis

AIMS: Several recent papers have advocated emergency cholecystectomy for patients with acute cholecystitis, stating that it is safe, cost effective and leads to less time off work. This study was designed to assess current practice in the management of acute cholecystitis in the UK. METHODS: A postal questionnaire was sent to 357 consultant surgeons who were thought to be involved in a general surgical on-call rota, to ascertain their current management of patients with acute cholecystitis. Replies were received from 250 consultants (70 per cent) of whom 242 (68 per cent) were involved in a general surgical take. Sixteen of these consultants, however, handed their patients with acute cholecystitis on to a different team the following day for further management. RESULTS: Twenty-seven consultants (12 per cent) routinely treat their patients by emergency cholecystectomy whenever possible, with 24 stating that they would do this within 72 h. Limiting factors to this practice were stated to be availability of surgical staff (15), theatre space (nine) and radiological investigations (four). The remaining consultants (n = 199) routinely manage their patients conservatively initially and providing they settle, either (1) book directly for cholecystectomy (n = 94, 47 per cent), (2) reassess as an outpatient (n = 65, 33 per cent), (3) either of above (n = 21; 11 per cent) or (4) refer on to a colleague (n = 19, 10 per cent). The commonest indications for acute cholecystectomy stated by consultants whose initial treatment policy is conservative are spreading peritonitis due to bile leak (93 per cent), empyema (89 per cent), unexpected space on a theatre list (28 per cent) and failure of an acute episode to settle (21 per cent). The laparoscopic method is the commonest for both elective and emergency cholecystectomy, but the percentage of consultants using an open method rises dramatically from 9 per cent in the elective situation to 48 per cent for emergency cholecystectomy. CONCLUSIONS: Despite evidence to support the increased use of emergency cholecystectomy, this practice is routinely carried out by only 12 per cent of consultants. However, of the consultants who treat their patients conservatively, 28 per cent are prepared to undertake emergency cholecystectomy if an unexpected space appears on the theatre list.

Proximal gastric vagotomy: does it have a place in the future management of peptic ulcer?

Proximal gastric vagotomy (PGV) is a modification of truncal vagotomy, which was introduced by Dragstedt for the treatment of duodenal ulcer (DU) in 1943. It is a technically demanding operation; but when performed by an experienced surgeon, it is safe and gives a cure rate for DU of more than 90%, with minimal side effects. The operation permanently alters the natural history of the disease and may be used for gastric ulcer (GU), with ulcer excision; but it is not as effective. Further adaptations, such as posterior truncal vagotomy with anterior seromyotomy, were introduced to simplify and shorten the operation, but they did not receive wide acceptance. Recently, with the identification of Helicobacter, it was found that DU can also be cured by eliminating the infection. PGV is therefore used electively in patients with persistent DU that is not Helicobacter-positive or in the few in whom Helicobacter cannot be eliminated. In patients with bleeding or perforated DUs, PGV may be used in conjunction with underrunning the vessel or patching the perforation. However, few surgeons doing emergency peptic ulcer surgery have experience with PGV, so simple suture followed by medical treatment is the safest option. Because elective PGV is now a rare procedure, patients should be referred to a center with special expertise. If Helicobacter becomes resistant to antibiotics in the future, surgery may be needed regularly again, but the technical nuances would have to be learned.

Mismatch between trainees' subspecialist interest and advertised jobs; worrying implications for upper gastrointestinal trainees

AIMS: The aim of this study was first to assess the primary subspecialist interests of general surgical specialist registrars who were accredited and still looking for a consultant position, or who were within 3 years of their CCST (certificate of completion of surgical training). These interests were then compared with subspecialist interests declared in consultant vacancies advertised in the British Medical Journal over the preceding 16 months. METHODS: All trainees in general surgery holding a national training number in six regions (Mersey, North West, Trent, Yorkshire, Northern, West Midlands) were identified, and those accredited or within 3 years of their CCST (n = 136) were telephoned to ascertain their primary subspecialist interest, whether they had a higher degree and what their desired consultant job would be. The consultant vacancies advertised in the British Medical Journal between 3 January 1998 and 8 May 1999 were assessed according to the required subspecialist interest. RESULTS: Upper gastrointestinal surgery is the second most popular subspecialty (n = 37; 27 per cent of trainees) after colorectal surgery (n = 40; 29 per cent of trainees). However, there were fewer consultant vacancies in upper gastrointestinal surgery (31 of 226; 14 per cent of jobs) than in any of the other three main subspecialist areas of general surgery (colorectal, vascular and breast/endocrine). The ratio of percentage of jobs to percentage of trainees was lowest in upper gastrointestinal surgery (0.50), compared with colorectal (0.77), vascular (0.89) and breast/endocrine (2.23) surgery. CONCLUSIONS: Upper gastrointestinal surgery appears to be the most competitive of the general surgical subspecialties at present, having by far the lowest ratio of jobs to trainees. In addition, 87 per cent of upper gastrointestinal trainees have or are completing a higher degree, and 43 per cent expressed a desire to work in a teaching hospital.

No evidence of increased risk of colorectal cancer in individuals heterozygous for the Cys282Tyr haemochromatosis mutation

BACKGROUND AND AIMS

Previous studies have suggested that increased body iron stores and heterozygosity for haemochromatosis are associated with an increased risk of colorectal carcinoma. The aim of this study is to determine if there is an association between (i) colorectal carcinoma and heterozygosity for the Cys282Tyr mutation of the haemochromatosis gene (HFE) and (ii) this mutation and tumour site or stage.

METHODS

Two hundred and twenty-nine unselected patients (127 males, 102 females, mean age 68.0 years) with sporadic colorectal carcinoma and 228 controls (145 males, 83 females, mean age 69.7 years) were studied. DNA was tested for the presence of the Cys282Tyr mutation by digestion with Rsa1 and fragments separated by electrophoresis.

RESULTS

Twenty-one patients with colorectal cancer and 23 control subjects were heterozygous for the Cys282Tyr mutation of HFE (relative risk 0.90). There was no association between heterozygosity of the Cys282Tyr mutation and tumour site or stage.

CONCLUSIONS

Heterozygosity for the Cys282Tyr mutation of HFE does not appear to be a risk factor for colorectal carcinoma.

The kinetics of mycophenolic acid and its glucuronide metabolite in adult kidney transplant recipients

BACKGROUND

Mycophenolic acid kinetics have been reported to vary after renal transplantation, and mycophenolic acid area under the concentration-time curve (AUC) is the best predictor of suppression of graft rejection.

METHODS

To determine whether mycophenolic acid kinetics vary after renal transplantation and to examine the potential role of enterohepatic recirculation, we investigated the kinetics of mycophenolic acid and mycophenolic acid glucuronide on days 2, 5, and 28 after transplantation in 10 kidney transplant recipients (male/female ratio, 1.5; mean age, 41.7 +/- 5.0 years) given 1 g mycophenolate mofetil twice a day. To facilitate therapeutic drug monitoring, we examined a limited sampling strategy for estimating 12-hour mycophenolic acid [AUC(0-12)].

RESULTS

The mean +/- SE AUC(0-12) for mycophenolic acid on day 28 was 38.5 +/- 1.6 mg x h/L, with a secondary peak 4 to 8 hours after dosing that was attributable to enterohepatic recirculation. Marked variability was shown in the kinetic profile of mycophenolic acid among patients across the three sampling days. Mycophenolic acid AUC(0-12) was positively predicted by both serum creatinine (P = .01) and serum albumin (P = .03) but not by time after transplantation, body weight, or trough concentration. Limited sampling (at 0, 1, 3, and 6 hours) accounted for 84.1% of the variability in the mycophenolic acid AUC(0-12) data and predicted the AUC(0-12) closely (r2 = 0.954) when evaluated in 10 different kidney transplant recipients.

CONCLUSIONS

Mycophenolic acid AUC(0-12) is predicted by serum albumin and creatinine after kidney transplantation, and the AUC(0-12) may be determined during the early posttransplant period while the patient remains hospitalized with use of a limited sampling strategy to facilitate therapeutic drug monitoring.

The preoperatively normal bile duct does not dilate after cholecystectomy: results of a five year study

BACKGROUND

The common hepatic duct (CHD) is commonly believed to dilate after cholecystectomy but previous studies have either not measured CHD diameter preoperatively or the follow up period is short.

AIMS

To measure CHD diameter before and after cholecystectomy.

METHODS

Patients undergoing (open) cholecystectomy and operative cholangiography had ultrasonographic measurement of CHD diameter before, and three and six months, and one and five years after cholecystectomy. The normal duct diameter was considered to be 5 mm or less, with an observer error of +/-1 mm.

RESULTS

Fifty nine patients with normal diameter ducts were studied. The majority (more than 95%) of patients did not have a dilatation of the CHD beyond 6 mm after cholecystectomy. The CHD appeared to increase as well as decrease with an overall trend towards a minor increase at five years. This was not statistically significant if the margin of error of 1 mm was taken into account.

CONCLUSION

A preoperatively normal CHD does not dilate after cholecystectomy and may require further investigation in symptomatic patients.

Evaluation of the potential interaction between NaCl and prostaglandin inhibition in elderly individuals with isolated systolic hypertension

OBJECTIVE

To evaluate whether prostaglandin inhibition with the non-steroidal anti-inflammatory drug (NSAID), indomethacin (I) interacts synergistically with different doses of salt (NaCl) in elevating systolic blood pressure (SBP).

DESIGN AND METHODS

This randomized, placebo-controlled, double-blind, crossover study examined the interaction between NaCl and the prostaglandin inhibitor, I in 31 healthy elderly individuals with a mean age (+/- SD) of 68.7+/-5.7 years (range 61-85 years). Participants aged more than 60 years on a 140 mmol/day NaCl dose for 6 weeks were chosen with normal blood pressure [24-h SBP <148 mm Hg, diastolic blood pressure (DBP) <85 mm Hg on the Takeda Ambulatory Blood Pressure Monitor (TABPM); n = 15] and isolated systolic hypertension (ISH), [24-h SBP >148 mm Hg, 24-h DBP <85 mm Hg on TABPM; n = 16]. Exclusion criteria included uncontrolled hypertension (SBP >220 mm Hg and/or DBP >110 mm Hg), cardiac disease, creatinine clearance <60 ml/min, dementia and recent cerebrovascular accident or secondary hypertension. A 2x2 Latin square design was structured using four treatment groups [low salt (NaCl = 90 mmol/day) + I placebo, high salt (NaCl = 240 mmol/day) + I placebo, low salt + I (25 mg three times daily) and high salt + I] for 2 weeks each, balanced and interspersed with 2 week washout periods to minimize carryover effects. Twenty-four hour SBP, DBP and heart rate were measured and summarized using a moving interval averaging technique. The mean change in 24-h SBP, DBP, heart rate, urinary Na+, K+, protein and creatinine, creatinine clearance and serum electrolytes were compared across treatments in the total cohort and in ISH and control groups separately using ANCOVA (SAS).

RESULTS

In the total cohort, compared with low NaCl, chronic high NaCl increased mean SBP (5.76 mm Hg; P = 0.0002) and DBP (3.36 mm Hg; P = 0.002). Indomethacin significantly increased mean SBP (2.66 mm Hg, P = 0.015) but not DBP (0.31 mm Hg, P = 0.419). High salt and I were additive (SBPT, DBPT) but there was no interaction (P = 0.795 and P = 0.739, respectively). Additionally, chronic high NaCl increased serum Na (P = 0.0001) and 24-h urinary Na (P = 0.0001) as expected. Indomethacin significantly decreased mean heart rate (P = 0.018). The effects of NaCl and I on SBP, DBP and heart rate were not modified by age, alcohol intake, serum K+, body mass index or treatment order. In the ISH group, NaCl dose significantly elevated SBP (9.87 mm Hg; P = 0.0001) and DBP (5.26 mm Hg, P = 0.006) but did not significantly alter blood pressure in the normotensive group. Indomethacin significantly elevated SBP (P = 0.03) in normotensive individuals but had no effect on blood pressure in the ISH group.

CONCLUSIONS

Chronic high salt diet elevated blood pressure more than I in the total cohort of elderly individuals. No interaction was demonstrated and their effects were additive. In the ISH group, chronic high salt diet significantly increased SBP and DBP while I failed to alter blood pressure. In the normotensive group, I, but not salt, elevated SBP. Patients with ISH are sensitive to the pressor effect of NaCl but resistant to the pressor effect of prostaglandin inhibition in contrast to elderly normotensive control individuals where the reverse was found.

A meta-analysis of randomised controlled trials (RCT) among healthy normotensive and essential hypertensive elderly patients to determine the effect of high salt (NaCl) diet of blood pressure

To examine the effect of chronic NaCl ingestion on blood pressure (BP) in the elderly, a meta-analysis was undertaken of 11 randomised controlled trials of which five included patients > or =60 years of age only and six included patients with a mean age close to 60 years. The following databases were used: Medline, Embase, Current Contents, The Cochrane Library, the AMI and IPA databases. Mean erect systolic and diastolic blood pressures (SBP/DBP) on chronic (> or =9 weeks) high and low NaCl diets were recorded, the pooled mean effect, the pooled standard error and 95% confidence intervals (Cl) were calculated and linear regression was used to evaluate the potential association between NaCl intake and BP. When all trials were pooled, a chronic high NaCl diet significantly increased mean SBP and DBP by 5.58 mm Hg (95%Cl 4.31-6.85) and 3.5 mm Hg (95%Cl 2.62-4.38) respectively. There was a significant association between the level of NaCl intake and SBP (P = 0.05, r2 = 0.37) but not DBP (P = 0.76, r2 = 0.01). When trials were pooled separately, a chronic high NaCl diet increased SBP by 5.46 mm Hg (95%Cl 3.56-7.36) and DBP by 2.63 mm Hg (95%Cl 1.18-4.08) in trials including patients > or =60 years of age only, and increased SBP by 3.27 mm Hg (95%Cl 1.23-5.31) and DBP by 2.69 mm Hg (95%Cl 1.44-3.94) in trials including patients with a mean age close to 60 years. These data suggest that a chronic high NaCl diet in elderly patients with essential hypertension is associated with an increase in SBP and DBP, the association is significant for both SBP and DBP but more marked for SBP than DBP, the effect is more pronounced the older the patient and NaCl dose strongly predicts SBP in older patients.

Analysis of promoters from tyrosine/dihydroxyphenylalanine decarboxylase and berberine bridge enzyme genes involved in benzylisoquinoline alkaloid biosynthesis in opium poppy

Tyrosine/dihydroxyphenylalanine decarboxylase (TYDC) and the berberine bridge enzyme (BBE) represent the entry point and a key branch point, respectively, in the biosynthesis of benzylisoquinoline alkaloids in select species of the Papaveraceae and Fumariaceae. Genomic clones for tydc7 and bbe1 from opium poppy (Papaver somniferum L.) were isolated. Deletion analysis of tydc7 and bbe1 5'-flanking regions revealed the location of putative regulatory domains necessary for expression of the beta-glucuronidase (gus) reporter gene in a transient assay system based on the microprojectile bombardment of cultured opium poppy cells. A 105-nucleotide region between -393 and -287 of the tydc7 5'-flanking region, and a 155-nucleotide region between -355 and -200 of the bbe1 5'-flanking region, were found to be essential for promoter activity. RNA gel blot analysis showed that tydc7 and bbe1 expression is induced in cultured opium poppy cells in response to wounding or treatment with a pathogen-derived elicitor. Time-courses for the induction of tydc7 and bbe1 mRNAs in wounded cells were nearly identical to those for GUS activity in cells bombarded with select promoter-gus constructs when the -393 to -287 region of tydc7, or the -355 to -200 region of bbe1, was present. Our data suggest that the wound signal caused by the entry of DNA-coated microcarriers into opium poppy cells was sufficient to induce tydc7 and bbe1 promoter activity, and that wound-responsive regulatory elements are located within domains identified by deletion analysis.

Measurement of plasma renin activity with use of HPLC-electrospray-tandem mass spectrometry

BACKGROUND

The measurement of renin activity is complicated by difficulties in the quantification of angiotensin 1 (Ang1), the product of the renin-catalyzed reaction. We report an HPLC-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantification of Ang1 as a measure of plasma renin activity (PRA).

METHODS

After incubation (37 degrees C for 3 or 18 h), samples were prepared using C18 solid-phase extraction. [Val]5Ang1 was used as the internal standard (IS). Chromatography was performed on a C18 column, using 200 mL/L ammonium acetate buffer-800 mL/L methanol as the mobile phase. The flow rate was 150 microL/min, with a chromatographic run time of 5 min/sample. Mass spectrometric detection was in the positive ionization mode with selected reaction monitoring (Ang1 m/z 649.0-->784.0; IS m/z 641.9-->770.4).

RESULTS

The assay was linear over the range 2.5-500 ng Ang1/mL, which corresponded to a limit of detection (signal-to-noise ratio of 3:1) of PRA of 0.14 ng Ang1. mL-1. h-1. The imprecision (CV) of the assay at PRA values of 26.1, 13.5, 3.2, and 0.78 ng Ang1. mL-1. h-1 was 7.0%, 7.0%, 15%, and 11%, respectively. Absolute recoveries were 92.3% (Ang1) and 87.4% (IS). Incubation times of 3 h vs 18 h in the PRA assay gave good agreement at PRA <2 ng Ang1. mL-1. h-1, but samples with a PRA of 2-5 ng Ang1. mL-1. h-1 gave lower PRA results after incubation for 18 h than after 3 h. We compared the HPLC-ESI-MS/MS assay and an RIA for the determination of PRA, with PRA incubation times of 3 h and 1.5 h, respectively. The mean PRA based on RIA of Ang1 was higher than that obtained using HPLC-ESI-MS/MS.

CONCLUSION

The HPLC-ESI-MS/MS method allows sensitive and specific measurement of PRA. The higher activities measured with the RIA method highlight its potential for overestimation of PRA.

The relationship between in vivo emptying of the gallbladder, biliary pain, and in vitro contractility of the gallbladder in patients with gallstones: is biliary colic muscular in origin?

BACKGROUND

This study sought to determine whether there is a positive correlation between gallbladder emptying, biliary pain, and in vitro contractility.

METHODS

Ultrasound measurements were carried out on 25 gallstone patients. The response of gallbladder strips to 1.75*10(-11) to 5.25*10(-7) M cholecystokinin-8 was recorded. In a second study 23 patients filled in pain questionnaires, and in vitro studies were again carried out.

RESULTS

Of five patients with no gallbladder emptying, four had in vitro contraction. Overall, a significant, positive linear correlation was found (P < 0.0001). In the second study in vitro contractility showed a positive linear correlation with pain.

CONCLUSION

Gallbladder emptying correlates with contractility. However, since most 'non-contractors' can contract, we suggest the term 'non-emptying' or 'emptying' to describe gallbladder dynamics. The positive correlation between pain and contractility suggests that biliary pain has a muscular component.

Common duct diameter as an independent predictor of choledocholithiasis: is it useful?

We have evaluated the value of ultrasonographic measurement of common duct diameter in isolation from other predictors of choledocholithiasis. A cohort of 223 patients who did not have a history of jaundice or pancreatitis and had normal liver function tests underwent pre-operative ultrasound of the common hepatic duct and then had elective (open) cholecystectomy with operative cholangiography. One hundred and ninety-one (86%) of all patients had a normal (< or = 5 mm) common duct and of these only 12 (6%) had common duct calculi. Of the 32 patients who had a common duct diameter greater than 5 mm on pre-operative ultrasonography, 12 (37.5%) patients had ductal calculi. A pre-operatively dilated duct on ultrasonography has a high chance of containing stones and should be considered as a strong indication for pre-operative bile duct imaging or operative cholangiography.

Variations in the monoamine oxidase B (MAOB) gene are associated with Parkinson's disease

The monoamine oxidase B gene (MAOB; Xp15.21-4) is a candidate gene for Parkinson's disease (PD) given its role in dopamine metabolism and its possible role in the activation of neurotoxins. The association of MAOB polymorphisms (a [GT] repeat allelic variation in intron 2 and an A-G transition in intron 13) with Parkinson's disease (PD) was studied in an Australian cohort of 204 (male:female ratio 1.60) people with PD and 285 (male:female ratio 1.64) age- and gender-matched control subjects. Genomic DNA was extracted from venous blood and polymerase chain reaction was used to amplify the appropriate regions of the MAOB gene. The length of each (GT) repeat sequence was determined by 5% polyacrylamide denaturing gel electrophoresis and a DNA fragment analyzer, while the G-A genotype was determined using 2% agarose gel electrophoresis. The G-A polymorphism showed no association with PD (odds ratio [OR] = 0.80; p = 0.51; 95% confidence interval [CI] = 0.42-1.53). There was a significant difference in allele frequencies of the (GT) repeat allelic variation between patients and control subjects (chi2 = 20.09; p<0.01). After statistical adjustment for potential confounders using a logistic regression analysis, the (GT) repeat alleles > or =188 base pairs in the intron 2 marker of the MAOB gene were significantly associated with PD (OR = 4.60; p<0.00005; 95% CI = 1.97-10.77). The 186 base pair allele was also significantly associated with PD (OR = 1.85; p = 0.048; 95% CI = 1.01-3.42). The GT repeat in intron 2 of the MAOB gene is a powerful marker for PD in this large Australian cohort.

Plasma indomethacin assay using high-performance liquid chromatography-electrospray-tandem mass spectrometry: application to therapeutic drug monitoring and pharmacokinetic studies

The authors report the use of high-performance liquid chromatography-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) for the quantification of indomethacin (IND) in plasma with microscale sample preparation. Plasma samples (100 microL) and mefanamic acid (internal standard [IS]), buffered to pH 3.5, were prepared using solid phase extraction and chromatographed using a C8 column. The mobile phase composition was 80% methanol to 20% ammonium acetate buffer (40 mM, pH 5.1). A flow rate of 300 microL per minute was used with a 1-to-12 postcolumn split into the mass spectrometer. Selected reaction monitoring with mass transitions m/z 357.9-->139.0 and m/z 242-->209.0 were used for IND and IS, respectively. The chromatographic analysis time was 4 minutes. The assay was linear from 5 microg/L to 2000 microg/L with interday imprecision (n=5) over the analytic range (5%). At four concentrations (10 microg/L, 25 microg/L, 250 microg/L, 1500 microg/L), assay imprecision was 9% (total coefficient of variation [CV]) and accuracy ranged between 96.5% and 102.8% (n=16). The absolute recovery of IND and IS was 74% (n=8) and 95% (n=24), respectively. This method was developed and validated in less than 10 working days, had a lower limit of quantification than reported HPLC-ultraviolet (UV) methods, and uses small sample volumes. These factors illustrate the power of HPLC-ESI-MS/MS for drug analysis. Furthermore, the ability of this method to measure IND over a wide concentration range makes it suitable for therapeutic drug monitoring and pharmacokinetic studies.

Quantitative analysis of sirolimus (Rapamycin) in blood by high-performance liquid chromatography-electrospray tandem mass spectrometry

We report here a quantitative method for the analysis of sirolimus in blood using solid-phase sample preparation and HPLC-electrospray-tandem mass spectrometry detection. Blood samples (500 microl) were prepared by pre-treatment with acetonitrile: 15 mM zinc sulphate (70:30, v/v), containing 32-demethoxysirolimus (internal standard) and C18 solid-phase extraction. The electrospray conditions were chosen to enhance the [M+NH4]+ species at the expense of other species. Detection was by multiple reactant monitoring with the mass transitions m/z 931.8-->864.6 and m/z 901.8-->834.4 employed for sirolimus and the internal standard, respectively. The method was linear over the range 0.2 to 100.0 microg l(-1). The accuracy and inter-day precision, over this concentration range, was 94.4% to 104.4% and 1.4% to 5.0%, respectively. The accuracy and total precision at the limit of quantitation (0.2 microg l(-1)) was 103.0% and 10.8%, respectively. The mean absolute recovery of sirolimus and the internal standard were 80.5% and 81.3%, respectively. The sensitivity and analytical concentration range of the method make it suitable for therapeutic drug monitoring and pharmacokinetic studies. Further, the ability of the method to measure parent drug specifically will facilitate the evaluation of immunoassays for sirolimus.

Current surgical practice in screening for colorectal cancer based on family history criteria

BACKGROUND

As awareness about colorectal cancer increases there has been a steady rise in the number of referrals of relatives of patients with colorectal cancer to colorectal surgeons for screening investigations based on family history criteria. Surgeons are generally not trained in either risk assessment of inherited colorectal cancer or genetic counselling. As this is a relatively new area of service, there is likely to be variation in the management of these individuals.

METHODS

This study investigated the family history criteria used and the colonic screening practices employed by a group of consultant colorectal surgeons by means of a postal questionnaire distributed and collected through their specialist association.

RESULTS

The results show not only wide variation in the practice of colorectal screening based on family history criteria, but also a considerable waste of resources in the provision of illogical and inappropriate investigations.

CONCLUSION

Given the lack of evidence on which to base this clinical practice and the current financial difficulties in the health service, the authors question whether it is appropriate for surgeons to continue to provide such a service.