Abstract P1-06-01: Upregulation of metabolism as a potential resistance mechanism to bevacizumab in primary breast cancer

Background: Recently the FDA has withdrawn the indication for bevacizumab in metastatic breast cancer after several clinical studies failed to demonstrate an overall survival benefit. These studies however did report an increase in response rates to chemotherapy and improvement in progression free survival, suggesting a pattern of response to the drug followed by the development of resistance. We have little knowledge of the molecular mechanisms driving the development of resistance to bevacizumab. To better understand these mechanisms, we have conducted a window of opportunity study using a single cycle of bevacizumab with detailed pharmacodynamic assessments using gene expression arrays and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

Methods: After ethical approval, 47 newly diagnosed locally advanced breast cancer patients were prospectively enrolled in this trial. Patients received single dose bevacizumab (15mg/ kg) 2 weeks prior to neoadjuvant chemotherapy and underwent core biopsies for gene expression and immunohistochemistry analysis and DCE-MRI scans before and 2 weeks after bevacizumab. 35 patients who had invasive ductal carcinoma together with good quality MRI scans and core biopsies before and after bevacizumab were included in this analysis. Pharmacokinetic (PK) modelling techniques were used to quantify PK parameters (Ktrans, kep, ve) from the DCE-MRI data. Gene expression profiling was performed using the Affymetrix Human Exon 1.0 ST arrays.

Results: The majority of patients (28/35) showed a significant reduction in vessel permeability and blood flow of at least 30% following bevacizumab, with a mean decrease in the forward transfer constant (P < 0.0001) and the reverse rate constant kep (P < 0.0001). From gene expression and immunohistochemistry analyses, we identified several key metabolism-related genes that are significantly up-regulated after bevacizumab treatment, including pyruvate dehydrogenase kinase isozyme 1 (PDK1) (fig.1) and carbonic anhydrase 9 (CA9). In addition, we found a number of interesting genes that are down-regulated after bevacizumab treatment, including sulfatase-1 (SULF1), and cyclin E1 (CCNE1).

Discussion: This study highlights that the combination of DCE-MRI and gene expression arrays can lead to an improved understanding of the molecular mechanisms governing response and resistance to anti-angiogenic therapy. Heterogeneity of response to bevacizumab was demonstrated, with some tumours showing increases or no change in Ktrans and others marked reductions, which may be of value in early stratification for therapy maintenance. Furthermore, the gene expression analysis showed activation of pathways, which could contribute to the development of resistance. For example, we observed significant up regulation of genes involved in regulating the switch from mitochondrial metabolism to glycolysis, such as PDK1. This suggests that using bevacizumab with the other targeted agents such as Dichloroacetate, a PDK1 inhibitor might be helpful in overcoming the development of resistance and ultimately lead to improved patient survival. Our preclinical studies strongly support this possibility.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-06-01.

A pilot study to evaluate assisted freehand ultrasound elasticity imaging in the sizing of early breast cancer: a comparison of B-mode and AFUSON elasticity ultrasound with histopathology measurements

OBJECTIVE

This pilot study investigates the role of assisted-freehand ultrasound (AFUSON) elasticity imaging of the breast in assessing the contour, size and area of 23 early breast cancers by making comparison of AFUSON with the equivalent B-mode ultrasound images and gold standard histopathology slides.

METHODS

The B-mode, AFUSON and digitised histopathology slides of three early breast cancers were compared for contour, size and area with histopathology scans. AFUSON features that corresponded to areas of known malignant change on the histopathology slides were regarded as diagnostic. These diagnostic criteria were then applied to the B-mode and AFUSON elasticity images of all 23 breast cancers in the pilot study without having the availability of the histopathology scans for reference. Corresponding diameters were measured and the results were compared with the equivalent measurements on the scans of the histology slides. The results were tabulated in histogram form. Diagnostic confidence levels were evaluated.

RESULTS

Size dimension accuracy increased from 66% using B-mode alone to 82% using combined B-mode and AFUSON elasticity images. Tumour area accuracy was also increased. A small number of cases had a striking visual similarity of shape on AFUSON elasticity scans and histopathology slides.

CONCLUSION

In spite of the shortfalls in this study, AFUSON elasticity imaging was capable of acquiring some high-quality images that showed strong correlation between AFUSON elasticity and scans of histology slides. Further studies will be carried out to refine the technique and determine if it has a role in the diagnosis and management of breast cancer.

Abstract P2-02-07: Predicting Response to Bevacizumab Therapy in Primary Breast Cancer Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging

Background: Anti-angiogenic therapy holds much promise for the treatment of breast cancer. In practice however, only a subset of patients who receive these drugs demonstrate a significant response to therapy. A key challenge therefore is to elucidate markers that are predictive of response to anti-angiogenic agents such as bevacizumab, and which would enable the selection of patients who would get the most benefit from these expensive therapies.

Materials and Methods: We used high temporal resolution dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to assess tumor vascularity in 20 patients with primary breast cancer. Patients were imaged both before and two weeks after single dose Bevacizumab therapy (15mg/kg). Pharmacokinetic modelling techniques were used to quantify the volume transfer constant Ktrans, the rate constant kep, and the fractional volume of the extra-vascular extracellular space ve. Specifically, we used Tofts model with a population-based arterial input function (modified Fritz-Hansen) to model the contrast agent concentration time courses on a voxel-wise basis. Non-enhancing voxels were detected automatically with the use of a Bayesian noise model, and the corresponding pharmacokinetic parameter values for these voxels were set to zero. The median pharmacokinetic parameter values over the tumor volumes of interest were then computed both pre-and post Bevacizumab. Results: We found marked variation across patients in the baseline level and percentage change in median Ktrans, kep and ve following Bevacizumab. In particular, median Ktrans at baseline ranged form 0.12 to 0.88. Changes in median Ktrans varied from −97% to +19% across all patients, with an average change of −49%. Notably, we found a highly significant negative correlation (r = −0.92, P = 1e-08) between the absolute change in median Ktrans and the median Ktrans at baseline. In particular, tumors with a high median Ktrans at baseline demonstrated the greatest change in Ktrans following Bevacizumab therapy, whereas tumors with low median Ktrans at baseline demonstrated relatively little change in Ktrans. Discussion: Although Ktrans is a complex function of vessel permeability, surface area, and tumor blood flow, it has previously been demonstrated to be a reliable biomarker of response to anti-angiogenic therapy in a number of different cancers. Our results illustrate that therapy-induced changes in Ktrans can be predicted from the value of Ktrans at baseline, and hence DCE-MRI scans may enable the selection of primary breast cancer patients who show the greatest response to single-dose Bevacizumab therapy. Whether this will translate into longer term benefit and improvements in outcome for patients remains to be shown. The relationship between baseline and pre-/post-therapy change in Ktrans with the corresponding changes in gene expression is currently under study in a larger number of patients. Figure available in online version.

Abstract P2-09-28: Integrated Gene Expression and MRI Analysis To Assess Early Therapeutic Response to Bevacizumab in Primary Breast Cancer

Background: Bevacizumab is an approved drug for advanced breast cancer alongside chemotherapy. To date there is no biomarker proven to be effective in patient stratification. To address this, a window of opportunity study was designed where bevacizumab is administered as a short-term first line treatment with a detailed pharmacodynamic assessment to identify the patients who are most likely to benefit from this therapy. This assessment consisted of Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) and gene expression analysis.

Method: This is an on going two-centre, Phase II, non-randomised study. 43 locally advanced breast cancer patients aged >18 years, with performance status 0-1 who have adequate bone marrow, renal and liver functions have been enrolled. A single infusion of bevacizumab (15mg/kg) was given prior to commencement of neoadjuvant chemotherapy. DCE-MRI and core biopsies for exon gene array analysis were performed both at baseline and 2 weeks after bevacizumab. Pharmacokinetic modelling of DCE-MRI was used to quantify the volume transfer constant Ktrans, the rate constant kep, and the fractional volume of the extra-vascular extracellular space ve. The median pharmacokinetic parameter values over the tumour volumes of interest were then computed both pre-and post-bevacizumab.

Results: Our initial gene expression analysis from 21 patients showed a high variability in the response. This was true for both single gene analysis and pathway signatures. In particular the expression fold changes of hypoxia and proliferation signatures after bevacizumab ranged from a minimum of 0.6 fold decrease to a maximum of 4.3 fold increase. Interestingly, fold changes in both these signatures were significantly positively correlated (Spearman rho=0.81, P<0.001). Changes in the proliferation signature were significantly inversely correlated with changes in mean and median ve (rho=-0.57, P<0.01 in both cases). Changes in the hypoxia signature were significantly inversely correlated with changes in mean and median kep (rho=-0.48, p=0.03 and rho=-0.58, p=0.007 respectively). Significantly over-represented pathways amongst genes up-regulated after bevacizumab were T-cell activation, inflammation, PDGF and apoptosis signalling. Discussion: Our initial results provide several potentially important avenues for further research, which may be useful in the identification of new therapeutic approaches. For example, the unexpected correlation of induction of hypoxia and proliferation in the same tumours has important implications for combination therapy. Furthermore, patients whose tumours showed the largest reduction in kep, a measure of vascular leakiness, also showed the greatest increase in hypoxia. In addition, patients who experienced the largest reduction in ve showed the highest fold change in proliferation. Although these results are preliminary and will need to be confirmed at study completion, they illustrate how the integrated analysis of DCE-MRI pharmacokinetic parameters and the corresponding gene expression profiles may enable an improved understanding of the mechanisms governing response and resistance to bevacizumab.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-09-28.

Percutaneous image-guided cutting needle biopsy of the pleura in the diagnosis of malignant mesothelioma

STUDY OBJECTIVES

Pleural fluid cytology and non-image-guided Abrams or Cope biopsies have sensitivities of approximately 30% for detecting malignant mesothelioma, and thoracoscopic biopsy has a sensitivity of approximately 90%. The difference between these two probably relates to obtaining adequate tissue. The use of immunohistochemical stains allows a firm diagnosis to be made from relatively small samples. This study explores whether percutaneous image-guided cutting needle biopsy (CNB) combined with immunohistochemistry is accurate in diagnosing pleural thickening due to mesothelioma.

DESIGN

Retrospective review of image-guided CNB of pleural thickening performed on consecutive patients over 7 years by a single radiologist.

SETTING

Teaching hospital chest radiology department.

PATIENTS

Twenty-one adult patients with a final diagnosis of malignant mesothelioma were identified from 53 consecutive patients who underwent percutaneous image-guided CNB. All 21 patients had pleural thickening identified on contrast-enhanced CT, and all had a final histologic diagnosis of mesothelioma confirmed by postmortem examination or thoracoscopy.

INTERVENTIONS

Fourteen-gauge and 18-gauge cutting needles were used. Biopsy guidance was by ultrasound in 6 patients and by CT in 15 patients.

MEASUREMENTS AND RESULTS

A correct histologic diagnosis of malignant mesothelioma was made by CNB in 18 patients (86% sensitivity and 100% specificity). Complications included one chest wall hematoma and a small hemoptysis. Four patients with a pleural thickness of < or = 5 mm underwent biopsy, and all specimens were diagnostic for mesothelioma.

CONCLUSIONS

Image-guided percutaneous CNB of pleural thickening is a safe procedure, with 86% sensitivity for detecting malignant mesothelioma. Pleural thickening of < or = 5 mm may be successfully sampled.

The natural history of transdural herniation of the spinal cord: case report

We report a patient with a Brown-Séquard syndrome who developed ventral transdural spinal cord herniation, showing the imaging findings changing over time from two thoracic disc protrusions with a normal spinal cord to a cord trapped within a bony defect in a thoracic vertebra.

Percutaneous image-guided cutting-needle biopsy of the pleura in the presence of a suspected malignant effusion

PURPOSE

To evaluate the diagnostic accuracy of percutaneous image-guided cutting-needle biopsy of pleural thickening in the presence of a suspected malignant pleural effusion.

MATERIALS AND METHODS

Thirty-three adult patients with diffuse or focal pleural thickening (median, 1.0 cm; range, 0.2-6.0 cm), pleural effusion, and suspected pleural malignancy underwent percutaneous image-guided cutting-needle biopsy. Biopsy guidance was performed with computed tomography in 24 patients and ultrasonography in nine patients. A final diagnosis of benign or malignant disease was established with radiologic and clinical follow-up findings and with other histologic or cytologic findings, when available.

RESULTS

A correct histologic diagnosis of malignant disease was made in 21 of 24 patients (sensitivity, 88%; specificity, 100%), including 13 of 14 patients with mesothelioma (sensitivity, 93%). A correct histologic diagnosis of benign pleural disease was made in nine patients. Positive and negative predictive values for malignant disease were 100% and 75%, respectively. The overall accuracy was 91%. Complications comprised a chest wall hematoma in one patient.

CONCLUSION

Image-guided percutaneous cutting-needle biopsy of pleural thickening in the presence of a pleural effusion is a safe procedure, with an overall accuracy of 91% in the diagnosis of malignancy.

Adrenal androgen and glucocorticoid dissociation in premenopausal rheumatoid arthritis: a significant correlate or precursor to onset?

Controlled studies of adrenal steroids in premenopausal women with rheumatoid arthritis (RA) have revealed subtle and inconsistent decreases in glucocorticosteroid (GCS) function, but prominent deficiencies of adrenal androgens (AA). Such findings have suggested that hypoandrogenicity may predispose to RA in younger women. However, recent prospective studies of serum cortisol and dehydroepiandrosterone sulfate (DHEAS) levels before (x = 12 yrs) the onset of the disease (pre-RA) offer an alternative perspective. Significant dissociation of serum cortisol and DHEAS levels was found only in the subgroup of premenopausal women who developed RA before age 50. This subgroup alone had significant deficiency in serum DHEAS levels. Aggregate data imply that the documented deficits of DHEAS (and other AA) in such young females are a correlate of relative adrenal insufficiency, and that subtle GCS dysfunction may either contribute to development of RA in such young women as well as pubertal girls or may predispose to earlier onset of disease.

Cutting needle biopsy in the diagnosis of clinically suspected non-carcinomatous disease of the lung

Most patients referred for lung biopsy have a focal lesion that is likely to be a carcinoma, and fine needle aspiration is usually sufficient to confirm the diagnosis. When non-carcinomatous disease is suspected, tissue architecture is important and potential diagnostic techniques include percutaneous cutting needle biopsy (CNB). We retrospectively reviewed 37 CNBs performed for clinically suspected non-carcinomatous disease; recording the biopsy result, final diagnosis, radiological nature of the pulmonary abnormality, distance from the pleura of the lesion biopsied and biopsy complications. 9 patients had a single pulmonary nodule/mass; 13 had multiple nodules/masses; 8 had a lobar consolidation/mass; and 7 had multifocal consolidation. The lesion abutted the pleura in 31 cases, lying within 1 cm in the other 6 cases. The minor complication rate was 14%, with no major complications. Specific malignant diagnoses were made in 9 patients, and specific benign in 23, in all of whom clinicoradiological follow-up was concordant. CNB did not yield a specific diagnosis in five patients, including two lymphomas and one case of unsuspected tuberculosis in which the sample was not cultured. The overall accuracy of CNB was 32/37 (86%). CNB is a safe and accurate means of achieving a tissue diagnosis for patients with peripheral pulmonary parenchymal disease thought not to represent carcinoma.

The cult of the double-blind placebo-controlled trial

The double-blind, placebo-controlled trial is held as the gold standard in medical knowledge, but this tool of investigation has its weaknesses. These include ethical limitations on the types of comparison that can be undertaken, the central conflict between best practice for an individual and trial protocols, problems of applicability to the general population and applicability of work done on one population to another, type II errors, publication bias, misuse and limitation of statistics, fraud, maintenance of blinding, asking the wrong question, and a simplistic, reductionist view of clinical management. The concentration on the randomised, controlled trial devalues information from other sources, such as natural history studies, clinical experience and case reports. The randomised, controlled trial is an important source of information and as physicians we should welcome more well-crafted trials, but they are not the only source of information.

Presence of N-acyl and acetoxy derivatives of putrescine and cadaverine in the human gut

N-acyl and acetoxy derivatives of putrescine and cadaverine have been found in the faeces of children and in cultures of isolates of gut bacteria. The evidence was accumulated from two dimensional, thin layer chromatography, field desorption mass spectrometry, and accurate mass measurement of the DANS derivatives of the amines. The acetoxy compounds of putrescine and cadaverine have not previously been reported.

Longterm drug therapy for rheumatoid arthritis in seven rheumatology private practices: I. Nonsteroidal antiinflammatory drugs

The probability of continuation of a particular nonsteroidal antiinflammatory drug (NSAID) over 5 years was estimated for 1,775 courses taken by 532 patients with rheumatoid arthritis treated in 7 rheumatology private practices. Similar results were seen for 15 different NSAID--48% of courses were continued at 12 months, 36% at 24 months, and 20% at 60 months. Only acetylated salicylates, other than plain aspirin, were continued significantly longer than any of the other NSAID. The probability of continuation of plain aspirin was similar to other NSAID, including nonacetylated salicylates and nonsalicylate NSAID. The first NSAID taken by an individual patient was continued only marginally longer than the 4th NSAID taken by the same patient. While most NSAID courses were not continued for long periods, 20% were continued for longer than 5 years, suggesting effective longterm results in this minority of courses.

Ovarian hydroxyeicosatetraenoic acids compared with prostanoids and steroids during ovulation in rats

Hydroxyeicosatetraenoic acid methyl esters (HETEs) are lipoxygenase products of arachidonic acid that are generated along with prostaglandins (PGs) during acute inflammatory reactions. Whereas it is well known that ovarian PG levels increase during the ovulatory process, little is known about ovarian HETEs. This report compares the ovarian changes in 5-, 12-, and 15-HETE with ovarian PGE and PGF, along with progesterone, 17 alpha-hydroxyprogesterone, 4-androstene-3,17-dione, testosterone, and 17 beta-estradiol. Ovulation was induced in immature Wistar rats by sequential treatment with pregnant mare's serum gonadotropin and human chorionic gonadotropin (hCG). Follicles began rupturing 10 h after hCG treatment. The greatest correlation was among 12-HETE, 15-HETE, and progesterone, which increased to peak levels at 10 h after hCG. In contrast, the ovarian levels of 5-HETE, 17 alpha-hydroxyprogesterone, testosterone, and 17 beta-estradiol all declined sharply beginning 4 h after hCG. 2 alpha,4 alpha,7-4,5-Epoxy-17-hydroxy-4,17-dimethyl-3-oxo-androstane-2- carbonitrile (epostane), a potent inhibitor of steroid synthesis and ovulation, sharply reduced the synthesis of all five steroids within 30 min after its injection at 3 h after hCG. Among the five eicosanoids, epostane mainly inhibited 15-HETE. The results suggest that 15-HETE, along with progesterone, may have an important role in ovulation.

Effects of epostane on ovarian levels of progesterone, 17 beta-estradiol, prostaglandin E2, and prostaglandin F2 alpha during ovulation in the gonadotropin-primed immature rat

The antiovulatory action of epostane, an inhibitor of 3 beta-hydroxysteroid dehydrogenase activity and progesterone synthesis, was studied in the immature rat. The ovulatory process was induced in 25-day-old rats by injecting them with hCG (10 IU, sc) 2 days after the animals had been primed with PMSG (10 IU). Epostane was administered at different times between 20 h before and 11 h after hCG. Maximum inhibition of ovulation occurred when the drug was given at 3 h after hCG. Epostane inhibited ovulation in a dose-dependent manner when administered in doses ranging from 1.0-50 mg/rat, while exogenous doses of progesterone restored the ovulation rate. A dose of 3.1 mg epostane/rat 3 h after hCG reduced ovarian progesterone levels within 15 min, but the production of this steroid rebounded within 2 h and approached normal levels by 12 h after hCG, i.e. when the follicles began to rupture in control animals. 17 beta-Estradiol synthesis was inhibited just as rapidly, but it remained suppressed for up to 12 h after hCG administration. The ovarian levels of prostaglandins E2 and F2 alpha decreased approximately 30% within 2 h after the administration of epostane, but such a moderate reduction in the synthesis of ovarian prostanoids is usually not sufficient to block ovulation. The results show that epostane has a rapid, but transient, effect on ovarian progesterone synthesis. The temporary decline in the local progesterone level is apparently sufficient to interfere with the normal sequence of metabolic events that lead to the rupture of follicles.

Staphylococcal pyomyositis with idiopathic dermatomyositis

We have described a patient with staphylococcal pyomyositis of the left pectoralis major muscle, complicating idiopathic dermatomyositis. Dermatomyositis and corticosteroids are possible predisposing factors. Patients with idiopathic muscle inflammation should be considered at risk for bacterial superinfection.

Role of erythrosine in the inhibition of adhesion of Lactobacillus fermentum strain 737 to mouse stomach tissue

The mechanism by which the food colour erythrosine inhibits the adhesion of Lactobacillus sp. to squamous epithelium in the mouse stomach was investigated using an in vitro adhesion assay. Inhibition of adhesion occurred only after growth of L. fermentum in erythrosine which bound to the bacterial cell surface. Erythrosine did not interfere with the receptor on the epithelial cell surface. Growth, but not the ATP content per cell, was affected by the presence of erythrosine in the growth medium. No consistent correlation between hydrophobicity and growth in two different broths was noted when erythrosine was present. Analyses of phenol/water extracts and transmission electron micrographs revealed no reduction in extracellular polysaccharide after growth in the presence of erythrosine. It was concluded that erythrosine affects bacterial metabolism thereby preventing production of the bacterial adhesin which is not the extracellular polysaccharide.

Studies of the free faecal amines of infants with gastroenteritis and of healthy infants

The free primary amines present in the faeces of 44 infants (1-18 months) with gastroenteritis have been examined by field desorption mass spectrometry of the lactone form of their fluorescamine derivatives without their prior separation. p-Tyramine, 2-phenylethylamine, the diamines, putrescine and cadaverine and several of their acyl derivatives were common constituents, but a number of other amines were also characterised. Using thin layer chromatography and field desorption mass spectrometry of the amine dansyl derivatives a comparative study was made of the faecal amines of 13 selected infants with gastroenteritis (diarrhoea) and of 13 healthy infants. p-Tyramine, the most abundant amine, was significantly higher (p = 0.02) in the sick infants. The overall presence of p-tyramine was more significantly related to the diet of the infants. Faecal tyramine was low in breast fed infants but significantly higher (p = 0.01) in infants fed cow's milk.

High-performance liquid chromatography of microbial acid metabolites

The use of high-performance liquid chromatography with a cation-exchange column and effluent monitoring at 210 nm has been evaluated for the profiling of selected microbial metabolites including aliphatic, dicarboxylic, and phenolic acids, as an adjunct to the identification of selected bacteria, detection of bacterial metabolites in foods, and the monitoring of industrial microbial fermentations. Advantages of the technique include the simultaneous profiling of different classes of organic acids without derivatization. Most applications require only qualitative or semi-quantitative data. For others, data are given on the day-to-day reproducibility for several acids.

Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay

Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoassay, enzyme immunoassay, and liquid chromatography. The essay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods.

Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay

Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoassay, enzyme immunoassay, and liquid chromatography. The essay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods.

A micro liquid column chromatography procedure for twelve anticonvulsants and some of their metabolites

Solvent extracts of 50 microliter volumes of serum were sufficient for the determination of twelve anticonvulsant drugs. The liquid chromatography procedure utilized a C-18 reversed-phase column and isocratic elution with 15% acetonitrile in water. No derivatization was required. Eluted anticonvulsants were detected by UV absorption at 195 nm and quantitated by drug--internal standard peak area ratios. The procedure provided linear working curves over the concentration range from 1 to 100 mg/l of drug in the serum. The procedure for serum provided recoveries of the drugs from 92 to 101%. Within-day precision was about 4% and day-to-day precision was about 6.5%. The procedures has been applied to urine samples to facilitate bioavailability studies. Data are also given for several metabolites. There is a discussion of many practical aspects of the procedure to improve the reliability of the results.

Liquid-chromatographic procedure for tricyclic drugs and their metabolites in plasma

We describe a procedure for determining amitriptyline and imipramine and their active metabolites nortriptyline and desipramine, respectively, at therapeutic concentrations in human plasma by use of liquid chromatography. The drugs are extracted at pH 10.5 into hexane/isoamyl alcohol, which is evaporated and the residue chromatographed. Protriptyline is used as the internal standard. As little as 10 microgram of each drug per liter could be detected in plasma, the limit being established by variability in drug-free plasmas. The day-to-day coefficient of variation for each drug at a concentration of about 100 microgram/liter was about 7%. Doxepin and diphenhydramine interfere with the analysis of amitriptyline. Total analysis time for a single sample is 20 min.

Liquid-chromatographic procedure for tricyclic drugs and their metabolites in plasma

We describe a procedure for determining amitriptyline and imipramine and their active metabolites nortriptyline and desipramine, respectively, at therapeutic concentrations in human plasma by use of liquid chromatography. The drugs are extracted at pH 10.5 into hexane/isoamyl alcohol, which is evaporated and the residue chromatographed. Protriptyline is used as the internal standard. As little as 10 microgram of each drug per liter could be detected in plasma, the limit being established by variability in drug-free plasmas. The day-to-day coefficient of variation for each drug at a concentration of about 100 microgram/liter was about 7%. Doxepin and diphenhydramine interfere with the analysis of amitriptyline. Total analysis time for a single sample is 20 min.

A fluorescence detector for high-pressure liquid chromatography

We describe a fluorescence spectrophotometer adapted with a micro quartz flow cell to record the output of modern liquid chromatographs. The optical system is double beam in that the light source variations are cancelled out by a second photomultiplier, thus enhancing the sensitivity of the technique. The emission spectra may be scanned by stopping the flow in the chromatographic column and scanning the fluorescence detector. Many specific applications have been studied: polycyclic aromatic hydrocarbons, several vitamins, porphyrins, methyl anthranilate, etc. These are studied in natural samples and it is shown that the specificity of the fluorescence detector frequently obviates the need for sample preparation. The sensivitity available with the fluorescence detector for fluorescing compounds is often much greater than is available with variable-wavelength ultraviolet spectrophotometers. We report picogram-level detectability in real samples for many of the compounds that we have studied.

Ultramicro GC determination of amino acids using glass open tubular columns and a nitrogen-selective detector

A glass open tubular (capillary) column together with a nitrogen-selective detector were evaluated for the analysis of amino acids by gas chromatography. Test samples included normal and abnormal human sera and urine and several hydrolysates of pure proteins. Amino acids in the biological samples were isolated by ion exchange pretreatment and derivatized to the n-propyl, N-acetyl derivatives. Protein hydrolysates were derivatized without pretreatment. Compared with a flame ionization detector, the nitrogen-selective detector gave a sensitivity enhancement of 80x-180x for the amino acid derivatives, depending on the particular amino acid. Long-term stability of the detector was excellent. Reproducibility studies gave a long-term precision of about 6% for serum or urine samples while a precision of 5% was obtainable on a day-to-day basis when analyzing protein hydrolyzates. The experiments showed that amino acids at the picomole level could be reliably analyzed with the system. The open tubular column coated with a mixture of Carbowax 20M and Silar 5 CP and having a very thin liquid phase film gave greatly improved thermal stability compared with a previously used packed column.

More sensitive high-pressure liquid-chromatographic determiantion of theophylline in serum

We present procedures for determining theophylline in 50 mul of serum. The drug is extracted into a small volume of solvent that contains an internal standard, 8-chlorotheophylline. The extract is Analyzed by isocratic reversedphase chromatography, with measurement of eluted theophylline at 273 nm. Day-to-day reproducibility within 5% is attainable for the concentration range 5--20 mg/liter. Other xanthines and related metabolites do not interfere. Sensitivity is 1 mg/liter. The correlation coefficient, when results by a spectrophotometric procedure were compared, was 0.989. Amobarbital, secobarbital, phenobarbital, and diphenylhydantoin do not interfere. Total analysis time for a single sample is 15 min.

More sensitive high-pressure liquid-chromatographic determiantion of theophylline in serum

We present procedures for determining theophylline in 50 mul of serum. The drug is extracted into a small volume of solvent that contains an internal standard, 8-chlorotheophylline. The extract is Analyzed by isocratic reversedphase chromatography, with measurement of eluted theophylline at 273 nm. Day-to-day reproducibility within 5% is attainable for the concentration range 5--20 mg/liter. Other xanthines and related metabolites do not interfere. Sensitivity is 1 mg/liter. The correlation coefficient, when results by a spectrophotometric procedure were compared, was 0.989. Amobarbital, secobarbital, phenobarbital, and diphenylhydantoin do not interfere. Total analysis time for a single sample is 15 min.

Ultramicro gas-chromatographic analysis for anticonvulsants, with use of a nitrogen-selective detector

We describe a procedure for determining phenobarbital, primidone, and diphenylhydantoin simultaneously in 50-mul volumes of serum by use of gas chromatography and a detector with heightened sensitivity and selectivity for nitrogenous compounds. The drugs, together with an internal standard, 5-allyl-5-phenyl barbituric acid, are extracted from serum by the procedure of MacGee [Anal. Chem. 42, 421 (1970)]. The drugs are converted to their methyl derivatives by a modification of the procedure of Greeley [Clin. Chem. 20, 192 (1974)] and then analyzed on a column containing 3% OV-1, with a temperature program, and detected by a nitrogen-selective detector. The method is reproducible to about 7%. Sensitivities of 0.5 mg/liter for 50-mul serum samples are attained routinely. Mephobarbital interferes with the analysis because methylation yields the same product as methylated phenobarbital. Total analysis time for a single sample is 15 min.

Ultramicro gas-chromatographic analysis for anticonvulsants, with use of a nitrogen-selective detector

We describe a procedure for determining phenobarbital, primidone, and diphenylhydantoin simultaneously in 50-mul volumes of serum by use of gas chromatography and a detector with heightened sensitivity and selectivity for nitrogenous compounds. The drugs, together with an internal standard, 5-allyl-5-phenyl barbituric acid, are extracted from serum by the procedure of MacGee [Anal. Chem. 42, 421 (1970)]. The drugs are converted to their methyl derivatives by a modification of the procedure of Greeley [Clin. Chem. 20, 192 (1974)] and then analyzed on a column containing 3% OV-1, with a temperature program, and detected by a nitrogen-selective detector. The method is reproducible to about 7%. Sensitivities of 0.5 mg/liter for 50-mul serum samples are attained routinely. Mephobarbital interferes with the analysis because methylation yields the same product as methylated phenobarbital. Total analysis time for a single sample is 15 min.

The simultaneous determination of lidocaine and procainamide in serum by use of high pressure liquid chromatography

This report describes an accurate, sensitive rapid procedure for the determination of lidocaine and procainamide at therapeutic concentrations in serum. The drugs and an added internal standard (procaine) are extracted from serum using charcoal adsorption. The analysis is carried out by high pressure liquid chromatography on a reverse-phase column using buffered aqueous acetonitrile as the mobile phase. Chromatography is complete in 10 min. C.V. values of 10% and 6% for concentrations of 1 mg/l and 20 mg/l, respectively, are attainable routinely. Total analysis time is 15 min.

Simultaneous high-pressure liquid-chromatographic determination of some anticonvulsants in serum

We describe procedures for simultaneously determining some anticonvulsants (phenobarbital, diphenylhydantoin, primidone, ethosuximide, methsuximide, carbamazepine) in serum by high-pressure liquid chromatography. The drugs, together with an internal standard, phenacetin, are adsorbed from serum onto charcoal and eluted from it with organic solvent. The eluate is analyzed isocratically on a reverse-phase column with a mobile phase consisting of acetonitrile/water (17/83 by volume). The eluted drugs are detected by their absorption at 195 nm, and quantities estimated from their peak areas as compared with those of extracted standards. Results are reproducible to about 6%. Sensitivities, for 0.5-ml serum samples, of 0.1 mg/liter for all the drugs analyzed except ethosuximide (0.5 mg/liter) are attained routinely. Correlation of results with gas chromatography was 0.912 for phenobarbital, 0.982 for diphenylhydantoin, 0.886 for primidone, and 0.966 for ethosuximide. Amobarbital and secobarbital interfere with the analysis; chlordiazepoxide, methaqualone, salicylate, diazepam, and oxazepam do not. Including extraction, analysis time for a single sample is 20 min.

Simultaneous high-pressure liquid-chromatographic determination of some anticonvulsants in serum

We describe procedures for simultaneously determining some anticonvulsants (phenobarbital, diphenylhydantoin, primidone, ethosuximide, methsuximide, carbamazepine) in serum by high-pressure liquid chromatography. The drugs, together with an internal standard, phenacetin, are adsorbed from serum onto charcoal and eluted from it with organic solvent. The eluate is analyzed isocratically on a reverse-phase column with a mobile phase consisting of acetonitrile/water (17/83 by volume). The eluted drugs are detected by their absorption at 195 nm, and quantities estimated from their peak areas as compared with those of extracted standards. Results are reproducible to about 6%. Sensitivities, for 0.5-ml serum samples, of 0.1 mg/liter for all the drugs analyzed except ethosuximide (0.5 mg/liter) are attained routinely. Correlation of results with gas chromatography was 0.912 for phenobarbital, 0.982 for diphenylhydantoin, 0.886 for primidone, and 0.966 for ethosuximide. Amobarbital and secobarbital interfere with the analysis; chlordiazepoxide, methaqualone, salicylate, diazepam, and oxazepam do not. Including extraction, analysis time for a single sample is 20 min.