Chemometrics in Forensic Chemistry - Part III: Quality assessment and interpretation of chemometric output

The number of samples sent to forensic laboratories as well as the complexity of the drug situation has increased tremendously during recent years. At the same time the amount of data gathered from chemical measurements has been mounting. This creates challenges for forensic chemists: how to handle the data, how to reliably answer the questions asked, and how to examine the data to find new properties or how to disclose connections with respect to source attribution of samples within a case or retrospective to past cases, stored in a database. Previously published articles Chemometrics in Forensic Chemistry - Part I and II discussed where in the forensic workflow of routine casework chemometrics is applied, and presented examples of chemometric methods used in cases of illicit drugs. This article explains through examples that the chemometric results must never stand-alone. Before such results are reported, quality assessment steps, which may consist of operational, chemical, and forensic assessments are required. In each case a forensic chemist needs to consider the suitability of chemometric methods, based on their strengths, weaknesses, opportunities and threats (SWOT). This is because while chemometric methods are powerful tools managing complex data, they are to some extent chemically blind.

Chemometrics in forensic chemistry - Part I: Implications to the forensic workflow

The forensic literature shows a clear trend towards increasing use of chemometrics (i.e. multivariate analysis and other statistical methods). This can be seen in different disciplines such as drug profiling, arson debris analysis, spectral imaging, glass analysis, age determination, and more. In particular, current chemometric applications cover low-dimensional (e.g. drug impurity profiles) and high-dimensional data (e.g. Infrared and Raman spectra) and are therefore useful in many forensic disciplines. There is a dominant and increasing need in forensic chemistry for reliable and structured processing and interpretation of analytical data. This is especially true when classification (grouping) or profiling (batch comparison) is of interest. Chemometrics can provide additional information in complex crime cases and enhance productivity by improving the processes of data handling and interpretation in various applications. However, the use of chemometrics in everyday work tasks is often considered demanding by forensic scientists and, consequently, they are only reluctantly used. This article and following planned contributions are dedicated to those forensic chemists, interested in applying chemometrics but for any reasons are limited in the proper application of statistical tools - usually made for professionals - or the direct support of statisticians. Without claiming to be comprehensive, the literature reviewed revealed a sufficient overview towards the preferably used data handling and chemometric methods used to answer the forensic question. With this basis, a software tool will be designed (part of the EU project STEFA-G02) and handed out to forensic chemist with all necessary elements of data handling and evaluation. Because practical casework is less and less accompanied from the beginning to the end out of the same hand, more and more interfaces are built in through specialization of individuals. This article presents key influencing elements in the forensic workflow related to the most meaningful chemometric application and evaluation.

Effects of atipamezole--a selective alpha-adrenoceptor antagonist--on cardiac parasympathetic regulation in human subjects

1 This double-blind, cross-over, placebo-controlled study on six healthy male volunteers was designed to evaluate the effects of alpha2-adrenoceptor antagonism on cardiac parasympathetic regulation. 2 The subjects received atipamezole intravenously as a three-step infusion, which aimed at steady-state serum concentrations of 10, 30 and 90 ng ml(-1) at 50-min intervals. 3 Drug effects were assessed with repeated recordings of blood pressure and electrocardiogram, in which the high-frequency (0.15-0.40 Hz) R-R interval variation is supposed to reflect cardiac parasympathetic efferent neuronal activity. 4 At the end of the three steps of the infusion, the mean (+/-SD) concentrations of atipamezole were 10.5 (3.9), 26.8 (5.6) and 81.3 (21.1) ng ml(-1). 5 Within this concentration range, atipamezole appeared to reduce slightly the high-frequency R-R interval fluctuations, indicating a minor vagolytic effect in the heart. 6 Atipamezole increased systolic and diastolic arterial pressure, on average by 20 and 14 mmHg (maxima at the second step of the infusion), which evidently reflects an overall sympathetic augmentation.

Prognostic value of the expression of tumor suppressor genes p53, p21, p16 and prb, and Ki-67 labelling in high grade astrocytomas treated with radiotherapy

Cumulative inactivation of tumor suppressor genes and/or amplification of oncogenes lead to progressively more malignant astrocytic tumors. We have analyzed the significance of tumor suppressor genes p53, p21, p16 and retinoblastoma protein (pRb) and proliferative activity for survival in 77 high grade astrocytic tumors. After operation, the patients--25 anaplastic astrocytomas (AA) and 52 glioblastomas (GBs)--were treated with similar radiotherapy. The expression of the suppressor genes and the proliferative activity were analyzed immunohistochemically. p53 immunopositivity was found in 44% of AAs and 46% of GBs. Tumors with aberrant p53 expression had lower proliferation indices than p53 immunonegative tumors. Neither p53 expression nor p21 immunonegativity (52% of AAs and 48% of GBs) correlated with survival. p16 immunostaining was negative in 16% of AAs and in 44% of GBs, and it correlated inversely with survival in both uni- and multivariate analyses. pRb immunostaining was negative only in 8% of both AAs and GBs and the absence of p16 and pRb were mutually exclusive. Ki-67 labelling index (LI) was significantly higher in GBs (26.8%) than in AAs (20.3%), and in multivariate analysis it was an independent prognostic factor for survival. In 48% of AAs Ki-67 LI exceeded 20% and this subset of AAs had similar prognosis as GB. In high grade astrocytic tumors p16 immunonegativity was an independent indicator of poor prognosis in addition to the previously established patient's age, histopathology and Ki-67 LI. Furthermore, there was a subset of AAs with a high proliferation rate (> 20%) in which the histopathological hallmarks of GB were lacking, but which had similarly dismal prognosis as GB.

Management of testicular cancer--16 years' experience from southwest Finland

OBJECTIVE

This study investigated the outcome of testicular cancer treatment in Finland.

MATERIAL AND METHODS

Data on 88 testicular cancer patients treated in Turku University Central Hospital between 1976 and 1992 were studied to analyse outcome and survival.

RESULTS

The histological diagnosis was seminoma for 39 patients and non-seminoma for 49 patients. Two seminoma patients relapsed (5%) and one patient died of progressive disease (3%; initially stage II seminoma). Eleven non-seminoma patients relapsed (22%), nine of whom were cured with chemotherapy. Four non-seminoma patients died of progressive disease (8%; initially one stage I non-seminoma and three stage III non-seminomas). The median time to relapse after the completion of treatment was 9 months (range 3-50 months). Non-seminoma patients had significantly more relapses than seminoma patients (p = 0.03). Most relapses (73% of the non-seminoma relapses) were found among the stage I non-seminoma patients who had not received adjuvant chemotherapy, while none of the stage I seminoma patients relapsed (p = 0.007).

CONCLUSIONS

Close surveillance is important for all non-seminoma patients to guarantee the early detection and treatment of recurrent disease. Treatment and surveillance should be covered by national guidelines and be conducted in centres with special interest in this rare but mostly curable cancer.

Sixty thousand woman-years of experience on the levonorgestrel intrauterine system: an epidemiological survey in Finland

OBJECTIVE

An epidemiological survey was carried out in Finland to establish the performance of the levonorgestrel intrauterine system (LNG-IUS) in a large population of women regularly using the system for contraception.

STUDY DESIGN

All women who had LNG-IUS inserted between 1990 and 1993 were sent a questionnaire with questions about general health status, reproductive and contraceptive history and gynecological problems and a set of questions about their experience on the LNG-IUS.

RESULTS

The women who had a LNG-IUS inserted between April 1990 and December 1993 were asked to participate in an epidemiological survey. At the insertion visit, the women were asked to fill in a questionnaire, to consent to further use of the information by signing their initials and to return the questionnaire to the manufacturer. The number of returned forms was 23,885. The names and addresses of these women were acquired from the National Register and a questionnaire with 75 questions was sent to them. Of the questionnaires, 75% were returned. Experience covered 58,600 woman-years. The mean age of the users of the LNG-IUS was 40 years. Most of them (99.3%) were parous, most often with two or three children. The cumulative 5-year Pearl index was 0.18 and there were 108 pregnancies in the study population during the use of the LNG-IUS. The continuation rates for 1, 2, 3, 4 and 5 years were 0.94, 0.87, 0.82, 0.76 and 0.65, respectively. Removal before the full 5 years was most common among the youngest age group. Bleeding disorders, infections and pain during LNG-IUS use were associated with the highest risk for discontinuation. The risk of premature removal was markedly diminished among women with totally or occasionally missed periods.

CONCLUSIONS

The response rate to the survey was high and the sample studied was exceptionally large. The continuation rate of LNG-IUS was high up to 5 years. The symptoms associated with premature removal agreed with results from earlier randomized studies of the LNG-IUS.

Docetaxel, a promising novel chemotherapeutic agent in advanced breast cancer

Clinical practice in chemotherapy of breast cancer is undergoing changes. This study investigated the efficacy and toxicity of docetaxel, a novel chemotherapeutic agent in metastatic breast cancer. Focus was on the effect of the cumulative dose of previous anthracycline treatment on response rate, toxicity and survival in our own patients; published data were reviewed.

PATIENTS AND METHODS

Thirty-one women, (median age 52 years, range 40-65) treated for metastatic breast cancer with docetaxel were included.

RESULTS

The overall response rate was 48%, with 3 complete and 11 partial responses (95% CI 29-66). The duration of response was 7 months (range 2 to 16 months), the median overall survival after docetaxel 13.7 months for responding patients, 14.3 months in no-change patients and 6.5 months in patients with progressive disease. The mean cumulative anthracycline dose prior to docetaxel was 860 mg (range 200-1760 mg); in the case of responders, the previous cumulative total epirubicin doses were 200-1575 mg (median 766 mg.). Total dose or schedule of previous epirubicin treatment had no impact on docetaxel response rate, toxicity or survival. The response seen in this study is within the published range (24 to 60%) observed for docetaxel in anthracycline-treated patients.

CONCLUSION

We conclude that docetaxel is active in metastatic breast cancer even as third- line treatment. Previous treatment with, or response to, epirubicin does not influence the response to docetaxel and this promising new drug is currently being tested for adjuvant use in breast cancer.

Length of use and symptoms associated with premature removal of the levonorgestrel intrauterine system: a nation-wide study of 17,360 users

OBJECTIVE

To establish the continuation rates of the levonorgestrel intrauterine system (LNG IUS) and symptoms associated with its premature removal.

SAMPLE AND SETTING

All women in Finland who had a LNG IUS inserted between April 1990 and December 1993 and whose doctor had filled in and returned a form at the insertion visit. This study population consists of 46% of all the LNG IUSs sold in Finland between 1990 and 1993.

DESIGN

A questionnaire on reproductive and contraceptive history, gynaecological problems and symptoms experienced during the use of the LNG IUS was sent to 23,885 LNG IUS users. A total of 17,914 questionnaires were returned (response rate 75%). The results cover experience from 58,600 woman years. A log-rank-test was used to test differences in continuation rates. Multivariate analyse were performed using Cox's proportional hazard model.

RESULTS

The LNG IUS was prematurely removed from 5175 women. The one, two, three, four and five year continuation rates were 93%, 87%, 81%, 75% and 65%, respectively. The symptoms during the use of the LNG IUS most strongly associated with its premature removal were excessive bleeding and spotting, and infections and pain. The risk of premature removal was markedly lower among women who had occasional or total absence of menstruation. Premature removal was less likely in the oldest age group.

CONCLUSIONS

The continuation rate of the LNG IUS compares favourably with other long-acting contraceptive systems. Totally or occasionally absent menstruation was strongly associated with prolonged continuation.

Pharmacokinetics of oral entacapone after frequent multiple dosing and effects on levodopa disposition

OBJECTIVE

Entacapone is a peripherally acting catechol O-methyltransferase (COMT) inhibitor used as an adjunct to each daily levodopa/dopa decarboxylase (DDC) inhibitor dose in the treatment of Parkinson's disease. Parkinsonian patients with advanced disease and motor fluctuations take several doses of levodopa daily, due to the short action of levodopa in this patient population. The present study was conducted in order to evaluate the pharmacokinetics of entacapone after multiple dosing and the pattern of COMT inhibition in erythrocytes during the first day of dosing as well as during steady state. Furthermore, the disposition of plasma levodopa and carbidopa was studied after a single dose of levodopa/carbidopa during the same conditions.

METHODS

Twelve healthy male volunteers received 200 mg entacapone eight times daily during study day 1 and day 6 at 2-h intervals from 0800 hours to 2200 hours. During days 3, 4 and 5, 200 mg of entacapone was taken ten times daily, from 0800 hours to 0200 hours on the following day. One levodopa/carbidopa tablet (100/25 mg) was taken on study day 1 and day 6 at 1000 hours. Plasma entacapone concentrations and erythrocyte COMT activities were measured frequently on study days 1-2 and 6-7, and twice daily on study days 3-5. Pharmacokinetic parameters calculated from plasma drug concentrations on days 1-2 and 6-7 were compared with each other.

RESULTS

There were no differences in maximal plasma concentration (Cmax), time to maximal drug concentration in plasma (tmax), elimination half-life (t1/2) and area under the plasma concentration-time curve (AUC) of entacapone between day 1 and day 6. The mean t1/2 values of entacapone were 1.3 h and 1.8 h during the first and sixth days, respectively; the difference was not significant. No signs of accumulation of entacapone were noted after the first day. Entacapone reduced erythrocyte COMT activity after the first dose, and this effect was quite stable during frequent dosing. There were no indications of accumulation of COMT inhibition during frequent dosing of entacapone. There were no between-day differences in Cmax, t1/2 (2.4 h on days 1-2 and 2.3 h on days 6-7) or AUC of levodopa, whereas tmax occurred at 0.8 h on day 1 and at 1.2 h on day 6 (P = 0.03). There were no between-day differences in the pharmacokinetic parameters (Cmax, tmax and AUC) of carbidopa.

CONCLUSION

Even when dosed frequently, there are neither indications of accumulation of entacapone nor of its COMT inhibiting activity.

Spectral analysis of heart rate variability as a quantitative measure of parasympatholytic effect--integrated pharmacokinetics and pharmacodynamics of three anticholinergic drugs

The time course and concentration-effect relationship of parasympatholytic effects of three anticholinergic drugs were investigated using spectral analysis of heart rate (HR) variability. Single intravenous (i.v.) doses of atropine (10 microg/kg), glycopyrrolate (5 microg/kg), scopolamine (5 microg/kg), and placebo were given to eight healthy volunteers in a double-blind, randomized cross-over study. Electrocardiogram (ECG) was recorded at baseline and 2.5, 5, 10, 20, and 30 minutes, and 1, 1.5, 2, 3, 4, 5, and 6 hours after drug administration, while the subjects breathed at a fixed 0.25 Hz frequency. The powers of two frequency bands (low frequency [LF] = 0.07-0.15 Hz and high frequency [HF] = 0.15-0.40 Hz) were calculated using stationary time series of R-R intervals (RRI) free from ectopic beats. To perform pharmacokinetic-pharmacodynamic (PK-PD) modeling, venous plasma drug concentrations were measured. Atropine and glycopyrrolate, and, to a lesser extent, scopolamine induced decreases in HF power and increases in LF/HF ratio of HR variability, indicating parasympatholytic activity and corresponding changes in sympathovagal balance. Maximal average decreases in HF power were 99%, 94%, and 82%, respectively, but in two scopolamine subjects, a parasympathomimetic effect was dominant. Interindividual variability was least for the Hayano index of HF power (square root (RRI HF-power)/RRI*100), and profound and consistent decreases were seen after atropine and glycopyrrolate. Pharmacokinetics were best fitted to a two-compartment open model, and effect compartment link modeling using the Hayano index was performed with the atropine and glycopyrrolate data. The best description of the PK-PD relationship for both drugs was achieved using the sigmoidal Emax model. Mean (+/-SD) EC50, sigmoidicity factor (gamma), and equilibration rate constant (k(e0)) estimates were 1.35 (+/-0.27) ng/mL, 6.07 (+/-1.98) and 11.0 (+/-5.28) l/h for atropine and 1.35 (+/-0.49) ng/mL, 4.34 (+/-1.55) and 2.26 (+/-0.81) l/h for glycopyrrolate. Spectral analysis of HR variability appears to be a powerful tool in monitoring parasympatholytic drug activity. A sigmoidal Emax model with an extremely steep concentration-response relationship was revealed for atropine and glycopyrrolate. The effects of scopolamine were more incongruous.

Docetaxel: standard recommended dose of 100 mg/m(2) is effective but not feasible for some metastatic breast cancer patients heavily pretreated with chemotherapy-A phase II single-center study

PURPOSE

Patients with metastatic breast cancer, especially those with progression after several prior chemotherapy treatments, need efficient chemotherapy. This study investigates the efficacy and toxicity of docetaxel in metastatic breast cancer patients with previous chemotherapy for metastatic disease.

PATIENTS AND METHODS

Thirty-one women (median age, 52 years; range, 40 to 65 years) treated for metastatic breast cancer with docetaxel were included. Eleven patients had one metastatic site, 10 patients had two, and 10 patients had three or more. The planned dose of docetaxel per course was the standard treatment of 100 mg/m(2) (or 75 mg/m(2) if liver enzyme levels were abnormal) every 3 weeks, given for six or eight cycles.

RESULTS

The overall response rate was 48% (three complete responses [CR] and 11 partial responses [PR] ), and the median duration of response was 7 months (range, 2 to 16 months). Twenty patients (65%) experienced fatigue, and 27 patients (87%) had alopecia. Fifteen cases (48%) of grade 4 leukopenia were observed. Edema with a weight gain of 2 to 15 kg was seen in 12 patients (39%), and mucositis occurred in 20 patients (65%). Twenty-three patients (74%) interrupted treatment before reaching the planned number of courses, nine patients owing to progression of cancer and 14 owing to toxicity. Dose reduction was required in 18 (61%) of the patients. Only two patients were able to receive the planned eight courses without dose reduction.

CONCLUSION

Docetaxel is highly active in metastatic breast cancer, even as a third-line treatment, and can be considered as an efficient standard option in second-line treatment. The standard recommended dose level of 100 mg/m(2) is not feasible in heavily pretreated patients; therefore, for such patients, an initial dose level not exceeding 75 mg/m(2) is recommended.

A double-blind study of MPV-2213ad, a novel aromatase inhibitor, in healthy male subjects

OBJECTIVE

Novel aromatase inhibitors are developed with requirements of high potency and selectivity for the aromatase enzyme. The hormonal effects of a new, non-steroidal competitive inhibitor of the aromatase enzyme, MPV-2213ad, were investigated in this study.

METHODS

The study was conducted as a double-blind, placebo controlled phase I study, where 32 healthy male volunteers were randomized to receive a single oral dose of either 0.3, 3 or 100 mg of MPV-2213ad or placebo. Serum concentrations of estradiol (E2), testosterone, follicle stimulating hormone (FSH), luteinizing hormone (LH), cortisol and aldosterone were determined from samples taken 0, 4, 8 h and 12 h during the day of drug administration and 1, 2, 4 and 7 days after drug intake. The individual diurnal variation of circulating hormone concentrations was determined in all participants at 0, 4, 8 h and 12 h on the day before drug intake. Specimens for hematological and biochemical analyses were also collected.

RESULTS

A dose-dependent and statistically significant (P < 0.001) decrease in serum E2 concentrations was induced by MPV-2213ad. Lowest mean values were observed 8-12 h after drug administration and at 24 h the reductions were 10%, 34% and 69% from baseline in the 0.3-mg, 3-mg and 100-mg groups, compared with an 18% increase in the placebo group. Serum E2 concentrations returned to baseline within 4 days in all study subjects. A significant increase was observed in the serum concentrations of testosterone (P = 0.016), LH (P = 0.002) and FSH (P < 0.001) after administration of MPV-2213ad. Serum concentrations of cortisol and aldosterone were unaffected by MPV-2213ad. The drug was well tolerated.

CONCLUSION

Single oral doses of MPV-2213ad, given to healthy male subjects, induced hormonal effects typical for a specific and selective inhibitor of the aromatase enzyme. Importantly, this study design with the determination of the diurnal rhythm in the levels of the corresponding hormones gives additional validity on the results.

Use of carbon-11 methionine positron emission tomography to assess malignancy grade and predict survival in patients with lymphomas

The aim of this study was to investigate whether uptake of carbon-11 methionine (MET) is associated with histological grade of malignancy and survival in patients with newly diagnosed or recurrent lymphoma. Thirty-two patients with histologically confirmed lymphoma participated in the study. Twenty-six (81%) were studied before any therapy and six before treatment for recurrent disease. Twenty-eight patients had non-Hodgkin's lymphoma and four had Hodgkin's disease. An ECAT 931/08-12 positron emission tomography (PET) scanner was used for PET imaging. After the transmission scan, a median dose of 293 MBq of MET was injected intravenously and dynamic images were acquired for 40 min. The uptake of MET in tumour was measured as the standardized uptake value (SUV) and influx constant (Ki). The SUV formula was also adjusted to the predicted value of lean body mass (SUVlean) and body surface area (SUVBSA). The PET results were correlated with the clinical follow-up data. The median SUV in 32 malignant lesions was 6.6 (range, 1.9-12.4) and the median Ki was 0. 116 min-1 (range, 0.025-0.201, n=23). The median SUV was 7.0 (range, 5.4-12.4, n=9) in high, 6.2 (range, 1.9-10.4, n=11) in intermediate and 5.7 (range, 3.8-8.3, n=8) in low grade lymphomas. One intermediate grade lymphoma of the skin was visually negative (SUV 1. 9). In Hodgkin's disease the median SUV was 7.0 (range, 3.2-7.9, n=4). The median Ki value was 0.162 min-1 (range, 0.147-0.197, n=7) in high, 0.099 (range, 0.025-0.152, n=10) in intermediate, and 0.078 (range, 0.056-0.152, n=4) in low grade lymphomas and 0.149 (range, 0. 096-0.201, n=2) in Hodgkin's disease. The difference between high and other grade non-Hodgkin's lymphomas was significant when using Ki (P<0.001), but not with SUV, SUVlean or SUVBSA. The final outcome of the patients was not related to MET uptake. Lymphomas with a high Ki value tended to have a high S-phase fraction (r2=0.46, P=0.043). It is concluded that MET PET is highly sensitive for the detection of untreated and recurrent lymphomas. Differentation of high grade lymphomas from lower malignancy grades seems to be possible if graphical analysis is applied to calculate Ki for MET. However, prediction of survival is not possible with MET PET.

Multivariate analysis of prognostic factors in 106 patients with malignant glioma

The aim of this study was to evaluate the outcome and prognostic factors influencing survival in 106 patients with supratentorial malignant gliomas treated with radiotherapy. The study group included 84 patients treated by surgery and post-operative radiotherapy and 22 patients treated by postbiopsy irradiation. Radiotherapy was delivered to the tumour area with a 2 cm margin, the aimed curative dose was 60 Gy in 6-7 weeks. The 60-month overall survival (Kaplan-Meier) was 20%. Following a univariate analysis, younger age (P < 0.001), longer duration of symptoms (P = 0.009), good performance status after radiotherapy (P < 0.001), other than grade 4 histology (P < 0.001) and higher radiation dose (P < 0.001) were associated with better overall survival rates. Multivariate analysis found that age, symptom duration, histology, extent of symptoms and radiation dose were independent prognostic factors influencing survival. In conclusion, conventional radiotherapy of supratentorial malignant gliomas results in survival that is comparable to results from clinical experiments with different fractionation schedules and radiation with chemotherapy or radiosensitisers. To improve the results, new approaches are needed, especially for patients with the poorest prognosis after standard treatment.