A brief history of toxicology in France during the last two centuries (1789-1989)

The history of toxicology in France over the last two centuries has been marked by numerous authors who have progressively broadened the fields of investigation: initially concerned with criminal or accidental poisonings, they have also taken an interest in the environment, workers' health, doping and illicit products, the dangers of radioactivity or combat gases, the risks associated with drugs, etc. Often pharmacists, these toxicology experts were specialists in analytical chemistry and developed numerous methods to refine the detection and characterization of potentially toxic products, and to better understand the mechanisms of toxicity produced by these substances.

Study of a more than a hundred years old theriac jar' content: A famous thousand-year-old counter-poison

The purpose of this article is to study the content of a 19th century white porcelain pot from the Pochet-Desroche fabric, offered to the National Order of Pharmacists and probably containing theriac. The aim is to identify the active ingredients of any substances that may still be present and to try to determine the preparation period of the panacea. All the analyzes were carried out according to the reference current methods. Liquid / liquid extractions in a separating funnel, high performance liquid chromatography coupled with three-dimensional diode array molecular absorption spectrophotometry and gas chromatography coupled with mass spectrometry have revealed 218 molecules which may belong to the ingredients of a theriac. 29 of these are clearly still present in the opiate studied. Their comparison with the French pharmacopoeias formulas of 1818 and 1884 pleads for manufacture according to the formula of 1884. The originality of our work lies in the rarity of this type of analysis on very old pharmaceutical samples and in the fact that it concerns a mixture of great complexity.

[Antoine Augustin Parmentier (1737-1813): military pharmacist, humanist and scholar]

From "Frison" pharmacy of his district, Sainte Croix square in Montdidier, where he learned the trade of a pharmacist when he was 15 years old, to the General Inspectorate of the health service of Army responsability he helds from the 1st Germinal, Year IV until his death, Antoine Augustin Parmentier was both an humanist and anerudite scholar even if often, posterity and legend reduce his image only to that of"the inventor" of the most common Solanaceae. His work, more than 189 publications, and his innovative ideas, made advancing scientific knowledge including food chemistry and nutritional health but also in various other areas: blood analysis, preparation of drugs...Better known as "Fighter of the only war that has a biological and moral justification: the war against hunger" as Jose Castro President of the FAO in 1954 recalls, less is known about the excep- tional longevity, 56 years, and riches of his military pharmacist career during which he participated in 17 campaigns and he was captured 5 times. Apothecary "sub-help" of the army of Hanover in 1757, he became apothecary "gagnant maitrise" in 1766 and transiently apothecary Major at the "Hotel des Invalides", then Royal Censor, chief pharmacist of Geneva Army, and Board Member Health to the Minister of War in 1788 and then again from 1792 to 1813. In 1796, he was charged with five other inspectors of the reorganization of the health service. Outstanding organizer, he simplifies and deeply streamlines, especially in the pharmaceutical field, evidenced by its pharmaceutical form for the use of military hospitals of the French Republic in 1793. He left his mark for a long time in the military health Service. Member of the general council of civilians hospices of Paris, he is responsible for organizing the central hospital pharmacy, which led him to publish in 1811 the pharmaceutical code for the use of civilian hospitals, relief at home and infirmaries of prison. Benefactor of mankind, but also recognized scholar, the Academy of Sciences made him one of its members in 1795. Parmentier was in 1803, the first president of the Society of Pharmacy of Paris who became the National Academy in October 1979. He died on December 17, 1813 leaving a considerable body of work.

Dichlorvos, chlorpyrifos oxon and Aldicarb adducts of butyrylcholinesterase, detected by mass spectrometry in human plasma following deliberate overdose

The goal of this study was to develop a method to detect pesticide adducts in tryptic digests of butyrylcholinesterase in human plasma from patients poisoned by pesticides. Adducts to butyrylcholinesterase in human serum may serve as biomarkers of pesticide exposure because organophosphorus and carbamate pesticides make a covalent bond with the active site serine of butyrylcholinesterase. Serum samples from five attempted suicides (with dichlorvos, Aldicarb, Baygon and an unknown pesticide) and from one patient who accidentally inhaled dichlorvos were analyzed. Butyrylcholinesterase was purified from 2 ml serum by ion exchange chromatography at pH 4, followed by procainamide affinity chromatography at pH 7. The purified butyrylcholinesterase was denatured, digested with trypsin and the modified peptide isolated by HPLC. The purified peptide was analyzed by multiple reaction monitoring in a QTRAP 4000 mass spectrometer. This method successfully identified the pesticide-adducted butyrylcholinesterase peptide in four patients whose butyrylcholinesterase was inhibited 60-84%, but not in two patients whose inhibition levels were 8 and 22%. It is expected that low inhibition levels will require analysis of larger serum plasma volumes. In conclusion, a mass spectrometry method for identification of exposure to live toxic pesticides has been developed, based on identification of pesticide adducts on the active site serine of human butyrylcholinesterase.

Detection of adduct on tyrosine 411 of albumin in humans poisoned by dichlorvos

Studies in mice and guinea pigs have shown that albumin is a new biomarker of organophosphorus toxicant (OP) and nerve agent exposure. Our goal was to determine whether OP-labeled albumin could be detected in the blood of humans exposed to OP. Blood from four OP-exposed patients was prepared for mass spectrometry analysis by digesting 0.010 ml of serum with pepsin and purifying the labeled albumin peptide by offline high performance liquid chromatography. Dimethoxyphosphate-labeled tyrosine 411 was identified in albumin peptides VRY(411)TKKVPQVSTPTL and LVRY(411)TKKVPQVSTPTL from two patients who had attempted suicide with dichlorvos. The butyrylcholinesterase activity in these serum samples was inhibited 80%. A third patient whose serum BChE activity was inhibited 8% by accidental inhalation of dichlorvos had undetectable levels of adduct on albumin. A fourth patient whose BChE activity was inhibited 60% by exposure to chlorpyrifos had no detectable adduct on albumin. This is the first report to demonstrate the presence of OP-labeled albumin in human patients. It is concluded that tyrosine 411 of human albumin is covalently modified in the serum of humans poisoned by dichlorvos and that the modification is detectable by mass spectrometry. The special reactivity of tyrosine 411 with OP suggests that other proteins may also be modified on tyrosine. Identification of other OP-modified proteins may lead to an understanding of neurotoxic symptoms that appear long after the initial OP exposure.

Mechanisms of respiratory insufficiency induced by methadone overdose in rats

Methadone may cause respiratory depression. We aimed to understand methadone-related effects on ventilation as well as each opioid-receptor (OR) role. We studied the respiratory effects of intraperitoneal methadone at 1.5, 5, and 15 mg/kg (corresponding to 80% of the lethal dose-50%) in rats using arterial blood gases and plethysmography. OR antagonists, including intravenous 10 mg/kg-naloxonazine at 5 minutes (mu-OR antagonist), subcutaneous 30 mg/kg-naloxonazine at 24 hours (micro1-OR antagonist), 3 mg/kg-naltrindole at 45 minutes (delta-OR antagonist) and 5 mg/kg-Nor-binaltorphimine at 6 hours (kappa-OR antagonist) were pre-administered. Plasma concentrations of methadone enantiomers were measured using high-performance liquid chromatography coupled to mass-spectrometry. Methadone dose-dependent inspiratory time (T(I)) increase tended to be linear. Respiratory depression was observed only at 15 mg/kg and characterized by an increase in expiratory time (T(E)) resulting in hypoxemia and respiratory acidosis. Intravenous naloxonazine completely reversed all methadone-related effects on ventilation, while subcutaneous naloxonazine reduced its effects on pH (P < 0.05), PaCO(2) (P < 0.01) and T(E) (P < 0.001) but only partially on T(I) (P < 0.001). Naltrindole reduced methadone-related effects on T(E) (P < 0.001). Nor-binaltorphimine increased methadone-related effects on pH and PaO(2) (P < 0.05) Respiratory effects as a function of plasma R-methadone concentrations showed a decrease in PaO(2) (EC(50): 1.14 microg/ml) at lower concentrations than those necessary for PaCO(2) increase (EC(50): 3.35 microg/ml). Similarly, increased T(I) (EC(50): 0.501 microg/ml) was obtained at lower concentrations than those for T(E) (EC(50): 4.83 microg/ml). Methadone-induced hypoxemia is caused by mu-ORs and modulated by kappa-ORs. Additionally, methadone-induced increase in T(E) is caused by mu1- and delta-opioid receptors while increase in T(I) is caused by mu-ORs.

Carbofuran poisoning detected by mass spectrometry of butyrylcholinesterase adduct in human serum

Carbofuran is a pesticide whose acute toxicity is due to inhibition of acetylcholinesterase. Butyrylcholinesterase (BChE) in plasma is inhibited by carbofuran and serves as a biomarker of poisoning by carbofuran. The goal was to develop a method to positively identify poisoning by carbofuran. Sera from an attempted murder and an attempted suicide were analyzed for the presence of carbofuran adducts on BChE. The BChE from 1 ml of serum was rapidly purified on a 0.2 ml procainamide-Sepharose column. Speed was essential because the carbofuran-BChE adduct decarbamylates with a half-life of about 2 h. The partially purified BChE was boiled to denature the protein, thus stopping decarbamylation and making the protein vulnerable to digestion with trypsin. The labeled peptide was partially purified by HPLC before analysis by LC/MS/MS in the multiple reaction monitoring mode on the QTRAP 2000 mass spectrometer. Carbofuran was found to be covalently bound to Ser 198 of human BChE in serum samples from two poisoning cases. Multiple reaction monitoring triggered MS/MS spectra positively identified the carbofuran-BChE adduct. In conclusion a mass spectrometry method to identify carbofuran poisoning in humans has been developed. The method uses 1 ml of serum and detects low-level exposure associated with as little as 20% inhibition of plasma butyrylcholinesterase.

A sensitive and selective method for the detection of diazepam and its main metabolites in urine by gas chromatography–tandem mass spectrometry

A gas chromatography-tandem mass spectrometry method for detection of diazepam, nordazepam and oxazepam is presented. The method associates electron capture ionization and multiple reaction monitoring (MRM). No derivatization is performed; oxazepam undergoes thermal degradation during chromatographic injection and is thus quantified via its decomposition product. The negative molecular ions are so stable that they do not dissociate when collision is performed under "classical" conditions (i.e. with argon as collision gas). With xenon as collision gas, the energy transfer is sufficient to provide two product ions for diazepam and nordazepam and one product ion for the decomposition product of oxazepam. The sample preparation part involves liquid/liquid extraction with TOXI-TUBES A extraction tubes; it provides recovery yields between 68 and 95%, depending of the benzodiazepine considered, with coefficients of variation below 6% for 10 samples. The applicability of the method was demonstrated on urine extracts. From 1 mL of urine, the method provides quantitation limits of 0.15 ng/mL for diazepam, 1.0 ng/mL for nordazepam and 1.5 ng/mL for oxazepam. Mechanisms of dissociation of M*(-) ions of benzodiazepines are suggested.

Liquid chromatographic-electrospray ionization mass spectrometric quantitative analysis of buprenorphine, norbuprenorphine, nordiazepam and oxazepam in rat plasma

A liquid chromatographic-mass spectrometric method with electrospray ionization is presented for the simultaneous determination of buprenorphine, nordiazepam and their pharmacologically active metabolites, norbuprenorphine and oxazepam, in rat plasma. The drugs were extracted from plasma by liquid-liquid extraction and chromatographically separated using a gradient elution of aqueous ammonium formate and acetonitrile. Following electrospray ionization, the analytes were quantified in the single ion storage mode. The assay was validated according to current acceptance criteria for bioanalytical method validation. It was proved to be linear from 0.7 to 200 ng/ml plasma for buprenorphine, 1.0 to 200 ng/ml for norbuprenorphine, 2.0 to 200 ng/ml for nordiazepam, and from 5.0 to 200 ng/ml for oxazepam. The average recoveries of buprenorphine, norbuprenorphine, nordiazepam and oxazepam were 89, 39, 88 and 82%, respectively, with average coefficients of variation ranging from 1.8 to 14.3%. The limits of quantitation for these drugs were 0.7, 1.0, 2.0 and 5.0 ng/ml, respectively, with associated precisions within 17% and accuracies within +/-18% of the nominal values. Both the intra- and inter-assay precision values did not exceed 11.3% for the four analytes. Intra- and inter-assay accuracies lay within +/-15% of the nominal values. The validated method was applied to the determination of buprenorphine, norbuprenorphine, nordiazepam and oxazepam in plasma samples collected from rats at various times after intravenous administration of buprenorphine and nordiazepam.

A critical review of the causes of death among post-mortem toxicological investigations: analysis of 34 buprenorphine-associated and 35 methadone-associated deaths

AIMS

To assess the trends in the number, mortality and the nature of forensic cases involving toxicological detection of buprenorphine or methadone among toxicological investigations performed in Paris from June 1997 to June 2002.

DESIGN

Retrospective, 5 year study with review of premortem data, autopsy, police reports, hospital data, and post-mortem toxicological analyses.

SETTING AND PARTICIPANTS

34 forensic cases of buprenorphine and 35 forensic cases of methadone detection among 1600 toxicological investigations performed at the Laboratory of Toxicology in the Medical Examiner's Office in Paris.

MEASUREMENTS AND RESULTS

Therapeutic, toxic or lethal drug concentrations were defined based upon the results of blood analyses and the published literature. Drug concentrations were cross-referenced with other available ante- and post-mortem data. Subsequently, we classified a 'clear responsibility', 'possible responsibility' or 'not causative' role for buprenorphine or methadone in the death process, or 'no explanation of death'. Buprenorphine and methadone can be regarded as being directly implicated in, respectively, four of 34 death cases (12%) and three of 35 death cases (9%), and their participation in the lethal process is strongly plausible in eight (buprenorphine) and 11 (methadone) additional deaths.

CONCLUSIONS

Analysis of causes of death reveals the difficulties in determining the role of substitution drugs in the death process, as many other factors may be involved, including circumstances surrounding death, past history, differential selection of subjects into either substitution modality and concomitant intake of other drugs (especially benzodiazepines and neuroleptics). The potential for synergistic or additive actions by other isolated molecules-particularly opioids, benzodiazepines, other psychotropes and alcohol-must be also considered.

Development and validation of a gas chromatography–mass spectrometry method for the simultaneous determination of buprenorphine, flunitrazepam and their metabolites in rat plasma: application to the pharmacokinetic study

Buprenorphine (BUP), a synthetic opioid analgesic, is frequently abused alone, and in association with benzodiazepines. Fatalities involving buprenorphine alone seem very unusual while its association with benzodiazepines, such as flunitrazepam (FNZ), has been reported to result in severe respiratory depression and death. The quantitative relationship between these drugs remain, however, uncertain. Our objective was to develop an analytical method that could be used as a means to study and explore, in animals, the toxicity and pharmacological interaction mechanisms between buprenorphine, flunitrazepam and their active metabolites. A procedure based on gas chromatography-mass spectrometry (GC-MS) is described for the simultaneous analysis of buprenorphine, norbuprenorphine (NBUP), flunitrazepam, N-desmethylflunitrazepam (N-DMFNZ) and 7-aminoflunitrazepam (7-AFNZ) in rat plasma. The method was set up and adapted for the analysis of small plasma samples taken from rats. Plasma samples were extracted by liquid-liquid extraction using Toxi-tubes A. Extracted compounds were derivatized with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA), using trimethylchlorosilane (TMCS) as a catalyst. They were then separated by GC on a crosslinked 5% phenyl-methylpolysiloxane analytical column and determined by a quadrupole mass spectrometer detector operated under selected ion monitoring mode. Excellent linearity was found between 0.125 and 25 ng/microl plasma for BUP, 0.125 and 12.5 ng/microl for NBUP and N-DMFNZ, 0.125 and 5 ng/microl for FNZ, and between 0.025 and 50 ng/microl for 7-AFNZ. The limit of quantification was 0.025 ng/microl plasma for 7-AFNZ and 0.125 ng/microl for the four other compounds. A good reproducibility (intra-assay CV=0.32-11.69%; inter-assay CV=0.63-9.55%) and accuracy (intra-assay error=2.58-12.73%; inter-assay error=0.83-11.07%) were attained. Recoveries were 71, 67 and 81%, for BUP, FNZ and N-DMFNZ, respectively, and 51% for NBUP and 7-AFNZ, with CV ranging from 5.4 to 13.9%, and were concentration-independent. The GC-MS method was successfully applied to the pharmacokinetic study of BUP, NBUP, FNZ, DMFNZ and 7-AFNZ in rats, after administration of BUP and FNZ.

Adsorption–desorption effects in ion trap mass spectrometry using in situ ionization

Quadrupole mass spectrometers were compared for the GC-MS analysis of six molecules frequently encountered in analytical toxicology: diazepam, alprazolam, triazolam, LSD (lysergic acid diethylamide), trimethylsilylated LSD and trimethylsilylated buprenorphine. Experiments performed with ion trap detectors using in situ ionization led to important chromatographic peak tailing for the most polar compounds; it was assumed to result from adsorption-desorption of neutral molecules in the mass spectrometer. This study showed that the degree of peak tailing is correlated with analyte polarity, with materials coating ion trap surfaces and with analysis temperature and that this anomaly can be greatly reduced using passivated surfaces and a high temperature of analysis.

A selective and sensitive method for quantitation of lysergic acid diethylamide (LSD) in whole blood by gas chromatography-ion trap tandem mass spectrometry

A gas chromatography-ion trap tandem mass spectrometry (GC-ion trap MS-MS) method for detection and quantitation of LSD in whole blood is presented. The sample preparation process, including a solid-phase extraction step with Bond Elut cartridges, was performed with 2 mL of whole blood. Eight microliters of the purified extract was injected with a cold on-column injection method. Positive chemical ionization was performed using acetonitrile as reagent gas; LSD was detected in the MS-MS mode. The chromatograms obtained from blood extracts showed the great selectivity of the method. GC-MS quantitation was performed using lysergic acid methylpropylamide as the internal standard. The response of the MS was linear for concentrations ranging from 0.02 ng/mL (detection threshold) to 10.0 ng/mL. Several parameters such as the choice of the capillary column, the choice of the internal standard and that of the ionization mode (positive CI vs. EI) were rationalized. Decomposition pathways under both ionization modes were studied. Within-day and between-day stability were evaluated.

Trends in opiate and opioid poisonings in addicts in north-east Paris and suburbs, 1995-99

AIMS

(1). To assess the trends in the number, mortality and the nature of severe opiate/opioid poisonings from 1995 to 1999 in north-east Paris and adjacent suburbs and (2). to examine the effects of the introduction of high-dose buprenorphine on these parameters.

DESIGN

Retrospective, 5-year study with review of pre-hospital, hospital and post-mortem data.

SETTING AND PARTICIPANTS

Eighty patients from the toxicological intensive care unit (TICU) in north-east Paris, 421 patients from the pre-hospital emergency medical service in a north-east suburb of Paris (SAMU 93) and 40 deaths from the coroner's office in Paris.

MEASUREMENTS AND RESULTS

We found that the number of pre-hospital opiate/opioid poisonings and deaths decreased over 5 years. During the same time frame, opiate/opioid poisoning admissions to our TICU remained steady, but the number of deaths declined. From 1995 to 1999, the detection of buprenorphine among opiate/opioid-poisoned TICU patients increased from two to eight occurrences per year while detection of opiates diminished from 17 to 10 occurrences per year. Increased buprenorphine detection correlated directly with increasing sales over this time period. In spite of the increased use of buprenorphine, the mortality associated with opiate/opioid poisonings has diminished in the pre-hospital environment from 9% in 1995 to 0% in 1999, and in the TICU from 12% in 1995 to 0% in 1997 and thereafter. We found a high frequency of multiple opiate/opioid use in severe poisonings, as well as the frequent association of other psychoactive drugs including ethanol.

CONCLUSIONS

The number and the mortality of opiate/opioid poisonings appear to be stable or decreasing in our region. The association of multiple opiates/ opioids appears nearly as common as the association with other psychoactive drugs. The introduction of high-dose buprenorphine coincides with a decrease in opiate/opioid poisoning mortality. Further study will be necessary to clarify this observation.

Sensitive method for the detection of 22 benzodiazepines by gas chromatography-ion trap tandem mass spectrometry

A gas chromatography-ion trap tandem mass spectrometry method for simultaneous detection of 22 benzodiazepines is presented. Four operating modes were first optimized: the electron impact ionization and chemical ionization modes were compared on both underivatized and trimethylsilylated drugs. Results were compared in terms of sensitivity in MS-MS experiments. The trimethylsilylation of benzodiazepines including a protic functional group allows decreasing their detection threshold by a factor of 10-100. In terms of sensitivity, the comparison between both ionization modes shows that the most efficient one depends on the benzodiazepine considered. The use of an ion trap analyzer allows switching from an ionization mode to another one during the chromatographic process. It also provides a great selectivity owing to the MS-MS and multiple reaction monitoring acquisition modes. The detection thresholds are in the range 10-500 pg/microl for all the studied benzodiazepines but the three "triazolo" ones: estazolam, alprazolam and triazolam, have a detection threshold of 1 ng/microl. The applicability of the method on whole blood and urine extracts was demonstrated on an example implying five benzodiazepines among the most frequently encountered in forensic toxicology: nordazepam, oxazepam, bromazepam, flunitrazepam and prazepam.

[Chemical weapons: antidotes. View about the real means, perspectives]

Chemical methods remain a credible threat in 1999. The doctrine for their use not only includes the battlefield but also domestic terrorism as was disclosed during the Tokyo metro attempt in 1995. International Treaties have not yet proven their efficacy. The arsenal of chemical weapons has changed little since the second World War but is now dispersed into many high-risk zones throughout the world. There has also been little change in antidotes: therapeutic prevention with pyridostigmine against organo-phosphorus compounds, protective treatment for seizure-induced brain lesions using anticonvulsants in association with oxime for acetylcholinesterase reactivation, and atropine are combined in a three-compartment syringe. Preventive measures against vesicants and other suffocating or toxic intracellular substances (CN, AsH(3), fluorocarbons.) can only be achieved with protective skin covering or protective breathing devices. There is no specific treatment and we often have to use symptomatic medications. Future perspectives include: phosphotriesterases as organo-phosphorus scavengers, huperzine as pretreatment and gacyclidine (GCK 11) which would effectively complete emergency multiple drug therapy against nerve agents. A new two-compartment syringe is now prepared with atropine, avisafone and HI6 or pralidoxine. A gel made of cyclodextrines for external and eventually internal use is under study.

Influence of free-to-total prostate specific antigen variability on the early diagnosis of prostate cancer: a comparative study of three immunoassays

OBJECTIVE

To compare three immunoassays for total prostate specific antigen (tPSA), free PSA (fPSA), free-to-total PSA ratio (f/tPSA), and the f/tPSA thresholds for optimal differentiation between benign prostatic hypertrophy (BPH) and prostate cancer in 141 consecutive patients referred for prostatic disease.

PATIENTS AND METHODS

The study included 43 patients with prostate cancer and 98 with BPH, all confirmed histologically. PSA levels were assessed using the following assay kits just before histological analysis of the prostate; Hybritech (Tandem-R PSA, normal values, NV, < 4 ng/mL, and Tandem-R free PSA), Cis Bio (PSA-RIACT, NV < 2.5 ng/mL and fPSA-RIACT) and Immunocorp (PSA-IRMA, NV < 4 ng/mL and Free PSA-IRMA). The results were assessed to determine the sensitivity, specificity and threshold values of the different assays to differentiate patients with BPH and cancer.

RESULTS

The mean tPSA and f/tPSA ratio were statistically different in assays with different NVs. The mean fPSA values differed significantly between the Hybritech and Cis Bio, between the Hybritech and Immunocorp but not between the Cis Bio and Immunocorp assays. With receiver operator curve analysis, there were no statistically significant differences among the three immunoassays in f/tPSA (0.72 for Hybritech, 0.73 for Cis Bio and 0.64 for Immunocorp) or between the tPSA and fPSA curves for each manufacturer. With the sensitivity fixed at 90%, different f/tPSA thresholds were defined (0.22, 0.34 and 0.25 for Hybritech, Cis Bio and Immunocorp, respectively). The specificities (i.e. the percentage of unnecessary biopsies spared) were 22%, 21% and 31%, respectively (not significantly different).

CONCLUSION

Each immunoassay could be used to distinguish prostate cancer and BPH at different f/tPSA thresholds, with 21-30% of unnecessary biopsies spared. There was no difference in overall performance among the different assays. Further studies are needed to better define the exact use of the f/tPSA ratio in the routine diagnosis of prostate cancer.

[The incidence of the variability of the free PSA/total PSA ratio on the early diagnosis of prostate cancer]

INTRODUCTION

In patients with moderate elevation of total PSA, the use of the Free PSA/Total PSa ratio (F+T PSA) has been shown to be useful in the diagnosis of impalpable prostatic cancer. However, the cut-off values proposed in the literature vary from study to study and according to the immunoassay kit used. Our prospective study was designed to compare 3 different kits (Tandem, Cis Bio and Immunocorp) on the same series of patients in order to determine on the basis of these results and a review of the literature, the optimal ratio for which prostatic biopsies should be indicated in the presence of an isolated elevation of Total PSA.

MATERIAL AND METHODS

Serum samples from 141 patients (43 cancers and 98 cases of histologically confirmed BPH) were included. Assays were performed concomitantly with histological examination of the prostate, using Tandem, Cis Bio and Immunocorp kits.

RESULTS

In the overall patient population, Total PSA and Free PSA assays were statistically different for the 3 kits (p < 0.001). The F/T PSA ratio was always statistically different between the cancer and benign prostatic hyperplasia groups (p < 0.002). The cut-off values defined by a sensitivity of 90% were of 0.22 for Tandem (specificity: 27.5%), 0.34 for Cis Bio (specificity: 19.4%) and 0.26 for Immunocorp (specificity: 26.5%). When the total PSA level was between 4.0 and 10.0 ng/ml, these cut-off values also differed: 0.23 for Tandem (specificity: 26.6%), 0.35 for Cis Bio (specificity: 17.2%) and 0.25 for Immunocorp (specificity: 29.7%). In patients with a non-suspicious digital rectal examination and a F/T PSA ratio less than 0.10, the cancer detection rate (number of biopsies required to diagnose 1 cancer) was 1.66 for Tandem, 1 for Cis Bio and 1.87 for Immunocorp versus 7.7 while, when the F/T PSA ratio was greater than 0.22, the cancer detection rate was infinity (no cancer beyond this limit), 12.5 and 23, respectively.

CONCLUSION

The F/T PSA ratio increases the specificity of prostatic cancer detection in patients with a total PSA between 4 and 10.0 ng/ml with a non-suspicious digital rectal examination, therefore resulting in a reduction of the useless biopsy rate and defining more relevant indications for biopsies in the case of periodic follow-up. The systematic indication of this ratio in the screening context cannot be recommended, but it can be useful to demonstrate stage TIC tumours in order to avoid numerous useless biopsies.

[Value of free/total prostate specific antigen in the early diagnosis of prostate cancer (study of 105 patients)]

INTRODUCTION

Prostate Specific Antigen (PSA) exists in the serum in several molecular forms which can be measured by immunoradiodetectable assays: free PSA and total PSA (which represent the sum of the free PSA and complexed PSA to alpha 1 antichymotrypsin). Recently, the proportion of free to total PSA could enhance the ability to distinguish benign histologic conditions from cancer.

MATERIAL AND METHODS

Serum samples of 105 patients (31 histologically confirmed prostate cancers and 74 histologically confirmed untreated benign prostatic diseases) were included in this study. The total and free PSA levels were determined using the PSA immunoradioassay of Tandem-R PSA and Tandem - R free PSA.

RESULTS

When all subjects were included, both total PSA and the proportion of free to total PSA significantly differentiated between patients with prostate cancer and patients with benign histologic conditions (p < 0.01 and p < 0.005). However, in men with total PSA values between 4.0 to 10.0 ng/ml, the proportion of free to total PSA significantly differentiated between the patients with benign and malignant histological conditions (p < 0.04). The most interesting was the ability of the proportion of free to total PSA to distinguish patients with total PSA value between 4.0 and 10.0 ng/ml and normal digital examination (p < 0.001). With these values of PSA-T, a free PSA cutoff of 0.23 detected at least 90.4% of cancers and would eliminate 19.4% of negative biopsies.

CONCLUSION

Measurement of the free to total PSA level improves specificity of prostate cancer screening in selected men with elevated total serum PSA levels between 4.0 to 10.0 ng/ml and normal digital examination, and can reduce unnecessary prostate biopsies with minimal effects on the cancer detection rate.

[Is plasma lipoprotein (a) level a reliable indicator predicting restenosis after angioplasty?]

Lipoprotein (a) [Lp(a)] is an independent genetically determined marker of coronary artery disease. It is present in the atheromatous plaque with a molecular structure similar to that of plasminogen. Its role in postangioplasty restenosis is a possibility but is controversial. A population of 103 coronary patients underwent angioplasty with control coronary angiography before the 6th month; there were 53 good results and 50 cases of restenosis. The Lp(a) was measured by immunonephelemetry (threshold value of 250 mg/l). A subgroup with Lp(a) concentrations > 250 mg/l was identified. The average concentrations of Lp(a) in the two groups without restenosis (368 +/- 350 mg/l) and with restenosis (418 +/- 434 mg/l) were not statisticaly different (p = 0.2). When cases with Lp(a) > 250 mg/l were considered alone, the tendency to higher average concentrations of Lp(a) in the group with restenosis (777 +/- 424 mg/l) compared with the group without restenosis (656 +/- 340 mg/l) was more clear-cut but did not achieve statistical significance (p = 0.08). The individual scatter of Lp(a) being very wide (83 to 1,450 mg/l in the group without restenosis and 90 to 1,740 mg/l in the group with restenosis), it is impossible to predict restenosis from this parameter in a given individual. No correlations were observed between the different lipid fractions and restenosis. The extension of the lesions and the angioplasty site did not correlate with restenosis in this study. The authors conclude: 1) that the Lp(a) concentration has no individual predictive value for restenosis; 2) individuals with Lp(a) concentrations > 250 mg/l have an increased risk of restenosis (NS); 3) these results confirm other recent publications; and 4) further research into the isoforms of Lp(a) in each group could provide interesting data.

[Evaluation of coronary risk: a new technique of measuring lipoprotein (a)]

The aim of this study was to assess the reliability of immuno-nephelemetric assay (INA) of lipoprotein (Lp(a)) compared with immuno-radiometric (IRMA) and immuno-enzymologic (ELISA) assays in a coronary (P1) and a non-coronary (P2) populations. The serums of 66 coronary subjects (P1) with an average age of 61.5 +/- 10 years and 137 non-coronary subjects (P2) with an average age of 54 +/- 12 years were analysed by the 3 techniques. The technical characteristics of the INA were: negligeable interference with plasminogen (PLG) (< 1/100) for PLG < 375 mg/l; excellent repeatability and reproducibility at low, medium and high concentrations, respectively 12.3 and 7.5%. 1.2 and 1.2%, 1.3 and 1.1%, low dependance on sample conservation (stable 5 days at +4 degrees C), excellent practicability (simple and quick automised analysis: 10 min). The linear correlations with the concentrations of Lp(a) were: excellent with INA/IRMA P1 and P2: 0.99; very good with INA/ELISA P1: 0.88 and P2: 0.85; very good between IRMA/ELISA P1: 0.91 and P2: 0.87. The average values of Lp(a) were 386 mg/l (INA), 339 mg/l (IRMA), 316 mg/l (ELISA) for P1, and 231 mg/l (INA), 212 mg/l (IRMA) and 153 mg/l (ELISA) for P2, with a significant difference between P1 and P2 with all three techniques: 0.0138 (INA), 0.0207 (IRMA) and 0.0001 (ELISA). The authors concluded that measuring Lp(a) by INA is reliable with respect to IRMA and ELISA techniques, as accurate, quicker, automatised and cheaper, compensating for a lower sensitivity, a calculated risk of a non-specific reaction and the necessity of a shorter delay of analysis. The comparative results in two populations demonstrate it to be an excellent marker of coronary risk for epidemiological studies, independant of other risk factors.

Radioimmunological determination of total thyroxin by antibodies immobilized on polystyrene tubes coated with styrene-maleic anhydride copolymers

In this new technique for preparing activated polystyrene tubes for assay of human thyroxin (T4) we coated plastic with styrene-maleic anhydride copolymers. The quantity of antibodies immobilized on these tubes was considerably greater than on non-activated polystyrene tubes, and the time required for immobilization was shortened. Calibration curves were plotted, and determination of total T4 in 200 serum samples confirmed the expected increase in sensitivity as compared with a commercial (Gammacoat) method. The manufacturing procedure is simple and could easily be automated. Thus, such copolymer-coated tubes constitute an advantageous and reliable component in the assay of total T4 that can be used to improve the sensitivity of this and various other radioimmunological determinations.

Radioimmunological determination of total thyroxin by antibodies immobilized on polystyrene tubes coated with styrene-maleic anhydride copolymers

In this new technique for preparing activated polystyrene tubes for assay of human thyroxin (T4) we coated plastic with styrene-maleic anhydride copolymers. The quantity of antibodies immobilized on these tubes was considerably greater than on non-activated polystyrene tubes, and the time required for immobilization was shortened. Calibration curves were plotted, and determination of total T4 in 200 serum samples confirmed the expected increase in sensitivity as compared with a commercial (Gammacoat) method. The manufacturing procedure is simple and could easily be automated. Thus, such copolymer-coated tubes constitute an advantageous and reliable component in the assay of total T4 that can be used to improve the sensitivity of this and various other radioimmunological determinations.

Antibody immobilization on swollen polystyrene tubes for the radioimmunological determination of total human serum IgE

A new technique for preparing activated polystyrene tubes was developed involving the controlled swelling of plastic. The quantity of antibodies immobilized on these tubes, and consequently the quantity of bound IgE, was considerably increased. Calibration curves were plotted and the determination of total IgE in 200 serum samples confirmed the expected increase in sensitivity compared to a standard method. The manufacturing procedure was simple and could easily be automated. Thus, swollen polystyrene tubes constitute an advantageous solid stage in the assay of total IgE, which can improve the sensitivity of various radioimmunological determinations.

[Experimental coronary angioplasty using hematoporphyrin coloration simultaneously with a pulsed laser beam]

The setting up of a reliable method for angioplasty by laser irradiation is based. On the one hand, on the simultaneous control of the observed thermal, mechanical and photochemical effects within the atheromatous material and, on the other, on the demonstration of the absence of effects damaging to the arterial tunica. Theoretical modelling and experimental use have together proved the unique importance of pulsed emission, which strongly reduces thermal diffusion. Labelling of the atheromatous plaque by a hematoporphyrin derivative (HPD), as exemplified in the carcinological process, cancels the superficial reflectivity and strongly reduces the diffusion coefficient in the plaque. It confers on it a spectral absorption characteristic which is the basis of the exact physical coupling between the frequency of the exciting radiation and the absorption which generates vaporization in the pathological material. The preparation of chemically more homogeneous HPD and the spectrometric study of other colouring agents in vivo point to a further development of this technique of angioplasty.