Evidence of an upper ionospheric electric field perturbation correlated with a gamma ray burst

Earth's atmosphere, whose ionization stability plays a fundamental role for the evolution and endurance of life, is exposed to the effect of cosmic explosions producing high energy Gamma-ray-bursts. Being able to abruptly increase the atmospheric ionization, they might deplete stratospheric ozone on a global scale. During the last decades, an average of more than one Gamma-ray-burst per day were recorded. Nevertheless, measurable effects on the ionosphere were rarely observed, in any case on its bottom-side (from about 60 km up to about 350 km of altitude). Here, we report evidence of an intense top-side (about 500 km) ionospheric perturbation induced by significant sudden ionospheric disturbance, and a large variation of the ionospheric electric field at 500 km, which are both correlated with the October 9, 2022 Gamma-ray-burst (GRB221009A).

Search for magnetic monopoles produced via the Schwinger mechanism

Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism¹. By electromagnetic duality, a sufficiently strong magnetic field would similarly produce magnetic monopoles, if they exist². Magnetic monopoles are hypothetical fundamental particles that are predicted by several theories beyond the standard model^3-7 but have never been experimentally detected. Searching for the existence of magnetic monopoles via the Schwinger mechanism has not yet been attempted, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory, as well as that the production of the magnetic monopoles should be enhanced by their finite size^8,9 and strong coupling to photons^2,10. Here we present a search for magnetic monopole production by the Schwinger mechanism in Pb-Pb heavy ion collisions at the Large Hadron Collider, producing the strongest known magnetic fields in the current Universe¹¹. It was conducted by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 per nanobarn, or approximately 1.8 × 10⁹, of Pb-Pb collisions with 5.02-teraelectronvolt center-of-mass energy per collision in November 2018. A superconducting quantum interference device (SQUID) magnetometer scanned the trapping detectors of MoEDAL for the presence of magnetic charge, which would induce a persistent current in the SQUID. Magnetic monopoles with integer Dirac charges of 1, 2 and 3 and masses up to 75 gigaelectronvolts per speed of light squared were excluded by the analysis at the 95% confidence level. This provides a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extends previous mass bounds.

A Review of the EUSO-Balloon Pathfinder for the JEM-EUSO Program

EUSO-Balloon is a pathfinder for JEM-EUSO, the mission concept of a spaceborne observatory which is designed to observe Ultra-High Energy Cosmic Ray (UHECR)-induced Extensive Air Showers (EAS) by detecting their UltraViolet (UV) light tracks "from above." On August 25, 2014, EUSO-Balloon was launched from Timmins Stratospheric Balloon Base (Ontario, Canada) by the balloon division of the French Space Agency CNES. After reaching a floating altitude of 38 km, EUSO-Balloon imaged the UV light in the wavelength range ∼290-500 nm for more than 5 hours using the key technologies of JEM-EUSO. The flight allowed a good understanding of the performance of the detector to be developed, giving insights into possible improvements to be applied to future missions. A detailed measurement of the photoelectron counts in different atmospheric and ground conditions was achieved. By means of the simulation of the instrument response and by assuming atmospheric models, the absolute intensity of diffuse light was estimated. The instrument detected hundreds of laser tracks with similar characteristics to EASs shot by a helicopter flying underneath. These are the first recorded laser tracks measured from a fluorescence detector looking down on the atmosphere. The reconstruction of the direction of the laser tracks was performed. In this work, a review of the main results obtained by EUSO-Balloon is presented as well as implications for future space-based observations of UHECRs.

First Search for Dyons with the Full MoEDAL Trapping Detector in 13 TeV pp Collisions

The MoEDAL trapping detector consists of approximately 800 kg of aluminum volumes. It was exposed during run 2 of the LHC program to 6.46  fb^{-1} of 13 TeV proton-proton collisions at the LHCb interaction point. Evidence for dyons (particles with electric and magnetic charge) captured in the trapping detector was sought by passing the aluminum volumes comprising the detector through a superconducting quantum interference device (SQUID) magnetometer. The presence of a trapped dyon would be signaled by a persistent current induced in the SQUID magnetometer. On the basis of a Drell-Yan production model, we exclude dyons with a magnetic charge ranging up to five Dirac charges (5g_{D}) and an electric charge up to 200 times the fundamental electric charge for mass limits in the range 870-3120 GeV and also monopoles with magnetic charge up to and including 5g_{D} with mass limits in the range 870-2040 GeV.

Magnetic Monopole Search with the Full MoEDAL Trapping Detector in 13 TeV pp Collisions Interpreted in Photon-Fusion and Drell-Yan Production

MoEDAL is designed to identify new physics in the form of stable or pseudostable highly ionizing particles produced in high-energy Large Hadron Collider (LHC) collisions. Here we update our previous search for magnetic monopoles in Run 2 using the full trapping detector with almost four times more material and almost twice more integrated luminosity. For the first time at the LHC, the data were interpreted in terms of photon-fusion monopole direct production in addition to the Drell-Yan-like mechanism. The MoEDAL trapping detector, consisting of 794 kg of aluminum samples installed in the forward and lateral regions, was exposed to 4.0  fb^{-1} of 13 TeV proton-proton collisions at the LHCb interaction point and analyzed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges equal to or above the Dirac charge are excluded in all samples. Monopole spins 0, ½, and 1 are considered and both velocity-independent and-dependent couplings are assumed. This search provides the best current laboratory constraints for monopoles with magnetic charges ranging from two to five times the Dirac charge.

Influence of age and co-medication on the steady-state pharmacokinetics of valproic acid in Tunisian patients with epilepsy

AIM

Valproic acid (VPA) is a widely prescribed broad-spectrum antiepileptic drug. However, the use of VPA is complicated in clinical practice by its remarkably wide variability of pharmacokinetics. The objective of this study was to investigate the effects of demographic factors and associated therapies on steady-state plasma VPA concentrations in patients with epilepsy.

METHODS

This retrospective cohort study was carried out using the routine therapeutic drug monitoring (TDM) database. Stepwise logistic regression analysis was used to compare serum VPA levels in 78 epilepsy patients treated with VPA in association with at least one other drug that could have interacted with CYP2C9, CYP2C19 or UGT enzymes.

RESULTS

The frequency of subtherapeutic serum VPA levels was significantly increased with younger age (P<0.02), the number of co-medications (P<0.007) and use of enzyme-inducing co-medications (P<0.02). No significant correlations between VPA dose and trough plasma concentrations were found, as the latter did not increase in proportion to the dose.

CONCLUSION

Routine monitoring of VPA serum levels would be extremely useful in epilepsy patients in the pediatric age group and in those who require associated enzyme-inducing medications.

Search for Magnetic Monopoles with the MoEDAL Forward Trapping Detector in 13 TeV Proton-Proton Collisions at the LHC

MoEDAL is designed to identify new physics in the form of long-lived highly ionizing particles produced in high-energy LHC collisions. Its arrays of plastic nuclear-track detectors and aluminium trapping volumes provide two independent passive detection techniques. We present here the results of a first search for magnetic monopole production in 13 TeV proton-proton collisions using the trapping technique, extending a previous publication with 8 TeV data during LHC Run 1. A total of 222 kg of MoEDAL trapping detector samples was exposed in the forward region and analyzed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges exceeding half the Dirac charge are excluded in all samples and limits are placed for the first time on the production of magnetic monopoles in 13 TeV pp collisions. The search probes mass ranges previously inaccessible to collider experiments for up to five times the Dirac charge.

Mucosal lichenoid drug reaction associated with glimepiride: a case report

We report the case of a 52-year-old man with type 2 diabetes, who developed severe mucosal erosions of the tongue, glans penis and perianal area, induced by glimepiride. A tissue biopsy was performed and revealed the characteristics of lichen planus (LP). The improvement of the patient's condition after withdrawal of glimepiride added to recurrence of the lesions when medication was reintroduced confirmed that the second generation anti-diabetic was the causative agent. To the best of our knowledge, this has not been reported previously.

[Relationship between plasma concentrations of valproic acid and hepatotoxicity in patients receiving high doses]

INTRODUCTION

Valproic acid (VPA) is an anticonvulsivant drug widely prescribed in the treatment of many forms of generalized epilepsy. In literature, the incidence of liver damage induced by AVP is 0.01%. It is potentialized by the combination therapy (phenobarbital, carbamazepine). Severe hepatotoxicity is rare and appears to be independent of dose and to cause a high mortality.

METHODS

The aim of our study was to evaluate the relationship between plasma concentrations of AVP and the occurrence of side effects especially hepatotoxicity in patients receiving high doses of AVP.

RESULTS

In this period, 425 plasmatic AVP monitoring were carried out in our laboratory. From 128 patients treated by high doses of AVP, only 73 were included in this study. Our work showed that adverse effects in epileptics under high doses of AVP was related to the association of the AVP with other antiepileptic in particular carbamazépine, phenobarbital and benzodiazepines rather than supra-therapeutic plasmatic concentrations of AVP. The association of AVP to major antiepileptics (carbamazépine and or phenobarbital) does not seem to generate an increase in the plasmatic concentration of AVP, which was not associated with a greater risque of adverse effects.

CONCLUSION

Consequently, clinical signs of liver toxicity may be present in AVP concentrations generally considered in the therapeutic range especially when used in high doses and or combined with antiepileptic drugs like phenobarbital or carbamazepine.

[Medication adherence of a sample of hypertensive patients in the region of Sfax (Tunisia)]

THE AIM OF THE STUDY

Medication noncompliance is one of the daily problems of the physician. Improving the medication adherence allows better management of hypertension. The aim of this work was to determine the level of compliance for patients with hypertension and to identify factors that determine compliance.

METHODS

A cross-sectional study was carried out among a sample of hypertensive patients attending general and specialist practitioners in public or private clinics of Sfax. Two hundred and seventy-three participants had accepted to be interviewed. Patients were identified as noncompliants using a questionnaire developed by the Comité de lutte contre l'hypertension artérielle (CFLHTA).

RESULTS

Non-compliance rate was 63.4%. The low level of education was associated with a lower adherence. The monotherapy, the once-daily regimen with fewer number of tablets were associated with a better adherence (p<10(-6)). The welcome and the availability of drugs in the public clinic affect positively the adherence of patients (p<0.0002). A patient very satisfied with his consultation and the explanation given by the doctor about his illness and its treatment had a better adherence (p<0.00003).

CONCLUSION

Our study had demonstrated a low compliance with antihypertensive drug therapy. Tunisian health care system should elaborate a management plan which takes into account our particular predictors of compliance to improve adherence to antihypertensive medication.

INVESTIGATION OF THE MICROCIRCULATION AND THE STATE OF OXIDATIVE STRESS IN THE RAT AFTER SCORPION ENVENOMATION

1. Severe cases of scorpion envenomation (SE) generally show both respiratory and cardiocirculatory dysfunction. However, the pathophysiology of SE remains controversial. In the present study, we tried to explain the pathophysiology of the haemodynamic perturbations and cardiac failure in rats poisoned by the venom of Buthus occitanus tunetanus through a histomorphometric study of myocardial and muscular skeletal microcirculation and analysis of the oxidative stress state in order to evaluate the implication of the inflammatory process in the pathogenesis of SE. 2. Experiments were performed on 96 rats divided into 16 groups (n = 6 in each group). Two groups were used to determine the optimum conditions of venom administration and times when to measure haemodynamic parameters. The B. occitanus tunetanus venom was administered at a dose of 800 microg/kg and tissues were removed 5 and 20 min after envenomation. Six groups were used for histomorphometric study: two control groups, two poisoned groups an two melatonin-pretreated and poisoned groups. The histomorphometric study was performed on isolated hearts and skeletal muscles. The final eight groups of rats (two control groups, two envenomated groups, two control groups pretreated with melatonin and two groups pretreated and envenomated) were used to investigate the state of tissue oxidative stress during SE and to evaluate the anti-oxidant effect of melatonin on rats poisoned with B. occitanus tunetanus venom. This study was based on the determination of tissue malondialdehyde in isolated organs as an indicator of thiobarbituric acid-reactive substances (TBARS). Melatonin was injected at a dose of 5 mg/kg, i.v., 15 min before the administration of serum or venom. Data were compared using analysis of variance and Tukey's test for multiple pair-wise comparisons. 3. Five minutes after venom injection, a significant reduction in the mean relative volume of venules and arterioles in the heart and skeletal muscles of poisoned rats was noted. Twenty minutes after venom injection, these volumes were significantly increased in the heart and skeletal muscles of poisoned rats. Pretreatment of envenomated rats with melatonin resulted in a significant decrease in the mean relative volume of the venules and arterioles in the heart and skeletal muscles 5 and 20 min after venom injection compared with untreated envenomated rats. Investigation of the oxidative stress state showed a highly significant increase in TBARS in poisoned rats compared with control groups 5 and 20 min after venom injection. Melatonin pretreatment of rats poisoned with B. occitanus tunetanus venom resulted in an important and highly significant reduction of TBARS compared with untreated envenomated rats. 4. It appears from the results of the present study that administration of B. occitanus tunetanus venom engendered an excessive myocardial and skeletal muscular vasoconstriction attributed to massive catecholamine release followed by arteriolar and venular vasodilatation. This venous stasis at the muscular microcirculation could be due to myocardiac failure. However, the concomitant presence of arteriolar vasodilatation suggests an inflammatory process in the pathophysiology of SE. This process was suggested by the genesis of a state of oxidative stress in relation to the important lipoperoxidation, which was inhibited by administration of the anti-oxidant melatonin. Thus, melatonin pretreatment seemed to accentuate the first phase of vascular reactivity in envenomed rats and inhibit the second vasodilator phase observed 20 min after administration of the venom.

[Hemodynamics and microcirculation in a rat poisoned by scorpion venom]]

The clinic table of serious scorpionic envenimation is dominated by cardiovascular and pulmonary perturbations. The physiopathology of cardiac failure in man as well as at animal is again badly elucidated. The aim of our study has consisted in evaluating the hemodynamic variations of the Rat poisoned by the venom of the Buthus occitanus scorpion and to contribute through the analyse of plasmatic concentrations of catecholamines and by an histomorphometric study of muscular microcirculation to explain the mechanism of the hemodynamic perturbations and cardiac failure. 51 rats corresponding to 9 groups (witness and poisoned) have been used. The venom of the scorpion Buthus occitanus has been administrated at 850 micrograms/kg. Two groups have been served for hemodynamic study, three groups for the dosage of catecholamines and four groups for histomorphometric study. It has been observed a biphasic variation of arterial pressure and cardiac frequency after venom injection. Four minutes after envenimation, the plasmatic level of catecholamines was strongly higher in the poisoned according to the witness one. Histomorphometric study of muscular skeletal microcirculation has shown a decrease of relative vascular volume contemporary with the increase of plasmatic catecholamines concentration and the peak of arteriel pressure appeared just after envenimation. 10 and 20 minutes after envenimation, the relative vascular volume has significantly increased as well as that interstitium according to witness lot. These hemodynamic perturbations can be attributed to the important dump in catecholamines. This hyperadrenergy was contemporary with decrease of relative muscular vascular volume. This decrease would be explained by a constriction of vessels. On the other hand, the second increase of the vascular relative volume suggests the possibility of development of venous stasis at the muscular microcirculation. It would be induced by a cardiac failure and/or the effect of vasoplegic mediators being able to entail an interstitial oedema in the muscular skeletal that would led to increase the relative interstitial volume observed in this study.

Sperm oxidative stress and the effect of an oral vitamin E and selenium supplement on semen quality in infertile men

Numerous studies have reported beneficial effects of antioxidant drugs on semen quality, but there is no well-defined therapeutical protocol in male infertility. This study aimed to test the effects of vitamin E and selenium supplementation on lipid peroxidation and on sperm parameters. The study included 54 voluntary and infertile men who produced semen samples for spermiogram and for spectrophotometric measurement of a lipid peroxidation marker, the malondialdehyde (MDA), and produced blood samples for high-performance liquid chromatography assessment of serum vitamin E level. The trial was randomized and open. Twenty-eight men were supplemented daily by vitamin E (400 mg) and selenium (225 microg), during 3 months. The remaining 26 patients received vitamin B (4,5 g/day) for the same duration. Only 20 patients achieved their treatment and returned for control analysis. MDA concentrations in sperm were much less than in seminal plasma and motility and viability were inversely correlated with semen MDA levels. In contrast to vitamin B supplementation, vitamin E and selenium supplementation produced a significant decrease in MDA concentrations and an improvement of sperm motility. The results confirm the protective and beneficial effects of vitamin E and selenium on semen quality and advocate their use in male infertility treatment.

Characterization and mechanisms of the cardiovascular and haemodynamic alterations induced by scorpion venom in rats

The scope of this work was to investigate the nature, chronology and mechanisms of the cardiovascular disorders induced by scorpion envenomation. Anaesthetized rats were instrumented for measurement of cardiac output (CO), renal (RBF) and muscular (HBF) blood flows (pulsed Doppler flowmetry), blood pressure, heart rate and dP/dt. Buthus occitanus venom (BO) was administered intravenously in the absence/presence of different pre-treatments. BO dose-dependently (150-300 microg/kg) increased blood pressure, dP/dt, total peripheral (TPR), renal (RVR) and muscular (HVR) vascular resistances, and decreased CO, RBF and HBF. Recovery occurred after 150 but not after 300 microg/kg. BO, 600 microg/kg, produced qualitatively similar effects but arrhythmias developed and mortality increased. Pre-treatment with phentolamine prevented the rises in TPR, RVR, HVR and blood pressure and the decreases in CO, RBF and HBF induced by BO, 300 microg/kg. Pre-treatment with propranolol prevented the rise in dP/dt and the occurrence of arrhythmias and limited the rise in RVR and the drop in RBF induced by BO, 300 microg/kg. Phentolamine, propranolol and their combination also prevented BO, 600 microg/kg-induced mortality. Other pre-treatments (bosentan, losartan, diltiazem, mepyramine) were almost ineffective vs. BO effects. Finally, BO, 300 microg/kg, induced a 30-40-fold increase in plasma epinephrine and norepinephrine levels, but no change in plasma endothelin-1 levels. Thus in anaesthetized rats, the pattern of the cardiac and systemic and regional haemodynamic effects of BO is typically that of and results from catecholamine outpouring-induced alpha- and beta-adrenoceptor stimulation.

[Free radicals and antioxidants: physiology, human pathology and therapeutic aspects (part II)]

Although they are considered as destructive agents, free radicals can sometimes become useful. Their presence is intimately coupled with the activity of certain hemal oxydases which insert an atom of oxygen into their substrate by a stereospecific radical mecanism. The cytochromes P450 and the enzymes of the eicosanoide metabolism are some examples. The free radicals can act as second cellular messengers, especially to modulate the metabolism of arachidonic acid and the prostaglandin tract or to infer a myorelaxation. They can even play the role of neurotransmitters such as azote monoxyde. The activation of phagocytes, which is an essential event in the inflammatory reaction, integrates these notions at several levels: in the mechanisms of bacterial death, in the spread of the inflammatory reaction and in the alteration of the extra-cellular matrix. The inflammatory reaction is initiated by interactions between vascular endothelium, platelets and leukocytes including signal exchanges, adhesion molecule expression and secretion of chimiotactic mediators. Activation of vascular endothelium is a key event in the initiation of the phenomenon. The cells intervening in the precocious inflammatory phase were tissular mastocytes and platelet-liberating mediators (histamine) and neutrophile cells responsible for vascular injuries induced by oxygen free radicals and nitric oxide. Reactive oxygen intermediates play a critical role, primarily to limit tissue damage and prevent or inhibit infection, secondary to enhancing and prolonging reaction. The monocytes and platelets liberate cytokines early, which appears to be important in activation and production of an inflammatory response. In fact, cytokines, especially TNF alpha and IL-1, induce synthesis and secretion endothelial adhesion molecules such as ICAM-1, VCAM-1 and E-selectin, which have been demonstrated to mediate leukocyte recruitment to sites of inflammation. The cytokines also activate the fibroblasts and endothelial cells that produce, among others, free radicals and other chimiotactic cytokines of which some (IL-8 and related) can induce neutrophil degranulation and stimulate oxidative stress and formation of free radicals. Furthermore, endothelial cells have been shown to make use of a broad repertoire of cytokines including IL-1, IL-6, IL-8, MCP-1 and gro/MGSA, which may be secreted during an inflammatory response and exercise pro-inflammatory functions. Under the influence of the inflammatory mediators, other enzymes are also activated. The inducible isoforms of cyclo-oxygenase (COX-2) and nitric oxide synthase (iNOS) play an important role in inflammatory reactions via the production respectively of prostaglandins and nitric oxide. The induction of cell adhesion molecules (ICAM-1, VCAM-1 and E-selectin), cytokines, acute phase proteins, growth factors, COX-2 and iNOS expression is mediated by the activation of transcriptional factors, especially the nuclear factor kappa B (NF-kappa B). The NF-kappa B system is essentially involved in immediate early expression of various immunoregulatory genes and has been demonstrated to represent an important regulatory system of endothelial activation. The target genes for NF-kappa B comprise a growing list of genes intrinsically linked to a coordinated inflammatory response. The NF-kappa B is a heterodimer composed of two subunits (p65 and p50). In non-stimulated cells, NF-kappa B resides in the cytoplasm as an inactive complex bound to its inhibitor, I kappa B. Upon stimulation with various agents including cytokines, mitogenes, viruses and reactive oxygen intermediates, I kappa B dissociates from the NF-kappa B-I kappa B complex and translocates to the nucleus, binding with high affinity to specific sites in the promoter regions of target genes and stimulating their transcription. In the case of any weakness of this anti-oxidizing defence or any over-production of radical species, a state of oxidative stress occurs. (ABSTRACT TRUNC

[Free radicals and antioxidants: human physiology, pathology and therapeutic aspects]

Oxygen has invaded progressively, and through the ages, an initially anaerobic world. Living organisms had to invent, in the course of evolution, diverse and ingenious defence systems, to survive the toxicity of this element, which was new for them. Strengthened by this experience over billions of years, the present superior organisms, and particularly human species, are thoroughly adapted to 21 per cent of atmospheric oxygen. Nevertheless, the equilibrium is fragile and the menace of oxygen hovers continually. This deleterious potential of oxygen is attributed to the formation, in vivo, of free radicals, a free radical being, by definition, any chemical species possessing one or several mismatched electrons. These free radicals are, in general, very active. They trigger chain reactions able to damage the different constituents of the living organism. Basic oxygen, must be pre-activated to manifest its toxicity. Such an activation can be achieved in two ways: it can be photodynamic, ending mainly in singlet oxygen, it can be reducing, followed by the formation of the anion hydrogen peroxide and of radical hydroxyl; the latter is the most reactive chemical species in the biological world. The reductive process is accelerated in the presence of transition metals, such as iron and copper, and/or specific enzymes (monoxygenase and certain oxydases). This activation takes place in different cellular compartments: mitochondria, microsomes, peroxysomes, cytoplasmic membrane. To this potential toxicity of oxygen the organism opposes different anti-oxidant defence systems. A first group works up the radical chain, inhibiting activation mechanisms. Such a group, as a consequence, warns of the initiation of radical reactions. The second group neutralizes the free radicals already formed and thus stops the chain of propagation. In this group can be found detoxifying enzymes, notably superoxide dismutase and catalase, producing jointly peroxidases, particularly peroxidase glutathions. Such enzymes for the most part have trace elements as cofactors. In this second group can also be found various molecules which act like 'substrate suicide', or as an anti-oxidant shield. Among these molecules, some can act in the lipidic phase, such as tocopherols, carotenoïds and ubiquinones. Other molecules which are lipophobic, mainly ascorbic acid and uric acid, are active in a hydrated environment. In the case of a weakening of such an antioxidant defence or excess production of radicals, a state of oxidative stress occurs. Uncontrolled, these radicals will damage different biological targets: lipids, DNA, proteins. Disturbances of cellular metabolism will occur, unless corrective defences intervene. The identification of these radical phenomena is an obligatory stage. But because of the very short life span of free radicals, identification poses a real analytical problem. However, three approaches are possible: identification of free radicals, either directly by means of paramagnetic electron resonance, or indirectly by identifying some more stable intermediates. evaluation of the traces of radical attack on biological molecules, for example by high performance liquid chromatography, gas-liquid chromatography, colorimetric tests, estimation of the antioxidant status, for example by colorimetric tests, immunoenzymatic methods, high performance liquid chromatography.

[Treatment of aplastic anemia with cyclosporine, prednisolone and androgens (primary results apropos of 10 cases]

Aplastic anaemia is a potentially fatal haematopoietic disorder whose aetiology is not yet clarified. In our preliminary study we have introduced cyclosporin in the aplastic anaemia treatment to evaluate its effect on the disease evolution. Ten aplastic anaemia patients, mean age 33.33 +/- 20.01 years, were treated with cyclosporine (9 +/- 2.35 mg/kg/d), prednisolone (0.5 mg/kg/d) and androgens (1 mg/kg/d). The prednisolone was always combined with cyclosporine. The androgens were administered concomitantly with the cyclosporine or alternately. Seven patients responded to the treatment after a median remission delay of 6 weeks (2-12 weeks). They became independent of blood requirements at a median of 36 weeks (8-108 weeks); the three other patients died during the first trimester without showing any improvement. Among the seven responders, two relapsed early and transiently. The rate of actuarial survival was 70 per cent. The median duration of survival was 10.5 months. The side effects observed included one case of malignant lymphoma, six cases of liver toxicity and five cases of kidney toxicity. This toxicity was reversible after dose adjustment of the cyclosporine. In our study, the introduction of cyclosporin in the aplastic anaemia treatment resulted in improved therapeutic response. Androgens should be used to maintain the haematologic response. This therapeutic protocol associated with drug monitoring seems promising and the side effects should not limit its use because of the severity of the underlying disease.

Pharmacokinetics of navelbine after oral administration in cancer patients

The pharmacokinetic behavior of navelbine was investigated in 19 patients presenting with advanced cancers (mainly women with breast cancer). Navelbine was given orally at seven dose levels of up to 200 mg/week. For a given dose, patients received four successive weekly treatments. Five subjects also received two different doses. After drug administration, plasma was collected for 48 or 72 h and monitored for navelbine concentration by radioimmunoassay. Absorption of navelbine was very rapid after oral administration: maximal drug concentrations were reached within the first 1 or 2 h (Tmax, 0.9-1.75 h; cmax, 70.9-832.6 ng/ml), with absorption constants ranging from 0.85 to 2.42 l/h. A comparison of dose-normalised plasma concentration profiles revealed significant time dependence in six evaluable patients (P less than 0.001). Only four subjects who received low doses (less than or equal to 100 mg/week) exhibited time-independent kinetics. All of the five patients who were treated at different doses displayed apparent dose dependence (P less than 0.001). No individual profile was characterised by both time- and dose-independent pharmacokinetics. In all, 18 patients presented biphasic plasma concentration-decay patterns, and only 1 subject exhibited monophasic decay kinetics. The navelbine pharmacokinetic parameters obtained following oral administration were similar to those observed after i.v. bolus injection and were characterised by high oral clearance (0.43-1.45 1 h-1 kg-1), a large apparent volume of distribution (27.4-45.9 1/kg), and a long terminal half-life (24.2-56.5 h). Large intra- and inter-individual variations in pharmacokinetic parameters were observed. Moreover, after a high dose of 200 mg, an enterohepatic cycle and/or a delay in navelbine's absorption at a distal intestinal site as evidenced by a marked plasma level rebound was observed.

Determination of 6-mercaptopurine and its metabolites in plasma or serum by high performance liquid chromatography

A sensitive and accurate reversed phase liquid chromatographic assay was developed for the determination of 6-mercaptopurine (6MP) (the active metabolite of azathioprine) in human plasma. The assay involved extraction into acetonitrile and dichloromethane from plasma pretreated with 0.038 M of dithiothreitol solution. The residue was analyzed by isocratic chromatography on a C18 analytical column with UV detection at 326 nm. The average extraction recovery of 6MP was 85%. The method has been applied successfully to the determination of 6MP and its metabolites in pharmacokinetic studies.