Is off-label thrombolysis safe and effective in a real-life primary stroke center? A retrospective analysis of data from a 5-year prospective database

BACKGROUND

Intravenous thrombolysis (IVT) use for acute ischemic stroke (AIS) varies among countries, partly due to guidelines and product labeling changes. The study aim was to identify the characteristics of patients with AIS treated with off-label IVT and to determine its safety when performed in a primary stroke center (PSC).

METHODS

This observational, single-center study included all consecutive patients admitted to Perpignan PSC for AIS and treated with IVT and patients transferred for EVT, between January 1, 2015 and December 31, 2019. Data of patients treated with IVT according to ("in-label group") or outside ("off-label") the initial guidelines and manufacturer's product specification were compared. Safety was assessed using symptomatic intracerebral hemorrhage (SIH) as the main adverse event.

RESULTS

Among the 892 patients in the database (834 screened by MRI, 93.5%), 746 were treated by IVT: 185 (24.8%) "in-label" and 561 (75.2%) "off-label". In the "off-label" group, 316 (42.4% of the cohort) had a single criterion for "off-label" use, 197 (26.4%) had two, and 48 (6.4%) had three or more criteria, without any difference in IVT safety pattern among them. SIH rates were comparable between the "off-label" and "in-label" groups (2.7% vs. 1.1%, P=0.21); early neurological deterioration and systematic adverse event due to IVT treatment were similar in the 2 groups. "Off-label" patients had higher in-hospital (8.7% vs. 3.8%, P=0.05) and 3-month mortality rates (12.1% vs 5.4%, P<0.01), but this is explained by confounding factors as they were older (76 vs 67 years, P<0.0001) and more dependent (median modified Rankin scale score 0.4 vs 0.1, P<0.0001) at admission.

CONCLUSIONS

"Off-label" thrombolysis for AIS seems to be safe and effective in the routine setting of a primary stroke center.

A regional strategy to decrease the time to thrombectomy in patients with low probability of treatment by thrombolysis

BACKGROUND AND PURPOSE

The best transportation strategy for patients with suspected large vessel occlusion (LVO) is unknown. Here, we evaluated a new regional strategy of direct transportation to a Comprehensive Stroke Center (CSC) for patients with suspected LVO and low probability of receiving intravenous thrombolysis (IVT) at the nearest Primary Stroke Center (PSC).

METHODS

Patients could be directly transported to the CSC (bypass group) if they met our pre-hospital bypass criteria: high LVO probability (i.e., severe hemiplegia) with low IVT probability (contraindications) and/or travel time difference between CSC and PSC<15 minutes. The other patients were transported to the PSC according to a "drip-and-ship" strategy. Treatment time metrics were compared in patients with pre-hospital bypass criteria and confirmed LVO in the bypass and drip-and-ship groups.

RESULTS

In the bypass group (n=79), 54/79 (68.3%) patients met the bypass criteria and 29 (36.7%) had confirmed LVO. The positive predictive value of the hemiplegia criterion for LVO detection was 0.49. In the drip-and-ship group (n=457), 92/457 (20.1%) patients with confirmed LVO met our bypass criteria. Among the 121 patients with bypass criteria and confirmed LVO, direct routing decreased the time between symptom discovery and groin puncture by 55 minutes compared with the drip-and-ship strategy (325 vs. 229 minutes, P<0.001), without significantly increasing the time to IVT (P=0.19).

CONCLUSIONS

Our regional strategy led to the correct identification of LVO and a significant decrease of the time to mechanical thrombectomy, without increasing the time to IVT, and could be easily implemented in other territories.

Capacities of atrial fibrillation detection after stroke: a French nationwide survey

Background

Atrial fibrillation (AFib) is a major contributor to recurrent but preventable ischemic Stroke (IS)/TIA. However, majority of stroke patients suffer from paroxysmal asymptomatic AFib, which implies stroke health system to implement accurate AFib detection strategies to large scale population. Current practices of AFib screening methods provided by Stroke Units (SU) organization and network in France are currently unknown and uncovered by dedicated guidelines.

Purpose

To assess the methodology of Afib screening in French SU.

Methods

A French Nationwide survey was led (September-November 2020) with on-line structured questionnaires sent to individual targeted stroke-physicians (SP) and heads of SU in France.We analyzed qualitative and quantitative availability and current use of AFib detection tools during acute inhospital and outpatient subacute and chronic post-IS phases.

Results

67% of 140 heads of SU and 33% of SP responded across all continental and overseas French regions.Main clinical characteristics that lead to search Afib are: TIA/IS recurrence under antiplatelet therapy (97%), patient's age (74%), proximal occlusion of a major cerebral artery (72%). Afib is highly suspected when there is: recent brain IS in multiple vascular territories (100%), previous IS in another vascular territory (98%), left atrial enlargement (96%), burst of supraventricular tachycardia &lt;30s (94%). In-hospital cardiac monitoring is considered to be mandatory by 90% of SU teams but only 1/3 of those possess telemetry out of intensive care unit. Outpatient cardiac monitoring is considered of major interest/necessary by 100% of SP. When first line 24-hour Holter monitor is normal and Afib is highly suspected, 75% of the SP required outpatient noninvasive monitoring (NIM) for at least 7 days and more than half required insertable cardiac monitor (ISC). ISC are implanted each year by SU for &lt;10 patients in 44% and &lt;50 patients in 94%. The delay IS-ICM implantation is &lt;1 month in 10%, 1–3 months in 52%, 3–6 months in 29% and &gt;6 months in 9%. Accessibility to outpatient monitoring modalities is graded: fairly easy for 24/48h-Holter (85%) and ISC (68%); rather difficult/impossible for 3–7 days NIM (51%), 8–21 days NIM (75%) or e-ECG tools (99%). Main obstacles to monitoring abilities development in SU were lack of: manpower (80%), efficient network with cardiologists (56%), familiarity of techniques (42%); and technical equipment cost (44%). 96.5% of SU teams deem necessary practice decision support flowchart with cardiologist partnership but 19% use for it.

Conclusion

The survey raises concern about lack of a systematic strategy and shortcomings for Afib detection capacities. These results are a call to establish practice-guidelines and to promote an improvement plan for AFib detection (selection of the patients, tools and prioritization of the exams) after TIA/IS in France which will require a strong collaboration between neurologists and cardiologists.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): BMS-Pfizer

Prevalence of carotid web in a French cohort of cryptogenic stroke

BACKGROUND AND PURPOSE

Carotid webs (CaW) may be an under-recognized cause of anterior circulation cryptogenic ischemic stroke (ACIS). Prevalence is still unknown in European patients with ACIS.

OBJECTIVE

To evaluate the prevalence of CaW in ACIS and describe patients with CaW phenotype in a cohort of patients from a French stroke center.

METHODS

We conducted a retrospective monocentric cohort study from 01/01/2015 to 31/12/2019 (Montpellier University Hospital, France), in consecutive anterior ischemic stroke (AIS) patients ≤65 years old from a prospective stroke database. Using ASCOD phenotyping, ACIS patients were selected and cervical CTA were reviewed to find CaW.

RESULTS

Among 1053 consecutive AIS patients, 266 ACIS patients with CTA were included. Among patients included (mean age 50, women 58%), CaW was in the ipsilateral carotid (iCaW) in 21 patients: 7.9% (95%CI [4.6-11.1]), (mean age 51, 11 women, 16 Caucasian). iCaW were uncovered during study review of CTA in 6/21 (29%) patients. Comparison between patients with iCaW and those without iCaW showed no differences except that of a higher rate of intracranial large vessel occlusion (LVO) (62.4 vs 37.6%; p = 0.03). Patients with iCaW under conservative medical therapy had an annualized stroke recurrence rate (SRR) of 11.4% (95%CI [8.4-15.1].

CONCLUSIONS

iCaW was identified as a source of stroke in about 8% of a French population ≤65 years with ACIS. iCaW was associated with a higher rate of LVO and a high SRR under conservative medical therapy.

Carotid webs associated with ischemic stroke. Updated general review and research directions

Carotid web (CaW) is an intimal variant of fibromuscular dysplasia strongly associated with ipsilateral cerebral infarction. Although considered rare, it is a recent and increasing concern for physicians involved in stroke diagnosis and management. The present general review relies on a systematic literature analysis and aims to update readers on the latest knowledge in the field of symptomatic CaW (syCaW). CaW associated with ipsilateral cerebral infarction or transient ischemic attack has been identified in 189 patients. Ischemic strokes (IS) mostly occur in middle age (mean 46 years) and predominately in females (66%). The high frequency of African descendant patients among case reports and series (58%) suggests an ethnic susceptibility for CaW development. CaW features are characterised by a shelf-like intraluminal defect on contrast sagittal imaging, a linear defect that splits the lumen on axial section, a post-contrast stagnation rostral to the lesion and a frequent contralateral mirrored CaW (26.6%). An artery-to-artery embolism mechanism is widely accepted via CaW blood stasis, thrombus formation and clot fragmentation scattered by blood flow. Therefore, cerebral infarctions are often large related to a high proportion of proximal occlusion (62.5%). CaW confers a high rate of IS recurrence despite standard anti-platelet treatment that reaches 33.3% of patients prospectively followed with a median time to event of one year. Although no randomised therapeutic studies are available, surgery (n=39) or stenting (n=50) have been often proposed and seem to avoid recurrences. CaW clearly emerges as a cause of cryptogenic embolic stroke and should be systematically investigated in routine. A large number of points remain to be elucidated and CaW patients should be steadily included in registries and randomised therapeutic studies.

Predictors of Favorable Outcome after Endovascular Thrombectomy in MRI: Selected Patients with Acute Basilar Artery Occlusion

BACKGROUND AND PURPOSE

Clinical outcomes after endovascular treatment for acute basilar artery occlusions need further investigation. Our aim was to analyze predictors of a 90-day good functional outcome defined as mRS 0-2 after endovascular treatment in MR imaging-selected patients with acute basilar artery occlusions.

MATERIALS AND METHODS

We analyzed consecutive MR imaging-selected patients with acute basilar artery occlusions endovascularly treated within the first 24 hours after symptom onset. Successful and complete reperfusion was defined as modified TICI scores 2b-3 and 3, respectively. Outcome at 90 days was analyzed in univariate and multivariate analysis regarding baseline patient treatment characteristics and periprocedural outcomes.

RESULTS

One hundred ten patients were included. In 10 patients, endovascular treatment was aborted for failed proximal/distal access. Overall, successful reperfusion was achieved in 81.8% of cases (n = 90; 95% CI, 73.3%-88.6%). At 90 days, favorable outcome was 31.8%, with a mortality rate of 40.9%; the prevalence of symptomatic intracranial hemorrhage within 24 hours was 2.7%. The median time from symptom onset to groin puncture was 410 minutes (interquartile range, 280-540 minutes). In multivariable analysis, complete reperfusion (OR = 6.59; 95% CI, 2.17-20.03), lower pretreatment NIHSS (OR = 0.77; 95% CI, 0.64-0.94), the presence of posterior communicating artery collateral flow (OR = 2.87; 95% CI, 1.05-7.84), the absence of atrial fibrillation (OR = 0.18; 95% CI, 0.03-0.99), and intravenous thrombolysis administration (OR = 2.75; 95% CI, 1.04-7.04) were associated with 90-day favorable outcome.

CONCLUSIONS

In our series of MR imaging-selected patients with acute basilar artery occlusions, complete reperfusion was the strongest predictor of a good outcome. Lower pretreatment NIHSS, the presence of posterior communicating artery collateral flow, the absence of atrial fibrillation, and intravenous thrombolysis administration were associated with favorable outcome.

Interlaboratory Validation of the Vidas SET2 Kit for Detection of Staphylococcal Enterotoxins in Milk Products

An earlier intralaboratory validation study based on the EN ISO 16140 Standard conducted by the Community Reference Laboratory for coagulase-positive staphylococci including Staphylocococcus aureus showed that, after an extraction step using dialysis concentration, the Vidas SET2 detection kit could be used to screen staphylococcal enterotoxins in milk and milk products. In order to fully validate Vidas SET2, an interlaboratory study was organized. Six freeze-dried samples and 3 ready-to-use concentrated extracts were analyzed by 21 laboratories according to the method, including a detection with Vidas SET2. Results did not show false-positive or -negative results. Accordance and concordance parameters were equal to 100%, corresponding to a concordance odds ratio of 1. This interlaboratory study confirmed the satisfactory outcome of the preliminary tests and of the intralaboratory study performed previously. The Vidas SET2 detection kit can be used as a method for the detection of staphylococcal enterotoxins in milk and milk products as well as the Transia Plate SET detection kit in the European screening method for official control purposes, after an extraction step followed by dialysis concentration.

Results of a 1-year quality-improvement process to reduce door-to-needle time in acute ischemic stroke with MRI screening

OBJECTIVE

To determine the effects of a 1-year quality-improvement (QI) process to reduce door-to-needle (DTN) time in a secondary general hospital in which multimodal MRI screening is used before tissue plasminogen activator (tPA) administration in patients with acute ischemic stroke (AIS).

METHODS

The QI process was initiated in January 2015. Patients who received intravenous (iv) tPA<4.5h after AIS onset between 26 February 2015 to 25 February 2016 (during implementation of the QI process; the "2015 cohort") were identified (n=130), and their demographic and clinical characteristics and timing metrics compared with those of patients treated by iv tPA in 2014 (the "2014 cohort", n=135).

RESULTS

Of the 130 patients in the 2015 cohort, 120 (92.3%) of them were screened by MRI. The median DTN time was significantly reduced by 30% (from 84min in 2014 to 59min; P<0.003), while the proportion of treated patients with a DTN time≤60min increased from 21% to 52% (P<0.0001). Demographic and baseline characteristics did not significantly differ between cohorts, and the improvement in DTN time was associated with better outcomes after discharge (patients with a 0-2 score on the modified rankin scale: 59% in the 2015 cohort vs 42.4% in the 2014 cohort; P<0.01). During the 1-year QI process, the median DTN time decreased by 15% (from 65min in the first trimester to 55min in the last trimester; P≤0.04) with a non-significant 1.5-fold increase in the proportion of treated patients with a DTN time≤60min (from 41% to 62%; P=0.09).

CONCLUSION

It is feasible to deliver tPA to patients with AIS within 60min in a general hospital, using MRI as the routine screening modality, making this QI process to reduce DTN time widely applicable to other secondary general hospitals.

Hemorrhagic risk of recent silent cerebral infarct on prethrombolysis MR imaging in acute stroke

BACKGROUND AND PURPOSE

EIH is a rare complication after thrombolysis in patients with acute stroke, occurring in brain regions without visible ischemic change on pretreatment imaging. RSCIs can be detected by multimodal MR imaging and might be associated with an increased risk of HT postthrombolysis, related to BBBD. We aimed to assess the incidence of RSCI on pretreatment MR imaging and the subsequent risk of HT within RSCI areas on follow-up CT performed <36 hours after rtPA administration and on additional cerebral imaging before patient discharge.

MATERIALS AND METHODS

Pretreatment MR imaging was retrospectively analyzed from consecutive patients with stroke who received intravenous or intra-arterial rtPA for 2 years. RSCI was defined on MR imaging as a parenchymal area markedly hyperintense on FLAIR, different from the hyperacute infarct, and mildly-to-markedly hyperintense on DWI or enhanced on postgadolinium T1WI imaging.

RESULTS

Eighty-six patients with a median age of 66 years and a median NIHSS score on admission of 15 were studied; 66.3% received rtPA intravenously. The presence of RSCI was identified in 10 patients (11.6%) and was associated with large-vessel-disease etiology (40% versus 5.3%, P < .001) on univariate analysis. No HT was identified within the RSCI areas on any follow-up cerebral imaging.

CONCLUSIONS

These preliminary results require validation but suggest that small RSCIs are rather frequent and might not pose a higher risk of postthrombolysis HT.

Une crampe de l’écrivain associée à une ataxie spinocérébelleuse de type 7

Spinocerebellar ataxia type 7 (SCA 7) is a rare autosomal dominant neurodegenerative disorder (ADCA) caused by expansion of a highly unstable CAG repeat. Clinical features including progressive cerebellar, retinal degeneration and pyramidal signs. We report a patient with SCA 7 diagnosis revealed by progressive cerebellar ataxia and writer's cramp.

Influence des poussées sur la survenue d’un handicap au long cours dans la sclérose en plaques de forme rémittente : étude observationnelle de 99 patients

INTRODUCTION

Rate of relapse occurring during the first 5 years of MS-RR is a prognosis factor of occurrence of disability or secondary progressive (SP) phase. Progressive phase, related to chronic axonal loss, is mainly considered as the principal factor of disability progression. Influence of acute relapses during the relapsing-remitting phase on disability development is not known as a prognosis factor.

OBJECTIVES

To determine the influence of the exacerbations among patients with RR-MS after the second clinical event on the disability occurrence.

METHODS

Diagnosis of multiple sclerosis was established according to Poser's classification. Disability measurement was made with the use of the Expanded Disability Status Scale (EDSS). The patients included in the study were classified as clinically definite RR-MS, with an EDSS score<or=3.5. The progressive phase was defined as the steady worsening of symptoms and signs for at least 6 months (Schumacher et al., 1965; Lublin and Reingold, 1996). The exacerbations were quoted and evaluated by a neurologist and the residual disability lasting at least 6 months after an acute event was measured with the EDSS. A score of 4.0 corresponds to limited walking ability, but without aid or rest for>500 m. The study began at the time of the second clinical event and ended when an EDSS score of 4.0 was reached or when a SP phase was beginning or at the last follow-up visit date if these two stages were not reached. The primary outcome measure was the comparison of the risk and the average time to reach an EDSS>or=4.0 or a SP form according to the annual exacerbation rate (AER) using Kaplan-Meier survival curve.

RESULTS

Among the 238 ms patients of the database, 136 patients were classified as having a definite RR-MS. Among these 136 patients, 99 patients could be included in the study according to the inclusion criteria. The median follow up of the patients since the first clinical event was 9.8 years (range 4 to 44). The average EDSS score was 0.7 at the beginning of the study and 2.3 at the end. 20.2p.cent of patients (n=20) reached an EDSS score of 4.0 or a SP-MS. The median AER was 0.4 and the average 0.62 (range 0 to 6.1). The time to reach the primary end point for 25p.cent of the population was 17.8 years in group with an AER<0.4 (group A) and 6.9 years in group with an AER>0.4 (group B) (logrank; p<0.0001). The relative risk for patients of the group B compared to group A to reach an EDSS of 4.0 or a SP form was 8.01 (IC-95p.cent: 2.74-23.46; p=0.0001).

CONCLUSIONS

In spite of a limited number of patients, this study gives evidence that a high rate of acute exacerbations in RR-MS patients after the second clinical event may be an independent predictive factor of long-term residual disability progression. High relapse rate leads to a more frequent and faster SP or EDSS>4.0 occurrence.

Traitement par chimiothérapie d’un syndrome neurologique paranéoplasique anti-Hu sans cancer actif associé

INTRODUCTION

Anti-Hu associated paraneoplastic neurological syndromes are rare and characterized by poor prognosis. The research and treatment of a related cancer, a small-cell lung cancer most of the time, remains the best therapeutic strategy.

CASE REPORT

We describe the clinical course of a paraneoplastic subacute sensory neuronopathy associated with anti-Hu antibodies in a male smoker treated by an early chemotherapy active against a small-cell lung cancer although no tumor could be found at repeated evaluations. In spite of this treatment, the neurological state deteriorated with the appearance of a cerebellar degeneration, and limbic encephalitis which resulted in a loss of autonomy. A small-cell lung cancer was found and treated 65 months after the onset of the neurological symptoms. The treatment of the underlying malignancy, when it can be found, is still considered as the optimal treatment for paraneoplastic neurological syndromes. Although no tumor could be found, we treated our patient with an empirical chemotherapy active against the most frequent malignancy associated to anti-Hu syndrome in a smoker man, without any improvement.

CONCLUSION

Active and repeated research for a cancer related to an anti-Hu neurological syndrome and its treatment are undispensable. For our patient without any identified cancer empirical chemotherapy treatment was unable to stop neurological worsening. When no tumor can be identified by conventional imaging techniques, an early FDG-PET scan should be considered and then repeated if normal.

Sirolimus-associated acute respiratory distress syndrome in a renal transplant recipient

Sirolimus is a new potent immunosuppressive drug used in organ transplantation; its major advantage is the absence of deterioration in renal function. Documented adverse effects include myelosuppression and hyperlipidemia. Recently several cases of sirolimus-associated interstitial pneumonitis have been reported, usually of mild severity. We report a new case that was complicated by a severe acute respiratory distress syndrome, which required several days of mechanical ventilation. No infectious or cardiogenic etiology was documented. Low sirolimus blood levels and acute CD4 lymphocytic alveolitis suggested an immune-related mechanism rather than a direct toxic effect of the drug. The patient recovered after discontinuation of sirolimus and the administration of corticosteroids.

Infarctus latéro-bulbaire sur dissection intracrânienne suivi d’une hémorragie sous-arachnoïdienne

INTRODUCTION

Intracranial vertebral artery dissecting aneurysms are a recognized cause of subarachnoid hemorrhage and the hemorrhagic recurrence risk after a first rupture of the dissecting aneurysm is high and of poor prognosis. However, when the dissection is discovered in a patient with vertebrobasilar territory ischemia, little is known about the risk of hemorrhagic rupture risk and there is no consensus on management.

OBSERVATION

We report the case of a 49-year-old man who developed subarachnoid hemorrhage 48 hours after the occurrence of a latero-bulbar syndrome caused by a spontaneous dissection with occlusion of the right vertebral artery. The subsequent angiography showed a V4 dissecting aneurysm of the right vertebral artery which was treated by stenting and coiling without any complications.

CONCLUSION

This case underlines the hemorrhagic risk of an intradural vertebral artery dissection and its possible progression to aneurysm. Subsequent angiographic imaging must be carefully examined to search for aneurysms which may require early specific treatment because of the high risk of recurrent bleeding.

Semi-synthesis, topoisomerase I and kinases inhibitory properties, and antiproliferative activities of new rebeccamycin derivatives

In the course of structure-activity relationship studies, new rebeccamycin derivatives substituted in 3,9-positions on the indolocarbazole framework, and a 2',3'-anhydro derivative were prepared by semi-synthesis from rebeccamycin. The antiproliferative activities against nine tumor cell lines were determined and the effect on the cell cycle of murine leukemia L1210 cells was examined. Their DNA binding properties and inhibitory properties toward topoisomerase I and three kinases PKCzeta, CDK1/cyclin B, CDK5/p25 and a phosphatase cdc25A were evaluated. The 3,9-dihydroxy derivative is the most efficient compound of this series toward CDK1/cyclin B and CDK5/p25. It is also characterized as a DNA binding topoisomerase I poison. Its broad spectrum of molecular activities likely accounts for its cytotoxic potential. This compound which displays a tumor cell line-selectivity may represent a new lead for subsequent drug design in this series of glycosylated indolocarbazoles.

Characterization and radiosensitivity at high or low dose rate of four cell lines derived from human thyroid tumors

PURPOSE

This study attempted to establish cell lines derived from human differentiated thyroid tumors, and to characterize and evaluate the radiation dose-rate effect.

METHODS AND MATERIALS

Two cell lines (K1 and K2) were derived from papillary carcinomas, one (K7) from a follicular less-differentiated carcinoma and one (A14) from a follicular adenoma. Cell-survival curves after irradiation were established by the in vitro colony method. Radiation doses were delivered either at a high (45.9 Gy/h) or low dose rate (0.6 Gy/h) by a 60Co source. The data were analyzed according to the linear quadratic and multitarget model of radiation action.

RESULTS

Doubling times were around 24 h. All cell lines were positive for intracellular thyroglobulin. Cyclic adenosine monophosphate (cAMP) response to thyrotropin (TSH) was significant for the cell lines derived from the follicular adenoma and follicular carcinoma. The two cell lines derived from papillary carcinomas were tumorigenic after inoculation into nude mice. After high-dose-rate irradiation, the surviving fraction at 2 Gy (SF2) was not significantly different for the three malignant cell lines K1, K2, and K7, and ranged from 0.39 to 0.42. For the adenoma cell line A14, we found a higher radiosensitivity with a lower SF2 value and a higher alpha parameter. After low-dose-rate irradiation, only one cell line (K2) showed a significant low-dose-rate sparing with a dose reduction factor of 1.35.

CONCLUSION

The major result of our study is the weak effect of the dose rate on the survival of thyroid cell lines.

Biological dosimetry in patients treated with iodine-131 for differentiated thyroid carcinoma

Biological dosimetry was applied to 30 patients with differentiated thyroid carcinoma who were treated with 131I (3.7 GBq) to ablate thyroid remnants after surgery or in case of metastases.

METHODS

Chromosomal aberrations were scored in peripheral blood samples obtained before and 4 days after the first administration of 3.7 GBq 131I according to two methods: conventional cytogenetics and chromosome 4 painting. This generated a dosimetric index that reflects the dose to the bone marrow.

RESULTS

Results of both techniques were in close agreement. The mean dosimetric index at Day 4 was 0.54 Gy (95% CI: 0.45-0.62 Gy) by conventional cytogenetics and 0.48 Gy (95% CI: 0.42-0.61 Gy) by chromosome 4 painting. This dose is 2-4 times higher than that derived from the MIRD estimates. Since blood was drawn at Day 4, this technique underestimates the dose by at least a third. The high dose estimate may be related to the hypothyroid status of these patients at the time of 131I administration, a condition which decreases renal clearance of 131I and thus increases whole-body irradiation. This dose estimate was closely related to whole-body retention of 131I at Day 4.

CONCLUSION

These data should be used to estimate the risk due to 131I exposure.

Simultaneous determination of plasma levels of fluvoxamine and of the enantiomers of fluoxetine and norfluoxetine by gas chromatography-mass spectrometry

A gas chromatographic-mass spectrometric method is presented which allows the simultaneous determination of the plasma concentrations of fluvoxamine and of the enantiomers of fluoxetine and norfluoxetine after derivatization with the chiral reagent, (S)-(-)-N-trifluoroacetylprolyl chloride. No interference was observed from endogenous compounds following the extraction of plasma samples from six different human subjects. The standard curves were linear over a working range of 10 to 750 ng/ml for racemic fluoxetine and norfluoxetine and of 50 to 500 ng/ml for fluvoxamine. Recoveries ranged from 50 to 66% for the three compounds. Intra- and inter-day coefficients of variation ranged from 4 to 10% for fluvoxamine and from 4 to 13% for fluoxetine and norfluoxetine. The limits of quantitation of the method were found to be 2 ng/ml for fluvoxamine and 1 ng/ml for the (R)- and (S)-enantiomers of fluoxetine and norfluoxetine, hence allowing its use for single dose pharmacokinetics. Finally, by using a steeper gradient of temperature, much shorter analysis times are obtained if one is interested in the concentrations of fluvoxamine alone.

High frequency deletion of the tumour suppressor gene P16INK4a (MTS1) in human thyroid cancer cell lines

p16INK4a (MTS1) is an important negative regulator of mammalian cell proliferation, acting via inhibition of CDK4/cyclin D-dependent phosphorylation of pRb to prevent progression through the G1 phase of the cell cycle. Loss of p16 activity by either gene deletion, mutation or transcriptional inactivation has now been found in a wide range of human cancers of both epithelial and mesenchymal origin, at a frequency rivalling that of p53 mutation. As a first step towards investigating its possible role as a tumour suppressor gene in thyroid tumorigenesis, we have carried out a Southern blot analysis of the p16 gene locus in a series of cell lines derived from differentiated human thyroid cancers. Homozygous deletion of the entire p16 coding sequence was observed in two of three follicular and two of four papillary cancer cell lines, but not in normal tissue or normal cells immortalised by SV40 T antigen. Given the co-existence of p16 abnormalities in primary tumours and cell lines observed in other tumour types, this high frequency of deletion suggests that p16 is a key tumour suppressor gene in the genesis of differentiated thyroid cancer.

Cytogenetic characterization of a new human papillary thyroid carcinoma permanent cell line (GLAG-66)

A new permanent cell line (GLAG-66) has been established from the metastases of a papillary thyroid carcinoma in a male patient. Herein are reported the cytogenetic characteristics of this new cell line, which is tumorigenic in athymic mice. An aneuploid chromosomal pattern was observed (48 chromosomes) with various chromosomal abnormalities. The karyotype was: 48,XY,der(1)t(9;1;9), +der(8)t(1;8),der(9)t(1;9),der(9)t(1;9), +14. This cell line should prove to be of great value in the study of the biology of human papillary thyroid carcinomas.

The initial slope of human tumor cell survival curves: its modification by the oxic cell sensitizer beta-arabinofuranosyladenine

The initial slope of the survival curve, which is a characteristic of each tumor cell line, varies with the histological group of the tumor. It is one of the factors on which clinical radioresponsiveness depends. The DNA dependant DNA polymerase inhibitor beta-ara A acts as an oxic cell sensitizer. This study was carried out on human tumor cell lines to look for a correlation between the degree of radiosensitization induced by beta-ara A and the radiosensitivity of a given cell line. Six human tumor cell lines with different radiosensitivities were used (the survival rate at 2 Gy and D ranged from 20 to 73% and from 1.2 to 3.2 Gy, respectively). beta-ara A had a major toxic effect on all cell lines but this varied greatly from one cell line to another and was concentration dependant; this toxic effect was taken into account when calculating the surviving fractions. For all cell lines, beta-ara A acted as an oxic radiosensitizer and the radiosensitization was concentration dependant. Analysis of the survival curves of the 6 cell lines using the linear quadratic model showed that concentrations of beta-ara A between 200 and 1000 microM induced an increase in the linear component while the quadratic component underwent no systematic change. The sensitizing enhancement ratio (SER) measured from the Ds ratios, varied greatly from one line to another. For example, at a concentration of 500 microM, the extreme values of Ds ratios were 1.5 and 2.6. The radiosensitization is greater, the higher the radiosensitivity of the cell line studied during exponential growth. The results do not favor the use of beta-ara A in the treatment of intrinsically radioresistant human tumors.