Computational approaches in cancer multidrug resistance research: Identification of potential biomarkers, drug targets and drug-target interactions.

Like physics in the 19th century, biology and molecular biology in particular, has been fertilized and enhanced like few other scientific fields, by the incorporation of mathematical methods. In the last decades, a whole new scientific field, bioinformatics, has developed with an output of over 30,000 papers a year (Pubmed search using the keyword "bioinformatics"). Huge databases of mass throughput data have been established, with ArrayExpress alone containing more than 2.7 million assays (October 2019). Computational methods have become indispensable tools in molecular biology, particularly in one of the most challenging areas of cancer research, multidrug resistance (MDR). However, confronted with a plethora of different algorithms, approaches, and methods, the average researcher faces key questions: Which methods do exist? Which methods can be used to tackle the aims of a given study? Or, more generally, how do I use computational biology/bioinformatics to bolster my research? The current review is aimed at providing guidance to existing methods with relevance to MDR research. In particular, we provide an overview on: a) the identification of potential biomarkers using expression data; b) the prediction of treatment response by machine learning methods; c) the employment of network approaches to identify gene/protein regulatory networks and potential key players; d) the identification of drug-target interactions; e) the use of bipartite networks to identify multidrug targets; f) the identification of cellular subpopulations with the MDR phenotype; and, finally, g) the use of molecular modeling methods to guide and enhance drug discovery. This review shall serve as a guide through some of the basic concepts useful in MDR research. It shall give the reader some ideas about the possibilities in MDR research by using computational tools, and, finally, it shall provide a short overview of relevant literature.

Atomistic Picture of Fluorescent Probes with Hydrocarbon Tails in Lipid Bilayer Membranes: An Investigation of Selective Affinities and Fluorescent Anisotropies in Different Environmental Phases.

By reverting to spectroscopy, changes in the biological environment of a fluorescent probe can be monitored and the presence of various phases of the surrounding lipid bilayer membranes can be detected. However, it is currently not always clear in which phase the probe resides. The well-known orange 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbo-cyanine perchlorate (DiI-C18(5)) fluorophore, for instance, and the new, blue BODIPY (4,4-difluoro-4-bora-3 a,4 a-diaza- s-indacene) derivative were experimentally seen to target and highlight identical parts of giant unilamellar vesicles of various compositions, comprising mixtures of dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylcholine (DOPC), sphingomyelin (SM), and cholesterol (Chol). However, it was not clear which of the coexisting membrane phases were visualized (Bacalum et al., Langmuir. 2016, 32, 3495). The present study addresses this issue by utilizing large-scale molecular dynamics simulations and the z-constraint method, which allows evaluating Gibbs free-energy profiles. The current calculations give an indication why, at room temperature, both BODIPY and DiI-C18(5) probes prefer the gel (So) phase in DOPC/DPPC (2:3 molar ratio) and the liquid-ordered (Lo) phase in DOPC/SM/Chol (1:2:1 molar ratio) mixtures. This study highlights the important differences in orientation and location and therefore in efficiency between the probes when they are used in fluorescence microscopy to screen various lipid bilayer membrane phases. Dependent on the lipid composition, the angle between the transition-state dipole moments of both probes and the normal to the membrane is found to deviate clearly from 90°. It is seen that the DiI-C18(5) probe is located in the headgroup region of the SM/Chol mixture, in close contact with water molecules. A fluorescence anisotropy study also indicates that DiI-C18(5) gives rise to a distinctive behavior in the SM/Chol membrane compared to the other considered membranes. The latter behavior has not been seen for the studied BODIPY probe, which is located deeper in the membrane.

Structural patterns of the human ABCC4/MRP4 exporter in lipid bilayers rationalize clinically observed polymorphisms.

The ABCC4/MRP4 exporter has a clinical impact on membrane transport of a broad range of xenobiotics. It is expressed at key locations for drug disposition or effects such as in the liver, the kidney and blood cells. Several polymorphisms and mutations (e.g., p.Gly187Trp) leading to MRP4 dysfunction are associated with an increased risk of toxicity of some drugs. So far, no human MRP4 structure has been elucidated, precluding rationalization of these dysfunctions at a molecular level. We constructed an atomistic model of the wild type (WT) MRP4 and the p.Gly187Trp mutant embedded in different lipid bilayers and relaxed them for hundreds of nanoseconds by molecular dynamics simulations. The WT MRP4 molecular structure confirmed and ameliorated the general knowledge about the transmembrane helices and the two nucleotide binding domains. Moreover, our model elucidated positions of three generally unresolved domains: L1 (linker between the two halves of the exporter); L0 (N-terminal domain); and the zipper helices (between the two NBDs). Each domain was thoroughly described in view of its function. The p.Gly187Trp mutation induced a huge structural impact on MRP4, mainly affecting NBD 1 structure and flexibility. The structure of transporter enabled rationalization of known dysfunctions associated with polymorphism of MRP4. This model is available to the pharmacology community to decipher the impact of any other clinically observed polymorphism and mutation on drug transport, giving rise to in silico predictive pharmacogenetics.

Mechanism of one-electron oxidation of metformin in aqueous solution.

Hydroxyl free radical-induced oxidation of metformin was studied in aqueous solution as a function of the pH. Hydroxyl free radicals were generated by gamma radiolysis of water and the oxidation end-products were quantified by high-performance liquid chromatography coupled to mass spectrometry (HPLC/MS), as a function of the radiation dose. This work is a joint experimental and theoretical (DFT) approach that has paved the way towards a comprehensive rationalization of the one-electron mechanisms of MTF oxidation, as a function of the pH.

Application of recent double-hybrid density functionals to low-lying singlet-singlet excitation energies of large organic compounds.

The present work assesses some recently developed double-hybrid density functionals (B2π-PLYP, PBE0-DH, and PBE0-2) using linear-response Tamm-Dancoff Time-Dependent Density Functional Theory. This assessment is achieved against experimentally derived low-lying excitation energies of large organic dyes of recent interest, including some excitations dominated by charge-transfer transitions. Comparisons are made with some of the best-performing methods established from the literature, such as PBE0 or B3LYP hybrid or the recently proposed B2-PLYP and B2GP-PLYP double-hybrid models, to ascertain their quality and robustness on equal footing. The accuracy of parameter-free or empirical forms of double-hybrid functionals is also briefly discussed. Generally speaking, it turns out that double-hybrid expressions always provide more accurate estimates than corresponding hybrid methods. Double-hybrid functionals actually reach averaged accuracies of 0.2 eV, that can be admittedly considered close to any intended accuracy limit within the present theoretical framework.

Friedreich's ataxia: autosomal recessive disease caused by an intronic GAA triplet repeat expansion.

Friedreich's ataxia (FRDA) is an autosomal recessive, degenerative disease that involves the central and peripheral nervous systems and the heart. A gene, X25, was identified in the critical region for the FRDA locus on chromosome 9q13. This gene encodes a 210-amino acid protein, frataxin, that has homologs in distant species such as Caenorhabditis elegans and yeast. A few FRDA patients were found to have point mutations in X25, but the majority were homozygous for an unstable GAA trinucleotide expansion in the first X25 intron.

Free radical scavenging properties of guaiacol oligomers: a combined experimental and quantum study of the guaiacyl-moiety role.

Natural polyphenols are known to exhibit a lot of different biological properties, including antioxidant activity. For some polyphenols these activities are attributed to the presence of a guaiacol moiety. In the present paper we focus on the role of this moiety. For this purpose nine different compounds were enzymatically synthesized from guaiacol. To elucidate the structure-activity relationship of these polyphenols, DFT-(PCM)B3P86/6-311+G(2d,3pd)//(PCM)B3P86/6-31+G(d,p) calculations supported the experimental DPPH free radical scavenging activities. The antioxidant activities were correlated to (i) O-H BDEs (bond dissociation enthalpies), (ii) BDE(D) (BDE of a second H atom abstraction from the phenoxyradicals), (iii) spin density, (iv) HOMO (highest occupied molecular orbital) distribution, (v) IPs (ionization potentials), (vi) DeltaG and DeltaG(#) free energies of HAT (H atom transfer), and (vii) HAT rate constants. BDE(D) appeared to be the most important descriptor to understand the free radical scavenging ability of these compounds.

[Long-term outcome in patients with symptomatic low-grade oligodendrogliomatous tumors treated by cytotoxic agents]. / Effets à long terme de la chimiothérapie chez 7 patients présentant un gliome de bas grade symptomatique.

INTRODUCTION: Whether aggressive treatment or no treatment is the optimal management for low-grade gliomas is controversial. However, symptomatic low-grade gliomas require prompt therapeutic intervention because of neurological impairment, uncontrolled seizures, and deterioration of life quality. METHODS: We report the long-term follow-up, 71 months, of seven patients treated by procarbazine, lomustine and vincristine (PCV) therapy for a symptomatic low-grade oligodendrogliomatous tumor. The mean age at diagnosis was 47 years, the mean time from first symptoms to initiation of PCV therapy was 62 months (range 15-147). RESULTS: All patients initially responded favorably, with improvement of the neurological symptoms and radiological response. Chemotherapy was clinically well tolerated, the main side effect being low hematological toxicity. During the follow-up, no progression was observed in two patients. For the five remaining patients, the time to progression after the PCV induction was 56+/-12 months (range 38 to 73). Four of these patients showed favorable response to a second line of treatment. CONCLUSION: PCV therapy is an interesting therapeutic option for progressively symptomatic low-grade gliomas, even in cases with large tumoral volume. This treatment, of moderate toxicity, improves the quality of life and can result in long-term tumor stabilization.

[Management of malignant gliomas diagnosed during pregnancy]. / Prise en charge des gliomes malins découverts au cours d'une grossesse.

INTRODUCTION: Glioma is seldom diagnosed during pregnancy. In this situation management presents difficult problems for both neuro-oncologists and obstetricians. We report four cases and discuss the management of this unusual situation. CASE REPORT: The first patient was admitted to hospital at 29 weeks' gestation because of a generalized seizure and a right hemiparesis. MRI showed a left fronto-insular lesion. A stereotactic biopsy was obtained and revealed an anaplastic oligodendroglioma. With corticosteroids the patient remained stable until cesarean delivery at 36 weeks. In post-partum additional treatment with chemotherapy was started. The second patient was hospitalized at 26 weeks' gestation because of cranial hypertension, right hemiparesis and aphasia. MRI showed an important left fronto-parietal lesion. Partial resection was performed at 28 weeks. Histology revealed a glioblastoma multiforme. With corticosteroids the patient remained stable until cesarean delivery at 33 weeks. In post-partum additional treatment with radiotherapy and chemotherapy was started. The third patient was admitted to the hospital at 12 weeks' gestation because of cranial hypertension. MRI showed a left frontal lesion. A subtotal resection was done at 13 weeks. Histology revealed a glioblastoma multiforme. Two weeks after surgery the patient's neurological condition worsened and in agreement with the patient a therapeutic abortion was decided. Afterwards additional treatment with radiotherapy and chemotherapy was started. The last patient received combined treatment with radiotherapy and chemotherapy for local recurrence of a mesencephalic high-grade glioma. A posteriori it was discovered that the patient was at 4 months' gestation during this treatment. Cesarean delivery was done at 36 weeks. The child was normal at birth and is still in good health 5 years later. CONCLUSION: The management of gliomas diagnosed during pregnancy should not be different from the standard management of gliomas in young non-pregnant adults. Pregnant women because of their young age can have a long survival. Their pregnancy should not prevent them from receiving the best treatment for their glioma. Treatment will depend upon clinico-radiological presentation, histology, gestational age and the patient's desires. Generally speaking, surgical resection of high-grade gliomas should not be delayed during pregnancy. Progress in anesthesia and neurosurgery have greatly reduced the risks for the foetus. After delivery, if the delay between surgery and delivery is too long it is possible to begin cerebral radiotherapy during pregnancy. After the first trimester of gestation this treatment can be given without any important risks for the child.

FDG-PET improves tumour detection in patients with paraneoplastic neurological syndromes.

To determine the usefulness of [18F]fluorodeoxyglucose (FDG) whole body FDG-PET in the diagnosis of tumours in patients with paraneoplastic neurological syndromes (PNS), we prospectively studied 20 patients with paraneoplastic antibodies in whom conventional imaging gave negative or inconclusive results for the presence of tumour. All 20 patients had neurological manifestations compatible with PNS and well-characterized paraneoplastic antibodies (12 anti-Hu, one anti-Hu and anti-CV2, one anti-CV2, four anti-Yo, one anti-Ri and one anti-amphiphysin). The mean delay between the onset of neurological symptoms and FDG-PET was 10 months (range 1-54). In these 20 patients, abnormal uptake was demonstrated in 18 patients, with some patients having abnormal signal in several areas. We observed abnormal uptake in the mediastinum (13 cases), lung (two cases), breast (two cases), parotid gland (one case), or the cervical, supraclavicular or axillary lymph nodes (seven cases). Following FDG-PET, the histological diagnosis of the tumour was made in 14 patients (small cell lung carcinoma in eight cases, breast adenocarcinoma in two, lung adenocarcinoma in two, axillary metastasis of ovary carcinoma in one, and malignant thymoma in one). Two other patients with abnormal FDG uptake showed radiological evidence of lung cancer, but a histological diagnosis could not be obtained. In two other patients, initial FDG-PET showed abnormal FDG uptake that was not confirmed a few months later by repeat FDG-PET. In the two patients with negative FDG-PET, peritoneal carcinomatosis was diagnosed in one and no tumour was found in the other. In our series, the sensitivity of FDG-PET for tumour detection was >83% demonstrating a clear role of this technique in the management of patients with PNS. However, in our series, the specificity of FDG uptake was only 25% due to unexplained abnormal FDG uptake in three patients and in abnormal FDG uptake due to a benign tumour in one patient. Over the study period, we saw 73 other patients with PNS and paraneoplastic antibodies. A tumour was demonstrated in 71 out of 73 by conventional techniques. Since false-positive and false-negative results are possible with FDG-PET and in most patients with PNS, the tumour is demonstrated by conventional techniques, we believe that FDG-PET should be reserved, at the moment, for patients with well-defined PNS antibodies when conventional imaging fails to identify a tumour or when lesions are difficult to biopsy.

Baseline magnetic resonance imaging parameters and stroke outcome in patients treated by intravenous tissue plasminogen activator.

BACKGROUND AND PURPOSE: We designed a prospective sequential pretreatment and posttreatment MRI study to assess the relation between neuroimaging parameters and clinical outcome in patients treated with intravenous recombinant tissue-type plasminogen activator (rtPA). METHODS: Patients with symptoms of acute hemispheric ischemic stroke were recruited. The National Institutes of Health Stroke Scale (NIHSS) score was assessed at baseline and at days 1, 7, and 60, and the modified Rankin scale (mRS) at day 60, by which outcome was classified in terms of independence (mRS score 0, 1, or 2) or severe disability or death (mRS score 3 through 6), was assigned. Multimodal stroke MRI was performed at presentation and repeated at day 1. MRI procedures included magnetic resonance angiography, T2* gradient-echo sequence, echoplanar imaging, and isotropic diffusion- (DWI) and perfusion-weighted (PWI) imaging. Patients were treated with intravenous rtPA after MRI completion. RESULTS: Twenty-nine patients (16 men and 13 women; mean+/-SD age, 65+/-14 years) underwent MRI; the mean time from symptom onset to treatment was 255+/-62 minutes. Twenty-six patients had a vessel occlusion, and 15 patients experienced a partial (Thrombolysis in Myocardial Infarction [TIMI]-2) or total (TIMI-3) recanalization at day 1, whereas 11 patients had a persistent occlusion. Mean NIHSS scores at day 60 were 5.7+/-5.4 if recanalization had occurred and 14+/-2 in cases of persistent occlusion. According to the mRS, 13 patients were independent (mRS 0 through 2), whereas severe disability or death (mRS 3 through 6) was observed in 15 patients. A better outcome was observed when recanalization was achieved (r=-0.68, P=0.0002). PWI volume and time to peak (TTP) within the DWI lesion assessed before therapy were correlated with day-60 NIHSS score (PWI volume: r=0.51, P=0.006, TTP: r=0.35, P=0.07). The day-0 DWI abnormality volume was well correlated with day-60 NIHSS score (r=0.58, P=0.001). Multiple regression linear analysis showed that 2 factors mainly influenced clinical outcome: (1) recanalization, with a high correlation with NIHSS score at day 60 (P=0.0001) and (2) day-0 DWI lesion volume, which is closely associated with day-60 NIHSS score (P=0.03). CONCLUSIONS: Baseline DWI volume and recanalization are the main factors influencing clinical outcome after rtPA for ischemic stroke.

Old microbleeds are a potential risk factor for cerebral bleeding after ischemic stroke: a gradient-echo T2*-weighted brain MRI study.

BACKGROUND AND PURPOSE: T2*-weighted gradient-echo MRI is known to detect old microbleeds (MBs), considered indicative of microangiopathy. MBs might be a potential risk factor for early cerebral bleeding (CB) after ischemic stroke. Therefore, we assessed the impact of MBs on the occurrence of CB after cerebral infarction. METHODS: We included prospectively stroke patients who had documented ischemic damage. The imaging protocol involved baseline CT scan, T2*-weighted gradient-echo MRI, diffusion-weighted imaging, T2-weighted imaging, and magnetic resonance angiography and had to be performed within 24 hours after symptom onset. The assessment of CB with T2*-weighted gradient-echo sequence necessitated a focal area of signal loss either within the ischemic area revealed by diffusion-weighted imaging or remote from it. Old MBs were defined on T2*-weighted images as homogeneous rounded areas of signal loss without surrounding edema. CT scan was systematically repeated within the first week to verify CB as diagnosed by the T2* weighted sequence. RESULTS: One hundred patients (mean age, 60 +/- 13 years; range, 19 to 83 years; 58 men, 42 women) met the inclusion criteria. MBs were seen in 20 patients on T2*-weighted imaging. Multivariate logistic regression analysis revealed that age, diabetes, previous use of antithrombotic drugs, evidence of an atherothrombotic source of stroke, and lacunar infarct were significantly associated with MBs (P<0.0001). CB was diagnosed in 26 patients: at the acute stage by T2*-gradient echo sequence in 18 patients and with CT scan performed within the first week in 8 patients. Multivariate logistic regression analysis showed that baseline National Institutes of Health Stroke Scale score, diabetes, and MBs were considered significant and independent predictors of CB (P<0.001). CONCLUSIONS: Although the pathogenesis of CB after ischemic stroke is multifactorial, the increased observation of CB in patients with MBs suggests that the associated vascular vulnerability contributes to CB.

Nuclear hemodynamic vertebrobasilar insufficiency. A new approach with the xenon Xe 133 method.

Vertebrobasilar insufficiency is a well-known syndrome, but no corresponding hemodynamic deficit has yet been established. We propose to define nuclear hemodynamic vertebrobasilar insufficiency on the basis of an oligemia lower than 35 mL/100 g per minute in the brain stem-cerebellar region with use of the xenon Xe 133 inhalation method. Fifteen patients fulfilling this criterion underwent four-vessel angiography, computed tomography, and a standardized neurologic examination. An acetazolamide test showed poor reactivity in more than half of the patients, sometimes specifically in the vertebrobasilar area. With use of single-photon emission computed tomography and intravenous technetium Tc 99m-labeled hexamethylpropyleneamineoxime in two cases, the considerable decrease of regional cerebral blood flow in the brain stem-cerebellar region was confirmed. An excellent correlation was observed between the existence of nuclear hemodynamic vertebrobasilar insufficiency and angiographically proved arterial occlusions. The dominant nuclear oligemic zone was regularly on the side of the anatomic arterial chief lesion. Clinical manifestations included rare transient ischemic attacks (in one of 15 patients), intermittent basilar symptoms (in 15 of 15 patients), and a subacute vertebrobasilar "threatening" syndrome. Thus, imaging of a nuclear hemodynamic vertebrobasilar deficit provides an objective basis to the diagnosis of vertebrobasilar insufficiency and useful objective data for revascularization surgery.

Improvement of cerebellar ataxia with levorotatory form of 5-hydroxytryptophan. A double-blind study with quantified data processing.

Some features of cerebellar ataxia have been reported to regress partially with long-term administration of 5-hydroxytryptophan or levorotatory form of 5-hydroxytryptophan. To test this effect further, 30 patients with various inherited or acquired cerebellar ataxias underwent a randomized, double-blind trial of placebo, and the levorotatory form of 5-hydroxytryptophan taken orally for four months. The levorotatory form of 5-hydroxytryptophan significantly improved the ataxia score. It also significantly modified the time of standing upright, the spread of feet, the speed of walking, speaking, and writing. In five cases in which the levorotatory form of 5-hydroxytryptophan therapy was maintained for 12 months, the effect continued progressively.

Autoantibodies to glutamate decarboxylase in a patient with cerebellar cortical atrophy, peripheral neuropathy, and slow eye movements.

OBJECTIVE: To study the existence of autoimmunity against the cerebellum in patients with sporadic cortical cerebellar atrophy. DESIGN: The presence of autoantibodies against the cerebellum in the serum and cerebrospinal fluid samples that were obtained from patients with sporadic cortical cerebellar atrophy and control patients was investigated by using immunohistochemical techniques. SETTING: University hospital and research laboratory in Lyons, France. PATIENTS: Eight patients with cortical cerebellar atrophy that was associated with or without other neurological symptoms; 350 patients with various neurological diseases; and 33 normal, healthy subjects. OUTCOME MEASURES: Serum and cerebrospinal fluid anti-cerebellar autoantibodies were investigated by using indirect immunofluorescence techniques in rat cerebellum. To characterize antigen labeled by patient's serum, we used an immunotrapping enzyme activity assay of glutamate decarboxylase. RESULTS: Serum and cerebrospinal fluid samples that were taken from one patient with sporadic cortical cerebellar atrophy associated with peripheral neuropathy and slow eye movements contained anti-glutamate decarboxylase autoantibodies. CONCLUSIONS: These results suggest a participation of autoimmunity in the pathogenesis of some cases of sporadic cerebellar cortical atrophy and the involvement of the cerebellar gamma-aminobutyric acid-ergic system in the pathogenesis of this disease.

Levorotatory form of 5-hydroxytryptophan in Friedreich's ataxia. Results of a double-blind drug-placebo cooperative study.

OBJECTIVE: To study the effect of the levorotatory form of 5-hydroxytryptophan on the cerebellar symptoms of Friedreich's ataxia. DESIGN: Cooperative double-blind study of the levorotatory form of 5-hydroxytryptophan vs placebo. SETTING: Twelve centers in research hospitals. PATIENTS: Twenty-six patients were included; 19 completed the study (mean +/- SD age of patients, 25.9 +/- 8.1 years). Of these 19 patients, eight were treated with placebo and 11 were treated with the drug. MAIN OUTCOME MEASURES: A semiquantitative scale for kinetic and static ("postural") cerebellar functions and quantitative measurements of time in standard tests that evaluated stance, speech, writing, and drawing. RESULTS: In the active treatment group, a significant decrease of the kinetic score was observed (P = .03), indicating an improvement in coordination. CONCLUSIONS: These results demonstrated that the levorotatory form of 5-hydroxytryptophan is able to modify significantly the cerebellar symptoms in patients with Friedreich's ataxia. However, the effect is only partial and not clinically major.

Buspirone, a 5-hydroxytryptamine1A agonist, is active in cerebellar ataxia. Results of a double-blind drug placebo study in patients with cerebellar cortical atrophy.

OBJECTIVE: To establish the antiataxic effect of buspirone hydrochloride, a serotonergic 5-hydroxytryptamine1A (5-HT1A) agonist, in a homogenous group of patients characterized by the same well-defined single condition, cerebellar cortical atrophy. SETTING: University ataxia research center. METHODS: Double-blind randomized study of buspirone vs placebo during a 4-month period. PATIENTS: Nineteen patients met the inclusion criteria; all completed the study. Of these 19 patients, 9 were treated with placebo and 10 were treated with the drug. MAIN OUTCOME MEASURES: A semiquantitative scale for kinetic and static ("postural") cerebellar functions; quantitative clinical measurements measuring time in standard tests that evaluated stance, speech, writing, and drawing; and posturographic analysis of the sway path and sway area of the center-of-foot pressure. The primary end point was improvement of the posttherapeutic change of one of the semiquantitative ataxic scores. The secondary end points were modification of the changes of quantitative measures--clinical or posturographic. RESULTS: In intention-to-treat analysis, a significant improvement of the primary end point, ie, the posttherapeutic change of the ataxic kinetic score, was shown. Among secondary end points, the maximum time of standing with feet together also was significantly improved. CONCLUSIONS: Buspirone is active in cerebellar ataxia of patients with cerebellar atrophy. These results confirm the data suggested by open-label studies with buspirone. However, the effect is partial and not clinically major. These pharmacological results might be due to serotonergic mechanisms and confirm a possible link between cerebellar ataxia and the metabolism of serotonin.

Giant lambl excrescences. An unusual source of cerebral embolism.

BACKGROUND: A possible association of giant Lambl excrescences (LEs) with stroke has been suggested. However, the treatment of giant LEs is controversial because minimal data are available. OBJECTIVE: To clarify the management of giant LEs through a clinicopathologic study. CASE SERIES: Three young patients (2 women and 1 man) who experienced ischemic stroke were studied. Results of general examinations were normal, as were chest x-ray films, electrocardiograms, ultrasonograms of the neck, and cerebral angiograms. Extensive serological and blood testing failed to show any coagulopathies or systemic disorders that favored a stroke in these patients. Transesophageal echocardiography showed a mitral valve lesion (width, > 1 mm). Two patients (cases 1 and 3) were discharged on a regimen of anticoagulant therapy and sequential transesophageal echocardiographic monitoring was planned, whereas 1 patient (case 2) was promptly scheduled for surgery. A second stroke occurred in patients 1 and 3 at 3 and 6 months, respectively, thus leading to surgery in these 2 patients. Findings from histopathologic studies were consistent with the diagnosis of giant LEs. The patients' outcomes were uneventful after surgery, and none had a recurrence of a stroke. CONCLUSIONS: A relationship between giant LEs and stroke may be suggested. In patients who have transesophageal echocardiographic findings that are consistent with this diagnosis and recurrent stroke despite antithrombotic therapy and without an alternative explanation for the ischemic symptoms, surgery should be considered in view of these findings.

Cerebellar ataxia with anti-glutamic acid decarboxylase antibodies: study of 14 patients.

BACKGROUND: Antibodies to glutamic acid decarboxylase (GAD-Ab) are described in patients with insulin-dependent (type 1) diabetes mellitus (IDDM), in stiff-man syndrome, and, recently, in a few patients with cerebellar ataxia. OBJECTIVES: To show a link between GAD-Ab and some patients with cerebellar ataxia and to clarify their clinical and immunologic profiles. METHODS: Serum samples were selected from 9000 samples of 4 laboratories. The selection criterion was an immunohistochemical pattern compatible with GAD-Ab that was confirmed by radioimmunoassay. We identified 22 patients with stiff-man syndrome and 14 with cerebellar ataxia and GAD-Ab. RESULTS: Thirteen of the 14 patients with cerebellar ataxia and GAD-Ab were women, and 11 had late-onset IDDM. Patients did not have clinical or radiologic evidence of brainstem involvement. Ten patients had oligoclonal IgG bands in the cerebrospinal fluid, and intrathecal GAD-Ab synthesis was observed in 5 of the 6 patients studied. The level of GAD-Ab of these patients was similar to those with stiff-man syndrome and significantly higher than those with IDDM or with polyendocrine autoimmunity (P<.001). However, the GAD-Ab levels of 6 of the 9 patients with polyendocrine autoimmunity overlapped with those of patients with cerebellar ataxia. CONCLUSIONS: These results suggest a link between high level of GAD-Ab and some cases of cerebellar ataxia, particularly women with IDDM. If high serum levels of GAD-Ab are detected, the cerebrospinal fluid should be evaluated for the presence of oligoclonal IgG bands and intrathecal synthesis of GAD-Ab to further prove an autoimmune origin of the syndrome.

Thrombolytic therapy in acute ischemic stroke patients with cardiac thrombus.

The authors describe the outcome of five patients with a cardiac thrombus selected among 183 patients with stroke (2.7 %) who were given IV tissue plasminogen activator (tPA). No early systemic or cerebral embolism occurred. Two patients made a complete recovery at 3 months. Two patients had a moderate outcome. One patient had late recurrent cerebral embolism and died. These data suggest that the presence of a cardiac thrombus is not associated with a high risk of recurrent embolism in patients with stroke who are given IV tPA.