Antitumor Effects of PRMT5 Inhibition in Sarcomas

Patients with advanced soft-tissue sarcomas (STS) have few therapeutic options. Protein arginine methyltransferase 5 (PRMT5), an anticancer target, has been extensively investigated in recent years in epithelial tumors. To date, no data related to the biological role of PRMT5 inhibition and its potential effect as a treatment in STS have been reported.To investigate the therapeutic potential of PRMT5 targeting in STS, we first evaluated the prognostic value of PRMT5 expression in two different cohorts of patients with STS. We then used the potent and selective GSK3326595 (GSK595) compound to investigate the antitumor effect of the pharmacologic inhibition of PRMT5 in vitro via MTT, apoptosis, cell cycle, clonogenicity, and proliferation assays. In vivo studies were performed with two animal models to evaluate the effects of GSK595 on tumor growth. The mechanisms of action were investigated by RNA sequencing, metabolic pathway analysis, Western blotting, and glucose uptake/lactate production assays.High PRMT5 gene expression levels were significantly associated with worsened metastasis-free survival of patients with STS. GSK595 decreased the global symmetric dimethylarginine level, the proliferation rate and clonogenicity of STS cell lines in vitro and tumor growth in vivo. Moreover, PRMT5 inhibition regulated aerobic glycolysis through downregulation of key enzymes of glycolysis as well as glucose uptake and lactate production.The current study demonstrated that PRMT5 regulates STS cell metabolism and thus represents a potential therapeutic target for STS. Additional studies in diverse sarcoma subtypes will be essential to confirm and expand upon these findings.

SIGNIFICANCE

STSs have limited therapeutic options. We show here the poor prognostic value of high PRMT5 expression in STS. Moreover, we demonstrate that the pharmacologic inhibition of PRMT5 has significant antitumor activity through the downregulation of glycolysis. Our findings support the clinical investigation of PRMT5 inhibition in STSs.

The hereditary N363K POLE exonuclease mutant extends PPAP tumor spectrum to glioblastomas by causing DNA damage and aneuploidy in addition to increased mismatch mutagenicity

The exonuclease domain of DNA polymerases epsilon's catalytic subunit (POLE) removes misincorporated nucleotides, called proofreading. POLE-exonuclease mutations cause colorectal- and endometrial cancers with an extreme burden of single nucleotide substitutions. We recently reported that particularly the hereditary POLE exonuclease mutation N363K predisposes in addition to aggressive giant cell glioblastomas. We knocked-in this mutation homozygously into human cell lines and compared its properties to knock-ins of the likewise hereditary POLE L424V mutation and to a complete proofreading-inactivating mutation (exo-null). We found that N363K cells have higher mutation rates as both L424V- or exo-null mutant cells. In contrast to L424V cells, N363K cells expose a growth defect, replication stress and DNA damage. In non-transformed cells, these burdens lead to aneuploidy but macroscopically normal nuclei. In contrast, transformed N363K cells phenocopy the enlarged and disorganized nuclei of giant cell glioblastomas. Taken together, our data characterize a POLE exonuclease domain mutant that not only causes single nucleotide hypermutation, but in addition DNA damage and chromosome instability, leading to an extended tumor spectrum. Our results expand the understanding of the polymerase exonuclease domain and suggest that an assessment of both the mutational potential and the genetic instability might refine classification and treatment of POLE-mutated tumors.

Distinct Cellular Origins and Differentiation Process Account for Distinct Oncogenic and Clinical Behaviors of Leiomyosarcomas

In leiomyosarcoma (LMS), a very aggressive disease, a relatively transcriptionally uniform subgroup of well-differentiated tumors has been described and is associated with poor survival. The question raised how differentiation and tumor progression, two apparently antagonist processes, coexist and allow tumor malignancy. We first identified the most transcriptionally homogeneous LMS subgroup in three independent cohorts, which we named 'hLMS'. The integration of multi-omics data and functional analysis suggests that hLMS originate from vascular smooth muscle cells and show that hLMS transcriptional program reflects both modulations of smooth muscle contraction activity controlled by MYOCD/SRF regulatory network and activation of the cell cycle activity controlled by E2F/RB1 pathway. We propose that the phenotypic plasticity of vascular smooth muscle cells coupled with MYOCD/SRF pathway amplification, essential for hLMS survival, concomitant with PTEN absence and RB1 alteration, could explain how hLMS balance this uncommon interplay between differentiation and aggressiveness.

Abstract 3937: PRMT5 inhibition suppress soft tissue sarcomas tumorigenicity through the regulation of glucose metabolism

Introduction: Soft tissue sarcomas (STS) are a heterogeneous group of rare tumors representing 1% of solid tumors in adults and 15% in children. Despite adequate locoregional treatment, up to 40% of patients will develop metastatic disease. Doxorubicin represents the 1st line standard of care for patients in this setting. However, its activity is limited with a response rate of only 10%, a progression-free survival of less than 6-months. New therapeutic strategies are therefore urgently needed. PRMT5 belongs to a family of enzymes that catalyze the methylation of arginine residues on both histones and non-histone proteins. Recent evidence shows that PRMT5 is upregulated in a wide variety of cancers. Its expression and activity are associated with tumorigenesis and with a decrease in patient survival in several cancers, a rationale for developing highly potent inhibitors.

Methods: We analyzed the transcriptome data from 255 translocation-related STS and 389 complex genomics STS with annotated clinical data from the French Sarcoma Group. We then investigated the anti-tumor activity of the first -in class PRMT5 specific inhibitor, GSK3226593 in a panel of 7 cell lines and in two xenograft models established at Institut Bergonié (Bordeaux, France).

Results: We found that high PRMT5 gene expression level was significantly associated with worse metastases-free survival in both translocation-related and complex genomics STS (p=0.003 and p=0.009, respectively), support the relevance of PRMT5 as a potential therapeutic target in this indication. We then found that pharmacological inhibition of PRMT5 by using GSK3226593, suppressed the viability and the cell proliferation of 7 STS cell lines in vitro (IC50 range between 0.01 and 1.4 µM) as well as in vivo in two models of xenograft cell lines. This inhibition of cell growth was concomitant with an increase of p53 and p21 expression. However, anti-tumor activity of GSK3226593 was independent of p53 since the compound was still active in shp53 expressing cell lines. Moreover, we did not notice any significant effect of GSK3226593 on cell cycle phases or apoptosis. To decipher the mechanism of action of PRMT5 inhibition in STS, we did a comparative transcriptomic analysis (RNAseq) of STS cells before and after 10 days of treatment with GSK3226593. Gene Ontology and gene set enrichment analysis revealed downregulation of metabolic processes especially glycolysis and mTORC1 pathways. A specific metabolic pathway panel was used to confirm and deepen the underlying molecular mechanism. The downregulation of several genes by GSK3226593 such as PCK2 was confirmed at the protein level by Western blot. Glycolysis inhibition was confirmed by a decrease of glucose uptake.

Conclusion: PRMT5 inhibition has anti-tumor activity in vitro and in vivo through the regulation of STS cell metabolism providing a clear rationale for its clinical investigation in this indication.

Citation Format: Stephanie Verbeke, Laura Leroy, Aurelien Bourdon, Vanessa Chaire, Elodie Richard, Jean-Philippe Guegan, Alban Bessede, Antoine Italiano. PRMT5 inhibition suppress soft tissue sarcomas tumorigenicity through the regulation of glucose metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3937.

ATRX Alteration Contributes to Tumor Growth and Immune Escape in Pleomorphic Sarcomas

Whole genome and transcriptome sequencing of a cohort of 67 leiomyosarcomas has been revealed ATRX to be one of the most frequently mutated genes in leiomyosarcomas after TP53 and RB1. While its function is well described in the alternative lengthening of telomeres mechanism, we wondered whether its alteration could have complementary effects on sarcoma oncogenesis. ATRX alteration is associated with the down-expression of genes linked to differentiation in leiomyosarcomas, and to immunity in an additional cohort of 60 poorly differentiated pleomorphic sarcomas. In vitro and in vivo models showed that ATRX down-expression increases tumor growth rate and immune escape by decreasing the immunity load of active mast cells in sarcoma tumors. These data indicate that an alternative to unsuccessful targeting of the adaptive immune system in sarcoma could target the innate system. This might lead to a better outcome for sarcoma patients in terms of ATRX status.

Comparison of Fast-Progression, Hyperprogressive Disease, and Early Deaths in Advanced Non–Small-Cell Lung Cancer Treated With PD-1/PD-L1 Inhibitors or Chemotherapy

PURPOSE

Hyperprogressive disease (HPD), fast progression (FP), and early death (ED) have been described in 13.8%, 4.7%, and 5.6% and in 5.1%, 2.8%, and 6.8%, respectively, of patients with non–small-cell lung cancer (NSCLC) treated with single-agent programmed cell death ligand 1 inhibitors (ICI) or chemotherapy, respectively. Whether FP/ED and HPD represent overlapping patterns is unknown.

PATIENTS AND METHODS

FP, ED, and HPD were retrospectively assessed in patients with NSCLC treated with single-agent ICI or chemotherapy. Eligibility required 2 computed tomography (CT) scans before and 1 CT scan during treatment. (1) HPD, (2) FP, (3) ED were defined as (1) RECIST version 1.1 progression at first CT scan and tumor growth rate variation per month > 50%, (2) ≥ 50% increase in the sum of the longest diameters of target lesions within 6 weeks from baseline, and (3) death as a result of radiologic progression within 12 weeks from baseline CT scan, respectively.

RESULTS

Of 406 ICI-treated NSCLC, 56 patients (13.8%), 9 patients (2.2%), and 36 patients (8.8%) were HPD, FP, and ED, respectively. Eight (14.2%) and 20 (35.7%) of 56 patients with HPD were also FP and ED. ED significantly correlated with baseline Eastern Cooperative Oncology Group performance status ≥ 2 compared with HPD (33% v 13%, P = .02). Overall survival was significantly longer for HPD (3.4 months [95% CI, 2.7 to 4.0 months]) compared with FP (0.7 months [95% CI, 0.6 to 0.8 months]); HR, 0.18 [95% CI, 0.08 to 0.42]; P < .0001) and ED (1.4 months [95% CI, 1.3 to 1.6 months]); HR, 0.19 [95% CI, 0.11 to 0.34]); P < .0001), whereas it did not differ between FP and ED (HR, 1.3 [95% CI, 0.56 to 3.0]; P = .55). Of 59 patients with NSCLC treated with single-agent chemotherapy, the HPD, FP, and ED rates were 5.1%, 1.7%, and 6.7%, respectively.

CONCLUSION

FP, ED, and HPD represent distinct progression patterns with limited overlap and different survival outcomes.

Hyperprogressive Disease in Patients With Advanced Non-Small Cell Lung Cancer Treated With PD-1/PD-L1 Inhibitors or With Single-Agent Chemotherapy

Importance

Hyperprogressive disease (HPD) is a new pattern of progression recently described in patients with cancer treated with programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors. The rate and outcome of HPD in advanced non-small cell lung cancer (NSCLC) are unknown.

Objectives

To investigate whether HPD is observed in patients with advanced NSCLC treated with PD-1/PD-L1 inhibitors compared with single-agent chemotherapy and whether there is an association between treatment and HPD.

Design, Setting, and Participants

In this multicenter retrospective study that included patients treated between August 4, 2011, and April 5, 2017, the setting was pretreated patients with advanced NSCLC who received PD-1/PD-L1 inhibitors (8 institutions) or single-agent chemotherapy (4 institutions) in France. Measurable disease defined by Response Evaluation Criteria in Solid Tumors (RECIST version 1.1) on at least 2 computed tomographic scans before treatment and 1 computed tomographic scan during treatment was required.

Interventions

The tumor growth rate (TGR) before and during treatment and variation per month (ΔTGR) were calculated. Hyperprogressive disease was defined as disease progression at the first evaluation with ΔTGR exceeding 50%.

Main Outcomes and Measures

The primary end point was assessment of the HPD rate in patients treated with IO or chemotherapy.

Results

Among 406 eligible patients treated with PD-1/PD-L1 inhibitors (63.8% male), 46.3% (n = 188) were 65 years or older, 72.4% (n = 294) had nonsquamous histology, and 92.9% (n = 377) received a PD-1 inhibitor as monotherapy in second-line therapy or later. The median follow-up was 12.1 months (95% CI, 10.1-13.8 months), and the median overall survival (OS) was 13.4 months (95% CI, 10.2-17.0 months). Fifty-six patients (13.8%) were classified as having HPD. Pseudoprogression was observed in 4.7% (n = 19) of the population. Hyperprogressive disease was significantly associated with more than 2 metastatic sites before PD-1/PD-L1 inhibitors compared with non-HPD (62.5% [35 of 56] vs 42.6% [149 of 350]; P = .006). Patients experiencing HPD within the first 6 weeks of PD-1/PD-L1 inhibitor treatment had significantly lower OS compared with patients with progressive disease (median OS, 3.4 months [95% CI, 2.8-7.5 months] vs 6.2 months [95% CI, 5.3-7.9 months]; hazard ratio, 2.18 [95% CI, 1.29-3.69]; P = .003). Among 59 eligible patients treated with chemotherapy, 3 (5.1%) were classified as having HPD.

Conclusions and Relevance

Our study suggests that HPD is more common with PD-1/PD-L1 inhibitors compared with chemotherapy in pretreated patients with NSCLC and is also associated with high metastatic burden and poor prognosis in patients treated with PD-1/PD-L1 inhibitors. Additional studies are needed to determine the molecular mechanisms involved in HPD.

Association of the Lung Immune Prognostic Index With Immune Checkpoint Inhibitor Outcomes in Patients With Advanced Non-Small Cell Lung Cancer

Importance

Derived neutrophils/(leukocytes minus neutrophils) ratio (dNLR) and lactate dehydrogenase (LDH) level have been correlated with immune checkpoint inhibitor (ICI) outcomes in patients with melanoma.

Objective

To determine whether pretreatment dNLR and LDH are associated with resistance to ICIs in patients with advanced non-small cell lung cancer (NSCLC).

Design, Setting, and Participants

Multicenter retrospective study with a test (n = 161) and a validation set (n = 305) treated with programmed death 1/programmed death ligand 1 (PD-1/PD-L1) inhibitors in 8 European centers, and a control cohort (n = 162) treated with chemotherapy only. Complete blood cell counts, LDH, and albumin levels were measured before ICI treatment. A lung immune prognostic index (LIPI) based on dNLR greater than 3 and LDH greater than upper limit of normal (ULN) was developed, characterizing 3 groups (good, 0 factors; intermediate, 1 factor; poor, 2 factors).

Main Outcomes and Measures

The primary end point was overall survival (OS). Secondary end points were progression-free survival (PFS) and disease control rate (DCR).

Results

In the pooled ICI cohort (N = 466), 301 patients (65%) were male, 422 (90%) were current or former smokers, and 401 (87%) had performance status of 1 or less; median age at diagnosis was 62 (range, 29-86) years; 270 (58%) had adenocarcinoma and 159 (34%) had squamous histologic subtype. Among 129 patients with PD-L1 data, 96 (74%) had PD-L1 of at least 1% by immunohistochemical analysis, and 33 (26%) had negative results. In the test cohort, median PFS and OS were 3 (95% CI, 2-4) and 10 (95% CI, 8-13) months, respectively. A dNLR greater than 3 and LDH greater than ULN were independently associated with OS (hazard ratio [HR] 2.22; 95% CI, 1.23-4.01 and HR, 2.51; 95% CI, 1.32-4.76, respectively). Median OS for poor, intermediate, and good LIPI was 3 months (95% CI, 1 month to not reached [NR]), 10 months (95% CI, 8 months to NR), and 34 months (95% CI, 17 months to NR), respectively, and median PFS was 2.0 (95% CI, 1.7-4.0), 3.7 (95% CI, 3.0-4.8), and 6.3 (95% CI, 5.0-8.0) months (both P < .001). Disease control rate was also correlated with dNLR greater than 3 and LDH greater than ULN. Results were reproducible in the ICI validation cohort for OS, PFS, and DCR, but were nonsignificant in the chemotherapy cohort.

Conclusions and Relevance

Pretreatment LIPI, combining dNLR greater than 3 and LDH greater than ULN, was correlated with worse outcomes for ICI, but not for chemotherapy, suggesting that LIPI can serve as a potentially useful tool when selecting ICI treatment, raising the hypothesis that the LIPI might be useful for identifying patients unlikely to benefit from treatment with an ICI.

Fast-progression (FP), hyper-progression (HPD) and early deaths (ED) in advanced non-small cell lung cancer (NSCLC) patients (pts) upon PD-(L)-1 blockade (IO)

9107

Background: HPD was described in 13.8% of NSCLC pts upon single-agent IO and correlated with high metastatic burden and poor prognosis. Other progression (PD) patterns as FP and ED within 12 weeks have been reported respectively in 4.7% and 5.6% of atezolizumab treated NSCLC pts. Whether FP/ED and HPD are different or overlapping patterns is currently unknown. Methods: We analyzed FP, ED and HPD in a multicentric (8 centers) retrospective cohort of IO treated NSCLC pts (11/2012-04/2017). Eligibility criteria required 2 CT scans before and one after IO start. HPD was defined as RECIST v 1.1 PD at first CT scan and a variation per month of tumor growth rate (TGR upon IO – TGR before IO) > 50%. ED was defined as deaths due to disease PD within 12 wks of IO start. FP was defined as ≥ 50% increase in the sum of long diameters within 6 weeks (wks) from baseline. The associations between PD patterns and pts’ characteristics were performed using Fisher or t-student tests. Median overall survival (mOS) was estimated by Kaplan-Meier method and compared by log-rank test. Results: Out of 406 NSCLC pts, 46% were ≥65 years, 72% had non-squamous NSCLC, > 90% received single agent IO in ≥2 line. 56 (13.8%) were HPD by TGR analysis. Among 72 pts (18%) who performed a CT scan within 6 wks after IO start, 6 (8.3%) were FP. These 6 FP pts were also classified as HPD by TGR analysis, while the other 50 (89%) of 56 HPD pts were not FP. The rate of PD in ≥ 3 sites (54% vs 0%, p = 0.002), the rate of liver PD (62% vs 5%, p = 0.002), the baseline tumor burden (BTB) (mean 176± 26 mm vs 55 ± 6 mm, p < 0.0001) and the TGR upon IO (mean 439± 119% vs 216 ± 41%, p = 0.03) were significantly higher in FP pts compared to HPD pts who were not FP. At 4.4 months of median follow-up, FP pts had significantly worse mOS compared to HPD pts not FP [0.7 months (95% CI 0.6,0.8) vs 1.6 months (95% CI 1.1, 2.1); p = 0.02]. Of 406 IO treated pts, 46 (11%) were ED within 12 wks, and 21 (46%) of ED pts had also HPD by TGR analysis. Conclusions: FP and ED are not a surrogate of HPD. FP occurs in a small subgroup (11%) of HPD and correlates with more aggressive features (PD in ≥3 sites, liver-PD, high BTB, high TGR upon IO) and worse OS. ED within 12 wks overlapped with HPD for only 46% of pts.

Hyperprogressive Disease in Patients With Advanced Non-Small Cell Lung Cancer Treated With PD-1/PD-L1 Inhibitors or With Single-Agent Chemotherapy

Importance

Hyperprogressive disease (HPD) is a new pattern of progression recently described in patients with cancer treated with programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors. The rate and outcome of HPD in advanced non-small cell lung cancer (NSCLC) are unknown.

Objectives

To investigate whether HPD is observed in patients with advanced NSCLC treated with PD-1/PD-L1 inhibitors compared with single-agent chemotherapy and whether there is an association between treatment and HPD.

Design, Setting, and Participants

In this multicenter retrospective study that included patients treated between August 4, 2011, and April 5, 2017, the setting was pretreated patients with advanced NSCLC who received PD-1/PD-L1 inhibitors (8 institutions) or single-agent chemotherapy (4 institutions) in France. Measurable disease defined by Response Evaluation Criteria in Solid Tumors (RECIST version 1.1) on at least 2 computed tomographic scans before treatment and 1 computed tomographic scan during treatment was required.

Interventions

The tumor growth rate (TGR) before and during treatment and variation per month (ΔTGR) were calculated. Hyperprogressive disease was defined as disease progression at the first evaluation with ΔTGR exceeding 50%.

Main Outcomes and Measures

The primary end point was assessment of the HPD rate in patients treated with IO or chemotherapy.

Results

Among 406 eligible patients treated with PD-1/PD-L1 inhibitors (63.8% male), 46.3% (n = 188) were 65 years or older, 72.4% (n = 294) had nonsquamous histology, and 92.9% (n = 377) received a PD-1 inhibitor as monotherapy in second-line therapy or later. The median follow-up was 12.1 months (95% CI, 10.1-13.8 months), and the median overall survival (OS) was 13.4 months (95% CI, 10.2-17.0 months). Fifty-six patients (13.8%) were classified as having HPD. Pseudoprogression was observed in 4.7% (n = 19) of the population. Hyperprogressive disease was significantly associated with more than 2 metastatic sites before PD-1/PD-L1 inhibitors compared with non-HPD (62.5% [35 of 56] vs 42.6% [149 of 350]; P = .006). Patients experiencing HPD within the first 6 weeks of PD-1/PD-L1 inhibitor treatment had significantly lower OS compared with patients with progressive disease (median OS, 3.4 months [95% CI, 2.8-7.5 months] vs 6.2 months [95% CI, 5.3-7.9 months]; hazard ratio, 2.18 [95% CI, 1.29-3.69]; P = .003). Among 59 eligible patients treated with chemotherapy, 3 (5.1%) were classified as having HPD.

Conclusions and Relevance

Our study suggests that HPD is more common with PD-1/PD-L1 inhibitors compared with chemotherapy in pretreated patients with NSCLC and is also associated with high metastatic burden and poor prognosis in patients treated with PD-1/PD-L1 inhibitors. Additional studies are needed to determine the molecular mechanisms involved in HPD.

Note: On-chip multifunctional fluorescent-magnetic Janus helical microswimmers

Microswimmers integrated into microfluidic devices that are capable of self-illumination through fluorescence could revolutionize many aspects of technology, especially for biological applications. Few illumination and propulsion techniques of helical microswimmers inside microfluidic channels have been demonstrated. This paper presents the fabrication, detachment, and magnetic propulsions of multifunctional fluorescent-magnetic helical microswimmers integrated inside microfluidics. The fabrication process is based on two-photon laser lithography to pattern 3-D nanostructures from fluorescent photoresist coupled with conventional microfabrication techniques for magnetic thin film deposition by shadowing. After direct integration inside a microfluidic device, injected gas bubble allows gentle detachment of the integrated helical microswimmers whose magnetic propulsion can then be directly applied inside the microfluidic channel using external electromagnetic coil setup. With their small scale, fluorescence, excellent resistance to liquid/gas surface tension, and robust propulsion capability inside the microfluidic channel, the microswimmers can be used as high-resolution and large-range mobile micromanipulators inside microfluidic channels.

Incoherent and coherent writing and erasure of cavity solitons in an optically pumped semiconductor amplifier

Cavity solitons in semiconductor amplifiers were, from the beginning of their study and observation, obtained either spontaneously or in a controlled manner by local coherent excitation. We describe two experiments that demonstrate coherent and, we believe for the first time, incoherent writing and erasure of cavity solitons in an optically pumped vertical-cavity semiconductor amplifier by short optical pulses.

Organization and orientation of amphiphilic push-pull chromophores deposited in Langmuir-Blodgett monolayers studied by second harmonic generation and atomic force microscopy

Orientation and organization of two amphiphilic push-pull chromophores mixed with two phospholipids (dipalmitoylphosphatidylcholine and dioleoylphosphatidylcholine) in Langmuir-Blodgett (LB) monolayers are investigated by second harmonic generation. The LB monolayers have also been characterized by atomic force microscopy and UV-vis spectroscopy. The effective molecular orientations and hyperpolarizabilities of the chromophores are studied as a function of the phospholipid concentrations. The experimental results are discussed within the frame of a model of orientational distribution of the chromophores which gives the orientational mean angle and bounds on the orientational disorder. The mean orientation of the chromophores is found to be within 45-55 degrees whereas their hyperpolarizability coefficients, measured with respect to quartz, are estimated to be in the range (0.3-0.7) x 10(-27) esu taking account of the maximal orientational disorder.

Sensitivity of transient evoked and distortion product otoacoustic emissions to the direct effects of noise on the human cochlea

Measurement of otoacoustic emissions (OAEs) has been proposed as a sensitive test to reliably assess the effects of noise exposure. The present study in humans was designed to evaluate the sensitivity and applicability of transient evoked OAEs (TEOAEs) and 2f1-f2 distortion product OAEs (DPOAEs) as quantitative indices of the functional integrity of the outer hair cells (OHC) during growth of and recovery from temporary threshold shift (TTS). This was examined in two different groups of volunteers by measuring the per- and post-stimulatory effects of a one hour BBN and an on-site five hour exposure to loud music from a discotheque. The results of both experiments show consistent growth and recovery patterns for both DPOAEs and TEOAEs. For TEOAEs, both the reproducibility scores and signal to noise ratio values for the 4 kHz frequency band exhibited the greatest sensitivity. The DPOAEs, on the other hand, showed the greatest sensitivity between 2 and 5.5 kHz. Thus, both the TEOAEs and DPOAEs have a great potential in the detection of TTS after noise exposure.

Physico-chemical properties of the heat-induced ‘superaggregates’ of amphotericin B

The aggregation state of amphotericin B (AmB) was previously reported to modulate its therapeutic efficiency. As a preliminary study to test the biological effects of 'superaggregates' generated by heat treatment, we present spectroscopic data related to their formation in aqueous solutions. Drastic changes in the AmB aggregation state in water were shown to occur on heating at 50-60 degrees C. The concentration of the aggregates formed at high (A(t)) or room (A) temperature, and the concentration of the monomeric form (M) of AmB were calculated by processing absorption data. The thermally induced conversion from A to A(t) depends on the AmB concentration. Rayleigh scattering measurements suggest that the A(t) aggregates are larger than the A aggregates. At room temperature, the condensation rate of A with M-leading to the 'superaggregated' form A(t)-was slower and depended on the concentration of M. The superaggregated species A(t) was shown to be the most chemically stable species. Physico-chemical properties of these superaggregates are discussed as a potential new solution to improve the therapeutic efficacy of AmB.

Release of amphotericin B from delivery systems and its action against fungal and mammalian cells

Spectroscopic studies of four amphotericin B (AmB) lipid preparations--small negatively charged unilamellar vesicles "AmBisome", positively charged oligolamellar liposomes "Ampholiposomes", AmB Lipid Complex "L-AmpB33"--and AmB association with gamma cyclodextrin demonstrated that the composition of drug delivery system directly influences AmB organization. The aggregation state and release in external medium of AmB was monitored by circular dichroism and UV-visible absorption. AmB short-term activity against Candida albicans (K+ leakage) was found to be correlated with the amount of free AmB released from lipid preparations. These data seem to indicate that lipid composition influences anti-Candida albicans activity, by modulation of AmB binding to lipids.

[Treatment of senile macular degeneration with Ginkgo biloba extract. A preliminary double-blind drug vs. placebo study]

Senile macular degeneration is a frequent cause of blindness for which there is no satisfactory medical treatment. A double-blind trial comparing Ginkgo biloba extract with a placebo was conducted in 10 out-patients at the Hôpital Foch. Drug effectiveness was assessed on the results of fundoscopy and of measurements of visual acuity and visual field. In spite of the small population sample, a statistically significant improvement in long distance visual acuity was observed after treatment with Ginkgo biloba extract. The assumed pathogenesis of senile macular degeneration is discussed with emphasis on free oxygenated radicals.