Thrombospondin-1 Silencing Improves Lymphocyte Infiltration in Tumors and Response to Anti-PD-1 in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is notoriously aggressive with a high metastatic potential, and targeted therapies are lacking. Using transcriptomic and histologic analysis of TNBC samples, we found that a high expression of thrombospondin-1 (TSP1), a potent endogenous inhibitor of angiogenesis and an activator of latent transforming growth factor beta (TGF-β), is associated with (i) gene signatures of epithelial-mesenchymal transition and TGF-β signaling, (ii) metastasis and (iii) a reduced survival in TNBC patients. In contrast, in tumors expressing low levels of TSP1, gene signatures of interferon gamma (IFN-γ) signaling and lymphocyte activation were enriched. In TNBC biopsies, TSP1 expression inversely correlated with the CD8+ tumor-infiltrating lymphocytes (TILs) content. In the 4T1 metastatic mouse model of TNBC, TSP1 silencing did not affect primary tumor development but, strikingly, impaired metastasis in immunocompetent but not in immunodeficient nude mice. Moreover, TSP1 knockdown increased tumor vascularization and T lymphocyte infiltration and decreased TGF-β activation in immunocompetent mice. Noteworthy was the finding that TSP1 knockdown increased CD8+ TILs and their programmed cell death 1 (PD-1) expression and sensitized 4T1 tumors to anti-PD-1 therapy. TSP1 inhibition might thus represent an innovative targeted approach to impair TGF-β activation and breast cancer cell metastasis and improve lymphocyte infiltration in tumors, and immunotherapy efficacy in TNBC.

BTN2A1, an immune checkpoint targeting Vγ9Vδ2 T cell cytotoxicity against malignant cells

The anti-tumor response of Vγ9Vδ2 T cells requires the sensing of accumulated phosphoantigens (pAgs) bound intracellularly to butyrophilin 3A1 (BTN3A1). In this study, we show that butyrophilin 2A1 (BTN2A1) is required for BTN3A-mediated Vγ9Vδ2 T cell cytotoxicity against cancer cells, and that expression of the BTN2A1/BTN3A1 complex is sufficient to trigger Vγ9Vδ2 TCR activation. Also, BTN2A1 interacts with all isoforms of BTN3A (BTN3A1, BTN3A2, BTN3A3), which appears to be a rate-limiting factor to BTN2A1 export to the plasma membrane. BTN2A1/BTN3A1 interaction is enhanced by pAgs and, strikingly, B30.2 domains of both proteins are required for pAg responsiveness. BTN2A1 expression in cancer cells correlates with bisphosphonate-induced Vγ9Vδ2 T cell cytotoxicity. Vγ9Vδ2 T cell killing of cancer cells is modulated by anti-BTN2A1 monoclonal antibodies (mAbs), whose action relies on the inhibition of BTN2A1 binding to the Vγ9Vδ2TCR. This demonstrates the potential of BTN2A1 as a therapeutic target and adds to the emerging butyrophilin-family cooperation pathway in γδ T cell activation.

Neutral Sphingomyelinase 2 Heightens Anti-Melanoma Immune Responses and Anti-PD-1 Therapy Efficacy

Dysregulation of lipid metabolism affects the behavior of cancer cells, but how this happens is not completely understood. Neutral sphingomyelinase 2 (nSMase2), encoded by SMPD3, catalyzes the breakdown of sphingomyelin to produce the anti-oncometabolite ceramide. We found that this enzyme was often downregulated in human metastatic melanoma, likely contributing to immune escape. Overexpression of nSMase2 in mouse melanoma reduced tumor growth in syngeneic wild-type but not CD8-deficient mice. In wild-type mice, nSMase2-overexpressing tumors showed accumulation of both ceramide and CD8⁺ tumor-infiltrating lymphocytes, and this was associated with increased level of transcripts encoding IFNγ and CXCL9. Overexpressing the catalytically inactive nSMase2 failed to alter tumor growth, indicating that the deleterious effect nSMase2 has on melanoma growth depends on its enzymatic activity. In vitro, small extracellular vesicles from melanoma cells overexpressing wild-type nSMase2 augmented the expression of IL12, CXCL9, and CCL19 by bone marrow-derived dendritic cells, suggesting that melanoma nSMase2 triggers T helper 1 (Th1) polarization in the earliest stages of the immune response. Most importantly, overexpression of wild-type nSMase2 increased anti-PD-1 efficacy in murine models of melanoma and breast cancer, and this was associated with an enhanced Th1 response. Therefore, increasing SMPD3 expression in melanoma may serve as an original therapeutic strategy to potentiate Th1 polarization and CD8⁺ T-cell-dependent immune responses and overcome resistance to anti-PD-1.

γδ T Cells in Tumor Microenvironment

Gamma delta (γδ) T cells which combine both innate and adaptive potential have extraordinary properties. Indeed, their strong cytotoxic and pro-inflammatory activity allows them to kill a broad range of tumor cells. Several studies have demonstrated that γδ T cells are an important component of tumor-infiltrated lymphocytes in patients affected by different types of cancer. Tumor-infiltrating γδ T cells are also considered as a good prognostic marker in many studies, though the presence of these cells is associated with poor prognosis in breast and colon cancers. The tumor microenvironment seems to drive γδ T-cell differentiation toward a tumor-promoting or a tumor-controlling phenotype, which suggests that some tumor microenvironments can limit the effectiveness of γδ T cells.The major γδ T-cell subsets in human are the Vγ9Vδ2 T cells that are specifically activated by phosphoantigens. This unique antigenic activation process operates in a framework that requires the expression of butyrophilin 3A (BTN3A) molecules. Interestingly, there is some evidence that BTN3A expression may be regulated by the tumor microenvironment. Given their strong antitumoral potential, Vγ9Vδ2 T cells are used in therapeutic approaches either by ex vivo culture and amplification, and then adoptive transfer to patients or by direct stimulation to propagate in vivo. These strategies have demonstrated promising initial results, but greater potency is needed. Combining Vγ9Vδ2 T-cell immunotherapy with systemic approaches to restore antitumor immune response in tumor microenvironment may improve efficacy.In this chapter, we first review the basic features of γδ T cells and their roles in the tumor microenvironment and then analyze the advances about the understanding of these cells' activation in tumors and why this represent unique challenges for therapeutics, and finally we discuss γδ T-cell-based therapeutic strategies and future perspectives of their development.

SEIS: Insight's Seismic Experiment for Internal Structure of Mars

By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars' surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking's Mars seismic monitoring by a factor of ∼ 2500 at 1 Hz and ∼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars' surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of M w ∼ 3 at 40 ∘ epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (10.1007/s11214-018-0574-6) contains supplementary material, which is available to authorized users.

Targeting the Sphingosine 1-Phosphate Axis Exerts Potent Antitumor Activity in BRAFi-Resistant Melanomas

BRAF inhibitors (BRAFi) are used to treat patients with melanoma harboring the V600E mutation. However, resistance to BRAFi is inevitable. Here, we identified sphingosine 1-phosphate (S1P) receptors as regulators of BRAF^V600E-mutant melanoma cell-autonomous resistance to BRAFi. Moreover, our results reveal a distinct sphingolipid profile, that is, a tendency for increased very long-chain ceramide species, in the plasma of patients with melanoma who achieve a response to BRAFi therapy as compared with patients with progressive disease. Treatment with BRAFi resulted in a strong decrease in S1PR1/3 expression in sensitive but not in resistant cells. Genetic and pharmacologic interventions, that increase ceramide/S1P ratio, downregulated S1PR expression and blocked BRAFi-resistant melanoma cell growth. This effect was associated with a decreased expression of MITF and Bcl-2. Moreover, the BH3 mimetic ABT-737 improved the antitumor activity of approaches targeting S1P-metabolizing enzymes in BRAFi-resistant melanoma cells. Collectively, our findings indicate that targeting the S1P/S1PR axis could provide effective therapeutic options for patients with melanoma who relapse after BRAFi therapy.

Downregulation of sphingosine kinase-1 induces protective tumor immunity by promoting M1 macrophage response in melanoma

The infiltration of melanoma tumors by macrophages is often correlated with poor prognosis. However, the molecular signals that regulate the dialogue between malignant cells and the inflammatory microenvironment remain poorly understood. We previously reported an increased expression of sphingosine kinase-1 (SK1), which produces the bioactive lipid sphingosine 1-phosphate (S1P), in melanoma. The present study aimed at defining the role of tumor SK1 in the recruitment and differentiation of macrophages in melanoma. Herein, we show that downregulation of SK1 in melanoma cells causes a reduction in the percentage of CD206^highMHCII^low M2 macrophages in favor of an increased proportion of CD206^lowMHCII^high M1 macrophages into the tumor. This macrophage differentiation orchestrates T lymphocyte recruitment as well as tumor rejection through the expression of Th1 cytokines and chemokines. In vitro experiments indicated that macrophage migration is triggered by the binding of tumor S1P to S1PR1 receptors present on macrophages whereas macrophage differentiation is stimulated by SK1-induced secretion of TGF-β1. Finally, RNA-seq analysis of human melanoma tumors revealed a positive correlation between SK1 and TGF-β1 expression. Altogether, our findings demonstrate that melanoma SK1 plays a key role in the recruitment and phenotypic shift of the tumor macrophages that promote melanoma growth.

TNFα blockade overcomes resistance to anti-PD-1 in experimental melanoma

Antibodies against programmed cell death-1 (PD-1) have considerably changed the treatment for melanoma. However, many patients do not display therapeutic response or eventually relapse. Moreover, patients treated with anti-PD-1 develop immune-related adverse events that can be cured with anti-tumor necrosis factor α (TNF) antibodies. Whether anti-TNF antibodies affect the anti-cancer immune response remains unknown. Our recent work has highlighted that TNFR1-dependent TNF signalling impairs the accumulation of CD8+ tumor-infiltrating T lymphocytes (CD8+ TILs) in mouse melanoma. Herein, our results indicate that TNF or TNFR1 blockade synergizes with anti-PD-1 on anti-cancer immune responses towards solid cancers. Mechanistically, TNF blockade prevents anti-PD-1-induced TIL cell death as well as PD-L1 and TIM-3 expression. TNF expression positively correlates with expression of PD-L1 and TIM-3 in human melanoma specimens. This study provides a strong rationale to develop a combination therapy based on the use of anti-PD-1 and anti-TNF in cancer patients.

Most melanoma patients do not respond to anti-PD1 therapy. Here, the authors show that TNFα blockade synergizes with anti-PD-1 by preventing anti-PD-1-induced CD8+ T cell death and TIM-3 expression on such cells.

[2013 update about arthropod envenomations in French Guyana]

French Guiana, by its geographical situation, its climate and its biodiversity, is often called "the green hell". Indeed, this French department of America shelters a wildlife rich, abundant among which many species of arthropods, some of which are responsible for envenomations. These accidents consist of scorpion's or hymenoptera's stings or spider's bites. The associated clinical aspect is variable, from simple pain to circulatory collapse, or lung oedema. However, symptomatology is generally mild; four deaths associated to arthropod envenomations have been reported in the past 25 years. This article focuses on envenomations in French Guiana, describing favoring human behavior, risks and venoms associated with the main related animal species.

The effect of aminocandin (HMR 3270) on the in-vitro adherence of Candida albicans to polystyrene surfaces coated with extracellular matrix proteins or fibronectin

Aminocandin is a new representative of the echinocandins that could potentially affect the cellular morphology and metabolic status of Candida albicans cells within biofilms. This study investigated the influence of a sub-inhibitory concentration (MIC/2) of aminocandin on in-vitro growth of C. albicans and subsequent fungal adherence to plastic surfaces coated with fibronectin or extracellular matrix (ECM) proteins. Eleven strains of C. albicans were studied, of which six were susceptible and five were resistant to fluconazole. All 11 strains were susceptible to aminocandin in vitro, regardless of the culture medium used for the microdilution method. Aminocandin induced a significant (p <0.005) decrease in adherence when polystyrene was coated with ECM gel (ten strains) or fibronectin (seven strains). Growth in medium containing aminocandin (MIC/2) decreased the adherence of five (ECM gel) or three (fibronectin) of the six strains susceptible to fluconazole, and inhibition was observed for all five (ECM gel) or four (fibronectin) of the five fluconazole-resistant strains. Overall, the study demonstrated the anti-adherent properties of aminocandin with fluconazole-susceptible strains, and suggested that this activity was at least equivalent with fluconazole-resistant strains. Thus, the ability of aminocandin to inhibit the first step in the development of C. albicans biofilms appeared to be independent of the in-vitro resistance of C. albicans to fluconazole.

Effect of matrix metalloprotease inhibitors on the 95 kDa metallopeptidase of Candida albicans

A 95 kDa metallopeptidase of Candida albicans could be involved in the process of dissemination of the yeast. Matrix metalloproteases (MMPs) are also responsible for collagen breakdown in inflammatory and malignant processes. We tested six compounds on the C. albicans enzyme. Doxycycline, gentamicin, cefalothin, galardin, and elaidic and oleic acids are known for their capacity to inhibit some MMPs. Amongst these agents, only oleic acid was able to markedly inhibit the purified metallopeptidase at very low concentrations. Moreover, this fatty acid inhibited the secretion of the enzyme in the culture medium without altering the yeast viability.

Influence of sub-inhibitory concentrations of conventional antifungals on metabolism of Candida albicans and on its adherence to polystyrene and extracellular matrix proteins

Five antifungal agents with different mechanisms of action were compared for their ability to affect mitochondrial dehydrogenase activity and adherence capacity of Candida albicans to polystyrene and extracellular matrix proteins. Only amphotericin B inhibited mitochondrial dehydrogenase activity when the culture medium was supplemented with galactose. 5-Fluorocytosine and terbinafine did not affect this activity, whereas itraconazole and fluconazole improved it. Furthermore, in these experimental conditions, the effect of sub-inhibitory concentrations of antifungals on adherence was dependent on the tested antifungal and the adherence surface: amphotericin B inhibited adherence to polystyrene and fibrinogen, but improved adherence to extracellular matrix. For all surfaces tested, when culture medium was supplemented with galactose, fluorocytosine did not affect adherence, and itraconazole, fluconazole and terbinafine inhibited adherence. Our results also confirmed the influence of the carbohydrates: sub-minimum inhibitory concentrations (MIC) of itraconazole increased or did not modify the mitochondrial metabolism of yeasts when the culture medium was supplemented with galactose, but this antifungal always decreased mitochondrial metabolism when the culture medium was supplemented with glucose. These data indicate that antifungals used below their MIC values can have various effects. It is important to distinguish the effects of antifungals on the metabolism of C. albicans from effects on its adherence capacity. The former effects are linked to the viability of the yeast and the latter depends on the colonization of cellular as opposed to inert surfaces.

Spontaneous long-term compensatory dopaminergic sprouting in MPTP-treated mice

The present study sought to determine whether severe 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication elicits spontaneous long-term compensatory sprouting in mice. Animals, once treated, were kept without further treatment for 0.5, 1, 5, or 7 months. The stability of the nigral degeneration was checked by evaluation of the number of tyrosine hydroxylase immunoreactive (TH-IR) neurons, whereas sprouting was assessed using both [(3)H]-dopamine (DA) uptake by striatal synaptosomes and optical density of TH-immunolabeled fibers in the striatum as markers. At 0.5 month after MPTP intoxication (80 mg/kg, i.p.), we observed comparable decreases of 83% in DA uptake, 83.3% in TH fiber density, and 74% in the number of TH-IR neurons compared to age-matched saline-treated animals. From 5 months onwards, both DA uptake and striatal TH fiber density increased significantly (50% and 34.9% at 5 months, 65% and 67.4% at 7 months, respectively) in comparison with age-matched saline-treated animals, although the number of TH-IR neurons remained stable (73% of degeneration at 7 months). These results indicate clearly that spontaneous long-term compensatory dopaminergic sprouting is a phenomenon that is not restricted to situations of partial nigral degeneration but can, on the contrary, constitute a response even to severe stable MPTP-induced nigral degeneration.

Comparison of eight clinical rating scales used for the assessment of MPTP-induced parkinsonism in the Macaque monkey

The most valuable model of Parkinson's disease available at present is the primate model treated with 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP), frequently used to study response to new drugs or surgical treatments. The evaluation of such therapies requires clinical rating scales which measure precisely motor behaviour in both normal and parkinsonian monkeys. It is obvious that such evaluation can only be valid if parallel studies are carried out under similar experimental conditions with well-defined objective criteria. Hence the need to compare and assess the different rating scales in use if we want to be able to compare the results of clinical studies. In order to give rise to some fresh thinking on the necessity of a certain uniformity of assessment, this study compares eight clinical rating scales and considers their capacity to express in quantitative terms both the severity of MPTP intoxication in five cynomolgus monkeys and the alleviation afforded by levodopa. None of the eight scales reaches all the criteria despite the Kurlan scale would appear as an interesting working basis for a further consensual definition of a worldwide used parkinsonian monkey clinical rating scale

Riluzole delayed appearance of parkinsonian motor abnormalities in a chronic MPTP monkey model

Preliminary studies have shown that riluzole, a Na+ channel blocker with antiglutamatergic activity, has neuroprotective efficacy in several models of acute dopaminergic neurodegeneration. A chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) monkey model which comes closer to the slow evolution of Parkinson's disease has recently been developed in order to allow dynamic studies. The present results show that riluzole delayed the appearance of parkinsonian motor abnormalities in this dynamic model, using from 10.2 +/- 1.6 daily injections for the MPTP-treated monkeys (n = 4) to 16.5 +/- 2.0 daily injections for the MPTP + riluzole-treated monkeys (n = 4). These results strongly suggest that riluzole may be beneficial to slow down the rate of progression of Parkinson's disease.

Experimental models of Parkinson's disease: from the static to the dynamic

The experimental models of Parkinson's disease (PD) available today can be divided into two categories according to the mode of action of the compound used: transient pharmacological impairment of dopaminergic transmission along the nigrostriatal pathway or selective destruction by a neurotoxic agent of the dopaminergic neurons of the substantia nigra pars compacta. The present article looks at the relative merits of each model, the clinical symptoms and neuronal impairment it induces, and the contribution it could make to the development of a truly dynamic model. It is becoming more and more clear that there is an urgent need for a chronic model integrating all the clinical features of PD including resting tremor, and reproducing the gradual but continuous nigral degeneration observed in the human pathology. Discrepancies have been reported several times between results obtained in classic animal models and those described in PD, and it would seem probable that such contradictions can be ascribed to the fact that animal models do not, as yet, reproduce the continuous evolution of the human disease. Dynamic experimental models which come closer to the progressive neurodegeneration and gradual intensification of motor disability so characteristic of human PD will enable us to investigate crucial aspects of the disease, such as compensatory mechanisms and dyskinesia.

A chronic MPTP model reproducing the slow evolution of Parkinson's disease: evolution of motor symptoms in the monkey

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been shown to induce parkinsonism both in man and non-human primates. Several models have now been developed, but acute MPTP administration does not consistently reproduce all the clinical features of the disease. To mirror the slow evolution observed in human pathology, a chronic model of intoxication is necessary. The present study describes a chronic MPTP protocol in the monkey. Six monkeys received daily injections of MPTP (0.2 mg/kg i.v.) until they reached a score over 8 on the clinical rating scale (15.5 days +/- 1.1). Full parkinsonism was first obtained on the 22nd day. Levodopa testing (20 mg/kg per os) alleviated motor abnormalities (51%), proving the parkinsonian nature of these disturbances. Histological lesions reproduced those observed in Parkinson's disease with a decrease in tyrosine hydroxylase immunoreactivity of 90%. This model so could be of great interest for the study of the dynamic physiopathological changes which occur in Parkinson's disease and consequently for research on new neuroprotective therapies.

Visual localization within single geometric planes of a space habitat

BACKGROUND

The present study investigated how human subjects capture and restore visual information within a line representation drawing the three-dimensional configuration of a space module.

METHODS

Nine subjects were asked to perform a visual localization task within this geometric model. The task consisted of localizing a light point appearing during 3 s in 40 different spatial positions and for 8 tilt angles of the model in the following random order: 0 degree, 45 degrees, 180 degrees, 225 degrees, 90 degrees, 315 degrees, 135 degrees, and 270 degrees.

RESULTS

Results showed symmetric variations of the point-localizing errors about 180 degrees of tilt angle (vertical orientation) and a decrease of the errors when the points occurred in the distal, then in the median and in the proximal planes (virtual depth). The performance also varied according to the virtual ceiling, floor, right, left and back planes. The results have been discussed using a three-dimensional space representation based on a conservative mode of spatial information up to 90 degrees of tilt (horizontal orientation), and on a transformation mode beyond 90 degrees of tilt.

CONCLUSION

We conclude that the visual localization in single geometric planes is orientation-dependent.

Percutaneous embolectomy: in vitro investigations of the self-expanding tulip sheath

A self-expanding sheath with a tulip-shaped distal end was designed for performance of percutaneous embolectomy. Its ability to retrieve clots was tested in an in vitro flow model; results were compared with those obtained with a conventional 10-F sheath. Simulated embolectomy of clots weighing 0.1-1.5 g was performed with a 0.75-mL Fogarty balloon on a 4-F catheter. The clot material that embolized distally during the procedure was sampled and quantified. No effective embolectomy was performed via a conventional sheath. With the tulip sheath, however, complete clot removal was achieved unless the clot size exceeded the tulip volume. On the basis of results of in vitro testing, the tulip design is promising for use in several applications during percutaneous interventions.

Emergency stenting for acute occlusion after coronary balloon angioplasty

Acute coronary artery occlusion complicates 2-12% of the balloon angioplasty procedures, and despite repeat angioplasty, emergency surgical revascularization is often necessary. We report our initial experience with the emergency implantation of endoluminal stents for acute vessel closure after coronary balloon angioplasty. Nine patients received one stent, and two patients received two stents during the study period. Implantation was technically successful in all patients; there were no deaths, no myocardial infarctions as evidenced by Q wave on the electrocardiogram, and no need for emergency surgery. One additional patient, not satisfying the study inclusion criteria, died 16 hours after stent implantation from left ventricular failure and intractable arrythmias. Two patients in the study group had a moderate creatinine phosphokinase rise during the first 48 hours after implantation. During a median follow-up period of 3 months (range, 1-20 months), there have been no deaths and no need for elective coronary bypass surgery. One patient required emergency recanalization 3 months after implantation because of acute occlusion of the stented segment with limited myocardial infarction. Six patients have undergone control angiography, and none has developed chronic restenosis within the stented segment. For selected patients, coronary artery stenting appears to be a promising alternative to emergency bypass surgery after acute vessel occlusion during balloon angioplasty.

Self-expanding endovascular prosthesis: an experimental study

A new type of endovascular prosthesis was inserted in 28 animals and evaluated for several factors, including thrombogenicity, tendency to migrate, critical implant zones, and incorporation into the vascular wall. The new prosthesis is a woven, multifilament structure of stainless steel alloy; its inherent elastic, self-expanding characteristics hold it against the vessel walls. Forty-seven endoprostheses (3-5 mm in diameter, 15-50 mm long) were percutaneously implanted with either a 6-F introducer sheath, a coaxial 9-F catheter, or a 0.014-inch (0.036-cm) guide wire into the femoropopliteal, coronary, carotid, and renal arteries and iliac veins. Anticoagulant or platelet antiaggregating agents were not used before or after implantation. Angiographic and histologic analyses showed that the prosthesis had a very low thrombogenicity when it was well adapted to the native vessel diameter and that it was incorporated into the vessel wall by a new intima by the 3d week after implantation. No migration occurred, and branch vessel flow was preserved even in those vessels in which ostia were traversed by the prosthesis. This prosthesis has potential for clinical application in the treatment of postangioplasty restenoses, particularly in the coronary arteries.

Percutaneous vascular stent: experimental studies and preliminary clinical results in peripheral arterial diseases

A new pattern of metallic intravascular stent has been experimentally and clinically tested. When the stent is percutaneously placed through a six french introducer, it is held against the vessel wall by its natural elastic properties. In 28 animals, 47 stents of different sizes (from 3 to 5 mm of luminal diameter and from 1.5 to 5 cm of length) have been implanted in the femoro-popliteal (16), the coronary (20), the carotid (3) and the renal arteries (5) and in 3 femoral veins. Angiographic and histological results have shown the stent's low thrombogenicity when it is well fit to the vessel's caliber. Moreover, they have shown its incorporation to the vessel wall by intimalisation as early as the third week after its implantation. The collateral vessels which covered by the stent remain permeable. At the end of this experimentation, 10 implants have been achieved in 8 patients (4 recurrences of iliac stenosis and 6 femoral stenosis). The angiographic results show the perfect tolerance of the organism at 6 months. This good tolerance is revealed by a thin intraluminal border which does not change the artery's diameter. This confirms the experimental results. The permeability is good except for two patients who had an obliteration after one month (one iliac and one femoral obliteration).

Raman microprobe analysis of preforms and optical fibers

The concentration profile of various dopants (germanium, phosphorus, and fluorine) in preforms and optical fibers has been obtained with a Raman microprobe. A 2-microm spatial resolution was achieved. In the case of germanium and phosphorus, the results agree quite well with those obtained with an electron microprobe. Raman spectroscopy easily detects fluorine. From measurements of various F-doped samples, diffusion of fluorine in undoped and doped silica is suggested.