Laue microdiffraction on polycrystalline samples above 1500 K achieved with the QMAX-µLaue furnace

X-ray Laue microdiffraction aims to characterize microstructural and mechanical fields in polycrystalline specimens at the sub-micrometre scale with a strain resolution of ∼10-4. Here, a new and unique Laue microdiffraction setup and alignment procedure is presented, allowing measurements at temperatures as high as 1500 K, with the objective to extend the technique for the study of crystalline phase transitions and associated strain-field evolution that occur at high temperatures. A method is provided to measure the real temperature encountered by the specimen, which can be critical for precise phase-transition studies, as well as a strategy to calibrate the setup geometry to account for the sample and furnace dilation using a standard α-alumina single crystal. A first application to phase transitions in a polycrystalline specimen of pure zirconia is provided as an illustrative example.

Grafted chitosan thin films of various degrees of acetylation as a reusable platform for the investigation of biological interactions

Surface treatment by adhesive polymers is a promising solution to immobilize and study bacteria cells through microscopic assays and, for example, control their growth or determine their susceptibility to antibiotic treatment. The stability of such functional films in wet conditions is crucial, as the film degradation would compromise a persistent use of the coated devices. In this work, low roughness chitosan thin films of degrees of acetylation (DA) ranging from 0.5 % to 49 % were chemically grafted onto silicon and glass substrates and we have demonstrated how the physicochemical properties of the surfaces and the bacterial response were DA-dependent. A fully deacetylated chitosan film presented an anhydrous crystalline structure while the hydrated crystalline allomorph was the preferred structure at higher DA. Moreover, their hydrophilicity increased at higher DA, leading to higher film swelling. Low DA chitosan-grafted substrate favored bacterial growth away from the surface and could be envisioned as bacteriostatic surfaces. Contrarily, an optimum of Escherichia coli adhesion was found for substrates modified with chitosan of DA = 35 %: these surfaces are adapted for the study of bacterial growth and antibiotic testing, with the possibility of reusing the substrates without affecting the grafted film - ideal for limiting single-use devices.

A compact-rigid multi-analyser for energy and angle filtering of high-resolution X-ray experiments. Part 2. Efficiency of a single-crystal-comb

Diffraction instruments using filtering by one or several analyser crystals exist since the 1980s and 1990s at synchrotron radiation sources, but, due to its low efficiency, this filtering is little used on laboratory sources. In order to overcome this limitation, the efficiency of a small diffraction filtering multi-analyzer block (MAD block) realized with a `single-crystal-comb' curved on a rigid support is demonstrated here. The geometry of this curved surface is logarithmic spiral and is optimized to allow multi-filtering over a relatively important diffraction angular range and to be also applicable over an X-ray spectral range. The efficiency of such a small rigid-compact MAD block consisting of this single-crystal-comb generating 20-50 Si(111) single-crystal blades, associated with a block of Soller collimators, is demonstrated. The angle between each crystal is 0.1°, so the measurement range of the comb is 2-5°. The geometry of this system has been optimized for operation with a synchrotron X-ray source over an energy range of 22 keV to 46 keV and could be used with laboratory X-ray sources (Ag Kα<sub>1</sub>, 22.1 keV). This MAD block complements and exploits the qualities of the `photon-counting' detectors which have very low intrinsic noise. Their joint efficacy is supported by powder pattern measurements of a LaB₆ reference sample and of several heterogeneous samples of cultural heritage materials, carried out at 22 keV on the D2AM beamline at the ESRF. Their signal-to-noise ratio is excellent (1000/1) and allows the detection thresholds of the measurements (from 3-1% to 0.1%) to detect minor phases in the studies of `real' heterogeneous materials to be drastically improved.

Oxygen crystallographic positions in thin films by non-destructive resonant elastic X-ray scattering

Precisely locating oxygen atoms in nanosized systems is a real challenge. The traditional strategies used for bulk samples fail at probing samples with much less matter. Resonant elastic X-ray scattering (REXS) experiments in the X-ray absorption near-edge structure (XANES) domain have already proved their efficiency in probing transition metal cations in thin films, but it is not feasible to perform such experiments at the low-energy edges of lighter atoms – such as oxygen. In this study, the adequacy of using REXS in the extended X-ray absorption fine structure (EXAFS) domain, also known as extended diffraction absorption fine structure (EDAFS), to solve this issue is shown. The technique has been validated on a bulk FeV2O4 sample, through comparison with results obtained with conventional X-ray diffraction measurements. Subsequently, the positions of oxygen atoms in a thin film were unveiled by using the same strategy. The approach described in this study can henceforth be applied to solve the crystallographic structure of oxides, and will help in better understanding the properties and functionalities which are dictated by the positions of the oxygen atoms in functional nanosized materials.

Full reciprocal-space mapping up to 2000 K under controlled atmosphere: the multipurpose QMAX furnace

A furnace that covers the temperature range from room temperature up to 2000 K has been designed, built and implemented on the D2AM beamline at the ESRF. The QMAX furnace is devoted to the full exploration of the reciprocal hemispace located above the sample surface. It is well suited for symmetric and asymmetric 3D reciprocal space mapping. Owing to the hemispherical design of the furnace, 3D grazing-incidence small- and wide-angle scattering and diffraction measurements are possible. Inert and reactive experiments can be performed at atmospheric pressure under controlled gas flux. It is demonstrated that the QMAX furnace allows monitoring of structural phase transitions as well as microstructural evolution at the nanoscale, such as self-organization processes, crystal growth and strain relaxation. A time-resolved in situ oxidation experiment illustrates the capability to probe the high-temperature reactivity of materials.

The Structure of the Amorphous (GeTe)1–x (Sb2Te3) x System and Implications for its Phase-Change Properties

We describe structural features of ternary Ge-Sb-Te glasses based on anomalous X-ray scattering experiments for four different compositions along the pseudo-binary line (GeTe)1–x (Sb2Te3) x for 0 ≤ x ≤ 2 3 $0\leq x\leq\frac{2}{3}$ , which comprises technologically important phase-change materials. The data are analyzed with reverse Monte Carlo modeling. This way, detailed information on the local environments around all constituent elements are obtained and their evolution with the chemical composition is described. This approach gives a consistent view of the atomic scale structure of the amorphous networks in these compounds. Thereby, it is possible to derive the relationship between the relevant material properties and the determining structural features. In particular, it is shown that the optical contrast related to the phase change is associated with the evolution of the Ge-Te core network.

New tools for calibrating diffraction setups

New calibration tools in the pyFAI suite for processing scattering experiments acquired with area detectors are presented. These include a new graphical user interface for calibrating the detector position in a scattering experiment performed with a fixed large area detector, as well as a library to be used in Jupyter notebooks for calibrating the motion of a detector on a goniometer arm (or any other moving table) to perform diffraction experiments.

Dessine-moi une réalité plus belle : la réalité virtuelle vue par les patientes atteintes d’un cancer du sein

Une enquête réalisée auprès de 300 femmes atteintes d’un cancer du sein a permis d’examiner leur intérêt pour la réalité virtuelle (RV), les modalités d’immersion attendues ainsi que leurs attentes vis-à-vis de ce dispositif. Les résultats indiquent que la majorité des femmes (93 %) souhaiterait avoir recours à la RV durant leurs traitements, sachant que leurs préférences d’immersion portent sur un environnement naturel accompagné de musique et/ou de relaxation guidée. La RV est envisagée comme un outil pertinent pour s’évader, mieux accepter les soins et réguler leurs émotions. Pour faciliter l’immersion virtuelle, cette étude souligne combien il est important de connaître leurs aspirations personnelles pour leur offrir un soutien technologique individualisé.

Cubic chemically ordered FeRh and FeCo nanomagnets prepared by mass-selected low-energy cluster-beam deposition: a comparative study

Near the point of equiatomic composition, both FeRh and FeCo bulk alloys exhibit a CsCl-type (B2) chemically ordered phase that is related to specific magnetic properties, namely a metamagnetic anti-ferromagnetic/ferromagnetic transition near room temperature for FeRh and a huge magnetic moment for the FeCo soft alloy. In this paper, we present the magnetic and structural properties of nanoparticles of less than 5 nm diameter embedded in an inert carbon matrix prepared by mass-selected low-energy cluster-beam deposition technique. We obtained a CsCl-type (B2) chemically ordered phase for annealed nanoalloys. Using different experimental measurements, we show how decreasing the size affects the magnetic properties. FeRh nanoparticles keep the ferromagnetic order at low temperature due to surface relaxation affecting the cell parameter. In the case of FeCo clusters, the environment drastically affects the intrinsic properties of this system by reducing the magnetization in comparison to the bulk.

Resonant Scattering in Condensed Matter, Experiments that Reveal Short to Long Range Atomic Order

After a historical introduction of the anomalous dispersion effect, the formalism used to investigate disordered materials using the resonant scattering of X-rays is exposed. As these experiments are sensitive to the experimental conditions, some experimental settings are discussed.

Structural Aspects of the Superionic Conduction Mechanism in Ag-GeSe3 Glasses

The local and intermediate-range atomic structure in the Ag ion conducting glasses Ag x (GeSe3)1−x with x = 0.15 and 0.50 has been investigated by Anomalous X-Ray Scattering experiments at the K absorption edges of each constituent element. This method can provide insight into the structural properties enabling the effect of superionic conductivity for compositions with x > 0.33 in the amorphous phase. The experimental results were analyzed with Reverse Monte Carlo modeling, providing the partial structure factors and the corresponding partial pair-distribution functions. Evidence is found for a high level of intermediate range order for low silver concentrations, whereas the superionic conducting phase formed at high silver concentrations is characterized by cluster-like configurations of Ag atoms on a nanometer scale.

Polarization Rotation in Ferroelectric Tricolor PbTiO3/SrTiO3/PbZr0.2Ti0.8O3 Superlattices

In ferroelectric thin films, controlling the orientation of the polarization is a key element to controlling their physical properties. We use laboratory and synchrotron X-ray diffraction to investigate ferroelectric bicolor PbTiO3/PbZr0.2Ti0.8O3 and tricolor PbTiO3/SrTiO3/PbZr0.2Ti0.8O3 superlattices and to study the role of the SrTiO3 layers on the domain structure. In the tricolor superlattices, we demonstrate the existence of 180° ferroelectric stripe nanodomains, induced by the depolarization field produced by the SrTiO3 layers. Each ultrathin SrTiO3 layer modifies the electrostatic boundary conditions between the ferroelectric layers compared to the corresponding bicolor structures, leading to the suppression of the a/c polydomain states. Combined with the electrostatic effect, the tensile strain induced by PbZr0.2Ti0.8O3 in the PbTiO3 layers leads to polarization rotation in the system as evidenced by grazing incidence X-ray measurements. This polarization rotation is associated with the monoclinic Mc phase as revealed by the splitting of the (HHL) and (H0L) reciprocal lattice points. This work demonstrates that the tricolor paraelectric/ferroelectric superlattices constitute a tunable system to investigate the concomitant effects of strains and depolarizing fields. Our studies provide a pathway to stabilize a monoclinic symmetry in ferroelectric layers, which is of particular interest for the enhancement of the piezoelectric properties.

K-edge imaging with the XPAD3 hybrid pixel detector, direct comparison of CdTe and Si sensors

We investigate the improvement from the use of high-Z CdTe sensors for pre-clinical K-edge imaging with the hybrid pixel detectors XPAD3. We compare XPAD3 chips bump bonded to Si or CdTe sensors in identical experimental conditions. Image performance for narrow energy bin acquisitions and contrast-to-noise ratios of K-edge images are presented and compared. CdTe sensors achieve signal-to-noise ratios at least three times higher than Si sensors within narrow energy bins, thanks to their much higher detection efficiency. Nevertheless Si sensors provide better contrast-to-noise ratios in K-edge imaging when working at equivalent counting statistics, due to their better estimation of the attenuation coefficient of the contrast agent. Results are compared to simulated data in the case of the XPAD3/Si detector. Good agreement is observed when including charge sharing between pixels, which have a strong impact on contrast-to-noise ratios in K-edge images.

The In situ growth of Nanostructures on Surfaces (INS) endstation of the ESRF BM32 beamline: a combined UHV-CVD and MBE reactor for in situ X-ray scattering investigations of growing nanoparticles and semiconductor nanowires

This paper presents the upgraded `In situ growth of Nanoscructures on Surfaces' (INS) endstation of the InterFace beamline IF-BM32 at the European Synchrotron Radiation Facility (ESRF). This instrument, originally designed to investigate the structure of clean surfaces/interfaces/thin-films by surface X-ray diffraction, has been further developed to investigate the formation and evolution of nanostructures by combining small- and wide-angle X-ray scattering methodologies, i.e. grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence X-ray diffraction (GIXD). It consists of a UHV chamber mounted on a z-axis type goniometer, equipped with residual gas analysis, reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES) to complete the X-ray scattering investigations. The chamber has been developed so as up to eight sources of molecular beam epitaxy (MBE) can be simultaneously mounted to elaborate the nanostructures. A chemical vapor deposition (CVD) set-up has been added to expand the range of growing possibilities, in particular to investigate in situ the growth of semiconductor nanowires. This setup is presented in some detail, as well as the first in situ X-ray scattering measurements during the growth of silicon nanowires.

Strains induced by point defects in graphene on a metal

Strains strongly affect the properties of low-dimensional materials, such as graphene. By combining in situ, in operando, reflection high-energy electron diffraction experiments with first-principles calculations, we show that large strains, above 2%, are present in graphene during its growth by chemical vapor deposition on Ir(111) and when it is subjected to oxygen etching and ion bombardment. Our results unravel the microscopic relationship between point defects and strains in epitaxial graphene and suggest new avenues for graphene nanostructuring and engineering its properties through introduction of defects and intercalation of atoms and molecules between graphene and its metal substrate.

Development of Vertically Integrated Imaging and Particle Sensors

Integrated imaging and particle sensors have been developed using thin-film on ASIC technology. For this purpose, hydrogenated amorphous silicon diodes, in various configurations, have been optimized for imaging and direct particle detection. These devices were first deposited on glass substrates and later on CMOS readout chips. With an optimization of the material properties and of the diode, a dark current of 1 pA/cm2 could be achieved on p-i-n structures at reverse bias voltage of 1 V. CMOS imagers, incorporating these optimized diodes were then fabricated and characterized. Very thick diodes (with thicknesses up to 50 μm) were also optimized and deposited on glass and on CMOS readout chips. Particle detectors in TFA technology with 12 and 30 μm a-Si:H n-i-p diodes have been fabricated and characterized using light pulse illumination. Direct detection of single low-energy beta particles has been demonstrated.

Prenatal isolated mild ventriculomegaly: outcome in 167 cases

OBJECTIVE

To define the contribution of prenatal investigation and evaluate the prognosis of isolated mild ventriculomegaly (IMV).

DESIGN

Retrospective study.

SETTING

University hospital between January 1992 and December 2002.

POPULATION

One hundred and sixty-seven cases of prenatal unilateral or bilateral IMV without any associated anomaly at the time of initial diagnosis.

METHODS

Complementary investigations were performed: amniocentesis with karyotyping, screening for viruses and acetylcholinesterase electrophoresis, magnetic resonance imaging (MRI), and ultrasonography every 3-4 weeks.

MAIN OUTCOME MEASURES

Results of prenatal investigations, pregnancy outcome, and postnatal psychomotor development.

RESULTS

IMV was diagnosed around 26.5 weeks. Amniocentesis revealed four chromosomal anomalies and two cytomegalovirus infections. MRI diagnosed brain-associated anomalies in 15 cases and ultrasonographic monitoring highlighted malformations not initially diagnosed in 28 cases. Termination of pregnancy (TOP) was considered in 21 pregnancies (12.6%). Indications were aneuploidy, fetal infectious disease or associated malformations. In women for whom a TOP was considered, consanguinity, fetus of female sex and frontal horn enlargement were statistically more frequent, ventriculomegaly was more often bilateral and asymmetrical, atrial width, and the rate of progressive ventricular enlargement were significantly higher. One hundred and one children with prenatal IMV were assessed between 19 and 127 months (mean age 54.68 +/- 2.87 months). Twelve children had neurological disease or psychomotor delay and 89 children had a normal psychomotor development. Poor neurological outcome was more often associated with atrial width greater than or equal to 12 mm, asymmetrical bilateral enlargement, and progression of the ventriculomegaly.

CONCLUSION

The detection of IMV raises the question of the child's psychomotor development and justifies meticulous prenatal investigation. In addition to associated anomalies, three criteria are often associated with an unfavourable outcome: atrial width greater than 12 mm, progression of the enlargement, and asymmetrical and bilateral ventriculomegaly.

High-density electrode array for imaging in vitro electrophysiological activity

The development of a high-density active microelectrode array for in vitro electrophysiology is reported. Based on the Active Pixel Sensor (APS) concept, the array integrates 4096 gold microelectrodes (electrode separation 20 microm) on a surface of 2.5 mmx2.5 mm as well as a high-speed random addressing logic allowing the sequential selection of the measuring pixels. Following the electrical characterization in a phosphate solution, the functional evaluation has been carried out by recording the spontaneous electrical activity of neonatal rat cardiomyocytes. Signals with amplitudes from 130 microVp-p to 300 microVp-p could be recorded from different pixels. The results demonstrate the suitability of the APS concept for developing a new generation of high-resolution extracellular recording devices for in vitro electrophysiology.

[Factors associated with childhood diabetes manifesting as ketoacidosis and its severity]

INTRODUCTION

Type 1 diabetes in children in France is frequently diagnosed at the stage of ketoacidosis (DKA).

PATIENTS AND METHODS

A prospective study was performed in a group of 72 children (mean age = 9.4 years) at onset of diabetes, in order to determine which factors were associated to DKA and to the severity of DKA (pH < 7.10) at diagnosis.

RESULTS

Younger age was related to DKA (p = 0.03), but not to its severity. A lesser frequency of DKA was found in children with a family history of insulin-treated diabetes ( p = 0.04). Misdiagnosis was more frequently observed in children with DKA than in children without DKA (p = 0.02) and in case of severe DKA at admission by comparison with non severe cases (76 vs 23%; p = 0.002). Children in low economic intake families exhibited more frequently a severe DKA (77 vs 23%; p = 0.002) and were more frequently misdiagnosed before admission (48% vs 10%; p < 0.01). Urine strips for glucose and ketone determinations were underused for diagnosis before admission (15% only).

CONCLUSION

Those results underline the need to both inform physicians and ameliorate the access to health care for low social class families, in order to take up the challenge of reducing the incidence of DKA at diagnosis in diabetic children in our country.

Late-onset cystic periventricular leukomalacia in premature infants: a threat until term

The purposes of this study are (1) to describe a "late-onset" form of cystic periventricular leukomalacia eventually appearing in premature infants whose neurological assessments were normal in the first month of life; (2) to retrospectively evaluate its incidence among a large population of premature infants; (3) to suggest that a few unexpected complications of prematurity may trigger the development of white matter damage, even several weeks after birth. Retrospective study in a population of 1452 surviving infants after 5 days born before 33 weeks. We identified 10 cases of late-onset cystic periventricular leukomalacia appearing beyond the first 5 weeks of life. In 8 cases, an intercurrent event associated with a systemic inflammatory response preceded the appearance of cysts: necrotizing enterocolitis (n = 5), septicemia (n = 2 cases), strangulated inguinal hernia in one infant. Neurological surveillance should be repeated until discharge in very preterm infants, especially after the occurrence of an intercurrent complication coming along with a systemic inflammatory response.

Pulmonary sarcoidosis in children: a follow-up study

Progression of pulmonary sarcoidosis in children remains poorly documented. The aim of this work was to gather follow-up information on pulmonary outcomes in children with sarcoidosis and to obtain data of relevance to a discussion of the optimal length and regimen of glucocorticoid therapy. In the present study, the authors experience of pulmonary sarcoidosis in 21 children referred to the paediatric pulmonary department over a 10-yr period is reported with a documented follow-up of at least 4 yr. Evaluation of the disease during the follow-up included analysis of clinical manifestations, chest radiographs, pulmonary function tests with measurements of the vital capacity (VC), dynamic lung compliance (CL,dyn), lung transfer for CO (TL,CO), and arterial blood gases, as well as bronchoalveolar lavage (BAL) with determination of total and differential cell counts. After initial evaluation the decision was a careful observation of four children without therapy. Corticosteroid treatment was initiated in 17 children. Analysis of results indicated that after 6-12 months of treatment most clinical manifestations of the disease and chest radiograph abnormalities disappeared, and beneficial effects on VC and TL,CO were apparent. After 18 months of steroids no benefit on pulmonary function tests could be noticed, with mainly persistence of alterations of CL,dyn. Results of BAL studies documented the presence of an alveolitis with increased lymphocyte populations throughout the follow-up. Relapses were observed in four children during tapering of prednisone; they were not reported after discontinuation of steroid therapy. Taken together data obtained in the presented population can lead to the following suggestions for the management of pulmonary sarcoidosis in children. BAL should be performed at the initial evaluation to document alveolitis; however, nothing seems to be gained from repeating this investigation during follow-up in the absence of specific reasons. Once the decision to initiate glucocorticoid therapy is made, 18 months may be a reasonable treatment duration. Discontinuation of therapy can be decided even if the pulmonary function tests remain abnormal, but the child should then be carefully monitored for a relapse.

Infantile spasms and Menkes disease

Epileptic seizures are a common feature in Menkes disease, an X-linked genetic disorder of copper metabolism. Details of type of seizures are rarely reported. We report the evolution of infantile spasms in two patients with Menkes disease and the relation with subcutaneous administration of copper-histidine.

[Severe ketoacidosis because of delayed diagnosis of diabetes in children. 4 cases to alert physicians]

BACKGROUND

In France, 48% of children with insulin-dependent diabetes mellitus (IDDM) are seen for the first time at the stage of keto-acidosis (DKA), a figure far higher than in other countries. The four consecutive cases reported in this paper suggest that severity at presentation is directly related to the delay of diagnosis.

CASE REPORTS

All children, aged 6 to 11, presented with severe clinical and metabolic conditions: coma, hemodynamic failure, severe dehydration and acidosis (pH = 6.86 to 7.06). However, clinical symptoms were a present from 2 to 4 months, parents did not worry about them. Family practitioners visited 2-21 days before admission failed to immediately make the diagnosis of IDDM. True DKA was however present in all cases 48 hours prior to admission.

CONCLUSIONS

Earlier diagnosis of IDDM in children is necessary to reduce morbidity and mortality of DKA. General practitioners, pediatricians and emergency care practitioners must be made fully aware to consider diabetes in children and to use more extensively glucose-tests based on urine and blood strips.

A method for early detection of graft failure in pancreas transplantation

Pancreatic transplantation is intended to normalize carbohydrate metabolism in insulin-dependent diabetics by restoring endogenous insulin release, and it is usually performed together with kidney transplantation in patients with end-stage renal failure. A major problem in these patients is the daily control of the grafted pancreas because traditional measurements do not appear to be adequate to evaluate pancreatic function. Aiming at early detection of graft failure, we have analyzed in 8 such patients and in 20 nondiabetic kidney-grafted patients (a control group) the following variables: 24-hr glycosuria (absolute values, or values after natural logarithmic transformation) and 24-hr urinary C-peptide excretion (corrected for 24-hr urinary creatinine). These measurements, considered alone, did not detect pancreatic graft failure; for instance, glycosuria can depend on immunosuppressive steroid treatment, and it was often found even in the control group. On the contrary, the ratio Ln 24-hr glycosuria: 24-hr urinary C-peptide varied from 0.00 to 0.18 in the control group and in normally working pancreatic grafts; when the pancreatic grafts failed, however, as confirmed by arteriographic evidence, histologic findings, or dynamic endocrine tests, this ratio rose far higher than 0.18, reaching values as high as 12.2. Use of this ratio provides a simple technique for daily evaluation of pancreatic graft function and for early detection of graft failure.

Endocrine responses of type 1 (insulin-dependent) diabetic patients following successful pancreas transplantation

The aim of the present study was to evaluate the insulin and glucagon responses to various stimuli in patients following pancreatic transplantation. Four Type 1 (insulin-dependent) diabetic patients with end-stage renal failure who had received a cadaveric segmental, neoprene-injected, pancreas transplant, in association with kidney transplantation, were investigated. Free-insulin, pancreatic glucagon, and growth hormone concentrations were measured after both oral and intravenous glucose tolerance tests, and following tolbutamide, arginine and arginine plus somatostatin infusions. Tests were performed 1 month (three cases) and 30 months (one case) after surgery, when no insulin administration was required. Four non-diabetic kidney grafted patients, matched for duration of graft survival and immunosuppressive treatment (steroids, azathioprine and anti-lymphocyte-globulins), served as control subjects. Impaired glucose tolerance was present in all diabetic and control patients. This was possibly related to immunosuppressive treatment. In comparison with control subjects, insulin release was normal in response to arginine and tolbutamide but was reduced in response to oral and intravenous glucose, while glucagon and growth hormone release were similar in both groups. Somatostatin was less effective in diabetic patients than in control subjects in suppressing insulin and glucagon release.

[Rejections and cytomegalovirus infections after renal transplantation]

Immunosuppressed patients are known to be susceptible to infectious agents. Association of allograft rejection and herpes virus infection (high incidence of cytomegalovirus) was yet reported after renal transplantation. Authors studied 19 rejection episodes on 24 renal transplantation performed for 17 months, cytomegalovirus infection being associated in 7. Because of the therapeutic difficulties observed in these cases, a preventive attitude is necessary.