Direct Structural Identification and Quantification of the Split-Vacancy Configuration for Implanted Sn in Diamond

We demonstrate formation of the ideal split-vacancy configuration of the Sn-vacancy center upon implantation into natural diamond. Using β^{-} emission channeling following low fluence ^{121}Sn implantation (2×10^{12}  atoms/cm^{2}, 60 keV) at the ISOLDE facility at CERN, we directly identified and quantified the atomic configurations of the Sn-related centers. Our data show that the split-vacancy configuration is formed immediately upon implantation with a surprisingly high efficiency of ≈40%. Upon thermal annealing at 920 °C ≈30% of Sn is found in the ideal bond-center position. Photoluminescence revealed the characteristic SnV^{-} line at 621 nm, with an extraordinarily narrow ensemble linewidth (2.3 nm) of near-perfect Lorentzian shape. These findings further establish the SnV^{-} center as a promising candidate for single photon emission applications, since, in addition to exceptional optical properties, it also shows a remarkably simple structural formation mechanism.

[Type 1 neurofibromatosis: Onset of two tumors before the age of 5years]

Neurofibromatosis type 1 (NF1) is a frequent autosomal dominant genetic disorder that predisposes to the development of benign and malignant tumors. Mutation of the NF1 gene affects the RAS-MAPK signaling pathway and leads to a dysfunction in cell proliferation and induces tumor development. Epidemiology of cancer in children with NF1 is very different from the general pediatric population, which requires regular and specific monitoring. Neurofibroma is the most frequent benign tumor. It can be very invalidating depending on the size and location of the tumor. Currently, there is no specific treatment for these tumors. The most frequent malignancies in children with NF1 are leukemias, rhabdomyosarcomas, malignant peripheral nerve sheath tumors and gliomas. The treatment of these tumors should consider the risk of second cancers induced by radio- and chemotherapy. We report on the case of a 5-year-old boy with NF1 developing two tumors.

Early outcomes of spinal growth tethering for idiopathic scoliosis with a novel device: a prospective study with 2 years of follow-up

QUESTIONS/PURPOSES

Adolescent idiopathic scoliosis is a 3D spine deformity that worsens during the whole growth. New methods for spinal growth modulation with flexible spinal implants have been described to avoid progression of the deformity during growth spurt. The main limitations are that no specific ancillaries and devices are available, which makes the surgery technically demanding.

METHODS

We have developed a new method of spinal growth tethering using minimal invasive videothoracoscopic approach. Fixation is performed with staples and synthetic ligament on the lateral aspect of vertebral bodies on main curvature convexity. Patients with progressive thoracic idiopathic scoliosis despite the brace treatment were included. The clinical and radiological examinations were compared before and 2 years after surgery.

RESULTS

Six patients with flexible thoracic curves with a mean age 11.2 ± 1.2 years and a mean Cobb angle 45° ± 10° (35-60) were operated. All were skeletally immature. At last follow-up, the Cobb angle was stable. None of the patient underwent fusion.

CONCLUSIONS

The procedure allowed a stabilization of the deformity during growth spurt. Validated devices and further studies with longer term follow-up are needed to confirm the efficiency of this technique. This small cohort of patients is a source of reflection for further medical devices developments.

LEVEL OF EVIDENCE

Level 4 case series comparing to not randomized studies.

[Pitfalls in the diagnosis of occult elbow fractures in children]

Elbow injuries are frequent but occult fractures are difficult to diagnose on x-rays. However, any delay in the diagnosis may severely impair the prognosis of some fractures. Simple tips may help the clinician read x-rays properly and avoid the classical pitfalls of elbow injuries in children. The chronology of appearance of ossification nuclei around the elbow is important to distinguish normal features from abnormality. Drawing simple geometric constructions on the x-rays may clarify most occult elbow fractures in children.

Photoelectric detection of electron spin resonance of nitrogen-vacancy centres in diamond

The readout of negatively charged nitrogen-vacancy centre electron spins is essential for applications in quantum computation, metrology and sensing. Conventional readout protocols are based on the detection of photons emitted from nitrogen-vacancy centres, a process limited by the efficiency of photon collection. We report on an alternative principle for detecting the magnetic resonance of nitrogen-vacancy centres, allowing the direct photoelectric readout of nitrogen-vacancy centres spin state in an all-diamond device. The photocurrent detection of magnetic resonance scheme is based on the detection of charge carriers promoted to the conduction band of diamond by two-photon ionization of nitrogen-vacancy centres. The optical and photoelectric detection of magnetic resonance are compared, by performing both types of measurements simultaneously. The minima detected in the measured photocurrent at resonant microwave frequencies are attributed to the spin-dependent ionization dynamics of nitrogen-vacancy, originating from spin-selective non-radiative transitions to the metastable singlet state.

Nitrogen-vacancy colour centre defects in diamond are one possible host for qubits, but such an application requires a method for reading out the colour centre spin state. Here, the authors demonstrate a photoelectric readout technique of the magnetic resonances of these colour centres.

Spica cast as an alternative to general anesthesia for lower limb MRI in young children

Background

The conventional approach for MRI procedures in very young children is to use general anesthesia which comes with inherent risks. Non-pharmacological strategies to reduce anxiety in children have also been described, but they all require patient cooperation. The purpose of the study was to evaluate the ability to complete diagnosis using temporary spica cast immobilization (TSCI) in children less than 3 years old undergoing MRI procedures for lower limb disorders.

Materials and methods

A retrospective review identified 14 children under 3 years old that had required an MRI for a lower limb disorder, using TSCI. The MRI procedure was performed for evaluation of hip dysplasia, bone infections, limping, evaluation of soft tissue tumor and femoral head osteonecrosis. A spica cast was fitted by the pediatric orthopedic team. The MRI procedure was subsequently performed.

Results

Diagnosis was achieved in all cases. The radiologist identified movement artifacts (14 %) that did not impair the image quality enough to prevent interpretation.

Conclusion

TSCI is a safe, effective and costless procedure avoiding general anesthesia for young patients under 3 years old who require MRI for pelvis or lower limb disorders.

Level of evidence

IV.

Minimal alveolar concentration of sevoflurane inhibiting the reflex pupillary dilatation after noxious stimulation in children and young adults

BACKGROUND

In children, sevoflurane is the most commonly used anaesthetic. Its excellent haemodynamic tolerance gives it a wide therapeutic index. This halogenated agent can abolish movement [minimal alveolar concentration (MAC)] or haemodynamic responses (MACBAR) to noxious stimulus in children as in adults. Reflex pupillary dilatation (RPD) has been demonstrated as a very sensitive measure of noxious stimulation. In order to investigate the effect of sevoflurane on the RPD, a subcortical reflex, we determined the MAC of sevoflurane inhibiting the RPD in 50% of the subjects in response to skin incision (MACpup) in pre- and post-pubertal subjects.

METHODS

We included 30 pre-pubertal children and 19 post-pubertal subjects. Patients received sevoflurane at preselected concentrations according to an 'up and down' design, and after a steady-state period, skin incision was performed. The RPD was considered as significant when the pupillary diameter increased by more than 100%. Heart rate (HR) and bispectral index (BIS) changes were analysed according to the pupillary response.

RESULTS

The MACpup of sevoflurane was 4.8% (95% confidence interval, 4.6-5.1%) in pre-pubertal children vs 3.4% (3.5-3.3%) in post-pubertal subjects (P<0.001). Inhibition of RPD was always associated with lack of significant HR response. In pre-pubertal children receiving high concentrations of sevoflurane, RPD in response to noxious stimulation was frequently associated with lack of HR response and low BIS values.

CONCLUSIONS

MACpup was higher than MAC and close to the MACBAR. Inhibition of RPD in pre-pubertal children required higher sevoflurane concentrations compared with post-pubertal subjects, suggesting that the relationship between the brain structure sensitivities may differ with brain maturation.

Identification of a new mutation on the beta-globin gene: codons 8/9 (+AGAA); GAG.AAG.TCT(Glu-Lys-Ser)>GAG. AAAGAAG, in a patient from the north of France with a phenotype of beta-thalassemia minor

A 37-year-old man presented a slight debility. The hemogram showed a phenotype of beta-thalassemia minor: Hb (13.1 g/dL), mean corpuscular volume (MCV) (62 fL) with low mean corpuscular hemoglobin (MCH) (20.8 pg), associated with a high level of Hb A(2) of 5.3%. The serum ferritin level was 1,072 ng/mL. The sequencing of the mutated fragment revealed a duplication of four bases of codons 7/8 involving a shift in the open reading frame starting from codon 9 with a TGA stop codon at codon 23: codons 7/8/9 (+AGAA); GAG.AAG.TCT(Gly-Lys-Ser)>GAG.AAAGAAG. The human hemoglobin (Hb) instability tests were negative. The patient did not present the high iron Fe (HFE) mutation (C282Y, H63D). The same mutation was found in five other unrelated families (representing a total of 23 patients). All of their ancestors came from the north of France. This mutation has not been described before and could have its origins in the native populations of Northern France.

Diversity of the Ty-1 copia retrotransposon Tos17 in rice (Oryza sativa L.) and the AA genome of the Oryza genus

Retrotransposons are mobile genetic elements, ubiquitous in Eukaryotic genomes, which have proven to be major genetic tools in determining phylogeny and structuring genetic diversity, notably in plants. We investigate here the diversity of the Ty1-copia retrotransposon Tos17 in the cultivated rice of Asian origin (Oryza sativa L.) and related AA genome species of the Oryza genus, to contribute understanding of the complex evolutionary history in this group of species through that of the element in the lineages. In that aim, we used a combination of Southern hybridization with a reverse transcriptase (RT) probe and an adapter-PCR mediated amplification, which allowed the sequencing of the genomic regions flanking Tos17 insertions. This analysis was carried out in a collection of 47 A-genome Oryza species accessions and 202 accessions of a core collection of Oryza sativa L. representative of the diversity of the species. Our Southern hybridization results show that Tos17 is present in all the accessions of the A-genome Oryza species, except for the South American species O. glumaepatula and the African species O. glaberrima and O. breviligulata. In O. sativa, the number of putative copies of Tos17 per accession ranged from 1 to 11 and multivariate analysis based on presence/absence of putative copies yielded a varietal clustering which is consistent with the isozyme classification of rice. Adapter PCR amplification and sequencing of flanking regions of Tos17 insertions in A-genome species other than O. sativa, followed by anchoring on the Nipponbare genome sequence, revealed 13 insertion sites of Tos17 in the surveyed O. rufipogon and O. longistaminata accessions, including one shared by both species. In O. sativa, the same approach revealed 25 insertions in the 6 varietal groups. Four insertion sites located on chromosomes 1, 2, 10, and 11 were found orthologous in O. rufipogon and O. sativa. The chromosome 1 insertion was also shared between O. rufipogon and O. longistaminata. The presence of Tos17 at three insertion sites was confirmed by retrotransposon-based insertion polymorphism (RBIP) in a sample of O. sativa accessions. The first insertion, located on chromosome 3 was only found in two japonica accessions from the Bhutan region while the second insertion, located on chromosome 10 was specific to the varietal groups 1, 2, and 5. The third insertion located on chromosome 7 corresponds to the only insertion shown active in rice so far, notably in cv. Nipponbare, where it has been extensively used for insertion mutagenesis. This copy was only found in a few varieties of the japonica group 6 and in one group 5 accession. Taken together, these results confirm that Tos17 was probably present in the ancestor of A-genome species and that some copies of the element remained active in some Oryza lineages--notably in O. rufipogon and O. longistaminata--as well as in the indica and japonica O. sativa L. lineages.

[Pseudoxanthoma elasticum-like syndrome associated with hemoglobinopathy: a case report]

INTRODUCTION

We report a case of hemoglobinopathy which could be associated with a pseudoxanthoma elastic-like syndrome.

EXEGESIS

We report the case of a 26-year-old male patient with sickle cell anemia for which the supra-aortic-doppler ultrasonography suggested an asymptomatic left carotid artery of 70% stenosis. The magnetic resonance imaging and angiography showed a left megadolichocarotid with plicature suggestive of pseudoxanthoma elastic or a dilatation relative to a high rate of blood explaining the acceleration speed. There was a cutaneous infiltration but other vasculopathies of neither carotide, nor cerebral, nor ocular have been discovered while they were sometimes found in pseudoxanthoma elastic-like syndrome. This acquired form is different of rare hereditary disease by a later diagnosis, a clinical expression often very incomplete and a frequent association with hemoglobinopathies.

CONCLUSION

This observation shows that RMA could be necessary to perform in adults, when cervical and transcranial Doppler ultrasonography is abnormal, particularly before deciding to start long term blood transfusions. The hemoglobinopathy and pseudoxanthoma elastic-like syndrome must not be ignored because the control of cardiovascular factors reduce the risks of arterial complications.

Efficacy of romiplostim in patients with chronic immune thrombocytopenic purpura: a double-blind randomised controlled trial

BACKGROUND

Chronic immune thrombocytopenic purpura (ITP) is characterised by accelerated platelet destruction and decreased platelet production. Short-term administration of the thrombopoiesis-stimulating protein, romiplostim, has been shown to increase platelet counts in most patients with chronic ITP. We assessed the long-term administration of romiplostim in splenectomised and non-splenectomised patients with ITP.

METHODS

In two parallel trials, 63 splenectomised and 62 non-splenectomised patients with ITP and a mean of three platelet counts 30x10(9)/L or less were randomly assigned 2:1 to subcutaneous injections of romiplostim (n=42 in splenectomised study and n=41 in non-splenectomised study) or placebo (n=21 in both studies) every week for 24 weeks. Doses of study drug were adjusted to maintain platelet counts of 50x10(9)/L to 200x10(9)/L. The primary objectives were to assess the efficacy of romiplostim as measured by a durable platelet response (platelet count > or =50x10(9)/L during 6 or more of the last 8 weeks of treatment) and treatment safety. Analysis was per protocol. These studies are registered with ClinicalTrials.gov, numbers NCT00102323 and NCT00102336.

FINDINGS

A durable platelet response was achieved by 16 of 42 splenectomised patients given romplostim versus none of 21 given placebo (difference in proportion of patients responding 38% [95% CI 23.4-52.8], p=0.0013), and by 25 of 41 non-splenectomised patients given romplostim versus one of 21 given placebo (56% [38.7-73.7], p<0.0001). The overall platelet response rate (either durable or transient platelet response) was noted in 88% (36/41) of non-splenectomised and 79% (33/42) of splenectomised patients given romiplostim compared with 14% (three of 21) of non-splenectomised and no splenectomised patients given placebo (p<0.0001). Patients given romiplostim achieved platelet counts of 50x10(9)/L or more on a mean of 13.8 (SE 0.9) weeks (mean 12.3 [1.2] weeks in splenectomised group vs 15.2 [1.2] weeks in non-splenectomised group) compared with 0.8 (0.4) weeks for those given placebo (0.2 [0.1] weeks vs 1.3 [0.8] weeks). 87% (20/23) of patients given romiplostim (12/12 splenectomised and eight of 11 non-splenectomised patients) reduced or discontinued concurrent therapy compared with 38% (six of 16) of those given placebo (one of six splenectomised and five of ten non-splenectomised patients). Adverse events were much the same in patients given romiplostim and placebo. No antibodies against romiplostim or thrombopoietin were detected.

INTERPRETATION

Romiplostim was well tolerated, and increased and maintained platelet counts in splenectomised and non-splenectomised patients with ITP. Many patients were able to reduce or discontinue other ITP medications. Stimulation of platelet production by romiplostim may provide a new therapeutic option for patients with ITP.

Large-scale characterization of Tos17 insertion sites in a rice T-DNA mutant library

We characterized the insertion sites of newly transposed copies of the tissue-culture-induced ty1-copia retrotransposon Tos17 in the Oryza Tag Line (OTL) T-DNA mutant library of rice cv. Nipponbare. While Nipponbare contains two native copies of Tos17 the number of additional copies, deduced from Southern blot analyses in a subset of 384 T-DNA lines and using a reverse transcriptase probe specific to the element, ranged from 1 to 8 and averaged 3.37. These copies were shown to be stably inherited and to segregate independently in the progenies of insertion lines. We took advantage of the absence of EcoRV restriction sites in the immediate vicinity of the 3' LTR of the native copies of Tos17 in the genome sequence of cv. Nipponbare, thereby preventing amplification of corresponding PCR fragments, to efficiently and selectively amplify and sequence flanking regions of newly transposed Tos17 inserts. From 25,286 T-DNA plants, we recovered 19,252 PCR products (76.1%), which were sequenced yielding 14,513 FSTs anchored on the rice pseudomolecules. Following elimination of redundant sequences due to the presence of T-DNA plants deriving from the same cell lineage, these FSTs corresponded to 11,689 unique insertion sites. These unique insertions exhibited higher densities in subtelomeric regions of the chromosomes and hot spots for integration, following a distribution that remarkably paralleled that of Tos17 sites in the National Institute for Agrobiological Sciences (NIAS) library. The insertion sites were mostly found in genic regions (77.5%) and preferably in coding sequences (68.8%) compared to unique T-DNA insertion sites in the same materials (49.1% and 28.3%, respectively). Predicted non- transposable element (TE) genes prone to a high frequency of Tos17 integration (i.e. from 5 to 121 inserts) in the OTL T-DNA collection were generally found to be also hot spots for integration in the NIAS library. The 9,060 Tos17 inserts inserted into non TE genes were found to disrupt a total of 2,773 genes with an average of 3.27 inserts per gene, similar to that in the NIAS library (3.28 inserts per gene on average) whereas the 4,472 T-DNA inserted into genes in the same materials disrupted a total of 3,911 genes (1.14 inserts per gene on average). Interestingly, genes disrupted by both Tos17 and T-DNA inserts in the library represented only 14.9% and 10.6% of the complement of genes interrupted by Tos17 and T-DNA inserts respectively while 52.1% of the genes tagged by Tos17 inserts in the OTL library were found to be tagged also in the NIAS Tos17 library. We concluded that the first advantage in characterizing Tos17 inserts in a rice T-DNA collection lies in a complementary tagging of novel genes and secondarily in finding other alleles in a same genetic background, thereby greatly enhancing the library genome coverage and its overall value for implementing forward and reverse genetics strategies.

Superconductivity in doped cubic silicon

Although the local resistivity of semiconducting silicon in its standard crystalline form can be changed by many orders of magnitude by doping with elements, superconductivity has so far never been achieved. Hybrid devices combining silicon's semiconducting properties and superconductivity have therefore remained largely underdeveloped. Here we report that superconductivity can be induced when boron is locally introduced into silicon at concentrations above its equilibrium solubility. For sufficiently high boron doping (typically 100 p.p.m.) silicon becomes metallic. We find that at a higher boron concentration of several per cent, achieved by gas immersion laser doping, silicon becomes superconducting. Electrical resistivity and magnetic susceptibility measurements show that boron-doped silicon (Si:B) made in this way is a superconductor below a transition temperature T(c) approximately 0.35 K, with a critical field of about 0.4 T. Ab initio calculations, corroborated by Raman measurements, strongly suggest that doping is substitutional. The calculated electron-phonon coupling strength is found to be consistent with a conventional phonon-mediated coupling mechanism. Our findings will facilitate the fabrication of new silicon-based superconducting nanostructures and mesoscopic devices with high-quality interfaces.

Liver iron content assessment by routine and simple magnetic resonance imaging procedure in highly transfused patients

BACKGROUND

Liver iron content (LIC) assessment by magnetic resonance imaging (MRI) is validated but not standardized. In a single center, we tried to assess the accuracy of a specific, simple MRI procedure adapted to high LIC from a well-established simple and routine procedure known to quantify LIC.

METHODS

In 27 cases of monthly transfused patients, we compared biochemical values of LIC assessed on liver biopsy specimens and results obtained by two signal intensity ratio of gradient echo imaging (R2*) MRI protocols. The first was Gandon's routine procedure previously validated in liver disease and the second, our own method, was an addition of a gradient echo sequence specifically adapted to high LIC encountered in hematology practice.

RESULTS

Twenty-seven liver biopsies were performed in 18 adult patients (myelodysplastic syndrome = 5, beta-thalassemia = 13). LIC by biopsy ranged from 1.4 to 54 mg/g liver dry weight (mg/g dw) (median 9.4 mg/g dw). Correlation between LIC by biopsy and by MRI with Gandon's procedure was good (R = 0.80) in patients with LIC falling within the range reported by Gandon. By contrast, a weak correlation was demonstrated (R = 0.52) in patients with high LIC (above 11.2 mg/g dw). With our sequences, the correlation was good both in the entire group of patients (R = 0.83) and in patients with LIC above 11.2 mg/g dw (R = 0.85).

CONCLUSION

Our results suggest that the addition of a specific shorter-gradient echo sequence to a very simple, fast technique produces an accurate estimation of LIC in post-transfusional iron overload.

Cytolytic function and survival of natural killer cells are severely altered in myelodysplastic syndromes

Natural Killer (NK) cells are critical in host defense against malignant transformation and are potent antileukemic cytotoxic effectors. In the present study, we investigated the peripheral NK function in patients with myelodysplastic syndromes (MDS). We demonstrated that the peripheral NK cell population was quantitatively normal in MDS patients. Furthermore, NK cells displayed an expression of the activating natural cytotoxicity receptors (NCR) NKp46 and NKp30 as well as NKG2D similar to that observed in donors, but exert a highly decreased constitutive cytolytic activity compared to resting normal NK cells. Although activation with IL-2 resulted in the upregulation of NKp46 expression by MDS-NK cells, their cytolytic function remained deeply altered as compared to activated donor NK cells. In addition, MDS NK cells did not proliferate in vitro, and displayed an increased rate of apoptosis in response to IL-2 stimulation although the spontaneous apoptosis was not significantly increased. Interestingly, a proportion of peripheral MDS-NK cells were derived from the MDS clone as the cytogenetic anomaly found in bone marrow karyotype was also detected in 20-50% of circulating NK cells. In conclusion, NK cells' cytolytic function and proliferative capacities in response to activation by cytokines are profoundly altered in MDS.

High throughput T-DNA insertion mutagenesis in rice: a first step towards in silico reverse genetics

A library of 29,482 T-DNA enhancer trap lines has been generated in rice cv. Nipponbare. The regions flanking the T-DNA left border from the first 12,707 primary transformants were systematically isolated by adapter anchor PCR and sequenced. A survey of the 7480 genomic sequences larger than 30 bp (average length 250 bp), representing 56.4% of the total readable sequences and matching the rice bacterial artificial chromosome/phage artificial chromosome (BAC/PAC) sequences assembled in pseudomolecules allowed the assigning of 6645 (88.8%) T-DNA insertion sites to at least one position in the rice genome of cv. Nipponbare. T-DNA insertions appear to be rather randomly distributed over the 12 rice chromosomes, with a slightly higher insertion frequency in chromosomes 1, 2, 3 and 6. The distribution of 723 independent T-DNA insertions along the chromosome 1 pseudomolecule did not differ significantly from that of the predicted coding sequences in exhibiting a lower insertion density around the centromere region and a higher density in the subtelomeric regions where the gene density is higher. Further establishment of density graphs of T-DNA inserts along the recently released 12 rice pseudomolecules confirmed this non-uniform chromosome distribution. T-DNA appeared less prone to hot spots and cold spots of integration when compared with those revealed by a concurrent assignment of the Tos17 retrotransposon flanking sequences deposited in the National Center for Biotechnology Information (NCBI). T-DNA inserts rarely integrated into repetitive sequences. Based on the predicted gene annotation of chromosome 1, preferential insertion within the first 250 bp from the putative ATG start codon has been observed. Using 4 kb of sequences surrounding the insertion points, 62% of the sequences showed significant similarity to gene encoding known proteins (E-value < 1.00 e(-05)). To illustrate the in silico reverse genetic approach, identification of 83 T-DNA insertions within genes coding for transcription factors (TF) is presented. Based both on the estimated number of members of several large TF gene families (e.g. Myb, WRKY, HD-ZIP, Zinc-finger) and on the frequency of insertions in chromosome 1 predicted genes, we could extrapolate that 7-10% of the rice gene complement is already tagged by T-DNA insertion in the 6116 independent transformant population. This large resource is of high significance while assisting studies unravelling gene function in rice and cereals, notably through in silico reverse genetics.

Identification of differentially expressed cDNA sequences and histological characteristics of Hevea brasiliensis calli in relation to their embryogenic and regenerative capacities

Different friable Hevea callus lines from the same genotype can display different embryogenic and regenerative potentials. These lines can not be distinguished on the basis of macroscopic criteria. A histological and molecular study was undertaken to characterize the differences existing between five callus lines with different potentials. The genes differentially expressed during induction were analyzed using the differential display (DD-RT) technique. Twenty-eight cDNAs were found to be differentially expressed during induction in the embryogenic regenerating line (ER). Embryogenic nodules were formed earlier in the ER lines than in the embryogenic non-regenerating lines and were completely absent in the non-embryogenic line. Of these 28 cDNAs, five could be used to distinguish between calli prior to induction, thereby enabling an early diagnosis of friable Hevea callus embryogenic potential.

Long-term follow-up of chronic autoimmune thrombocytopenic purpura refractory to splenectomy: a prospective analysis

Splenectomy remains the most effective treatment of chronic autoimmune idiopathic thrombocytopenia (ITP) (i.e. of > 6 months duration). Treatment of patients refractory to splenectomy (with absence of response or relapse after initial response) is difficult, and their long-term outcome is not well known. Over a 10-year period, 183 patients with chronic ITP were splenectomized including 158 adults and 25 children (</= 15 years). Forty-seven of them, who were refractory to this treatment, were prospectively followed up for 5-15 years (median 7.5 years). Twelve of them, with moderate thrombocytopenia, remained untreated, and 35 were treated by a median of two regimens (range 1--6), to which 27 responded. Thirty-six (77%) of the refractory cases reached platelet counts durably > 100 x 10(9)/l, nine of them without treatment and 27 of them with low-dose steroids or azathioprine; six (13%) remained moderately thrombocytopenic (35 x 10(9)/l to 100 x 10(9)/l platelets); the last five patients, without response to any treatment (up to six regimens), remained severely thrombocytopenic (platelets < 20 x 10(9)/l), and three of them died from bleeding. Twenty-seven (57%) of the 47 refractory cases required at least one hospitalization, in the majority of cases for intravenous immunoglobulin (IVIg) infusions. Seven of the refractory cases occurred in children. Six of them subsequently reached platelet counts > 100 x 10(9)/l, but one died from bleeding. Our findings confirm the overall favourable long-term prognosis of chronic ITP refractory to splenectomy.

Role of splenectomy in the treatment of myelodysplastic syndromes with peripheral thrombocytopenia: a report on six cases

Thrombocytopenia is generally of central origin in MDS, but can be due to peripheral platelet destruction in some cases. We studied platelet lifespan in 61 MDS cases with platelets < 70,000/mm3 and marrow blasts < 10%. Nine of them (15%) had a major platelet lifespan reduction (< 3.5 days), and were considered for splenectomy. Three of them were not splenectomized due to rapid death, patient refusal and older age plus liver predominance of platelet sequestration, respectively. The remaining six patients (two females and four males, median age 50 years, range 32 to 65) were splenectomized 3 to 21 months after diagnosis. Before splenectomy, five of them had RA and one had CMML. Platelets counts ranged from 5000 to 30,000/mm3 and did not durably respond to other treatments. Three of the patients has a relapse of platelet counts, concomitantly required platelet transfusion due to recurrent blending, whereas three had anemia (two required erythrocyte transfusion) and four had neutropenia. Three months after surgery, platelet counts ranged from 55,000 to 160,000/mm3 (> 100,000/mm3 in four cases), no patient required platelet or erythrocyte transfusion, but there was no effect on neutrophil counts. Three patients had a relapse of platelet counts, concomitant with progression to AML in two of them, whereas the third relapsing case achieved normal platelet counts with further danazol. One patient died with normal platelet counts 12 months after splenectomy (from sepsis, probably related to neutropenia rather than splenectomy). Two patients remained with normal platelet counts 10 and 52 months after surgery. Our findings suggest that the mechanism of thrombocytopenia should be studied more often in 'low risk' MDS (i.e. with low bone marrow blast counts) with thrombocytopenia, as about 15% of them appear to have peripheral platelet destruction. Some of those patients may benefit from splenectomy.

Gemcitabine as a single agent in the treatment of relapsed or refractory low-grade non-Hodgkin's lymphoma

A multicentre phase II trial was conducted to evaluate the efficacy and toxicity of gemcitabine in patients with refractory or relapsed indolent non-Hodgkin's lymphoma. Thirty-six patients were enrolled onto the study, including 11 cases of mantle cell lymphoma (MCL), 10 cases of chronic lymphocytic leukaemia (CLL)/lymphocytic lymphoma, nine cases of follicular lymphoma, four cases of lymphoplasmacytic lymphoma and two cases of T-cell lymphoma. Gemcitabine 1 g/m(2) was administered as a 30-min infusion on d 1, 8 and 15 of a 28-d schedule, up to a maximum of six cycles. Complete responses were observed in two patients with MCL, and partial responses were observed in seven patients, including three patients with CLL/lymphocytic lymphoma, two patients with T-cell lymphoma, one patient with MCL and one patient with follicular lymphoma. Minor responses were observed in three patients, including two patients with MCL and one patient with CLL. The median duration of response was 150 d and the overall progression-free survival was 342 d. Haematological toxicity was observed as grade 3-4 leucopenia in 12 patients (33%) and grade 3-4 thrombocytopenia in 18 patients (50%). Severe non-haematological toxicity included one case of fatal veno-occlusive disease, one case of thrombotic microangiopathy leading to terminal renal failure, one case of capillary leak syndrome, one case of myocardial infarction and drug-induced fever in two patients. These data suggest that gemcitabine displays activity in patients with MCL and CLL/lymphocytic lymphoma. Haematological toxicity was frequent in these heavily treated patients. Severe non-haematological toxicity was significant and should be taken into account in the design of future trials.

Survival and recovery of perennial forage grasses under prolonged Mediterranean drought: II. Water status, solute accumulation, abscisic acid concentration and accumulation of dehydrin transcripts in bases of immature leaves

Swards of cocksfoot (cvs KM2, Lutetia) and perennial ryegrass (cvs Aurora, Vigor) were grown under full irrigation or severe (80 d) drought in a field experiment in the South of France. Responses of the bases of immature leaves plus enclosed tissues were made during the drought period and after rewatering. By the end of the drought, water content had fallen from 3·0 to 0·8 g_water g^-1 _dm , and osmotic potential from -1·0 to -4·5 MPa in all cvs. Measured minerals and water-soluble carbohydrates contributed, respectively, c 19 and 44% to osmotic potential in droughted leaf bases. The drought-sensitive cocksfoot cv. Lutetia was characterized by a large proportion of fructans having a low degree of polymerization (DP=3, 4). As drought progressed, accumulation of dehydrin transcripts and ABA were higher in leaf bases of the sensitive cv. Lutetia than in the resistant cv. KM2. After rewatering, the water status of immature leaf bases returned to control levels in 1-2 d, and then increased further as leaves began to grow and new tissue was produced. High-DP-fructans remained unchanged in leaf bases of 'Lutetia' but were depleted by over 55%, and therefore remobilized, in leaf bases of other cvs after 8 d. It is concluded that enclosed immature leaf bases survive drought by tolerating a low water status and that changes conventionally associated with desiccation tolerance are expressed most strongly in susceptible plants least able to maintain their water supply.

Purification of myeloperoxidase from equine polymorphonuclear leucocytes

Increases of plasma concentrations of neutrophil myeloperoxidase (MPO) can be used as markers of polymorphonuclear leucocytes (PMN) activation in pathological situations (sepsis, acute lung injury, acute inflammation). To develop an assay for measurement of plasma MPO in horses during the above-mentioned infectious and inflammatory conditions, MPO was purified from equine PMN isolated from blood anticoagulated with citrate. PMN were extracted in a saline milieu (0.2 M Na acetate, 1 M NaCl, pH 4.7) to eliminate most of cellular proteins. Pellets were then extracted in the same buffer containing cationic detergent (1% cetyltrimethyl ammonium bromide). The supernatant was further purified by ion exchange chromatography (Hiload S Sepharose HP column 0.5 x 26 cm, equilibrated with 25 mM Na acetate, 0.2 M NaCl, pH 4.7) with a NaCl gradient (until 1 M). Most of the peroxidase activity of MPO (spectrophotometrically measured by the oxidation of orthodianisidine by hydrogen peroxide) was eluted at 0.65 M NaCl. MPO was further purified by gel filtration chromatography (Sephacryl S 200 column 2.6 x 42 cm with 25 mM Na acetate, 0.2 M NaCl, pH 4.7). MPO (specific activity: 74.3 U/mg) was obtained with a yield of 30% from the detergent extraction supernatant. Electrophoresis (non-reducing conditions) showed 3 bands identified, by comparison with human MPO, (i) the mature tetrameric enzyme (150 kDa) with 2 light and 2 heavy subunits, (ii) the precursor form (88 kDa) and (iii) a form of the heavy subunit without the prosthetic heme group (40 kDa). The mature enzyme and its precursor were glycosylated and possessed peroxidase activity. Equine MPO showed strong similarities with human and bovine MPO, with an absorption peak at 430 nm (Soret peak) characteristic of ferrimyeloperoxidase. Enzymatic activity was pH dependent (optimal value at pH 5.5).

Metabolic regulation of asparagine synthetase gene expression in maize (Zea mays L.) root tips

Differential hybridization of a cDNA library constructed with poly(A)+ mRNA from 24 h starved maize (Zea mays L.) root tips, resulted in the isolation of a cDNA (called pZSS1) that was highly induced during glucose deprivation. The nucleotide sequence analysis of the full-length cDNA allowed its identification by comparison with sequence data bases. The 586 amino acid sequence encoded by pZSS1 was shown to be about 60% identical to sequences of asparagine synthetases (EC 6.3.5.4) from Asparagus officinalis, Pisum sativum, Arabidopsis thaliana and Brassica oleracea. Southern blot analysis of maize genomic DNA showed that asparagine synthetase may be encoded by at least two genes. The use of a specific probe for the 3' untranslated region of pZSS1 in Northern blot experiments, revealed that the isolated AS gene was essentially expressed in roots of maize seedlings. Time course analysis revealed that maximal expression of the gene corresponding to pZSS1 occurs between 18 and 24 h after the onset of the starvation treatment. The steady-state levels of transcripts in maize root tips were found to change under various incubation conditions. Exogenous supply of metabolizable sugars downregulated the gene expression, while carbohydrate deprivation or feeding with non-metabolizable sugars resulted in the induction of gene expression. In addition to carbohydrate deprivation, the effects of nitrogen metabolite supply and stress conditions indicate that gene expression might be under metabolic control in maize root tips. The intracellular nitrogen to carbon ratio might be an important factor for the regulation of asparagine synthetase gene expression.

Association of Mycoplasma penetrans with human immunodeficiency virus infection

A cross-sectional study was done to determine the seroprevalence of Mycoplasma penetrans in human immunodeficiency virus (HIV) type 1-seropositive and -seronegative persons recruited in France. The data were analyzed with respect to the sociodemographic, clinical, and biologic status of the patients. M. penetrans seropositivity was associated with HIV infection (18.2% of HIV-seropositive vs. 1.3% of HIV-seronegative persons were M. penetrans-seropositive; P < .001). M. penetrans infection was predominantly but not exclusively associated with homosexual practices in HIV-seropositive subjects and thus presumably sexually transmitted. M. penetrans seroprevalence increased with progression of HIV-associated disease. No association was found between M. penetrans and Kaposi's sarcoma. Thus, there is an unambiguous association between M. penetrans and HIV, particularly among homosexual persons, but its clinical significance remains to be investigated.

Molecular cloning and characterization of six cDNAs expressed during glucose starvation in excised maize (Zea mays L.) root tips

In order to isolate glucose-starvation-related cDNAs in maize (Zea mays L.) root tips, a cDNA library was constructed with poly(A)+ mRNA from 24 h starved root tips. After differential screening of the library, we isolated six different cDNAs (named pZSS2 and pZSS7) which were expressed during glucose starvation. Time course analysis revealed that maximum expression of five of these genes occurs 30 h after the onset of the starvation treatment. On the contrary, the expression of mRNAs corresponding to pZSS4 was maximal at an early stage of starvation and then dramatically decreased. The expression of this gene did not seem to be specific for glucose starvation. The pattern of induction of the genes corresponding to pZSS2, pZSS3, pZSS5, pZSS6 and pZSS7 revealed that non-metabolizable sugars such as L-glucose and mannitol induce mRNA transcription similarly to glucose starvation. When D-glucose or any other metabolizable sugar was supplied, the level of transcripts was reduced. Nucleotide sequence analyses of the six cDNAs allowed identification of five of them by comparison with sequence data bases. The protein encoded by clone pZSS2 is analogous to a wound-induced protein from barley. Clones pZSS4 to pZSS7 encode, respectively, a transmembrane protein, a cysteine protease, a metallothionein-like protein and a chymotrypsin/subtilisin-like protease inhibitor. Clone pZSS3 shares no significant homology with any known sequence.

Demonstration of muramyl dipeptide (MDP)-induced T suppressor cells responsible for MDP immunosuppressive activity

Muramyl dipeptide (MDP), a synthetic immunostimulant, has been previously shown to increase or decrease the humoral and cellular immune responses, depending upon the experimental conditions used. In the present study we have investigated the mechanisms of MDP-induced immunosuppression. After repeated injections of high dosages of MDP in vivo, both adherent and B cell-enriched cell populations from MDP-treated mice were able to collaborate with normal complementary populations. In contrast, T cell-enriched populations exhibited suppressive activity which could be removed by treatment with anti-Thy-1.2 antiserum and complement. These results clearly indicate that MDP-induced immunosuppression is mediated by T cells.

Inhibition of mitogen-induced polyclonal activation by by a synthetic adjuvant, muramyl dipeptide (MDP)

A synthetic adjuvant, N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), was previously shown to enhance polyclonal antibody response in murine spleen cell cultures. When MDP was added to the culture together with a potent murine B cell mitogen (such as bacterial lipopolysaccharide (LPS)), it inhibited completely the LPS-induced polyclonal activation without affecting either the 3H-thymidine incorporation or the number of blast cells in cultures. Strong suppression of mitogen-induced polyclonal activation by MDP was obtained by using a large range of cell concentrations in cultures and over various dosage levels of the stimulating mitogens (LPS and NWSM). An inhibition could be obtained even when MDP was added 24 hr after the addition of the mitogen, and highly significant suppression was observed in the absence of cell division in the cultures.

Inhibition of mitogen-induced polyclonal activation by by a synthetic adjuvant, muramyl dipeptide (MDP)

A synthetic adjuvant, N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), was previously shown to enhance polyclonal antibody response in murine spleen cell cultures. When MDP was added to the culture together with a potent murine B cell mitogen (such as bacterial lipopolysaccharide (LPS)), it inhibited completely the LPS-induced polyclonal activation without affecting either the 3H-thymidine incorporation or the number of blast cells in cultures. Strong suppression of mitogen-induced polyclonal activation by MDP was obtained by using a large range of cell concentrations in cultures and over various dosage levels of the stimulating mitogens (LPS and NWSM). An inhibition could be obtained even when MDP was added 24 hr after the addition of the mitogen, and highly significant suppression was observed in the absence of cell division in the cultures.

Enhancement by muramyl dipeptide of in vitro nude mice responses to a T-dependent antigen

N-acetyl-muramyl-L-alanyl-D-isoglutamine (referred to as MDP for muramyl dipeptide) has been shown to enhance in vivo and in vitro immune responses to various antigens. It has previously been reported that in the case of T-dependent antigens, the adjuvant activity of MDP was mediated by a helper T-cell. Our present findings demonstrate that in vitro responses of nude mice spleen cells to T-independent, TNP-PAA or T-dependent SRBC can also be markedly increased by this synthetic adjuvant. Moreover, under the same conditions, MDP produced polyclonal activation.