Exploring photoionization of gas-phase free radicals with a widely tunable VUV laser at moderate spectral resolution.

The VUv Laser for Considering Astrophysical and Isolated Molecules (VULCAIMs) setup [Harper et al., Phys. Chem. Chem. Phys. 24, 2777 (2022)] integrates a narrow-bandwidth tunable vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) nanosecond-pulsed laser system (6-16 eV) and a photoelectron spectrometer, designed for recording high-spectral-resolution (rotationally resolved) photoelectron spectra of gas-phase free radicals. This approach usually needs beforehand medium-resolution synchrotron data to guide the selection of specific spectral regions to be investigated at higher resolution with the VULCAIM setup. We present an upgraded version of the VUV laser system integrating an optical parametric oscillator for continuously scanned medium-resolution measurements (<3 cm-1) across the whole VUV and XUV spectral ranges. This innovation enables broader coverage without the need to access synchrotron facilities. Furthermore, rapid mode switching allows for maintaining optimized radical production conditions from mid-resolution to high-resolution operation mode, enhancing spectroscopy capabilities significantly. The new capabilities of the VULCAIM setup are illustrated on two showcases of photoionization studies: the nitric oxide (NO) stable molecular species and the benzyl (C6H5CH2) free radical produced by pyrolysis.

Highly asymmetrical distribution of muscle wasting correlates to the heteroplasmy in a patient carrying a large-scale mitochondrial DNA deletion: a novel pathophysiological mechanism for explaining asymmetry in mitochondrial myopathies.

Mitochondrial diseases are a heterogeneous group of pathologies, caused by missense mutations, sporadic large-scale deletions of mitochondrial DNA (mtDNA) or mutations of nuclear maintenance genes. We report the case of a patient in whom extended muscle pathology, biochemical and genetic mtDNA analyses have proven to be essential to elucidate a unique asymmetrical myopathic presentation. From the age of 34 years on, the patient has presented with oculomotor disorders, right facial peripheral palsy and predominantly left upper limb muscle weakness and atrophy. By contrast, he displayed no motor weakness on the right hemi-body, and no sensory symptoms, cerebellar syndrome, hypoacusis, or parkinsonism. Cardiac function was normal. CK levels were elevated (671 UI/L). Electroneuromyography (ENMG) and muscle MRI showed diffuse myogenic alterations, more pronounced on the left side muscles. Biopsy of the left deltoid muscle showed multiple mitochondrial defects, whereas in the right deltoid, mitochondrial defects were much less marked. Extended mitochondrial biochemical and molecular workup revealed a unique mtDNA deletion, with a 63.4% heteroplasmy load in the left deltoid, versus 8.1% in the right one. This case demonstrates that, in mitochondrial myopathies, heteroplasmy levels may drastically vary for the same type of muscle, rising the hypothesis of a new pathophysiological mechanism explaining asymmetry in hereditary myopathies.

Mitochondrial DNA content reduction in the most fertile spermatozoa is accompanied by increased mitochondrial DNA rearrangement.

STUDY QUESTION: Is there an association between male fertility and spermatozoa mitochondrial DNA (mtDNA) copy number and genome rearrangements? SUMMARY ANSWER: Normal spermatozoa not only have a lower mtDNA copy number but also more DNA rearrangements than spermatozoa of men with severe oligoasthenospermia (SOA). WHAT IS KNOWN ALREADY: While there is a consensus that mtDNA content is decreased in the most fertile spermatozoa, the role of mtDNA sequence alteration in male infertility is unclear. High-throughput sequencing, which allows an exhaustive analysis of mtDNA rearrangements and mutations, could be helpful in this context, but has yet to be used. STUDY DESIGN, SIZE, DURATION: This is an observational study of semen samples obtained from 44 men undergoing ART at an academic infertility centre in France, from October 2018 to November 2020. The men were classified into two groups: 20 men in the SOA group and 24 men with normal semen parameters in the control group. PARTICIPANTS/MATERIALS, SETTING, METHODS: For each patient and control, mtDNA was isolated from sperm fractions from the 40% and 90% layers of the density gradient. The average mtDNA content of each sample was assessed using digital PCR. Deep sequencing was performed using next-generation sequencing. Signal processing and base calling were performed via the embedded pre-processing pipeline, the variants were analysed using an in-house workflow and a dedicated tool, based on soft-clipping, was used to study large mtDNA rearrangements. The distribution and the type of rearrangements and variants were compared between patients with SOA and controls on one hand, and between the 40% and 90% gradient layers, on the other hand. MAIN RESULTS AND THE ROLE OF CHANCE: The mtDNA content of spermatozoa in the SOA group was significantly higher than in the control group (P < 0.0001). Moreover, mtDNA content was significantly higher in spermatozoa from the 40% layer (the most fertile spermatozoa) compared to the 90% layer, both in the SOA (P = 0.02) and the control group (P < 0.0001). The frequency of large mtDNA deletions and duplications was significantly higher in the control group (P = 0.002). Most of these rearrangements are potentially related to DNA breaks and their number was reduced by the removal of the linear mtDNA from the samples. Heteroplasmic variants were found more frequently in the SOA group (P = 0.05) and in the 40% layer (P = 0.03), but none had any obvious functional consequence. LIMITATIONS, REASONS FOR CAUTION: Our findings are novel and significant but should be verified in larger cohorts and other types of male infertility. WIDER IMPLICATIONS OF THE FINDINGS: Our findings suggest that sperm mtDNA rearrangements are not necessarily associated with mitochondrial dysfunction and male infertility. Instead, they seem to be concomitant with the process of mtDNA content reduction in the most potentially fertile spermatozoa. Furthermore, they refute the hypothesis that, in the case of mtDNA alteration, a compensatory mechanism allows an increase in mtDNA copy number to rectify the energy deficit. The increased frequency of mtDNA rearrangements in the most fertile spermatozoa is a novel result that offers new insight into the relation between sperm quality and mtDNA. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by Angers University Hospital (grant AOI CHU Angers 2018), Angers University and the French national research centres INSERM and CNRS. There are no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Deep sequencing shows that oocytes are not prone to accumulate mtDNA heteroplasmic mutations during ovarian ageing.

STUDY QUESTION: Does ovarian ageing increase the number of heteroplasmic mitochondrial DNA (mtDNA) point mutations in oocytes? SUMMARY ANSWER: Our results suggest that oocytes are not subject to the accumulation of mtDNA point mutations during ovarian ageing. WHAT IS KNOWN ALREADY: Ageing is associated with the alteration of mtDNA integrity in various tissues. Primary oocytes, present in the ovary since embryonic life, may accumulate mtDNA mutations during the process of ovarian ageing. STUDY DESIGN, SIZE, DURATION: This was an observational study of 53 immature oocyte-cumulus complexes retrieved from 35 women undergoing IVF at the University Hospital of Angers, France, from March 2013 to March 2014. The women were classified in two groups, one including 19 women showing signs of ovarian ageing objectified by a diminished ovarian reserve (DOR), and the other, including 16 women with a normal ovarian reserve (NOR), which served as a control group. PARTICIPANTS/MATERIALS, SETTING, METHODS: mtDNA was extracted from isolated oocytes, and from their corresponding cumulus cells (CCs) considered as a somatic cell compartment. The average mtDNA content of each sample was assessed by using a quantitative real-time PCR technique. Deep sequencing was performed using the Ion Torrent Proton for Next-Generation Sequencing. Signal processing and base calling were done by the embedded pre-processing pipeline and the variants were analyzed using an in-house workflow. The distribution of the different variants between DOR and NOR patients, on one hand, and oocyte and CCs, on the other, was analyzed with the generalized mixed linear model to take into account the cluster of cells belonging to a given mother. MAIN RESULTS AND THE ROLE OF CHANCE: There were no significant differences between the numbers of mtDNA variants between the DOR and the NOR patients, either in the oocytes (P = 0.867) or in the surrounding CCs (P = 0.154). There were also no differences in terms of variants with potential functional consequences. De-novo mtDNA variants were found in 28% of the oocytes and in 66% of the CCs with the mean number of variants being significantly different (respectively 0.321, SD = 0.547 and 1.075, SD = 1.158) (P < 0.0001). Variants with a potential functional consequence were also overrepresented in CCs compared with oocytes (P = 0.0019). LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Limitations may be due to the use of immature oocytes discarded during the assisted reproductive technology procedure, the small size of the sample, and the high-throughput sequencing technology that might not have detected heteroplasmy levels lower than 2%. WIDER IMPLICATIONS OF THE FINDINGS: The alteration of mtDNA integrity in oocytes during ovarian ageing is a recurring question to which our pilot study suggests a reassuring answer. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the University Hospital of Angers, the University of Angers, France, and the French national research centers, INSERM and the CNRS. There are nocompeting interests.

Some variance reduction methods for numerical stochastic homogenization.

We give an overview of a series of recent studies devoted to variance reduction techniques for numerical stochastic homogenization. Numerical homogenization requires that a set of problems is solved at the microscale, the so-called corrector problems. In a random environment, these problems are stochastic and therefore need to be repeatedly solved, for several configurations of the medium considered. An empirical average over all configurations is then performed using the Monte Carlo approach, so as to approximate the effective coefficients necessary to determine the macroscopic behaviour. Variance severely affects the accuracy and the cost of such computations. Variance reduction approaches, borrowed from other contexts in the engineering sciences, can be useful. Some of these variance reduction techniques are presented, studied and tested here.

Perspectives of drug-based neuroprotection targeting mitochondria.

Mitochondrial dysfunction has been reported in most neurodegenerative diseases. These anomalies include bioenergetic defect, respiratory chain-induced oxidative stress, defects of mitochondrial dynamics, increase sensitivity to apoptosis, and accumulation of damaged mitochondria with instable mitochondrial DNA. Significant progress has been made in our understanding of the pathophysiology of inherited mitochondrial disorders but most have no effective therapies. The development of new metabolic treatments will be useful not only for rare mitochondrial disorders but also for the wide spectrum of common age-related neurodegenerative diseases shown to be associated with mitochondrial dysfunction. A better understanding of the mitochondrial regulating pathways raised several promising perspectives of neuroprotection. This review focuses on the pharmacological approaches to modulate mitochondrial biogenesis, the removal of damaged mitochondria through mitophagy, scavenging free radicals and also dietary measures such as ketogenic diet.

[In vitro activity of tigecycline on 760 bacterial strains isolated in the hospital university of Angers--2006-2009 TEST study]. / Activité in vitro de la tigécycline vis-à-vis de 760 souches bactériennes isolées au CHU d'Angers--le programme TEST 2006-2009.

Tigecycline (TGC), an antibiotic belonging to glycylcyclines, is active against Gram-positive bacteria, including multi-resistant bacteria, and most of the Gram-negative bacteria, including extended spectrum ß-lactamase-producers (ESBL) and Acinetobacter sp. TGC is not active on Pseudomonas aeruginosa. The microbiological laboratory from the university hospital of Angers participates in the Tigecycline Evaluation and Surveillance Trial (TEST) since 2006. The objective of this study is to evaluate the effectiveness of TGC and of various comparators against nosocomial and community-acquired pathogens. We also evaluated the effectiveness of TGC on a panel of strains isolated between 2006 and 2009 in the university hospital of Angers. Minimum inhibitory concentrations (MIC) were determined using the microdilution method. A total of 760 clinical strains were tested. TGC had a very good activity against Gram-positive bacteria, with 100 % of susceptibility for all the strains tested, irrespective of their resistance profile. Concerning Gram-negative bacteria, TGC was active against 93 % of Enterobacteriaceae, with a MIC 90 not exceeding 2mg/L. Whole of the 20 strains ESBL-producers tested were susceptible to TGC. Acinetobacter sp. were also inhibited at low concentrations of TGC, with a MIC 90 of 1mg/L. These results suggest that TGC can be a useful therapeutic alternative, especially for infections involving multiresistant bacteria.

[Gallium-67 scintigraphy in malignant lymphoma]. / Apport de la scintigraphie au gallium-67 dans les lymphomas malins.

The presence of a residual mass is a frequent and difficult problem in the treatment of Hodgkin's or non-Hodgkin's lymphoma: since it is of major importance to determine whether the lesion is a fibrous mass or a still progressing tumour requiring additional therapy. Gallium-67 scanning, performed in a series of 52 patients, provides an answer to this question since there is an excellent correlation between gallium uptake by the tumoral masses and their progressiveness. Magnetic resonance imaging was carried out in half of our patients: the finding of a low-intensity signal on T2-weighted sequences proved that the residual mass was fibrous, whereas a high-intensity signal on T2-weighted sequences did not distinguish between fibrous and tumour masses. The priceless information provided by the simple and non invasive method that is gallium scanning is extremely useful to evaluate the extension of lymphomas and to determine whether residual masses are tumoral or fibrous.

The significance of a residual mediastinal mass following treatment for aggressive non-Hodgkin's lymphomas.

The chest radiographs of 252 patients with aggressive non-Hodgkin's lymphoma, prospectively treated according to one of three protocols of combination chemotherapy, were reviewed to determine the incidence and prognostic significance of mediastinal abnormalities following treatment. Residual mediastinal masses were defined as any abnormality, greater than 2 cm in diameter, that had initially responded to chemotherapy and then remained stable in size for at least three months after its maximal response, together with the disappearance of all other clinical and biological signs of active lymphoma. At the end of treatment, 21 (8%) patients had some residual mediastinal abnormality. The predominant histological pattern was the diffuse large cell subtype (p less than 0.001). Disease free survival and overall survival for these patients were similar to those observed among patients in complete remission without a persisting radiological mass after treatment. We conclude that mediastinal residual masses after completion of treatment for aggressive lymphoma are frequent and do not indicate a poorer prognosis. Such patients can be observed clinically without any need for additional chemotherapy or radiotherapy.

[Magnetic resonance imaging and preoperative evaluation of cancer of the kidney. The results apropos of 60 cases]. / Imagerie par résonance magnétique et bilan pré-opératoire des cancers du rein. Résultats à propos de soixante cas.

Sixty renal carcinomas confirmed at surgery or autopsy were studied. Capsular effraction, present in 17 cases, was well assessed in 8 cases, under staged in 8 cases and over staged in 5 cases (sensitivity 47%, specificity 88%). Renal vein involvement was present in 11 cases. In 8 of these 11 cases, a thrombus was present in the inferior vena cava. MRI detected a thrombus in the renal veins in 10/11 cases and in 7/8 cases of caval invasion. The false negative case was due to a huge right upper pole tumor laminating the inferior vena cava. The false positive case was due to an enlarged lymph node compressing the inferior vena cava. Cranial extension of the thrombus was well assessed in 6 of the 7 cases. One thrombus in the right atrium was missed. Lymph node involvement was present in 10 cases and correctly diagnosed by MRI in 7 cases. Three false negative cases were noted, because of microscopic invasion in non enlarged lymph nodes. Adjacent organ invasion, present in 2 cases, was detected in 1 case of liver invasion. Initial results of MRI seem very promising and at present, the best indications of MRI in pre-operative evaluation of a renal carcinoma are assessment of caval extension and spread to adjacent organs in patients with large tumors.

Supernumerary microtubules and prolongation of the middle piece in two infertile patients.

A new type of sperm abnormality was described in two patients. There was at the same time a high percentage of immotile spermatozoa, supernumerary microtubules organized in more or less complete axonemes, and prolongation of the middle piece, whose mitochondria retain their normal enzymatic activity.