Enhancing Evanescent Wave Coupling of Near-Surface Waveguides with Plasmonic Nanoparticles

Evanescent field excitation is a powerful means to achieve a high surface-to-bulk signal ratio for bioimaging and sensing applications. However, standard evanescent wave techniques such as TIRF and SNOM require complex microscopy setups. Additionally, the precise positioning of the source relative to the analytes of interest is required, as the evanescent wave is critically distance-dependent. In this work, we present a detailed investigation of evanescent field excitation of near-surface waveguides written using femtosecond laser in glass. We studied the waveguide-to-surface distance and refractive index change to attain a high coupling efficiency between evanescent waves and organic fluorophores. First, our study demonstrated a reduction in sensing efficiency for waveguides written at their minimum distance to the surface without ablation as the refractive index contrast of the waveguide increased. While this result was anticipated, it had not been previously demonstrated in the literature. Moreover, we found that fluorescence excitation by waveguides can be enhanced using plasmonic silver nanoparticles. The nanoparticles were also organized in linear assemblies, perpendicular to the waveguide, with a wrinkled PDMS stamp technique, which resulted in an excitation enhancement of over 20 times compared to the setup without nanoparticles.

Functional Imaging in Olfactory Disorders

Purpose of Review

The aim was to synthesize key findings regarding the use of functional MRI (fMRI) to assess olfactory dysfunction (OD), and thus, to evaluate whether fMRI could be a reliable clinical diagnostic tool.

Recent Findings

In response to olfactory stimulation, patients with quantitative OD display reduced activation in olfactory-related brain regions but also stronger activation in non-olfactory brain areas. Parosmic patients also seem to show both weaker and higher brain signals. As to trigeminal chemosensory system, fMRI suggests that central processing may be declined in patients with OD. Functional connectivity studies report a possible correlation between altered neuronal connections within brain networks and olfactory performances.

Summary

fMRI emerges as a valuable and promising objective method in OD evaluation. Yet, its high inter-individual variability still precludes its routine clinical use for diagnostic purpose. Future research should focus on optimizing stimulation paradigms and analysis methods.

Reducing social isolation during the COVID-19 pandemic: Assessing the contribution of courtesy phone calls by volunteers

Context

During the COVID-19 pandemic, restrictions were imposed on visits in hospitals in the province of Quebec, Canada in an effort to reduce the risk of viral exposure by minimizing face-to-face contact in order to protect patients, visitors and staff. These measures led to social isolation for patients. In order to reduce this isolation, CHUM (the Centre hospitalier de l’Université de Montréal, a teaching hospital) shifted from in-person visits to courtesy telephone calls delivered by volunteers from CHUM’s Volunteers, Recreation and Leisure Department.

Objectives

To study: (1) the contribution made by these calls to reducing isolation and their limitations, (2) how the calls can be improved, and (3) whether they should be maintained, based on the views of patients and volunteers.

Methodology

This study examined two populations. The first one consisted of 189 adult patients hospitalized at CHUM who received a courtesy phone call from a volunteer and the second one consisted of the 25 CHUM volunteers who made these calls. Quantitative data were collected from patients and volunteers through questionnaires and a Smartsheet. The patient questionnaire evaluated isolation, the courtesy phone calls, the relationship of trust with the volunteer and sociodemographic questions. The volunteer questionnaire evaluated the appropriateness of the technology for the intervention, the support and training received, the impacts of the courtesy phone call on both the patients and the volunteers, an experience report and sociodemographic information. In addition, a focus group was held with 7 volunteers. Then the verbatim were transcribed and analyzed using QDA miner software.

Results

From April 27, 2020 to September 5, 2020 more than 11,800 calls were made, mainly concerning hospitalization conditions or home follow-ups (n = 83), and relationships with relatives, friends, and family (n = 79). For 73.6% of hospitalized patients, the courtesy calls from volunteers were a good response to their needs, and 72% of volunteers agreed. 64.5% of patients felt less isolated and 40% of volunteers felt useful.

Conclusion

Our data suggest that patients felt less isolated during their hospitalization because of the courtesy calls made by the volunteers, that smartphones could also be used for video calls and, finally, that maintaining this type of service seems as relevant after as during a pandemic to provide social interactions to people isolated for medical reasons.

Developing a Canadian evaluation framework for patient and public engagement in research: study protocol

BACKGROUND

Patient and public engagement (PPE) in research is growing internationally, and with it, the interest for its evaluation. In Canada, the Strategy for Patient-Oriented Research has generated national momentum and opportunities for greater PPE in research and health-system transformation. As is the case with most countries, the Canadian research community lacks a common evaluation framework for PPE, thus limiting our capacity to ensure integrity between principles and practices, learn across projects, identify common areas for improvement, and assess the impacts of engagement.

OBJECTIVE

This project aims to build a national adaptable framework for the evaluation of PPE in research, by: 1. Building consensus on common evaluation criteria and indicators for PPE in research; 2. Defining recommendations to implement and adapt the framework to specific populations.

METHODS

Using a collaborative action-research approach, a national coalition of patient-oriented research leaders, (patient and community partners, engagement practitioners, researchers and health system leaders) will co-design the evaluation framework. We will develop core evaluation domains of the logic model by conducting a series of virtual consensus meetings using a nominal group technique with 50 patient partners and engagement practitioners, identified through 18 national research organizations. We will then conduct two Delphi rounds to prioritize process and impact indicators with 200 participants purposely recruited to include respondents from seldom-heard groups. Six expert working groups will define recommendations to implement and adapt the framework to research with specific populations, including Indigenous communities, immigrants, people with intellectual and physical disabilities, caregivers, and people with low literacy. Each step of framework development will be guided by an equity, diversity and inclusion approach in an effort to ensure that the participants engaged, the content produced, and the adaptation strategies proposed are relevant to diverse PPE.

DISCUSSION

The potential contributions of this project are threefold: 1) support a national learning environment for engagement by offering a common blueprint for collaborative evaluation to the Canadian research community; 2) inform the international research community on potential (virtual) methodologies to build national consensus on common engagement evaluation frameworks; and 3) illustrate a shared attempt to engage patients and researchers in a strategic national initiative to strengthen evaluation capacity for PPE.

Microelimination or Not? The Changing Epidemiology of Human Immunodeficiency Virus-Hepatitis C Virus Coinfection in France 2012–2018

Background

The arrival of highly effective, well-tolerated, direct-acting antiviral agents (DAA) led to a dramatic decrease in hepatitis C virus (HCV) prevalence. Human immunodeficiency virus (HIV)-HCV–coinfected patients are deemed a priority population for HCV elimination, while a rise in recently acquired HCV infections in men who have sex with men (MSM) has been described. We describe the variations in HIV-HCV epidemiology in the French Dat’AIDS cohort.

Methods

This was a retrospective analysis of a prospective cohort of persons living with HIV (PLWH) from 2012 to 2018. We determined HCV prevalence, HCV incidence, proportion of viremic patients, treatment uptake, and mortality rate in the full cohort and by HIV risk factors.

Results

From 2012 to 2018, 50 861 PLWH with a known HCV status were followed up. During the period, HCV prevalence decreased from 15.4% to 13.5%. HCV prevalence among new HIV cases increased from 1.9% to 3.5% in MSM but remained stable in other groups. Recently acquired HCV incidence increased from 0.36/100 person-years to 1.25/100 person-years in MSM. The proportion of viremic patients decreased from 67.0% to 8.9%. MSM became the first group of viremic patients in 2018 (37.9%). Recently acquired hepatitis represented 59.2% of viremic MSM in 2018. DAA treatment uptake increased from 11.4% to 61.5%. More treatments were initiated in MSM in 2018 (41.2%) than in intravenous drug users (35.6%). In MSM, treatment at the acute phase represented 30.0% of treatments in 2018.

Conclusions

A major shift in HCV epidemiology was observed in PLWH in France from 2012 to 2018, leading to a unique situation in which the major group of HCV transmission in 2018 was MSM.

Clinical Trials Registration. NCT02898987.

Co-construction of health technology assessment recommendations with patients: An example with cardiac defibrillator replacement

CONTEXT

The National Institute of Excellence in Health and Social Services (INESSS), which functions as the Québec health technology assessment (HTA) agency, tested a new way to engage patients along with health-care professionals in the co-construction of recommendations regarding implantable cardioverter-defibrillator replacement.

OBJECTIVE

The objective of this article was to describe the process of co-construction of recommendations and to propose methods of building best practices for patient involvement (PI) in HTA.

DESIGN

Throughout the process, documents were collected and participant observations were made. Individual interviews were conducted with patients, health-care professionals and the INESSS scientific team, from January to March 2018.

RESULTS

Three committees were established: an expert patient committee to reflect on patient experience literature; an expert health professional committee to reflect on medical literature; and a co-construction committee through which both patients and health-care professionals contributed to develop the recommendations. The expert patients validated and contextualized a literature review produced by the scientific team. This allowed the scientists to consider aspects related to the patient experience and to integrate the feedback from patients into HTA recommendations. The most important factor contributing to a positive PI experience was the structured methodology for selecting patient participants, and a key factor that inhibited the process was a lack of training in PI on the part of the scientific team.

CONCLUSIONS

This experience demonstrates that it is possible to co-construct recommendations, even for technically complex HTA subjects, through a more democratic process than usual which led to more patient-focused guidance.

Disruptive viability selection on a black plumage trait associated with dominance

Traits used in communication, such as colour signals, are expected to have positive consequences for reproductive success, but their associations with survival are little understood. Previous studies have mainly investigated linear relationships between signals and survival, but both hump-shaped and U-shaped relationships can also be predicted, depending on the main costs involved in trait expression. Furthermore, few studies have taken the plasticity of signals into account in viability selection analyses. The relationship between signal expression and survival is of particular interest in melanin-based traits, because their main costs are still debated. Here, we first determined the main factors explaining variability in a melanin-based trait linked to dominance: the bib size of a colonial bird, the sociable weaver Philetairus socius. We then used these analyses to obtain a measure representative of the individual mean expression of bib size. Finally, we used capture-recapture models to study how survival varied in relation to bib size. Variation in bib size was strongly affected by year and moderately affected by age, body condition and colony size. In addition, individuals bearing small and large bibs had higher survival than those with intermediate bibs, and this U-shaped relationship between survival and bib size appeared to be more pronounced in some years than others. These results constitute a rare example of disruptive viability selection, and point towards the potential importance of social costs incurred by the dominance signalling function of badges of status.

Control of the estrous cycle in guinea-pig (Cavia porcellus)

The aim of this work was to look for a simple method to obtain synchronized ovulation in guinea pigs under farming conditions while respecting animal welfare. The luteolytic activity of three different prostaglandins F2alpha (PGF2α) analogs (D-cloprostenol, D,L-cloprostenol and luprostiol) and a daily treatment with oral progestagen (altrenogest) was tested successively at different stages of the estrous cycle on the same group of females during a period of 8 mo. The estrous cycle length was not modified by the administration of PGF2α analogs, whatever the stage of the estrous cycle when the treatment was initiated. Our results led us to reject the use of PGF2α analog to induce practical synchronization of the estrus in this species. In females (n = 29), given 15 days with altrenogest (0.1 mL po once a day), ovulation occurred 4.43 ± 0.13 days after the end of the treatment. Altrenogest treatment was followed by mating. No negative impacts of the treatment on the pregnancy rates, delivery rates and litter sizes were observed. This standard method of guinea-pig estrus synchronization is less stressful for the animals compared to techniques using progesterone tubing.

115 FIRST SUCCESSFUL PREGNANCY AFTER EMBRYO TRANSFER INTO SYNCHRONIZED FEMALES IN GUINEA PIG (CAVIA PORCELLUS)

The guinea pig (Cavia porcellus) has been used as a laboratory animal since the late 18th century and still remains essential in many research areas. It also plays an important role in the Andes societies as a source of protein for many low-income highlanders and as part of rituals and traditional medicines. Thus, the conservation of genetic diversity is a long-term issue that must be considered. To establish an embryo cryobank, it is necessary to develop a method of embryo transfer. Up to now no pregnancies after surgical embryo transfer into synchronized females have been reported in guinea pigs. The aim of this work was to design a standard embryo transfer method in this species. Eight normally cycling female guinea pigs from the Maria-Marcela Farm (Puente Piedra, Peru), weighing from 1 to 1.5 kg, were used in this study. Females were housed under farming conditions and fed on commercial pellets and tap water ad libitum. Three donor females were superovulated using 15 IU of human menopausal gonadotrophin (hMG, Massone®, Buenos Aires, Argentina) and mated as soon as the vagina opened. Copulatory plug was observed and vaginal smears were taken to guarantee successful mating. Thirty-eight embryos were collected between Days 3.5 and 4.5 after ovulation at the morula and early blastocyst stages. Five recipient females were synchronized by a daily 0.1-mL dose of altrenogest (Regumate® Equine, Intervet, France) per os by means of a syringe for 15 days. Two embryos were transferred into each uterine horn by laparotomy at Day 3.5 and 4.5 after ovulation. Two types of pipettes were tested for embryo transfer: pulled glass pipettes approximately 0.3 mm in diameter in 2 female recipients and plastic open pulled straws (OPS, Minitüb®, Germany) in 3 recipients. Pregnancy diagnosis was detected by observation of no return to oestrus at Day 16 and confirmed by ultrasonography. None of the 3 OPS-transferred females were pregnant. One of the 2 pulled glass pipette–transferred females was diagnosed as pregnant and delivered 2 stillbirths (one per uterine horn). There were no postsurgical complications and the females undergoing embryo transfer returned to normal reproduction. We demonstrated that a classic surgical embryo transfer method is possible under field conditions to obtain pregnancy in this species. We suggest further studies using glass pipettes, which allow a more precise embryo deposition. Future experiments will incorporate the transfer of frozen-thawed embryos on a larger scale.

Functional consequences of chronic ENT inflammation on the development of hearing and communicative abilities

Hearing processing and communication abilities development may be influenced by chronic inflammation of the airways in children, especially in case of otitis media and/or adenotonsillar hypertrophy. The present review summarizes the influence of adenotonsillar hypertrophy on speech abilities as well as the consequences of otitis media, with a particular focus on peripheral and central hearing, on the development of language, attention, and memory skills.

[CT guided neurolysis of the sphenopalatine ganglion for management of refractory trigeminal neuralgia]

The authors present the case of a patient with recurrent trigeminal neuralgia, refractory to medical treatment and ablation of the trigeminal ganglion, who underwent three separate CT guided injections for pterygopalatine ganglion ablation over a two year period. Ablation of the pterygopalatine ganglion may be an effective technique for pain management in patients suffering from atypical facial pain syndrome, cluster headache, or neuritis. The technique used for CT guided ablation using alcohol or radiofrequency is described. The advantages and pitfalls of this technique are reviewed.

[Symptomatic venous congestion of the brain stem after embolization for dural fistula of the cavernous sinus]

We report the case of a 60-year old woman presenting, 3 days after arterial embolization of a dural arteriovenous fistula, with diplopia and gait disturbance in relation with right oculomotor nerve palsy and cerebellar dysfunction. On T2 weighted MR images, several hyperintense areas appeared in the pons and the midbrain. After one month, clinical symptoms and diffuse hyperintense areas resolved spontaneously, as the patient was treated by anti-vitamin K. This complication probably corresponds to reversible pontine venous congestion caused by poor venous drainage of the dural arteriovenous fistula.

Differential influence of Pomphorhynchus laevis (Acanthocephala) on the behaviour of native and invader gammarid species

Although various species of acanthocephalan parasites can increase the vulnerability of their amphipod intermediate hosts to predation, particularly by altering their photophobic behaviour, their influence on the structure of amphipod communities and the success of invader species has so far received little attention. We compared the prevalence and behavioural influence of a fish acanthocephalan parasite, Pomphorhynchus laevis, in two species of amphipods, Gammarus pulex and Gammarus roeseli in sympatry in the river Ouche (Burgundy, eastern France). There, G. pulex is a resident species, whereas G. roeseli is a recent coloniser. Both uninfected G. pulex and G. roeseli were strongly photophobic. although less so in the invading species. However, there was no significant difference in reaction to light between infected and uninfected G. roeseli, whereas infected G. pulex were strongly photophilic. We discuss our results in relation to the parasite's ability to manipulate invading host species, the possibility that resistant individuals have been selected during the invasion process, and the role that acanthocephalan parasites can play in shaping the structure of amphipod communities.

Plasma serotonin level after 1 day of fluoxetine treatment: a biological predictor for antidepressant response?

RATIONALE

Antidepressant treatments present a delayed onset of action.

OBJECTIVE

The present study investigated whether plasma or serum serotonin, 5-hydroxytryptamine (5-HT), could predict clinical improvement.

METHODS

Biological parameters were determined after a 4-week drug-free period (day 0) and 1, 14 and 28 days after the beginning of the treatment with fluoxetine 20 mg daily in depressed patients. Clinical evaluations were assessed on days 0, 14 and 28.

RESULTS

One day after a single dose, the mean values of plasma 5-HT (5.4 +/- 2.6 nmol/l) and serum 5-HT (484 +/- 215 nmol/l) were not statistically different from basal mean values (4.5 +/- 2.5 nmol/l and 523 +/- 263 nmol/l, respectively). The repeated treatment significantly reduced serum 5-HT to 34% (P = 0.002) and 17% (P = 0.0004) of pretreatment values after 14 and 28 days of treatment, respectively; plasma 5-HT was also reduced significantly to 28% and 15% of pretreatment values (P < 0.05 in both cases). At day 28, four of the eight patients responded by showing a reduction in MADRS score of at least 50% of the baseline score. No correlation was found between pretreatment values of serum or plasma 5-HT and clinical evolution, even if a tendency (P < 0.07) to lower serum 5-HT pretreatment values was observed in responders. Plasma 5-HT after 1 day of treatment was significantly different between responders and non-responders: the plasma 5-HT concentration in responders was 3.4 +/- 1.7 nmol/l versus 7.4 +/- 1.6 nmol/l in non-responders (P = 0.02). Moreover, plasma 5-HT levels after 1 day of treatment were positively correlated to the final MADRS score (r = +0.89, n = 8, P = 0.003) and inversely correlated to its change from the initial score (r = -0.76, n = 8, P = 0.02).

CONCLUSION

These preliminary data show that fluoxetine and norfluoxetine might influence 5-HT peripheral venous blood parameters and that plasma 5-HT after 1 day of treatment might be a biological predictor for antidepressant response.

Masc2, a gene from Ascobolus encoding a protein with a DNA-methyltransferase activity in vitro, is dispensable for in vivo methylation

We have shown previously that masc1, a gene encoding a putative C5-DNA-methyltransferase (MTase), was necessary for the de novo 'Methylation Induced Premeiotically' (MIP) process and sexual reproduction in Ascobolus, whereas it was dispensable for maintenance methylation. A second MTase gene from Ascobolus, masc2, encodes a protein, Masc2, which possesses the large amino-terminal part characteristic of eukaryotic maintenance MTases. In vitro assays have shown that Masc2 displays a methylation activity, suggesting that it might be the MTase responsible for maintenance methylation. To check its function in vivo, we engineered a disruption of the masc2 gene. The resulting mutant strains did not exhibit any particular phenotype during either vegetative growth or sexual reproduction. Neither the masc2 mutation nor the double masc1 masc2 mutation had any detectable effect upon the maintenance of the pre-existing methylation of single gene copies previously subjected to MIP, natural retroelement-like repeats and tandemly repeated rDNA. The masc2 mutation did not alter either MIP or the other de novo methylation process that operates in vegetatives cells. Nor did it impair the meiotic process of methylation transfer. These results suggest that at least a third MTase gene responsible for maintenance and vegetative de novo methylation is present in Ascobolus.

An in vivo and in vitro structure-function analysis of the Saccharomyces cerevisiae U3A snoRNP: protein-RNA contacts and base-pair interaction with the pre-ribosomal RNA

The structure and accessibility of the S. cerevisiae U3A snoRNA was studied in semi-purified U3A snoRNPs using both chemical and enzymatic probes and in vivo using DMS as the probe. The results obtained show that S. cerevisiae U3A snoRNA is composed of a short 5' domain with two stem-loop structures containing the phylogenetically conserved boxes A' and A and a large cruciform 3' domain containing boxes B, C, C' and D. A precise identification of RNA-protein contacts is provided. Protection by proteins in the snoRNP and in vivo are nearly identical and were exclusively found in the 3' domain. There are two distinct protein anchoring sites: (i), box C' and its surrounding region, this site probably includes box D, (ii) the boxes B and C pair and the bases of stem-loop 2 and 4. Box C' is wrapped by the proteins. RNA-protein interactions are more loose at the level of boxes C and D and a box C and D interaction is preserved in the snoRNP. In accord with this location of the protein binding sites, an in vivo mutational analysis showed that box C' is important for U3A snoRNA accumulation, whereas mutations in the 5' domain have little effect on RNA stability. Our in vivo probing experiments strongly suggest that, in exponentially growing cells, most of the U3A snoRNA molecules are involved in the 10-bp interaction with the 5'-ETS region and in two of the interactions recently proposed with 18S rRNA sequences. Our experimental study leads to a slightly revised version of the model of interaction proposed by J. Hughes. Single-stranded segments linking the heterologous helices are highly sensitive to DMS in vivo and their functional importance was tested by a mutational analysis.

Prevention of bleomycin-induced pulmonary fibrosis after adenovirus-mediated transfer of the bacterial bleomycin resistance gene

A serious limitation in the use of the DNA-cleaving, antitumoral-antibiotic, bleomycin during chemotherapy is pulmonary toxicity. Lung injury induced by bleomycin is characterized by an increased deposition of interstitial extracellular matrix proteins in the alveolar wall that compromises respiratory function. Several drugs have been tested in animal models to prevent the pulmonary toxicity of bleomycin, but have not led to a useful clinical treatment because of their adverse effects on other tissues. We have shown that transgenic mice expressing Streptoalloteichus hindustanus (Sh) ble bleomycin resistance protein in pulmonary epithelial cells in the lungs are protected against bleomycin-induced toxicity in lungs. In the present study, we used intranasal administration by adenovirus-mediated gene transfer of the bleomycin resistance Sh ble gene to mouse lung for prevention of bleomycin-induced pulmonary fibrosis. We constructed recombinant adenoviruses Ad.CMVble and Ad.RSVble harboring the bleomycin resistance Sh ble gene under the control of the cytomegalovirus early promoter and the Rous sarcoma virus early promoter, respectively. Transgene expression was detected in epithelia of conducting airways and alveolar septa by immunostaining with a rabbit polyclonal antibody directed against the bleomycin resistance protein and persisted for the duration of drug treatment; i.e., up to 17 d. No toxic effect was seen in adenovirus-treated mice. Pretreatment of mice with Ad.CMVble or Ad.RSVble completely prevented collagen deposition 42-133 d after bleomycin treatment, as measured by lung OH-proline content. Histologic studies indicated that there was little or no lung injury in the adenovirus/bleomycin-treated mice compared with the bleomycin-treated mice. These observations may lead to new approaches for the prevention of bleomycin-induced pulmonary fibrosis.

Secondary structure of the yeast Saccharomyces cerevisiae pre-U3A snoRNA and its implication for splicing efficiency

The Saccharomyces cerevisiae U3 snoRNA genes contain long spliceosomal introns with noncanonical branch site sequences. By using chemical and enzymatic methods to probe the RNA secondary structure and site-directed mutagenesis, we established the complete secondary structure of the U3A snoRNA precursor. This is the first determination of the complete secondary structure of an RNA spliced in a spliceosome. The peculiar cruciform structure of the U3A snoRNA 3'-terminal region is formed in the precursor RNA and the conserved Boxes B and C are accessible for binding the U3 snoRNP proteins. The intron forms a highly folded structure with a long central stem-loop structure that brings the 5' box and the branch site together. This is in agreement with the idea that secondary structure interactions are necessary for efficient splicing of long introns in yeast. The 3' splice site is in a bulged loop and the branch site sequence is single-stranded. Surprisingly, the 5' splice site is involved in a 6-base pair interaction. We used in vitro splicing experiments to show that, despite a noncanonical branch site sequence and a base paired 5' splice site, transcripts that mimic the authentic pre-U3A snoRNA are spliced very efficiently in vitro. Sequestering the 5' splice site in a more stable structure had a negative effect on splicing, which was partially compensated by converting the branch site sequence into a canonical sequence. Analysis of spliceosomal complex formation revealed a cumulative negative effect of a base pair interaction at the 5' splice site and of a deviation to the consensus sequence at the branch site on the efficiency of spliceosome formation in vitro.

Methylation of DNA repeats of decreasing sizes in Ascobolus immersus

In Ascobolus immersus, DNA duplications are subject to the process of methylation induced premeiotically (MIP), which methylates the cytosine residues within the repeats and results in reversible gene silencing. The triggering of MIP requires pairing of the repeats, and its detection requires maintenance of the resulting methylation. MIP of kilobase-size duplications occurs frequently and leads to the methylation of all C residues in the repeats, including those belonging to non-CpG sequences. Using duplications of decreasing sizes, we observed that tandem repeats never escaped MIP when larger than 630 bp and showed a sudden and drastic drop in MIP frequencies when their sizes decreased from 630 to 317 bp. This contrasted with the progressive decrease of MIP frequencies observed with ectopic repeats, in which apparently the search for homology influences the MIP triggering efficiency. The minimal size actually required for a repeat to undergo detectable MIP was found to be close to 300 bp. Genomic sequencing and Southern hybridization analyses using restriction enzymes sensitive to C methylation showed a loss of methylation at non-CpG sites in short DNA segments, methylation being restricted to a limited number of CpG dinucleotides. Our data suggest the existence of two distinct mechanisms underlying methylation maintenance, one responsible for methylation at CpG sites and the other responsible for methylation at non-CpG sites.

A unique U5-->A substitution in the Physarum polycephalum U1 snRNA: evidence at the RNA and gene levels

The 5' terminal sequence of U1 snRNA that base-pairs with the intron 5' splice site in the course of spliceosome assembly was considered to be universally conserved. A study of the P polycephalum U1 snRNA at both RNA and gene levels shows that there are exceptions to this rule: the P polycephalum U1 snRNA has a U to A substitution at position 5, that is partially compensated by a high frequency of T residue at position +4 of introns. In contrast to the yeast genome, the P polycephalum genome contains several U1 snRNA coding sequences (about 20). They either encode the U1A snRNA expressed in microplasmodia or correspond to the previously cloned U1B coding sequence. Both coding sequences show the U5A substitution. The ratio of U1A versus U1B coding sequences is of about 3. A U1A gene was cloned. The 60 nt region upstream of the coding sequence has the same sequence as in the U1B gene. The U1B gene is probably expressed at another stage of the P polycephalum life cycle.

Secondary structure conservation of the U3 small nucleolar RNA introns in Saccharomyces

Using a strategy based on PCR amplification of DNA and sequence analysis, we showed that the presence of introns with the characteristic features of introns spliced in a spliceosome, in the U3A and U3B snoRNA genes that code for the U3 small nucleolar RNA, is not a property restricted to Saccharomyces cerevisiae. It is probably an ancient property of yeasts from the genus Saccharomyces. We detected the U3A and U3B snoRNA genes in Saccharomyces bayanus and in a lager brewing yeast strain. The U3A and U3B intronic sequences are highly conserved. Two additional "U3B-like" snoRNA genes were detected in the lager brewing yeast. Their intronic sequences show several differences, when compared to the U3B intronic sequence. However, despite the numerous mutations, the intron secondary structure is conserved, especially, the central structure. This strongly suggests an important role of this central stem/loop structure for spliceosome assembly and efficient splicing.

Clustering of multiple transgene integrations in highly-unstable Ascobolus immersus transformants

A large proportion of Ascobolus immersus transformants are highly unstable in crosses: the phenotype conferred by the transgene is not transmitted to the progeny, irrespective of the endogenous or foreign origin of the transgene. They all have integrated multiple transgene copies, clustered at a single chromosomal site or at tightly-linked sites. Clustered non-homologous integrations are always rearranged. Yet they never escape the "methylation induced premeiotically" (MIP) process. This always results in gene silencing, even when the transgene is partially repeated, accounting for the high instability of these transformants.

Long-term correction of mouse dystrophic degeneration by adenovirus-mediated transfer of a minidystrophin gene

Duchene muscular dystrophy (DMD) is a fatal progressive X-linked muscle disorder, caused by mutations in the dystrophin gene. We have investigated adenovirus-mediated transfer of a dystrophin minigene in a mutant mouse lacking dystrophin, the mdx mouse. We report here that six months after a single intramuscular injection of a recombinant adenovirus containing a human dystrophin minigene, a large number of dystrophin-positive fibres are still detected in the injected muscles. Moreover, although the minigene encodes a truncated protein, its expression is able to protect the fibres efficiently against the degeneration process that affects the dystrophin-deficient mdx myofibres.

An experimental study of Saccharomyces cerevisiae U3 snRNA conformation in solution

The conformation of Saccharomyces cerevisiae U3 snRNA (snR17A RNA) in solution was studied using enzymatic and chemical probes. In vitro synthesized and authentic snR17A RNAs have a similar conformation in solution. The S. cerevisiae U3 snRNA is folded in two distinct domains. The 5'-domain has a low degree of compactness; it is constituted of two stem-loop structures separated by a single-stranded segment, which has recently been proposed to basepair with the 5'-ETS of pre-ribosomal RNA. We demonstrate that, as previously proposed, the 5'-terminal region of U3 snRNA has a different structure in higher and lower eukaryotes and that this may be related to pre-rRNA 5'-ETS evolution. The S. cerevisiae U3 snRNA 3'-domain has a cruciform secondary structure and a compact conformation resulting from an higher order structure involving the single-stranded segments at the center of the cross and the bottom parts of helices. Compared to tRNA, where long range interactions take place between terminal loops, this represents another kind of tertiary folding of RNA molecules that will deserve further investigation, especially since the implicated single-strands have highly evolutionarily conserved primary structures that are involved in snRNP protein binding.

[Mammography]

Mammography is the most important method for the diagnosis and the screening of breast diseases. Sensitivity and accuracy of mammography are very high in the detection of breast cancer. The use of the stereotaxic localization and fine-needle aspiration of nonpalpable breast lesions improve its effectiveness. The American Breast Cancer Detection Demonstration Project (BCDDP) has demonstrated the benefits of breast screening for women over 40 years of age. Many American medical associations and societies have adopted the guidelines based on the BCDDP results, promoting breast cancer screening for these women. However, recently released results of some randomized breast screening studies demonstrated only a 5% reduction in mortality from breast cancer in women 40-49 years of age, and a 40% reduction for women aged over 50 years. There is no explanation for this dilemma at the present time. However, screening mammography should stay available for women over 40 years of age.

Effect of a macrolide (spiramycin) on the pharmacokinetics of L-dopa and carbidopa in healthy volunteers

In one well-equilibrated parkinsonian patient treated with combined L-dopa and carbidopa (Sinemet), we have observed changes in treatment efficacy while receiving spiramycin (Rovamycine) for an intercurrent respiratory infection. A preliminary study of the pharmacokinetics of L-dopa and its main metabolites 3-O-methyldopa (3-OMD) and dihydroxyphenylacetic acid (dopac) in two parkinsonian patients treated with Sinemet has revealed a marked decrease in the AUC0-360 of these two metabolites after a 3-day course of Rovamycine. In order to confirm this interaction, we have studied the modifications of the pharmacokinetics of L-dopa, 3-OMD, dopac, and carbidopa in eight male healthy volunteers after a single dose of Sinemet 250 (L-dopa, 250 mg and carbidopa, 25 mg) before and after a 3-day course of Rovamycine. Our study confirms this interaction. After spiramycin, we observed a marked reduction in AUC0-360 for L-dopa (p less than 0.001), 3-OMD (p less than 0.001), and carbidopa (p less than 0.001), and an increase in AUC0-360 for dopac (p less than 0.01). The L-dopa elimination half-life was increased (p less than 0.012); differences in peak plasma concentrations did not attain statistical significance. We think that these modifications in L-dopa pharmacokinetics after spiramycin are due to nonabsorption of carbidopa secondary to modified gastrointestinal motility.

Stable allele replacement and unstable non-homologous integration events during transformation of Ascobolus immersus

An homologous transformation system for the filamentous fungus Ascobolus immersus has been developed, based on the complementation of a met2 mutation by the wild-type (wt) allele gene encoding homoserine O-transacetylase. Transformation of A. immersus met2 mutants occurs with moderate frequencies (about 50 transformants per microgram input DNA). Analysis of the DNA of the met2+ transformants showed that transformation resulted either in a single integration of the donor DNA into the genome by many different nonhomologous recombination events or in the substitution of the endogenous met2 mutation by the wt transforming allele. The relative frequencies of both events depended on the vector sequences carrying the cloned met2 gene. Whereas the substitution event led, as expected, to genetically stable transformants, the non-homologous integration was always associated with a strong instability when transformants were crossed and underwent meiosis.

[Inflammatory aneurysm of the aorta. Value of x-ray computed tomography and ultrasonography in the diagnosis of a case and review of the literature]

Until recently inflammatory aneurysm of the aorta was discovered only at the time of surgery and confirmed by the pathologist. New imaging modalities, such as ultrasound and CT-scan now enable the radiologist to diagnose this entity before surgery, thus leading to a better surgical planning and reducing the operative morbidity. The authors report a case of inflammatory aneurysm of the aorta and review the literature on this entity.

Detection of an interferon antagonist, sarcolectin, in human sarcomas and muscles

In a variety of human sarcomas we detected the presence of a sarcolectin which reversed an established antiviral protection induced by interferon (IFN). For the same protein concentration, this biological activity was significantly increased when compared to that of normal muscles. All the biological characteristics were comparable to those of a sarcolectin found in hamster tissues; namely the capacity to agglutinate cells and its inhibition by specific sugars, migration in sodium dodecyl sulfate gel, and pepsin, heat and sodium dodecyl sulfate stability. Except for its anti-IFN function and cell agglutinating activity, the biological significances of this sarcolectin is presently poorly understood.

Narrowband teleradiology

A narrowband communication system using the Canadian satellite ANIK-B was used to transmit radiographic images from northern Quebec to Montreal. This slow scan television (SSTV) system was used to study the accuracy of the radiologist's interpretation, both with samples of pre-selected films and current patients. Several hours of training in the technique of radiographic interpretation from a static image displayed on a TV monitor was an important factor affecting performance. In selected patients, based on a sample of 124 error-free direct viewing interpretations by four radiologists, SSTV reading by the same fully trained radiologists was correct in 84.5%. With actual patients, and assuming the interpretation from direct viewing to be the correct one, SSTV reading of the radiographs by the same radiologist gave a corresponding figure of 84.1% in a sample of 518 patients containing 73.4% of negative findings, and 89.4% in another sample of 305 patients, including 82% of negative findings. The present error rate on SSTV reading is twice as great as radiographic interpretation using a broadband television system.

[How to obtain a a front-view of the knee in extension? Anatomy and tomodensitometry show the superiority of the radiographic method based upon the middle 3d of the knee compared with the one based upon posterior condyles]

1) To obtain a true "en-face"" projection of the middle third of a knee, we must, on the fluoroscopic screen, put the apex of the femoral intercondyloid fossa just above the middle of the tibial intercondyloid eminence. The extended knee rests on its middle third which thus constitutes the guide-mark for the gonometry. This "middle third" projection gives also the opportunity to measure adequately the physiological lateralisation of the patella, which normally does not exceed 12% of the maximal width of the femoral epiphysis, or practically 12 millimeters. 2) The method using the perpendicular to the posterior aspects of the femoral condyles is not always accurate because of the variable curvature of the intercondyloid fossa and the discrepancy between the depths of the femoral condyles. The medial condyle would be frequently a little longer in the woman than in the male. This method gives a true "en-face"" projection of only the posterior third of the knee and is thus not reliable to assess the position of the patella and to perform a valid gonometry.

Teleradiology in northern Quebec

A two-way television network using the Canadian satellite ANIK-B was utilized to transmit radiographic images from Northern Quebec to Montreal. The accuracy of the radiologist's interpretation and his satisfaction with the TV system were studied using a series of 67 preselected cases and 425 current clinical cases. The four participating radiologists gave correct TV interpretations in 81% of the 39 selected cases presented at the beginning of the experiment. This value reached 94% for the other 28 selected cases presented after three months of regular use of the TV system. With current clinical cases, the agreement between TV and direct interpretations was 93%. Although magnification was available, correct identification of very small lesions proved to be the major source of error. On the whole, the radiologists were satisfied with the TV system.

Protective effect of interferon on target cells exposed to cellular cytotoxicity

In order to explore by immunological methods the interferon-induced cell membrane modulation, the effect of interferon in parental and monkey-mouse hybrid cells was studied in the presence of sensitized lymphocytes from isologous mice. After primary immunization to the hybrids, both parental interferons increased the lymphocyte-induced specific cytotoxicity in the same hybrid cells used as targets. In addition, a significnt increase of spontaneous lysis due to the two interferons was observed. In contrast, after secondary sensitization, in spite of the higher specific cytotoxicity induced by the lymphocytes, the same interferon preparation significantly protected the cells. These results are probably related to a greater number of sensitized effector cells after secondary sensitizationn. It is likely that, although interferon increases the affinity of sensitized T lymphocytes for the target cell membrane, in case of unsuccessful encounters, the target cells become resistant to new hits. Interferon could augment the number of such immune cells.

[Protective effect of interferon on the target cells of cytotoxic lymphocytes]

Interferon treatment of sensitized T lymphocytes enhances cytotoxicity against target cells. On the contrary, the same treatment of the target cells alone protects them, whatever the cytotoxicity of effector cells might be. We suggest that the cells having once survived contact with cytotoxic T lymphocytes could become resistant to any new attack by the same cells.

Lower urinary tract trauma

Twenty-eight patients with lower urinary tract injuries were reviewed at Hôtel-Dieu de Montréal. Eighteen involved the urethra and ten involved the bladder. Pelvic rami fractures are the main cause of bladder rupture, including almost all cases of extraperitoneal bladder rupture. Pelvic fractures are also the main cause of posterior and bulbo-menbranous urethra rupture. Endoscopy and indwelling catheter insertions follow in importance. Rupture of the bladder can be either extraperitoneal (80%) or intraperitoneal (20%). Ruptures of the urethra involve mainly the posterior and bulbo-membranous segments of the urethra. Post-traumatic strictures nevertheless affect the anterior segment more commonly. In all suspected cases of injury involving the lower urinary tract, retrograde urethrography should be done first, followed by retrograde cystography if indicated. A good knowledge of the relationship of the anatomic compartments is essential to the assessment of communicating injury.

Urethral valves as a cause of dilated Cowper's glands and perineal pain

Symptoms of lower urinary tract obstruction are the most frequent manifestation of congenital posterior valves. A case is presented in which the initial symptom was perineal pain. Diagnosis was delayed because of a false diagnosis of prostatitis. Urethrography and cystography showed posterior urethral valves and dilated Cowper's glands. Bilateral incisions of the valves with the knife electrode resulted in disapperance of the pain and regression of the dilated Cowper's glands.