Clinical and genetic keys to cerebellar ataxia due to FGF14 GAA expansions

BACKGROUND

SCA27B caused by FGF14 intronic heterozygous GAA expansions with at least 250 repeats accounts for 10-60% of cases with unresolved cerebellar ataxia. We aimed to assess the size and frequency of FGF14 expanded alleles in individuals with cerebellar ataxia as compared with controls and to characterize genetic and clinical variability.

METHODS

We sized this repeat in 1876 individuals from France sampled for research purposes in this cross-sectional study: 845 index cases with cerebellar ataxia and 324 affected relatives, 475 controls, as well as 119 cases with spastic paraplegia, and 113 with familial essential tremor.

FINDINGS

A higher frequency of expanded allele carriers in index cases with ataxia was significant only above 300 GAA repeats (10.1%, n = 85) compared with controls (1.1%, n = 5) (p < 0.0001) whereas GAA250-299 alleles were detected in 1.7% of both groups. Eight of 14 index cases with GAA250-299 repeats had other causal pathogenic variants (4/14) and/or discordance of co-segregation (5/14), arguing against GAA causality. We compared the clinical signs in 127 GAA≥300 carriers to cases with non-expanded GAA ataxia resulting in defining a key phenotype triad: onset after 45 years, downbeat nystagmus, episodic ataxic features including diplopia; and a frequent absence of dysarthria. All maternally transmitted alleles above 100 GAA were unstable with a median expansion of +18 repeats per generation (r2 = 0.44; p < 0.0001). In comparison, paternally transmitted alleles above 100 GAA mostly decreased in size (-15 GAA (r2 = 0.63; p < 0.0001)), resulting in the transmission bias observed in SCA27B pedigrees.

INTERPRETATION

SCA27B diagnosis must consider both the phenotype and GAA expansion size. In carriers of GAA250-299 repeats, the absence of documented familial transmission and a presentation deviating from the key SCA27B phenotype, should prompt the search for an alternative cause. Affected fathers have a reduced risk of having affected children, which has potential implications for genetic counseling.

FUNDING

This work was supported by the Fondation pour la Recherche Médicale, grant number 13338 to JLM, the Association Connaître les Syndrome Cérébelleux - France (to GS) and by the European Union's Horizon 2020 research and innovation program under grant agreement No 779257 ("SOLVE-RD" to GS). DP holds a Fellowship award from the Canadian Institutes of Health Research (CIHR). SK received a grant (01GM1905C) from the Federal Ministry of Education and Research, Germany, through the TreatHSP network. This work was supported by the Australian Government National Health and Medical Research Council grants (GNT2001513 and MRFF2007677) to MB and PJL.

DETECTION OF ATXN2 EXPANSIONS IN AN EXOME DATASET: AN UNDERDIAGNOSED CAUSE OF PARKINSONISM

Background

CAG-repeat expansions in Ataxin 2 (ATXN2) are known to cause spinocerebellar ataxia type 2 (SCA2), but CAA interrupted expansions may also result in autosomal dominant Parkinson's disease (AD PD). However, because of technical limitations, such expansions are not explored in whole exome sequencing (WES) data.

Objectives

To identify ATXN2 expansions using WES data from PD cases.

Methods

We explored WES data from a cohort of 477 index cases with PD using ExpansionHunter (Illumina DRAGEN Bio-IT Platform, San Diego, CA). Putative expansions were confirmed by combining polymerase chain reaction and fragment length analysis followed by sub-cloning and sequencing methods.

Results

Using ExpansionHunter, we identified three patients from two families with AD PD carrying either ATXN2 22/39 or 22/37 repeats, both interrupted by four CAA repeats.

Conclusion

These findings demonstrate the usefulness of WES to detect pathogenic CAG repeat expansions, which were found in 1.7% of AD PD in the ATXN2 gene in our exome dataset.

Laryngeal paralysis secondary to cervical bite injuries in five dogs

CASE HISTORIES

Medical records of a veterinary hospital in Belgium were reviewed for dogs (n = 5) that presented between 2016 and 2019 with laryngeal paralysis secondary to bite wounds to the cervical region received while fighting with other dogs. The time elapsed between the trauma and presentation was from a few hours up to 5 days.

CLINICAL FINDINGS AND TREATMENT

Bilateral laryngeal paralysis was identified in three dogs and unilateral laryngeal paralysis in two dogs via endoscopic assessment of laryngeal function. The primary concomitant lesions included tracheal injury in 3/5 dogs and oesophageal injury in 1/5 dogs. One dog with bilateral laryngeal paralysis was treated medically as no signs of dyspnoea were present. Surgical management was elected in 4/5 dogs based on evaluation of their clinical status and lesions revealed by endoscopic examination of upper gastrointestinal and respiratory tracts. Dogs underwent surgical procedures that were determined to be appropriate for treatment of the lesions identified on clinical examination, diagnostic imaging, and endoscopy. The cervical region was explored through a ventral midline approach in 2/4 cases, to close tracheal perforations. Temporary tracheostomy was performed in 2/4 cases. Procedures to correct brachycephalic airway obstructive syndrome were performed in 2/4 cases. Cricoarytenoid lateralisation was performed in 2/4 dogs. Dogs were hospitalised for 2-10 days and received antimicrobial therapy before surgery and for 2-3 weeks after surgery. Physical examination and respiratory function were normal in 3/5 dogs 4-6 months after discharge. Information regarding outcomes for two cases was obtained from the owners by telephone assessment 1-6 months after surgery. The owner of each dog reported the respiratory function to be excellent.

DIAGNOSIS

Uni- or bilateral, transient or permanent laryngeal paralysis with concomitant oesophageal, tracheal, or laryngeal lesions following cervical dog bite injuries diagnosed by endoscopic examination of upper gastrointestinal and respiratory tracts.

CLINICAL RELEVANCE

This case series describes the diagnosis and management of dogs with laryngeal paralysis secondary to cervical dog bite injuries. To the authors' knowledge, this is the first published report documenting bilateral laryngeal paralysis secondary to cervical dog bite injuries. Clinicians should be aware of this pathology and the importance of investigating laryngeal function in dogs presenting with cervical bites, particularly those with inspiratory dyspnoea. Upper airway and digestive endoscopy are recommended for complete assessment of cervical traumatic injuries.

Propensity for somatic expansion increases over the course of life in Huntington disease

Recent work on Huntington disease (HD) suggests that somatic instability of CAG repeat tracts, which can expand into the hundreds in neurons, explains clinical outcomes better than the length of the inherited allele. Here, we measured somatic expansion in blood samples collected from the same 50 HD mutation carriers over a twenty-year period, along with post-mortem tissue from 15 adults and 7 fetal mutation carriers, to examine somatic expansions at different stages of life. Post-mortem brains, as previously reported, had the greatest expansions, but fetal cortex had virtually none. Somatic instability in blood increased with age, despite blood cells being short-lived compared to neurons, and was driven mostly by CAG repeat length, then by age at sampling and by interaction between these two variables. Expansion rates were higher in symptomatic subjects. These data lend support to a previously proposed computational model of somatic instability-driven disease.

Mucoviscidosis: fisiopatología, genética, aspectos clínicos y terapéuticos

La mucoviscidosis es la enfermedad autosómica recesiva grave más frecuente que afecta a la población caucásica. En Francia, por ejemplo, la incidencia es de un caso por cada 4.500 nacimientos. Esta enfermedad se debe a mutaciones en el gen CFTR (cystic fibrosis transmembrane conductance regulator, regulador de conductancia transmembrana de la fibrosis quística), situado en el brazo largo del cromosoma 7, que codifica una proteína transmembrana implicada en la regulación del transporte transepitelial de iones cloruro (Cl–). En Francia, la mutación más frecuente (alrededor del 80% de los casos) es la deleción del aminoácido 508 (fenilalanina), denominada F508del. La ausencia o la disfunción de la proteína CFTR provoca un defecto en el transporte de Cl– y un aumento de la reabsorción de sal y agua, en particular en el epitelio bronquial, lo que conlleva una reducción del líquido de la superficie bronquial. Esta exocrinopatía generalizada conduce a la producción de «moco viscoso» (de ahí el nombre de mucoviscidosis), que obstruye varios sitios en el cuerpo, en particular el sistema respiratorio, el tracto digestivo y sus anexos (páncreas, vías biliares e hígado). La detección neonatal se ha generalizado desde 2002. La prueba del sudor es la prueba complementaria de referencia, validada por la identificación de dos mutaciones patógenas, para la confirmación del diagnóstico. El tratamiento es multidisciplinario. Se basa ante todo en la kinesiterapia respiratoria diaria y el tratamiento de las sobreinfecciones broncopulmonares, así como en las recomendaciones nutricionales con el uso de extractos pancreáticos. Es probable que el pronóstico, todavía muy desfavorable, se modifique con la llegada de terapias proteínicas o de edición de ácido ribonucleico o de gen.

Data driven optimization of sexual assault case processing

In recent years, several forensic laboratories have noted an increase in the number of sexual assault cases submitted for testing, often leading to longer turnaround times. In that context, forensic laboratories may be interested in reviewing their procedures to increase productivity. Here, we present two different strategies that were put in place in our laboratory. First, we changed the way sexual assault evidence kits (SAEK) are processed by implementing an optimized workflow that prioritizes the internal samples (vaginal, anal, and oral). This new procedure allowed for a drastic decrease in turnaround time, while maintaining a similar investigative power.

Secondly, we used data from casework to target cases and samples that were likely to yield biological material from the perpetrator, in an attempt to avoid dedicating time and effort to cases for which there is a very low probability of obtaining foreign DNA evidence. Among other things, we looked at the likelihood of obtaining DNA from the perpetrator when the complainant reported the use of a condom, has showered after the assault or when the complainant has no memory of the assault. Results show that those circumstances do not dramatically decrease the probability of finding DNA from the perpetrator.

Hydrogenation of hydrophobic substrates catalyzed by gold nanoparticles embedded in Tetronic/cyclodextrin-based hydrogels

Hydrogenation of alkenes, alkynes and aldehydes was investigated under biphasic conditions using Au nanoparticles (AuNP) embedded into combinations of α-cyclodextrin (α-CD) and a poloxamine (Tetronic®90R4).

Evaluation of urinary and serum level of chemokine (C-C motif) ligand 2 as a potential biomarker in canine urothelial tumours

Chemokine (C-C motif) ligand 2 (CCL2) is a chemotactic cytokine recruiting monocytes, releasing growth factors and promoting adhesion in vascular endothelium. Elevated serum and urinary CCL2 levels and expression of its receptor (CCR2) have been associated with tumorigenesis in human urinary malignancies. CCL2 implication has not been investigated in canine urothelial carcinoma. The aim of this study was to evaluate CCL2 serum and urine levels (measured by ELISA) in dogs with urothelial carcinoma or non-neoplastic urinary tract disease. CCL2 serum and urine levels were significantly higher in diseased dogs compared with healthy dogs (P < 0.001). Dogs with carcinoma had significantly higher serum and urine CCL2 levels (P = 0.001) than healthy dogs. Dogs with metastases showed significantly lower serum and urine CCL2 levels compared with the non-metastasised tumour group (P = 0.007). CCL2 as a diagnostic marker for urothelial carcinoma held a sensitivity of 95.2% and a specificity of 38.2% in the urine. As a staging marker, sensitivity was 85.7% and specificity was 57.1% with a positive predictive value of 75.7% and a negative predictive value of 71.9%. Further investigation is needed to define the role of CCL2 as a prognostic marker in canine urothelial carcinoma.

[Not-for-profit: A report from the fourth annual symposium of ethics held by the National Institute for Blood Transfusion (France)]

The not-for-profit issue has been debated in November 2016 in Paris; this issue is one of the four canonical pillars of ethical blood donation. It is intimately bound to benevolence though it is distinct, as not-for-profit calls for institutions while benevolence calls for individuals. It is indeed intended that voluntary blood donors do not benefit from their donation and are thus non-remunerated. Not-for-profit is essential since it refers to the public character of blood as a putative public resource aimed at being shared as a tribute of solidarity. A central question however is linked to the capacity- or not -of public sectors to ensure that blood components are universally available, with special mention to plasma derived drugs, without the contribution of the for profit, private sector.

Partial deletions of the GRN gene are a cause of frontotemporal lobar degeneration

Mutations in the progranulin gene (GRN) are an important cause of frontotemporal lobar degeneration (FTLD). Most known GRN mutations are null mutations, such as nonsense and frameshift mutations, which create a premature stop codon resulting in loss of function of the progranulin protein. Complete or near-complete genomic GRN deletions have also been found in three families, but heterozygous partial deletions that remove only one or two exons have not been reported to date. In this study, we analysed three unrelated FTLD patients with low plasma progranulin levels but no point GRN mutations by multiplex ligation-dependent probe amplification (MLPA) and quantitative multiplex polymerase chain reaction of short fluorescent fragments (QMPSF). We detected two heterozygous partial GRN deletions in two patients. One deletion removed exon 1 and part of intron 1. The second deletion was complex: it removed 1,410 bp extending from the part of intron 1 to the part of exon 3, with a small 5-bp insertion at the breakpoint junction (c.-7-1121_159delinsGATCA). Our findings illustrate the usefulness of a quantitative analysis in addition to GRN gene sequencing for a comprehensive genetic diagnosis of FTLD, particularly in patients with low plasma progranulin levels.

Combination of ammonia and xylanase pretreatments: impact on enzymatic xylan and cellulose recovery from wheat straw

Soaking in aqueous ammonia (SSA) and/or xylanase pretreatments were developed on wheat straw. Both pretreatments were conducted at high-solids conditions: 15% and 20%, respectively, for SSA and xylanase pretreatments. SSA pretreatment led to the solubilisation of 38%, 12% and 11% of acid insoluble lignin, xylan and glucan, respectively. In case of xylanase pretreatment, 20% of xylan were removed from native wheat straw. When pretreatments were applied consecutively (SSA and xylanase) on straw, 56% of xylans were hydrolysed and a rapid reduction of media viscosity occurred. The enzymatic hydrolysis of cellulose with cellulases was evaluated from the different combinations of pretreated wheat straw. Cellulose hydrolysis was improved by 2.1, 2.2 and 2.9, respectively, for xylanase, SSA and SSA/xylanase pretreated straw. Xylans from untreated and pretreated wheat straws were also solubilised with cellulases. Chemical analysis of pretreated straw residues in connection with yields of cellulose hydrolysis highlighted the role of phenolic acids, acetyl content and cellulose crystallinity for cellulase efficiency.

[Morbidity of irregular work schedules]

This paper provides a review of literature on the effects of shift work on physical health, mental health and well-being. In Europe, 20% of the workforce is involved in irregular work schedules. Up to 70% of workers report problems, with increasing age, associated with more difficulties in adjusting to shift work. Epidemiologic studies on large populations have suggested a relation between employment in shift work and the incidence of sleep disorders, cancer, cardiovascular disease, diabetes, obesity, metabolic syndrome, reduced fecundity, preterm births, low birth weight, spontaneous abortion, work and traffic accidents, etc. Shift work exerts major influences on the physiological functions of the human body, mediated by the disruption of circadian rhythms.

Use of a low-cost biosorbent to remove pesticides from wastewater

A lignocellulosic substrate (LS) obtained from our local agroindustry was used as a low-cost and effective adsorbent for the removal of pesticides from wastewaters. The studied pesticides were terbumeton (N-(1,1-dimethyl)-Nethyl-6-methoxy-1,3,5-triazine-2,4-diamine), desethyl terbumeton (N-(1,1-dimethylethyl)-6-methoxy-1,3,5-triazine-2,4-diamine), dimetomorph (4-[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)acryloyl]morpholine), and isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea). Batch and column experiments were conducted as a function of pH and pesticide concentration under laboratory and industrial conditions. The concentration range studied for the pesticides varied from 2 x 10(-7) to 3 x 10(-4) mol L(-1). The influence of organic and inorganic pollutants was assessed by studying the retention of pesticide in the presence of copper(II) and a surfactant. These experiments indicated that LS is an efficient adsorbent toward the investigated pesticides and has little influence of the other pollutants. The kinetic adsorptions are fast, and the amounts of adsorbed pesticide varied from 1 to 8 g kg(-1) of LS. These retention capacities show that LS can provide a simple, effective, and cheap method for removing pesticides from contaminated waters. Thus, this biomaterial may be useful for cleaning up polluted waters.

Molecular identification of two species of myiasis-causing Cuterebra by multiplex PCR and RFLP

The myiasis-causing flies Cuterebra grisea (Coquillet) and Cuterebra fontinella (Clark) (Diptera: Oestridae) are normally parasites of mice, predominantly of the genus Peromyscus. The morphological similarities of these species and the existence of intermediate morphotypes bearing characters of both species make the identification of adults problematic; furthermore the identification of larvae is apparently not possible. This study presents two molecular approaches to discriminate between these species using specific band patterns: (i) species-specific primers designed in the cytochrome oxidase II (COII) region used in multiplex polymerase chain reaction (PCR) and (ii) restriction fragment length polymorphism (RFLP) on amplified segments of cytochrome oxidase I (COI) gene. Both methods were tested on Cuterebra larvae and on adult museum specimens. The two techniques showed a clear difference between C. grisea and C. fontinella, although species-specific primers were more successful than RFLP for degraded DNA. No intraspecific variation in RFLP and species-specific amplifications were detected for the two species of Cuterebra. The results exhibit discrepancies between molecular and morphological identification, suggesting that some of the adults were misidentified.

Study of potatoes' sprout inhibitor treatments with chlorprophame

Studies carried out in 1999 by the University of Ghent showed that 36% of potatoes' samples contained Chlorprophame (CIPC) residues and that 7.9% of them exceeded the maximal limit of residues (RML), fixed at 5 ppm. The heterogeneity of sprout inhibitor application would be one of the causes of over-dosage. However, this heterogeneity would also cause under-dosages leading to problems when controlling the sprouting in potatoes stored over 6 degrees C. This study aims at determining some technical causes of the heterogeneity of CIPC sprout inhibitor treatments when storing potatoes. The study concerns two treatment techniques: dusting and spraying. To draw up an inventory of mechanical treatments in Belgium, a survey has been conducted among 28 farmers throughout Belgium. 35 samples have been taken at random in the different storage rooms to analyse the content of CIPC residue. In order to do so, a method of analysis: the gas chromatography in capillary phase with detection by mass spectrophotometry, has been developed. Tests have been carried out by changing several parameters such as the material, the product or the place in the storage line, in order to assess the CIPC application techniques. The survey made it possible to analyse qualitatively, from the declarations of farmers, the causes of heterogeneity linked to treatment techniques. An almost systematically over-dosage of the CIPC quantity has been noticed. However, out of the 35 samples analysed, only 2 had residue contents higher than the RML. The comparative analysis of the quantities applied and the residues contained in the samples made it possible to quantify the heterogeneity of the applications depending on the techniques. The tests carried out show in a general way that mechanical dusting, even though having a less constant flowrate than sprayers, leads to less important variation of the residue between samples. In testing conditions, the heterogeneity of the antigerminative treatment decreases when applied by means of a mechanical duster. In practise, these results are distorted by topical applications of CIPC. The combination of this practise with a too high heterogeneity of the treatment are to be avoided in order to have a good preservation and meet the residues standards.

The heterogeneity of sprout inhibitor application with chlorpropham

The CIPC or chlorpropham is used on potatoes as "sprouting inhibitor". These lasts years, some set of belgian potatoes treated by CIPC exceeded the Maximum Residue Limit (MRL), fixed at 5 mg/kg. The heterogeneity of sprout inhibitor application would be one of the causes of over-dosage. In order to estimate the distribution of CIPC between potatoes, according to the formulation used (DP, EC and HN), a research project financed by "le fond budgétaire des matières premieres" has been set up. In order to evaluate the distribution of CIPC into the pile of potatoes, the efficiency of the different formulations as well as the residues caused by their application on tubers, some tests have been placed in the storage hall. These tests consist in taking off some samples at different places into the pile of potatoes during storage and destocking. The content of CIPC is analysed by capillary gas chromatography with detection by mass spectrometry detection (GC-MS) or nitrogen specific detection (GC-NPD). To estimate the efficiency, the sprouting are observed every month and samples of potatoes are taken off on the top of the pile to control the evolution of CIPC content. Considering the results of the tests, the inhibitor treatment with the formulation DP+HN seems to be the more efficient. As for the residues, the formulation DP leads to a higher content of CIPC than HN, that has a very low concentration. After treatment, the quantity really applied on tubers depends on the formulation used. In fact, 50% of CIPC applied by DP formulation are found on tubers but hardly 10%, after gas application.

[Neurologic and muscular mechanisms of fatigue]

Fatigue of voluntary muscular effort is a complex phenomenon, influenced by peripheral and central nervous system factors. Peripheral mechanisms of fatigue include impairment in neurotransmission and impulse propagation down the sarcolemna, dysfunction within the sarcoplasmic reticulum involving calcium release and uptake, impairment in the actin-myosin cross-bridge interactions and substrate depletion or accumulation of metabolites. The central fatigue is associated with reduction of motor cortical excitability, failure to drive the motoneurons adequately, changes in neurotransmitter activity, etc. Is fatigue an unexplained disabling symptom or a protective mechanism to prevent muscle fiber degeneration?

Molecular detection of Y chromosome microdeletions: an Irish study

The region of the Y chromosome most critical for male fertility is called the azoospermia factor (AZF) region and it is located within subintervals five and six on the long arm of the Y chromosome. Several genes, all residing here, contribute to spermatogenesis and deletions in these genes are thought to be pathogenetically involved in some cases of male infertility associated with azoospermia or oligozoospermia. The aim of this study was to establish the prevalence of microdeletions in the AZF region of the Y chromosome in an Irish male population undergoing fertility treatment. To do this, we applied and compared two independent polymerase chain reaction (PCR) based screening methods, namely, a PCR protocol using several sequence-tagged site (STS) primer sets and a recently published multiplex PCR Y chromosome screening protocol. A total of 78 patients, attending the IVF unit at University College Hospital, Galway, were included in this study. Of them, 56 suffered from idiopathic azoospermic/oligozoospermic infertility. The remaining 22 patients had various conditions, which may have contributed to their infertility. A total of 50 age-matched normospermic men were included as controls. Two microdeletions were found; one in the AZFa region and one in AZFb region. These deletions were observed among the truly idiopathic cases. Further analysis was performed to study the extent of the deletions and it was confirmed that each deletion encompassed the respective AZF region including the AZF candidate gene.

Trypanosoma cruzi: infectivity of clonal genotype infections in acute and chronic phases in mice

Eight Trypanosoma cruzi stocks pertaining to the clonal genotypes 19/20, 32, and 39 have been characterized for three experimental parameters of infectivity in Balb/c mice: (i) percentage of mice with a patent parasitemia (% MPP), (ii) maximum parasitemia (MP), and (iii) percentage of mice with positive hemoculture (% MPH). By order of decreasing values, the values recorded for the clonal genotypes ranked as follows: 19/20, 32, and 39, except for the % MPP parameter, for which 19/20 and 32 were not statistically different. The rate of successful reisolation after infection in mice, analyzed by multilocus enzyme electrophoresis and random amplified polymorphic DNA typing, was statistically different according to the clonal genotype and was different for uniclonal infections and for mixed infections by two different clonal genotypes. These results confirm that T. cruzi clonal genotypes differ significantly in their infectivity in mice.

Is Leishmania (Viannia) peruviana a distinct species? A MLEE/RAPD evolutionary genetics answer

A set of 38 Leishmania stocks from the Andean valleys of Peru was characterized by both Multilocus Enzyme Electrophoresis (MLEE) and Random Amplified Polymorphic DNA (RAPD). Data were analyzed in terms of taxonomy and evolutionary genetics. Synapomorphic MLEE and RAPD characters, clear-cut clustering, and strong agreement between the phylogenies inferred from either MLEE or RAPD supported the view that Leishmania (Viannia) peruviana and Leishmania (Viannia) braziliensis correspond to two closely related, but distinct monophyletic lines (clades) and can therefore be considered as "discrete typing units" (DTUs). The question whether the L. (V.) peruxviana DTU deserves species status is dependent upon the desirability of it, in terms of epidemiological and medical relevance. A previous Orthogonal Field Alternating Gel Electrophoresis (OFAGE) analysis of the same L. (V.) peruviana isolates was published by Dujardin et al. (1995b). The data from the different markers (i.e. MLEE, RAPD and OFAGE) were compared by population genetics analysis. RAPD and OFAGE provided divergent results, since RAPD showed a strong linkage disequilibrium whereas OFAGE revealed no apparent departure from panmictic expectation. MLEE showed no linkage disequilibrium. Nevertheless, contrary to OFAGE, this is most probably explainable by the limited variability revealed by this marker in L. (V.) peruviana (statistical type II error). RAPD data were consistent with the hypothesis that the present L. (V.) peruviana sample displays a basically clonal population structure with limited or no genetic exchange. Disagreement between RAPD and OFAGE can be explained either by accumulation of chromosomal rearrangements due to amplification/deletion of repeated sequences, or by pseudo-recombinational events.

Release of deuterated nonenal during beer aging from labeled precursors synthesized in the boiling kettle

The use of labeled nonenal enabled the demonstration that the appearance of the cardboard flavor in finished beer comes from lipid auto-oxidation during wort boiling and not from lipoxygenasic activity during mashing. Free trans-2-nonenal produced by linoleic acid auto-oxidation in the kettle disappears, owing to retention by wort amino acids and proteins. This binding linkage protects trans-2-nonenal from yeast reduction but is reversible, allowing release of the compound at lower pH during aging. Labeled trans-2-nonenal is detected after aging when deuterated precursors form in the boiling kettle. The amount of alkenal released correlates with the concentration of reversible associations in the pitching wort. This work brings new illumination to the formation of trans-2-nonenal and overturns many previous hypotheses. It also explains why a reduction in the beer pH intensifies the cardboard flavor.

A phylogenetic analysis by multilocus enzyme electrophoresis and multiprimer random amplified polymorphic DNA fingerprinting of the Leishmania genome project Friedlin reference strain

We have assessed the phylogenetic status of the Leishmania genome project Friedlin reference strain by MLEE and multiprimer RAPD including a set of 9 stocks representative of the main Leishmania species and of the whole genetic diversity of the Leishmania genus. To our knowledge, the detailed genetic characterization of the Friedlin strain has never been published before. As previously recorded (Tibayrenc et al. 1993), MLEE and RAPD data gave congruent phylogenetic results. The Friedlin reference strain was definitely attributed to Leishmania (Leishmania) major Yakimoff et Schokhor, 1914. Five specific RAPD patterns made it possible to distinguish between the Friedlin strain and the 2 other L. (L.) major stocks included in the study. Various specific MLEE and RAPD characters permitted to distinguish between the Leishmania species included in the study. All these characters are usable to detect accidental laboratory mix-ups involving the Friedlin reference strain. In confirmation with previous studies involving a more limited set of genetic markers, the general genetic diversity of the Leishmania genus proved to be considerable. It must be made clear that only one strain cannot be considered as representative of the whole genetic variability of the genus Leishmania. In the future, it is therefore advisable to complement the results obtained in the framework of the Leishmania genome project with data from other strains that should be selected on a criterion of important genetic differences with the Friedlin strain.

Kinetic evidence for the formation of a Michaelis-Menten-like complex between horseradish peroxidase compound II and di-(N-acetyl-L-tyrosine)

The formation of a reversible adsorption complex between a dimer of N-acetyl-L-tyrosine [di-(N-acetyl-L-tyrosine), (NAT)2] and horseradish peroxidase (HRP) compound II (CII) was demonstrated using a kinetic approach. A specific KIIm value (0.58 mM) was deduced for this step from stopped-flow measurements. The dimerization of the dipeptide Gly-Tyr was analysed at the steady state and compared with (NAT)2 dimerization [(NAT)2-->(NAT)4]. A saturation of the enzyme was observed for both substrates within their range of solubility. In each case the rate of dimerization reflected the rate-limiting step of compound II reduction to the native HRP (E) (kappcat/Kappm approximately kII-->E). The kappcat values for (Gly-Tyr)2 and (NAT)4 formation were 254 s-1 and 3.6 s-1 respectively. The KappM value of Gly-Tyr was 24 mM. It was observed that the value (0.7 mM) for (NAT)2 was close both to its specific KIIm value for the second step of reduction (CII-->E) and to its thermodynamic dissociation constant (Kd=0.7 mM) with the resting form of the enzyme. As (NAT)2 was a tighter ligand but a poorer substrate than Gly-Tyr, a steady-state kinetic study was performed in the presence of both substrates. A kinetic model which includes an enzyme-substrate adsorption prior to each of the two steps of reduction was derived. This one agreed reasonably well with the experimental data.

Trypanosoma cruzi: compared vectorial transmissibility of three major clonal genotypes by Triatoma infestans

Twenty Trypanosoma cruzi stocks attributed to the 19/20, 32, and 39 major clones (Tibayrenc et al. 1986) were used to infect experimentally third instar larvae of Triatoma infestans. Three variables were considered: (i) percentage of infected insects; (ii) number of flagellates per insect (NFI); and (iii) percentage of metacyclic trypomastigotes per insect. Differences between the genotypes under study for all parameters considered were detected. These differences were statistically significant (P < 10(-3)), except between the 39 and 32 clonal genotypes for the NFI parameter. The correlation coefficient between the genetic distance and the biological parameters determined by the nonparametric Mantel's test was strongly significant (P < 10(-4)). Data obtained suggest clearly that populations of parasites belonging to the 19/20 genotype are more efficiently transmitted (high transmissibility genotype) by the vector than the 32 genotype (low transmissibility genotype), while the 39 genotype presents intermediary characteristic. Results confirm the working hypothesis that the subdivision of T. cruzi into discrete clonal lineages has an impact on the vectorial competence of T. infestans, the most important vector of the chagasic infection in South America, and that different clonal lineages do not exhibit the same vectorial transmissibility. This fact is relevant both for Chagas' disease epidemiology and for the use of xenodiagnosis.

The gp63 gene locus, a target for genetic characterization of Leishmania belonging to subgenus Viannia

In the present study the gp63 gene locus was used as a target for genetic characterization of Leishmania parasites by 2 methods: (i) RFLP analysis with several restriction enzymes (gp63-RFLP), and (ii) intra-genic PCR amplification coupled with restriction analysis (PCR-RFLP). Both methods were applied to a large number of natural isolates belonging to 4 species of the subgenus Viannia, namely L. (V.) braziliensis, L. (V.) peruviana, L. (V.) guyanensis and L. (V.) lainsoni; reference stocks of subgenus Leishmania were included as outgroups. Multilocus isoenzyme typing (MLEE) was used as a reference. On the one hand gp63-RFLP evidenced an extensive polymorphism and revealed specific markers for subgenus, species and geographical populations: congruence with MLEE was demonstrated statistically. The particular interest of gp63-RFLP was illustrated by infra-specific polymorphism, because of the possible relationship with phenotype diversity. On the other hand intra-genic amplification was less resolutive than gp63-RFLP, but also allowed discrimination of the 2 subgenera (PCR alone) and all the species tested in the subgenus Viannia (PCR-RFLP). PCR-RFLP presents an important operational advantage as it allows genetic characterization of minute amounts of parasites, using Leishmania specific primers. The polymorphism revealed by gp63-RFLP and PCR-RFLP illustrates the very high genomic and genetic plasticity of gp63 genes.

Compared vectorial transmissibility of pure and mixed clonal genotypes of Trypanosoma cruzi in Triatoma infestans

A total of 15 mixtures involving 9 different stocks attributed to the 19/20, 32 and 39 major clonal genotypes of Trypanosoma cruzi were used to infect third-instar nymphs of Triatoma infestans via an artificial feeding device. Three biological parameters were considered: (1) the percentage of infected insects (%II), (2) the number of flagellates per insect (NFI), and (3) the percentage of trypomastigotes per insect (%DIF). Genetic characterization by both multilocus enzyme electrophoresis (MLEE) and random amplification of polymorphic DNA (RAPD) indicated that in almost all cases (87%), mixtures remained present after completion of the whole cycle in the insect vector. Two lines of comparison were performed: (1) pure clonal genotypes versus corresponding mixed clonal genotypes and (2) the actual behavior of mixed clonal genotypes versus the expected behavior of the theoretical mixture (i.e. the arithmetic mean of the results observed for each of the two clonal genotypes taken separately). Statistical analyses of the variables were made difficult because of the presence of large standard deviations. Nevertheless, in several cases, mixtures differed significantly from pure clonal genotypes, and in one case the actual mixture differed significantly from the theoretical mixture. In some cases, interaction (either potentialization or reciprocal inhibition) could be suspected.

A phylogenetic analysis of the Trypanosoma cruzi genome project CL Brener reference strain by multilocus enzyme electrophoresis and multiprimer random amplified polymorphic DNA fingerprinting

We have assessed the phylogenetic status of the Trypanosoma cruzi Genome Project CL Brener reference strain by multilocus enzyme electrophoresis (MLEE) and multiprimer random amplified polymorphic DNA (RAPD) including a set of cloned stocks representative of the whole genetic diversity of T. cruzi. MLEE and RAPD data gave congruent phylogenetic results. The CL Brener reference strain fell into the second major phylogenetic subdivision of T. cruzi, and was genetically very close to the Tulahuen reference strain. No reliable RAPD character and only one MLEE character permitted us to distinguish between the CL Brener and Tulahuen reference strains. In contrast, many RAPD and MLEE characters were able to distinguish between the CL Brener reference strain and the other T. cruzi genotypes analyzed here, in particular the formerly described principal zymodemes I, II and III. It is suspected that both CL Brener and Tulahuen are hybrid genotypes, a fact that should be taken into account when interpreting sequence data. Moreover, our study confirms that the species T. cruzi is genetically very heterogeneous. We recommend future comparison of sequencing data from the CL Brener reference strain with those of at least one radically distinct T. cruzi genotype, belonging to the other major phylogenetic subdivision of this species.

Trypanosoma cruzi: impact of clonal evolution of the parasite on its biological and medical properties

Trypanosoma cruzi populations are subdivided into natural clones that can exhibit considerable genetic differences. It has been proposed that T. cruzi clonal structure has a major impact on this parasite's biological properties. The present work aims at testing this hypothesis. Twenty-one stocks isolated from various ecological cycles, places, and hosts were characterized by multilocus enzyme electrophoresis (MLEE) with 22 genetic loci and random amplification of polymorphic DNA (RAPD) with 10 primers on the one hand and by 14 different biological parameters on the other hand. These parameters were related to: (i) growth kinetics of epimastigotes and amastigotes; (ii) infection of culture cells by amastigotes; (iii) viability of extracellular trypomastigotes; or (iv) sensitivity of epimastigotes, trypomastigotes, and amastigotes to Benznidazole and Nifurtimox. MLEE and RAPD results exhibited parity to each other, as previously noted (M. Tibayrenc, K. Neubauer, C. Barnabé, F. Guerrini, D. Skarecky, and F. J. Ayala, 1993, Proceedings of the National Academy of Sciences of the USA 90, 1335-1339), and showed that the 21 stocks were distributed into three main genetic groups, 19/20, 32, and 39, corresponding to the major clones 19, 20, 32, and 39 previously described on the basis of 15 isozyme loci. Most biological parameters showed a strong correlation to the genetic distances evaluated from either MLEE or RAPD, which favors the working hypothesis. The only exception came from drug sensitivity estimated on trypomastigote forms. The overall results made it possible to firmly reject the null hypothesis that there is no relationships between evolutionary distances and biological differences in T. cruzi natural clones.

Unusual occurrence of cervical myelopathy in a case of Stickler's syndrome

We report the occurrence of progressive Brown-Séquard syndrome as the presenting clinical feature of cervical spondylosis in a young patient with Stickler's syndrome.

[Vasculitis of the central nervous system]

The involvement of the central nervous system (CNS) by a vasculitic process is an infrequent but serious manifestation of several systemic diseases. The neurological disturbances are most often due to cerebral ischemia; however, vascular inflammation is not the only pathogenetic factor of CNS disease in systemic vasculitis. Most often, the specific diagnosis of CNS vasculitis depends on identifying clinical or histologic evidence of target organ involvement outside the CNS. The primary angiitis of the central nervous system (PACNS) is a rare form of vasculitis limited to the central nervous system. The diagnosis of this disorder is difficult owing to its various clinical manifestations and to the poor specificity of the neurological investigations. The demonstration by cerebral angiography and/or tissue examination of an arteritic process is mandatory for establishing this diagnosis.

Auriculo-ventricular block and distal myopathy with rimmed vacuoles and desmin storage

A young patient had an auriculo-ventricular block and a distal myopathy with muscle biopsy findings suggestive of inclusion body myositis. What was most unusual was the presence of numerous sarcoplasmic bodies identified as desmin by electron microscopy and immunocytochemistry. The nosological situation of this condition is discussed.