Listeria monocytogenes-associated spontaneous bacterial peritonitis in France: a nationwide observational study of 208 cases

BACKGROUND

Listeriosis is a foodborne infection caused by Listeria monocytogenes. Three main forms of listeriosis are well characterised, but little is known about L monocytogenes-associated spontaneous bacterial peritonitis. We used data from the French national surveillance of listeriosis to perform a nationwide retrospective study.

METHODS

All patients with L monocytogenes isolated by culture from a peritoneal fluid sample in France between April 1, 1993, and Dec 31, 2022, were included. Individuals for whom bacterial peritonitis was not confirmed and those who also had another type of invasive listeriosis were excluded. A standardised checklist was used to collect demographic, clinical, and biological data as well as antibiotic treatment and follow-up data. The primary outcome was to determine the characteristics of L monocytogenes-associated spontaneous bacterial peritonitis. We did descriptive analyses and assessed risk factors for 1-month mortality using an exploratory multivariable Cox model analysis.

FINDINGS

Among the 8768 L monocytogenes cases reported, 208 (2%) were patients with L monocytogenes-associated spontaneous bacterial peritonitis. Mean age was 65 years (SD 13), 50 (24%) of 208 patients were female, and 158 (76%) were male (no data on race or ethnicity were available). 200 (98%) of 205 patients with L monocytogenes-associated spontaneous bacterial peritonitis with available data had immunosuppressive comorbidities, including cirrhosis (148 [74%] of 201 with available data), ongoing alcoholism (58 [62%] of 94), and ongoing neoplasia (60 [31%] of 195). Causes of ascites included cirrhosis (146 [70%] of 208), ongoing neoplasia (26 [13%]), end-stage heart failure (13 [6%]), and peritoneal dialysis (11 [5%]). Among those with available data, presentation was pauci-symptomatic and non-specific; only 67 (50%) of 135 patients presented with fever, 49 (37%) of 132 with abdominal pain, and 27 (21%) of 129 with diarrhoea. 61 (29%) of 208 patients were dead at 1 month, 92 (44%) were dead at 3 months, and 109 (52%) were dead at 6 months after diagnosis. Ongoing neoplasia (hazard ratio 2·42 [95% CI 1·05-5·56]; p=0·039), septic shock (8·03 [2·66-24·02]; p=0·0021), and high blood leukocyte count (1·05 [1·00-1·09]; p=0·045) were independently associated with 1-month mortality.

INTERPRETATION

Despite the non-specific and mild presentation of L monocytogenes-associated spontaneous bacterial peritonitis, the outcome is poor and similar to that of neurolisteriosis, and so identification of L monocytogenes in ascitic fluid samples requires urgent parenteral amoxicillin-based treatment to avoid a fatal outcome.

FUNDING

Institut Pasteur, Inserm, and French Public Health Agency.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Phenotypic and genotypic antimicrobial resistance of Listeria monocytogenes: an observational study in France

Background

Large-scale studies are needed to clarify antimicrobial resistance in the foodborne pathogen Listeria monocytogenes (Lm) and the effectiveness of listeriosis treatment options. Here we examined the antimicrobial resistance patterns in Lm over time and assessed genotype-phenotype concordances.

Methods

We analyzed 5339 Lm isolates (2908 clinical and 2431 food isolates) collected in France and overseas territories, between 2012 and 2019. Whole genome sequencing was performed for all isolates and antimicrobial resistance profiles inferred from draft assemblies. Antimicrobial susceptibility towards 22 antimicrobials was determined for all clinical isolates, and in food isolates with acquired resistance genes.

Findings

All tested isolates were resistant to at least 3 different classes of antimicrobials, consistent with Lm intrinsic traits. Acquired antimicrobial resistance in Lm was rare (2.23% isolates) and more prevalent in food (mainly lineage II) compared to clinical isolates (mainly lineage I) (3.74% vs 0.98%, p < 0.0001), and in isolates with disinfectants or stress resistance traits (e.g. bcrABC, 20.20% vs 7.20%, p < 0.0001), suggesting co-selection of resistance in food-production environments. Acquired antimicrobial resistance could be predicted from genomes with high accuracy (>99%), except for ciprofloxacin. Acquired antimicrobial phenotypes were towards tetracyclines (mostly due to tetM), trimethoprim (dfrD), lincosamides (lnuG), macrolides (ermB, mphB) and phenicols (fexA).

Interpretation

The reference treatment for listeriosis (aminopenicillins/aminoglycosides) remains effective, with no acquired resistance observed. Continuous surveillance of antimicrobial resistance in clinical and food isolates is crucial to detect the emergence of novel resistance.

Funding

Institut Pasteur, INSERM, Santé Publique France, Investissement d'Avenir program Laboratoire d'Excellence 'Integrative Biology of Emerging Infectious Diseases' (ANR-10-LABX-62-IBEID).

Genome-Based Characterization of Listeria monocytogenes, Costa Rica

Genomic data on the foodborne pathogen Listeria monocytogenes from Central America are scarce. We analyzed 92 isolates collected during 2009-2019 from different regions in Costa Rica, compared those to publicly available genomes, and identified unrecognized outbreaks. Our findings suggest mandatory reporting of listeriosis in Costa Rica would improve pathogen surveillance.

Fatal neonatal listeriosis following L. monocytogenes horizontal transmission highlights neonatal susceptibility to orally acquired listeriosis

We report a case of fulminant fatal neonatal listeriosis due to horizontal transmission of Listeria monocytogenes (Lm) in a neonatal double room. Genomic analyses reveal a close genetic relationship between clinical isolates, supporting cross-contamination. Oral inoculation experiments in adult and neonatal mice show that neonates are susceptible to a low Lm inoculum and that this susceptibility results from the immaturity of the neonatal gut microbiota. Infected neonates should therefore be isolated for as long as they shed Lm in their feces to avoid horizontal transmission and its dire consequences.

Genomic characterization of Listeria spp. isolated from tonsils, udder and feces of domestic dairy ruminants in Spain

Two species of Listeria are pathogenic, Listeria monocytogenes and Listeria ivanovii. Although studies have shown that dairy ruminants shed Listeria spp. in feces, there is little information about ruminants that do not shed Listeria spp. in their feces but asymptomatically carry them in organs. We evidence that ruminants can asymptomatically carry L. ivanovii in udders and L. monocytogenes and L. ivanovii in tonsils without fecal shedding. Whole-genome sequence of L. monocytogenes and L. ivanovii contained known core genes involved in virulence and antibiotic resistance. This work highlights tonsils and udders as a Listeria intra-host site of colonization.

Listeria ilorinensis sp. nov., isolated from cow milk cheese in Nigeria

During microbial assessment of cow milk cheese products in the city of Ilorin, Nigeria, a Listeria -like isolate was detected that could not be assigned to any known species. Whole-genome sequence analyses against all currently known 26 Listeria species confirmed that this isolate constitutes a new taxon within the genus Listeria , with highest similarity to Listeria costaricensis (average nucleotide identity blast of 82.66%, in silico DNA–DNA hybridization of 28.3%). Phenotypically, it differs from L. costaricensis by the inability to ferment sucrose, l-fucose and starch. The absence of haemolysis and Listeria pathogenic islands suggest that this novel species is not pathogenic for humans and animals. The name Listeria ilorinensis sp. nov. is proposed, with the type strain CLIP 2019/01311T (=CIP 111875T=DSM 111566T).

Listeria-Associated Lymphadenitis: A Series of 11 Consecutive Cases and Review of the Literature

We studied 11 cases of culture-proven Listeria-associated lymphadenitis reported to the French National Reference Center for Listeria from 1994 to 2019 and 8 additional published cases. Listeria-associated lymphadenitis is rare, but it is associated with a mortality as high as for invasive listeriosis, and it is frequently diagnosed with concomitant neoplasia.

Ruminant-associated Listeria monocytogenes isolates belong preferentially to dairy-associated hypervirulent clones: a longitudinal study in 19 farms

Studies have shown that ruminants constitute reservoirs of Listeria monocytogenes, but little is known about the epidemiology and genetic diversity of this pathogen within farms. Here we conducted a large-scale longitudinal study to monitor Listeria spp. in 19 dairy farms during three consecutive seasons (N = 3251 samples). L. innocua was the most prevalent species, followed by L. monocytogenes. Listeria monocytogenes was detected in 52.6% of farms and more frequently in cattle (4.1%) and sheep (4.5%) than in goat farms (0.2%). Lineage I accounted for 69% of L. monocytogenes isolates. Among animal samples, the most prevalent sublineages (SL) and clonal complexes (CC) were SL1/CC1, SL219/CC4, SL26/CC26 and SL87/CC87, whereas SL666/CC666 was most prevalent in environmental samples. Sixty-one different L. monocytogenes cgMLST types were found, 28% common to different animals and/or surfaces within the same farm and 21% previously reported elsewhere in the context of food and human surveillance. Listeria monocytogenes prevalence was not affected by farm hygiene but by season: higher prevalence was observed during winter in cattle, and during winter and spring in sheep farms. Cows in their second lactation had a higher probability of L. monocytogenes faecal shedding. This study highlights dairy farms as a reservoir for hypervirulent L. monocytogenes.

Ruminant-associated Listeria monocytogenes isolates belong preferentially to dairy-associated hypervirulent clones: a longitudinal study in 19 farms

Studies have shown that ruminants constitute reservoirs of Listeria monocytogenes, but little is known about the epidemiology and genetic diversity of this pathogen within farms. Here we conducted a large-scale longitudinal study to monitor Listeria spp. in 19 dairy farms during three consecutive seasons (N = 3251 samples). L. innocua was the most prevalent species, followed by L. monocytogenes. Listeria monocytogenes was detected in 52.6% of farms and more frequently in cattle (4.1%) and sheep (4.5%) than in goat farms (0.2%). Lineage I accounted for 69% of L. monocytogenes isolates. Among animal samples, the most prevalent sublineages (SL) and clonal complexes (CC) were SL1/CC1, SL219/CC4, SL26/CC26 and SL87/CC87, whereas SL666/CC666 was most prevalent in environmental samples. Sixty-one different L. monocytogenes cgMLST types were found, 28% common to different animals and/or surfaces within the same farm and 21% previously reported elsewhere in the context of food and human surveillance. Listeria monocytogenes prevalence was not affected by farm hygiene but by season: higher prevalence was observed during winter in cattle, and during winter and spring in sheep farms. Cows in their second lactation had a higher probability of L. monocytogenes faecal shedding. This study highlights dairy farms as a reservoir for hypervirulent L. monocytogenes.

Neonatal listeriosis presentation and outcome: a prospective study of 189 cases

CONTEXT

Listeriosis is caused by the foodborne pathogen Listeria monocytogenes. It can present as a maternal-neonatal infection. We implemented the nationwide prospective cohort MONALISA and analyzed the features of neonatal listeriosis.

METHODS

We studied all neonates born alive from mothers with microbiologically-proven maternal-neonatal listeriosis enrolled from November 2009 to December 2017. We analyzed presentation, neonatal outcome at discharge and predictors of severe presentation and outcome. The study is registered at clinicaltrials.gov (NCT01520597).

RESULTS

We studied 189 infants. 133/189 (70%) had abnormal clinical status at birth, including acute respiratory distress in 106/189 (56%). 132/189 (70%) infants developed early-onset listeriosis and 12/189 (6%) late onset listeriosis who all presented with acute meningitis. 17/189 (9%) had major adverse outcomes: 3% death (5/189), 6% (12/189) severe brain injury, 2% (3/189) severe bronchopulmonary dysplasia, 15/17 in infants born < 34 weeks of gestation (p < 0.0001 versus infants born ≥ 34 weeks of gestation). Maternal antimicrobial treatment ≥ 1 day before delivery was associated with a significant decrease of infants' severity (resulting in significantly less inotropic drugs, fluid resuscitation, or mechanical ventilation requirement), OR 0.23 [95% confidence interval CI 0.09-0.51], p < 0.0001).

CONCLUSION

Antenatal maternal antimicrobial treatment is associated with reduced neonatal listeriosis severity, justifying the prescription of preemptive maternal antimicrobial therapy when maternal-fetal listeriosis is suspected. Neonatal outcome is better than reported earlier, and its major determinant is gestational age at birth.

Listeria valentina sp. nov., isolated from a water trough and the faeces of healthy sheep

In the context of a study on the occurrence of Listeria species in an animal farm environment in Valencia, Spain, six Listeria-like isolates could not be assigned to any known species. Phylogenetic analysis based on the 16S rRNA gene and on 231 Listeria core genes grouped these isolates in a monophyletic clade within the genus Listeria, with highest similarity to Listeria thailandensis. Whole-genome sequence analyses based on in silico DNA-DNA hybridization, the average nucleotide blast and the pairwise amino acid identities against all currently known Listeria species confirmed that these isolates constituted a new taxon within the genus Listeria. Phenotypically, these isolates differed from other Listeria species mainly by the production of acid from inositol, the absence of acidification in presence of methyl α-d-glucoside, and the absence of α-mannosidase and nitrate reductase activities. The name Listeria valentina sp. nov. is proposed for this novel species, and the type strain is CLIP 2019/00642^T (=CIP 111799^T=DSM 110544^T).

Outbreak of Listeriosis in South Africa Associated with Processed Meat

BACKGROUND

An outbreak of listeriosis was identified in South Africa in 2017. The source was unknown.

METHODS

We conducted epidemiologic, trace-back, and environmental investigations and used whole-genome sequencing to type Listeria monocytogenes isolates. A case was defined as laboratory-confirmed L. monocytogenes infection during the period from June 11, 2017, to April 7, 2018.

RESULTS

A total of 937 cases were identified, of which 465 (50%) were associated with pregnancy; 406 of the pregnancy-associated cases (87%) occurred in neonates. Of the 937 cases, 229 (24%) occurred in patients 15 to 49 years of age (excluding those who were pregnant). Among the patients in whom human immunodeficiency virus (HIV) status was known, 38% of those with pregnancy-associated cases (77 of 204) and 46% of the remaining patients (97 of 211) were infected with HIV. Among 728 patients with a known outcome, 193 (27%) died. Clinical isolates from 609 patients were sequenced, and 567 (93%) were identified as sequence type 6 (ST6). In a case-control analysis, patients with ST6 infections were more likely to have eaten polony (a ready-to-eat processed meat) than those with non-ST6 infections (odds ratio, 8.55; 95% confidence interval, 1.66 to 43.35). Polony and environmental samples also yielded ST6 isolates, which, together with the isolates from the patients, belonged to the same core-genome multilocus sequence typing cluster with no more than 4 allelic differences; these findings showed that polony produced at a single facility was the outbreak source. A recall of ready-to-eat processed meat products from this facility was associated with a rapid decline in the incidence of L. monocytogenes ST6 infections.

CONCLUSIONS

This investigation showed that in a middle-income country with a high prevalence of HIV infection, L. monocytogenes caused disproportionate illness among pregnant girls and women and HIV-infected persons. Whole-genome sequencing facilitated the detection of the outbreak and guided the trace-back investigations that led to the identification of the source.

Phage resistance at the cost of virulence: Listeria monocytogenes serovar 4b requires galactosylated teichoic acids for InlB-mediated invasion

The intracellular pathogen Listeria monocytogenes is distinguished by its ability to invade and replicate within mammalian cells. Remarkably, of the 15 serovars within the genus, strains belonging to serovar 4b cause the majority of listeriosis clinical cases and outbreaks. The Listeria O-antigens are defined by subtle structural differences amongst the peptidoglycan-associated wall-teichoic acids (WTAs), and their specific glycosylation patterns. Here, we outline the genetic determinants required for WTA decoration in serovar 4b L. monocytogenes, and demonstrate the exact nature of the 4b-specific antigen. We show that challenge by bacteriophages selects for surviving clones that feature mutations in genes involved in teichoic acid glycosylation, leading to a loss of galactose from both wall teichoic acid and lipoteichoic acid molecules, and a switch from serovar 4b to 4d. Surprisingly, loss of this galactose decoration not only prevents phage adsorption, but leads to a complete loss of surface-associated Internalin B (InlB),the inability to form actin tails, and a virulence attenuation in vivo. We show that InlB specifically recognizes and attaches to galactosylated teichoic acid polymers, and is secreted upon loss of this modification, leading to a drastically reduced cellular invasiveness. Consequently, these phage-insensitive bacteria are unable to interact with cMet and gC1q-R host cell receptors, which normally trigger cellular uptake upon interaction with InlB. Collectively, we provide detailed mechanistic insight into the dual role of a surface antigen crucial for both phage adsorption and cellular invasiveness, demonstrating a trade-off between phage resistance and virulence in this opportunistic pathogen.

L. monocytogenes is a Gram-positive, food-borne, intracellular pathogen that causes severe infection in susceptible individuals. Interestingly, almost all infections are caused by a subset of strains belonging to certain serovars featuring a complex glycosylation pattern on their cell surface. Using an engineered bacteriophage that specifically recognizes these modifications we selected for mutants that lost these sugars. We found that the resulting strains are severely deficient in invading host cells as we observed that a major virulence factor mediating host cell entry requires galactose decoration of the cell surface for its function. Without this galactose decoration, the strain represents a serovar not associated with disease. Altogether, we show a complex interplay between bacteriophages, bacteria, and the host, demonstrating that cellular invasiveness is dependent upon a serovar-defining structure, which also serves as a phage receptor.

Hypervirulent Listeria monocytogenes clones' adaption to mammalian gut accounts for their association with dairy products

Listeria monocytogenes (Lm) is a major human and animal foodborne pathogen. Here we show that hypervirulent Lm clones, particularly CC1, are strongly associated with dairy products, whereas hypovirulent clones, CC9 and CC121, are associated with meat products. Clone adaptation to distinct ecological niches and/or different food products contamination routes may account for this uneven distribution. Indeed, hypervirulent clones colonize better the intestinal lumen and invade more intestinal tissues than hypovirulent ones, reflecting their adaption to host environment. Conversely, hypovirulent clones are adapted to food processing environments, with a higher prevalence of stress resistance and benzalkonium chloride tolerance genes and a higher survival and biofilm formation capacity in presence of sub-lethal benzalkonium chloride concentrations. Lm virulence heterogeneity therefore reflects the diversity of the ecological niches in which it evolves. These results also have important public health implications and may help in reducing food contamination and improving food consumption recommendations to at-risk populations.

Peyer's patch myeloid cells infection by Listeria signals through gp38+ stromal cells and locks intestinal villus invasion

The foodborne pathogen Listeria monocytogenes (Lm) crosses the intestinal villus epithelium via goblet cells (GCs) upon the interaction of Lm surface protein InlA with its receptor E-cadherin. Here, we show that Lm infection accelerates intestinal villus epithelium renewal while decreasing the number of GCs expressing luminally accessible E-cadherin, thereby locking Lm portal of entry. This novel innate immune response to an enteropathogen is triggered by the infection of Peyer's patch CX3CR1⁺ cells and the ensuing production of IL-23. It requires STAT3 phosphorylation in epithelial cells in response to IL-22 and IL-11 expressed by lamina propria gp38⁺ stromal cells. Lm-induced IFN-γ signaling and STAT1 phosphorylation in epithelial cells is also critical for Lm-associated intestinal epithelium response. GC depletion also leads to a decrease in colon mucus barrier thickness, thereby increasing host susceptibility to colitis. This study unveils a novel innate immune response to an enteropathogen, which implicates gp38⁺ stromal cells and locks intestinal villus invasion, but favors colitis.

Listeria monocytogenes-associated respiratory infections: a study of 38 consecutive cases

OBJECTIVES

Listeria monocytogenes (Lm) is a foodborne human pathogen responsible for severe infections, including septicaemia, neurolisteriosis, and maternal-foetal and focal infections. Little is known about Lm-associated respiratory tract or lung infections.

METHODS

We conducted a retrospective study of culture-proven cases of Lm pleural infections and pneumonia reported to the French National Reference Centre for Listeria from January 1993 to August 2016.

RESULTS

Thirty-eight consecutive patients with pleural infection (n = 32), pneumonia (n = 5), or both (n = 1) were studied; 71% of these were men. Median age was 72 (range 29-90). Two patients presented with concomitant neurolisteriosis. All patients but one reported at least one immunosuppressive condition (97%), with a median number of 2 (range 0-5), including 29% (8/28) with current exposure to immunosuppressive therapy and 50% (17/34) with ongoing neoplasia; 75% (21/28) reported previous pleural or pulmonary disease. Antibiotic therapy mostly consisted in amoxicillin (72%) associated with aminoglycoside in 32%. Chest-tube drainage was performed in 7/19 patients with empyema (37%); 25% of the patients (7/30) required intensive care management. In-hospital mortality reached 35% and occurred after a median time interval of 4 days (range 1-33 days). Three patients had recurrence of empyema (time interval of 1 week to 4 months after treatment completion). Altogether, only 13/31 patients (42%) diagnosed with Lm respiratory infection experienced an uneventful outcome at 2-year follow-up.

CONCLUSION

Lm is a rare but severe cause of pneumonia and pleural infection in older immunocompromised patients, requiring prompt diagnosis and adequate management and follow-up.

MALDI-TOF mass spectrometry-based identification of Listeria species in surveillance: A prospective study

This study aimed to evaluate MALDI-TOF MS for species discrimination of Listeria in the context of routine surveillance. MALDI-TOF MS yielded 100% accuracy for the identification of L. monocytogenes, L. innocua, L. ivanovii, L. fleischmannii, L. grayi, L. seeligeri, L. weihenstephanensis and L. welshimeri, as confirmed by whole genome sequence analyses.

Real-Time Whole-Genome Sequencing for Surveillance of Listeria monocytogenes, France

During 2015–2016, we evaluated the performance of whole-genome sequencing (WGS) as a routine typing tool. Its added value for microbiological and epidemiologic surveillance of listeriosis was compared with that for pulsed-field gel electrophoresis (PFGE), the current standard method. A total of 2,743 Listeria monocytogenes isolates collected as part of routine surveillance were characterized in parallel by PFGE and core genome multilocus sequence typing (cgMLST) extracted from WGS. We investigated PFGE and cgMLST clusters containing human isolates. Discrimination of isolates was significantly higher by cgMLST than by PFGE (p<0.001). cgMLST discriminated unrelated isolates that shared identical PFGE profiles and phylogenetically closely related isolates with distinct PFGE profiles. This procedure also refined epidemiologic investigations to include only phylogenetically closely related isolates, improved source identification, and facilitated epidemiologic investigations, enabling identification of more outbreaks at earlier stages. WGS-based typing should replace PFGE as the primary typing method for L. monocytogenes.

Yeast cells reveal the misfolding and the cellular mislocalization of the human BRCA1 protein

Understanding the effect of an ever-growing number of human variants detected by genome sequencing is a medical challenge. The yeast Saccharomyces cerevisiae model has held attention for its capacity to monitor the functional impact of missense mutations found in human genes, including the BRCA1 breast and ovarian cancer susceptibility gene. When expressed in yeast, the wild-type full-length BRCA1 protein forms a single nuclear aggregate and induces a growth inhibition. Both events are modified by pathogenic mutations of BRCA1. However, the biological processes behind these events in yeast remain to be determined. Here, we show that the BRCA1 nuclear aggregation and the growth inhibition are sensitive to misfolding effects induced by missense mutations. Moreover, misfolding mutations impair the nuclear targeting of BRCA1 in yeast cells and in a human cell line. In conclusion, we establish a connection between misfolding and nuclear transport impairment, and we illustrate that yeast is a suitable model to decipher the effect of misfolding mutations.

Functional Assessment of Genetic Variants with Outcomes Adapted to Clinical Decision-Making

Understanding the medical effect of an ever-growing number of human variants detected is a long term challenge in genetic counseling. Functional assays, based on in vitro or in vivo evaluations of the variant effects, provide essential information, but they require robust statistical validation, as well as adapted outputs, to be implemented in the clinical decision-making process. Here, we assessed 25 pathogenic and 15 neutral missense variants of the BRCA1 breast/ovarian cancer susceptibility gene in four BRCA1 functional assays. Next, we developed a novel approach that refines the variant ranking in these functional assays. Lastly, we developed a computational system that provides a probabilistic classification of variants, adapted to clinical interpretation. Using this system, the best functional assay exhibits a variant classification accuracy estimated at 93%. Additional theoretical simulations highlight the benefit of this ready-to-use system in the classification of variants after functional assessment, which should facilitate the consideration of functional evidences in the decision-making process after genetic testing. Finally, we demonstrate the versatility of the system with the classification of siRNAs tested for human cell growth inhibition in high throughput screening.

Human genetics has entered a new age with the advent of next generation sequencing. However, this great advance also comes with new concerns. Currently, the extensive use of multi-gene panels, whole exome and whole genome sequencing, is generating an ever-growing number of new DNA sequence variations detected in the disease-predisposing genes of human patients. The pathogenic or neutral status of these variants needs to be known before planning any medical act or follow-up. We show here that the status of the variants identified in the BRCA1 breast/ovarian cancer susceptibility gene can be estimated thanks to experimental systems using yeast cells and a novel computational model. Importantly, this model provides a probabilistic classification of variants, opening the possibility to integrate results from functional assays into clinical decision-making. Moreover, our computational model is directly compatible with all kinds of experimental system without any requirement for skills in statistics thanks to ready-to-use online tools. We believe that this work is a step forward in the clinical interpretation of human genetic variants.

Management of intramedullary cystic pilocytic astrocytoma with rhenium-186 intracavitary irradiation: case report

OBJECTIVE

We report a case of cystic spinal cord pilocytic astrocytoma treated with surgical resection and 2 intracavitary injections of rhenium.

CLINICAL PRESENTATION

A 22-year-old man presented with low-back pain, saddle dysesthesia, and sphincter and sexual dysfunction. Spinal cord magnetic resonance showed a large, cystic, intramedullary tumor extending from T9 to T12.

TREATMENT

Two surgical approaches and 1 computed tomography (CT)-scan guided tapping allowed shrinkage of the cystic component but each time the cyst enlarged and neurological symptoms worsened. Pathological examination allowed the diagnosis of pilocytic astrocytoma. The patient underwent 2 intracystic CT-scan guided injections of rhenium that achieved good control of cystic component.

CONCLUSION

Interstitial intracavitary rhenium brachytherapy of recurrent spinal cord cystic astrocytomas achieved excellent stabilization of the cyst with minor side-effects and dramatic improvement of neurological deficits.

Radiofrequency-induced carcinogenesis: cellular calcium homeostasis changes as a triggering factor

The aim was to study the effects of radiofrequency (Rf) in a mice strain characterized by age-determined carcinogenesis of lymphatic tissues. Mice were treated with a 1?h/week Rf exposure for 4 months. A group submitted to sham exposure was used as control animals. The evolution of carcinogenesis was followed up to 18 months. The maximal life span of control mice was about 24 months. All dead animals were clinically and histologically examined to give an age-determined comparative quantification of the evolving carcinogenesis. A radiocalcium tracer method permitted the evaluation of Rf effects on transmembrane transport of extracellular calcium at 1 and 24 h after exposure. The determination of induced lipid peroxidation completed this second study. The findings show that Rf provoked an earlier general lymphocyte cell infiltration, formation of lymphoblastic ascites and extranodal tumours of different histological types, as well as an increased early mortality. The results suggest that in Rf-exposed mice, carcinogenesis may be induced earlier and with different pathological forms than in control animals. The modifications in cellular calcium homeostasis and the age-determined thymus involution appear to be important factors involved in this carcinogenesis process.

Evaluation of health risks caused by radio frequency accelerated carcinogenesis: the importance of processes driven by the calcium ion signal

The acceleration of carcinogenesis, which was induced either by radio frequency radiation from a cellular telephone or by the ferric-ATP complex, was similar in a mouse strain characterized by age-determined carcinogenesis of lymphoid tissues. Organ hypertrophy, the presence of lymphoid blood and ascites, the development of solid tumours, and mortality were very different to those found in control animals. These results emphasize the role of calcium ion signal influx in the activation of oncogenes and the failure of thymus-determined immune defences.

Individualized treatment of craniopharyngioma in children: ways and means

BACKGROUND

Medium- and long-term prognosis of craniopharyngioma is overwhelmed by the risks of hypothalamic and visual impairment. This problem has been underestimated for a long time because the major concern for the neurosurgeon was the risk of recurrences, their best prevention being thought to be complete tumour resection. Today, we know that radical surgery not only is not an absolute guarantee against recurrences but also can cause hypothalamic and visual complications.

METHODS

The authors suggest that instead of complete removal, the first choice treatment should be, when possible, a less aggressive, multistaged and personalized treatment. In this perspective they focus on other therapeutic methods: endocavity treatment of cysts with rhenium-186, triconformational radiotherapy, radiosurgery, and widespread use of the trans-sphenoidal approach.

CONCLUSIONS

These simple methods should reduce the risks of visual aggravation and metabolic syndrome.

Role of iron-ATP complex in lymphocyte proliferation and infiltration

The roles of sodium-ATP (NaATP) and ferric-ATP complex (FeATP) on the proliferation and infiltration of lymphocytes have been studied by evaluation of the hypertrophy and histopathologic examination of spleen and liver, as well of the modifications in the elemental balance of iron, calcium, magnesium, and phosphorus. The results showed that in the implicated biochemical processes, calcium and magnesium have a principal role. An in vitro study on a cell model has permited one to evaluate the effects of deferoxamine, a known iron chelator and inhibitor of human lymphocyte proliferation, on FeATP-modified cellular calcium fluxes. These findings showing a reduced 45Ca2+ uptake in the presence of deferoxamine appear to indicate that in vivo the chelation of blood-borne iron by ATP might play a key role in proliferation and infiltration of lymphocytes, leading to lymphoma development.

Molecular exchange of metal ions and tissular calcium overload

In vitro and in vivo, mouse tissues assayed for 45Ca2+ uptake have shown that ATP increases the Ca2+ take-up in the presence of lactates of iron and aluminum, but this effect is absent with the citrates. The in vitro metal ion exchange with ATP has been demonstrated by electrophoresis and by chromatography. It is considered the cause of the increased capacity of ATP to modify the cellular effects of lactates. The in vitro modifications of Ca2+ uptake by lactates when in the presence of ATP are much more important than those of citrate. In general, aluminum compounds show a higher Ca2+ uptake and, coincidentally, they have shown a higher carcinogenic capacity than iron ATP.

Toxic and carcinogenic effects of parenteral and percutaneous ATP and its iron complex

The long term effects of percutaneous, subcutaneous and intraperitoneal administration of sodium-ATP (NaATP) and ferric iron-ATP (FeATP) were studied on an animal model. Both compounds induce a generalized lymphoadenitis which in the case of FeATP led to lymphomas. The analytical study of the involved target tissues showed intracellular composition changes that result from the impairment of the cell membrane permeability. The morbidity and mortality rate were higher with FeATP which seems to be the result of two different, in intensity and duration, interactions with the cell plasma membrane. The influence of the changes in cellular calcium homeostasis, and its relationship with carcinogenesis and immuno response are discussed.

Cellular calcium homeostasis changes in lymphoma-induction by ATP iron complex

An in vivo comparative study of 45Ca-uptake and lipid peroxidation in tissues of mice treated with ATP complex of iron and sodium salt of ATP shows that only the iron complex produces a sustained increase of intracellular calcium on the organs susceptibles to develop lymphomas. A paralled study of 59Fe-uptake from 59Fe-iron complex of ATP presents a coincidental increase of iron uptake in those organs. To prove the involvement of the calcium homeostasis change in lymphoma-induction we have studied it with the lanthanum complex of ATP. Lanthanum is a well known cellular calcium entry modifier. Based on the results, the increased and sustained entry of extracellular calcium ion appears as the cause of lymphoma-induction by the iron complex. The effects of the calcium-overload in proliferation and neoplastic transformation of lymphocytes, as well as in reducing the immuno-response induced by thymus is discussed.

Role of iron in lymphoma-induction by ATP

Iron complexed by ATP induces lymphomas in mouse organs other than the specific targets of the lympho-adenitis provoked by sodium ATP: lymph nodes, spleen and liver. The reduction of life spans and the production of substantial volumes of ascites, that are lacking in the case of sodium ATP, are an index of the degree of malignancy of the induced lymphomas. On the basis of the known characteristics of iron-ATP complex of cellular calcium homeostasis alteration, the mechanism of these phenomena is discussed.

Iron- and aluminum-induced carcinogenesis

Ferric and aluminum complexes with ATP have shown the induction of tumors in the site of subcutaneous injection, whereas sodium ATP has not. A concomitant but apparently independent phenomenon was a severe lymphoadenitis. The tumor calcium concentration showed an inverse relationship with the tumor growth rate. Carcinogenesis and lymphoadenitis are discussed considering well known effects of ferric and aluminum complexes with ATP on the cellular calcium homeostasis and of ATP on lymphatic tissue proliferation.

Natural polyphenols-iron interaction: its biological importance

The iron-binding capacity of different fractions of natural polyphenols extracts was determined by chromatographic and electrophoretic methods. Their effects on iron-induced calcium homeostasis changes in liver tissue suspension showed that mate tea and green tea extracts provoke a very significant inhibition of the iron effects, whereas it is much less significant with red wine extract. The biological importance of this phenomenon is discussed.

Comparison of the biodistribution in mice of 111indium oxine encapsulated into poly(lactic-co-glycolic)-D,L-85/15 and poly(epsilon caprolactone) nanocapsules

Poly(lactic-co-glycolic)-D,L-85/15 (PLAGA) nanocapsules and poly(epsilon caprolactone) (PCL) nanocapsules were labeled with a relatively long half-life compound that is usually used in humans; that is, 111In-labelled oxine (111In oxine). This labeling technique led to a high 111In oxine entrapment efficiency and good stability during dialysis against phosphate buffer and phosphate buffered albumin solution. Because of these characteristics, the nanocapsules biodistribution was followed up after intravenous administration for up to 96 h by determining the gamma activity in the tissues after sampling. The administration of the PCL-encapsulated 111In oxine led to a decrease in the blood radioactivity and an increase in the liver radioactivity compared with the solution. This effect was even more pronounced with the PLAGA nanocapsules. Finally, the activity level in other tissues, such as the kidneys, the lungs, and the spleen, appeared to be rather low and only slightly affected by the encapsulation into one or the other polymer.

Evaluation of peroral silicone dosage forms in humans by gamma-scintigraphy

Gastric emptying of oral silicone dosage forms was studied in humans by gamma-scintigraphy. To achieve a constant and predictable residence time in the stomach, three different formulations based on known concepts such as controlled swelling were investigated. The importance of physical parameters such as size or shape were also examined to assess the feasibility of designing a dosage form for gastric retention. Three shapes: minimatrices, extruded rods and moulded slabs were screened. To label the silicone polymer, two isotopes, used routinely in nuclear medicine departments, were selected: iodine-123 and indium-111. To select the most suitable isotope, the yield and the stability of the labelling were determined in vitro on the pharmaceutical dosage forms. The residence time of these silicone formulations, labelled with iodine and administered in hard gelatine capsules, was monitored in 12 subjects with a gamma camera. The study was performed under fed conditions after ingestion of a standardised meal labelled with indium. The minimatrices provided at least 3 h retention, slabs exhibited 4 h 40 min retention. For the rods the mean residence time in the stomach was around 4 h 20 min. In addition, a correlation was established between the gastric emptying of rods and the half-gastric residence time of meal. On the contrary, such a correlation was not observed for the slabs.

Effects of low-molecular-weight aluminum complexes on brain tissue calcium homeostasis

The in vitro effects of low-molecular-weight aluminum complexes (citrate, lactate, and ATP complex) on the Ca2+ uptake and aluminum-induced lipid peroxidation of brain tissue show that the modification of the calcium homeostasis is determined by the nature of the ligand and that there is no correlation between the aluminum-induced lipid peroxidation and the Ca2+ uptake. The same characteristics have been shown by a similar study performed with Ehrlich carcinoma cells. The electrophoretic analyses of the aluminum lactate-albumin and aluminum lactate-ATP interactions indicate an aluminum transfer from the lactate to the albumin and ATP ligands. The increased Ca2+ uptake when ATP is present in the incubation medium with aluminum citrate and aluminum lactate corroborates the suggested mediator role of ATP in cellular calcium homeostasis modification induced by iron.

ATP in iron overload-induced intracellular calcium changes

The cellular iron uptake from low molecular weight iron complexes (ferric citrate, ferric lactate and ferric ATP complex) is concentration-dependent, and only a small part of the iron penetrates the cell as shown by deferoxamine treatment. A threshold of iron concentration in the cell must be reached for the iron complex-induced increase of cellular Ca2+-uptake. ATP seems to play a key role in an iron translocation that enhances the effects of the iron complexes. A non-specific and competitive iron-binding by proteins seems to act as a buffer system that reduces the iron overload effects. Calcium channel blockers have no effects on the iron complex-cell interaction or iron-induced Ca2+-uptake modification. An iron complex concentration-dependent inhibition of the CaATPase activity, and its consequent Ca2+-extrusion impairment appear as the likely cause of calcium overload. The relevance of these findings in iron overload-induced pathologies is discussed.

ATP in cellular calcium-overload by trivalent metal ions

Extracellular Ca2+-influx induced by trivalent metal ions (Fe3+, Al3+, Cr3+, In3+, Ga3+, and La3+) in Ehrlich carcinoma cells is enhanced by ATP. This action seems to be related to the high coordination capacity of the ATP ligand that inhibits the polymerization of the solvated cations taking place at physiological pH, and consequently permits their biological activity. A general relationship between induced lipid peroxidation and increased calcium uptake was not found. These results emphasize the ATP role in the toxicity of trivalent metals, and its possible involvement, via cellular calcium overload, in a neurodegenerative process, such as Alzheimer's and Parkinson's diseases, in whose etiology the implication of aluminum and iron has been suggested.

Influence of different physicochemical conditions on the release of indium oxine from nanocapsules

The main purpose of this study was to determine the influence of factors (pH, enzymes, etc.) chosen partially to mimic in vivo conditions on the release of a model drug, indium oxine, from polyepsiloncaprolactone (PCL) nanocapsules in vitro. A nanocapsule suspension, an emulsion (O/W), and a solution in olive oil were prepared in order to compare the release of a radioactive tracer, indium oxine, as a function of time by an in vitro dialysis method. Nanocapsules were prepared by interfacial deposition of PCL and characterized by particle size distribution (laser light scattering) and determination of the polymer molecular weight by gel permeation chromatography (GPC). The results of this study suggest that the partition coefficient between the acceptor medium and the olive oil is the major parameter governing the release of the isotope, at least in the absence of significant enzyme activity. The PCL wall of nanocapsules is a barrier that does not seem to retard the release of indium. The addition of porcine liver esterases accelerated the degradation of PCL. This study confirms that the release of a drug from nanocapsules may be very different depending on the in vivo location, that is, the administration site.

Non-transferrin-bound iron and tumor cells

The study of iron uptake from low molecular weight complexes by Ehrlich carcinoma cells shows concentration-dependence, and ATP increases the iron uptake from citrate and lactate complexes. Blood proteins can act as inhibitors, and deferoxamine chelation of cell-bound iron complex indicates that the percentage of iron penetrating the cell is about the same for a wide range of iron complex concentrations in the incubation medium (about 5% for ferric lactate). Ascorbic acid increases iron uptake and simultaneously decreases lipid peroxidation. Electrophoresis shows a very high iron transfer from ferric lactate to ATP, and to a lesser extent to ADP and AMP. In the pathological evolution of iron overload to a neoplasia, the probable involvement of an iron exchange between iron complexes from non-transferrin-bound iron of plasma and ATP is discussed.

Effects of iron complexes on brain calcium homeostasis

The effects of two physiological low molecular weight iron complexes, ferric lactate and ferric adenosine triphosphate (ATP) on brain Ca2+ homeostasis modification, have been studied in vitro and in vivo. In vitro ferric ATP complex shows a higher efficiency as modifier of Ca2+ homeostasis. This higher reactivity and the in vivo observed effect of increased brain uptake of iron from ferric lactate provoked by the presence of ATP, corroborate in vitro results showing an iron transfer from ferric lactate to ATP, as well as the mediator role of ATP in the iron-induced cellular Ca2+ homeostasis modification process. The possible role of this process in Parkinson's disease is discussed.

Role of lipid peroxidation in iron-induced cellular calcium overload

Calcium overload is the common pathway leading to cell injury. The role of iron-induced lipid peroxidation in the modification of Ehrlich carcinoma cells calcium homeostasis has been studied. There is a lack of correlation between that modification and the value of lipid peroxidation. The stability characteristics of low-mol-weight iron complexes affect lipid peroxidation and, to a lesser extent, cellular calcium uptake. Lipid peroxidation appears not as a triggering factor of cellular calcium homeostasis modification, but as a concomitant phenomenon.

Effect of egg consumption in healthy volunteers: influence of yolk, white or whole-egg on gastric emptying and on glycemic and hormonal responses

The effects of the ingestion of 2 whole eggs (E), 2 egg whites, 2 egg yolks (Y), or no eggs with a standard breakfast on gastric emptying, glycemic and hormonal responses have been studied in 12 healthy young males. E and Y induce a significant delay of gastric emptying, together with reduced blood glucose and insulin peaks (Y). Egg ingestion, whatever the part, increases gastric inhibitory peptide level in blood. Cholecystokinin is enhanced after E or Y ingestion. The results indicate that egg ingestion, especially yolk ingestion, may be of interest in regulating metabolic variables of glucose metabolism.

Cardiotoxicity of parenterally administered iron complexes

The role of cell calcium overload in the cardiotoxicity of low molecular weight iron complexes has been studied using 45Ca(2+)-uptake determinations in mice intraperitoneally injected with ferric lactate and ferric-ATP complex. Heart tissue shows a very high increase of 45Ca(2+)-uptake which appears to corroborate the hypothesis of cardiotoxicity by calcium overload. ATP seems to play a role in the degree of iron complex efficiency as cell calcium homeostasis modifier.

The role of ATP as a mediator in the action of iron complexes on cellular calcium homeostasis

The effects of the interaction between low molecular weight iron complexes (citrate, lactate, and ATP complexes) with ATP and proteins, on the modification of Ehrlich carcinoma cell calcium homeostasis have been studied. In that modification the ferric-ATP complex shows much higher activity than the others. Sodium ATP, by iron translocation from citrate and lactate, increases their activity. This phenomenon implicates ATP as a mediator on the cellular activity of the complexes. Proteins, particularly ferritin, appear to moderately reduce their activity, whereas glutathione and ascorbic acid, acting as lipid peroxidation-inhibitors, show only a slight reduction of the iron complex's effects on cellular calcium uptake.