Implantation of a novel insertable cardiac monitor: preliminary multicenter experience in Europe

BACKGROUND

The LUX-Dx™ is a novel insertable cardiac monitor (ICM) introduced into the European market since October 2022.

PURPOSE

The aim of this investigation was to provide a comprehensive description of the ICM implantation experience in Europe during its initial year of commercial use.

METHODS

The system comprises an incision tool and a single-piece insertion tool pre-loaded with the small ICM. The implantation procedure involves incision, creation of a device pocket, insertion of the ICM, verification of sensing, and incision closure. Patients receive a mobile device with a preloaded App, connecting to their ICM and transmitting data to the management system. Data collected at European centers were analyzed at the time of implantation and before patient discharge.

RESULTS

A total of 368 implantation procedures were conducted across 23 centers. Syncope (235, 64%) and cryptogenic stroke (34, 9%) were the most frequent indications for ICM. Most procedures (338, 92%) were performed in electrophysiology laboratories. All ICMs were successfully implanted in the left parasternal region, oriented at 45° in 323 (88%) patients. Repositioning was necessary after sensing verification in 9 (2%) patients. No procedural complications were reported, with a median time from skin incision to suture of 4 min (25th-75th percentiles 2-7). At implantation, the mean R-wave amplitude was 0.39 ± 0.30 mV and the P-wave visibility was 91 ± 20%. Sensing parameters remained stable until pre-discharge and were not influenced by patient characteristics or indications. Procedural times were fast, exhibited consistency across patient groups, and improved after an initial experience with the system. Operator Operator feedback on the system was positive. Patients reported very good ease of use of the App and low levels of discomfort after implantation.

CONCLUSIONS

LUX-Dx™ implantation appears efficient and straightforward, with favorable post-implantation sensing values and associated with positive feedback from operators and patients.

Chromosomal characterization in native populations of Elymus scabrifolius from Argentina through classical and molecular cytogenetics (FISH–GISH)

The karyotype of Elymus scabrifolius (Döll) J.H. Hunz. (2n = 4x = 28) was investigated by DAPI staining and in situ hybridization. All the accessions studied presented a symmetric and uniform karyotype constituted by 9m+2m–sm+3sm. DAPI stain showed 1–7 conspicuous bands in all the chromosomes and polymorphisms between accessions. FISH experiments carried out with 45S rDNA as probe (pTa71) showed strong hybridization signals on the metacentric SAT-chromosome pair 8; the submetacentric SAT-chromosome pair 13 presented weaker hybridization. FISH using pSc119.2 clone as probe identified five chromosome pairs. Then, the combination of chromosome morphology, DAPI-staining, and FISH enabled the accurate identification of each chromosome pair in E. scabrifolius. Genomic in situ hybridization (GISH) experiments using Hordeum DNA as probe on mitotic metaphases confirmed unequivocally the presence of the H genome in E. scabrifolius, allowing us to observe six uniformly labeled chromosome pairs and two chromosome pairs with only one arm labeled. The remaining six chromosome pairs were weakly labeled. The rehybridization of FISH slides with Hordeum DNA as probe allow us to assign the genomic provenance of most of the chromosomes in the studied accessions. Moreover, intergenomic rearrangement was detected between genome H and the still unknown progenitor genome.

Cytological characterization of sunflower by in situ hybridization using homologous rDNA sequences and a BAC clone containing highly represented repetitive retrotransposon-like sequences

In the present work we report new tools for the characterization of the complete chromosome complement of sunflower (Helianthus annuus L.), using a bacterial artificial chromosome (BAC) clone containing repetitive sequences with similarity to retrotransposons and a homologous rDNA sequence isolated from the sunflower genome as probes for FISH. The rDNA signal was found in 3 pairs of chromosomes, coinciding with the location of satellites. The BAC clone containing highly represented retroelements hybridized with all the chromosome complement in FISH, and used together with the rDNA probe allowed the discrimination of all chromosome pairs of sunflower. Their distinctive distribution pattern suggests that these probes could be useful for karyotype characterization and for chromosome identification. The karyotype could be subdivided into 3 clear-cut groups of 12 metacentric pairs, 1 submetacentric pair, and 4 subtelocentric pairs, thus resolving previously described karyotype controversies. The use of BAC clones containing single sequences of specific markers and (or) genes associated with important agricultural traits represents an important tool for future locus-specific identification and physical mapping.

Meiotic behavior and DNA content in alloplasmic lines of maize

The cytoplasm of Zea mays ssp. mexicana (teosinte) affects several inherited traits when combined with genotypes of maize (Zea mays ssp. mays). The meiotic behavior and the total DNA content of four lines of maize with teosinte cytoplasm were compared with those of the parental lines. The results obtained suggest that the cytoplasm of teosinte promotes an increase in total nuclear DNA content, perhaps through an increase of highly repetitive DNA in the knob zones. The analysis of meiotic behavior indicates that the cytoplasm of teosinte can alter the spatial distribution of the genomes, since two groups of five bivalents each were observed at a high frequency. During prophase I - anaphase I, each group of five bivalents behaves in a slightly asynchronous way with respect to the other group and, moreover, two nucleoli were observed in 10% of the cells. These results suggest that the cytoplasm of teosinte could induce changes affecting genomic structure and function in some maize genotypes. These changes are of potential importance for breeding programs and evolutionary studies.

Genetic diversity in maize landraces from indigenous settlements of Northeastern Argentina

In South America, native maize germplasm has been extensively studied particularly for the Andean region. However, relatively few genetic diversity studies include materials from the eastern region of the continent. Herein we present a genetic diversity characterization of four Popcorn maize landraces, maintained in indigenous settlements, from Northeastern Argentina (NEA). In addition, one Popcorn landrace from Northwestern Argentina (NWA) was incorporated for comparison. We characterized these landraces using ten microsatellite markers. For the whole data set, a total of 65 alleles were found, with an average of 7.22 alleles per locus. The average gene diversity was 0.370. Global fit to Hardy-Weinberg proportions was observed in all landraces. Global estimates of F (ST) revealed a significant differentiation among the populations. Individual Neighbor-joining clustering and Bayesian analyses allowed the recognition of most populations studied. Two main groups were distinguished by the Neighbor-joining clustering of populations. This grouping pattern would be consistent with a hypothesis of successive introductions of Popcorn in South America. The results presented will be useful to design strategies that maximize the utility of maize genetic resources.

Complex mutational patterns and size homoplasy at maize microsatellite loci

Microsatellite markers have become one of the most popular tools for germplasm characterization, population genetics and evolutionary studies. To investigate the mutational mechanisms of maize microsatellites, nucleotide sequence information was obtained for ten loci. In addition, Single-Strand Conformation Polymorphism (SSCP) analysis was conducted to assess the occurrence of size homoplasy. Sequence analysis of 54 alleles revealed a complex pattern of mutation at 8/10 loci, with only 2 loci showing allele variation strictly consistent with stepwise mutations. The overall allelic diversity resulted from changes in the number of repeat units, base substitutions, and indels within repetitive and non-repetitive segments. Thirty-one electromorphs sampled from six maize landraces were considered for SSCP analysis. The number of conformers per electromorph ranged from 1 to 7, with 74.2% of the electromorphs showing more than one conformer. Size homoplasy was apparent within landraces and populations. Variation in the amount of size homoplasy was observed within and between loci, although no differences were detected among populations. The results of the present study provide useful information on the interpretation of genetic data derived from microsatellite markers. Further efforts are still needed to determine the impact of these findings on the estimation of population parameters and on the inference of phylogenetic relationships in maize investigations.

Genomic affinities between maize and Zea perennis using classical and molecular cytogenetic methods (GISH-FISH)

In this study we have analysed and compared the genomic composition, meiotic behaviour, and meiotic affinities of Zea perennis and Zea mays ssp. mays. To do so we studied the parental taxa and the interspecific hybrid Zea perennis x Zea mays ssp. mays, using classical cytogenetic methods, as well as GISH and FISH. GISH enabled us to recognize the genomic source of each chromosome involved in the meiotic configurations of this hybrid, and established the genomic affinities between their parental species. The results obtained here reinforce the hypothesis of the amphiploid origin of Zea perennis and, together with previous research, indicate that the chromosomes with divergent repetitive sequences in maize and Zea luxurians could be the remnants of a relict parental genome not shared with Zea perennis.

The genome organization and diversification of maize and its allied species revisited: evidences from classical and FISH-GISH cytogenetic analysis

The present review summarizes our classical and molecular cytogenetic investigations in the genus Zea. The results obtained from the meiotic behavior analysis of Zea species and hybrids, confirm the amphiploid nature of all species in the genus, with a basic number of x = 5 chromosomes. All species with 2n = 20 are diploidized allotetraploids, whereas Z. perennis (2n = 40) is an allooctoploid with four genomes somewhat divergent from one another. These analyses also revealed the existence of postzygotic reproductive isolation among Zea species. Our studies using genomic in situ hybridization (GISH) provide evidence about the evolutionary relationships among maize and its allied species, and reveal remarkable genomic divergences. Particularly, knob sequences were not completely shared between taxa previously considered to be closely related. Our data strongly suggest that the teosinte Z. mays parviglumis is not the only progenitor of cultivated maize. Introgression of Tripsacum into cultivated maize cannot be discarded.

GISHGenomic in situ hybridization reveals cryptic genetic differences between maize and its putative wild progenitor Zea mays subsp. parviglumis

The aim of this paper is to test with genomic in situ hybridization the genomic affinities between maize and its putative progenitor Zea mays subsp. parviglumis. Blocking procedures were applied for the purpose of improving discrimination among chromosome regions. Unlabeled genomic DNA from Z. mays subsp. parviglumis as a blocking agent and labeled genomic DNA from maize were hybridized on maize chromosomes. On the other hand, mitotic metaphases from Z. mays subsp. parviglumis were blocked with unlabeled genomic DNA of maize and hybridized with labeled genomic DNA from Z. mays subsp. parviglumis. Both experiments showed that either maize or Z. mays subsp. parviglumis chromosomes have their own unique sequences. This means an unexpected degree of divergence if Z. mays subsp. parviglumis is the only progenitor of maize, a result that is discussed in relation to our previous genomic in situ hybridization observations and to the different scenarios proposed about the origin of maize.

Behaviour of ring bivalents in holokinetic systems: Alternative sites of spindle attachment in Pachylis argentinus and Nezara viridula (Heteroptera)

Heteropteran chromosomes are holokinetic; during mitosis, sister chromatids segregate parallel to each other but, during meiosis, kinetic activity is restricted to one pair of telomeric regions. This meiotic behaviour has been corroborated for all rod bivalents. For ring bivalents, we have previously proposed that one of the two chiasmata releases first, and a telokinetic activity is also achieved. In the present work we analyse the meiotic behaviour of ring bivalents in Pachylis argentinus (Coreidae) and Nezara viridula (Pentatomidae) and we describe for the first time the chromosome complement and male meiosis of the former (2n = 12 + 2m + X0, pre-reduction of the X). Both species possess a large chromosome pair with a secondary constriction which is a nucleolus organizer region as revealed by in-situ hybridization. Here we propose a new mode of segregation for ring bivalents: when the chromosome pair bears a secondary constriction, it is not essential that one of the chiasmata releases first since these regions or repetitive DNA sequences adjacent to them become functional as alternative sites for microtubule attachment and they undertake chromosome segregation to the poles during anaphase I.

Antidepressant drug prescribing in Italy, 2000: analysis of a general practice database

OBJECTIVE

Databases of subjects receiving antidepressants provide evidence on the use of drugs in typical patients and settings under real-world conditions. This study analysed a general practice database to estimate the prevalence of antidepressant drug use, describe the use of these compounds by gender and age and estimate the prevalence of occasional versus non-occasional users.

METHODS

The general practice database of Chivasso, a city near Turin in Piedmont, was analysed. The database includes all community (i.e. outside hospitals) prescriptions reimbursed by the National Health System in the population living in the study area. From the database, the total number of units of antidepressant drugs prescribed over a 6-month period was extracted. Using the general practice patient code, all records were converted into a sample of patients receiving one or more prescriptions of one or more antidepressants.

RESULTS

During the 6 months surveyed, 12,930 antidepressant prescriptions were dispensed to 3751 patients, resulting in a prevalence of use of 19 patients per 1000 inhabitants (confidence interval 18.3, 19.5). The prevalence of use progressively increased with age and was more than double in females than males (female/male ratio 2.16). Paroxetine was the most prescribed compound, followed by amitriptyline and fluoxetine. However, in older subjects, the top two antidepressants were trazodone and amitriptyline. Nearly one-fourth of all dispensed antidepressants were prescribed on one occasion only; occasional users were slightly younger than non-occasional users.

CONCLUSIONS

In Italy, databases have been used to monitor the prescription of medicines, but they have always provided aggregate data on drug sales and consumption. In this study, a sample of typical patients receiving antidepressants under real-world conditions was analysed to help clarify what happens in clinical practice. Databases of patients receiving antidepressants should be adopted to suggest public health priorities and generate original research hypotheses to be formally tested with experimental studies.

Is maize B chromosome preferential fertilization controlled by a single gene?

In previous work, genotypes for high and low B chromosome transmission rate were selected from a native race of maize. It was demonstrated that the B transmission is genetically controlled. The present work reports the fourth and fifth generations of selection and the F1 hybrids between the lines. The native B is characterized by a constant behaviour, with normal meiosis and nondisjunction in 100% of postmeiotic mitosis. It is concluded that genetic variation for B transmission between the selected lines is due to the preferential fertilization process. The F1 hybrids show intermediate B transmission rate between the lines. They are uniform, the variance of the selected character being one order of magnitude lower than that of the native population. In addition, 0B x 2B and 2B x 2B crosses were made to study the effect of the presence of B chromosomes in the female parent, resulting in non-significant differences. Several crosses were made both in Buenos Aires and in Madrid to compare the possible environmental effect, but significant differences were not found. Our results are consistent with the hypothesis of a single major gene controlling B transmission rate in maize, which acts in the egg cell at the haploid level during fertilization. It is also hypothesized that maize Bs use the normal maize fertilization process to promote their own transmission.

Genomic affinities of Zea luxurians, Z. diploperennis, and Z. perennis: Meiotic behavior of their F1 hybrids and genomic in situ hybridization (GISH)

Since 1987 cytological evidence has arisen in our laboratory, pointing to x = 5 as the original basic chromosome number of maize and its related wild species. This paper deals with the analysis of the meiotic behavior of F1 hybrids Zea luxurians × Z. diploperennis (2n = 20) and Z. luxurians × Z. perennis (2n = 30). In the first hybrid the most frequent configuration was 8ll + 4l and in the latter was 5lll + 5ll + 5l. Applying GISH (genomic in situ hybridization) to mitotic chromosomes of Z. luxurians we found that DAPI (4', 6-diamidino-2-phenylindole) positive bands located in all telomeric regions of this species did not hybridize with either Z. perennis or Z. diploperennis genomic probe. Therefore, Z. luxurians has a repetitive sequence that can be used in fluorescent staining to identify its chromosomes. When GISH was employed on metaphase I of the 2n = 30 hybrid, all the univalents showed distinctive telomeres of Z. luxurians, while the bivalents did not present any signal. These findings show that the formation of bivalent-univalent configurations is not a random event. The bivalents tend to be spatially separated and are very often observed forming an independent group of 5II. Finally, trivalents were composed by one chromosome labeled in its telomeric regions, and two smaller and unlabeled ones. The use of chromosome markers of Z. luxurians demonstrated to be a good step forward in interpreting the nature of meiotic configurations in 2n = 30 Zea spp. hybrids. They can help to clarify the relationship between genomes and provide a useful addition to the taxonomic classification in the genus Zea.Key Words: Zea hybrids, evolution, cytogenetics, repetitive sequences, heterochromatic knobs.

Genomic in situ hybridization (GISH) of Tripsacum dactyloides and Zea mays ssp. mays with B chromosomes

Genomic affinities between Tripsacum dactyloides (2n = 72) and Zea mays ssp. mays (2n = 20 + 5 B) were analyzed through GISH (genomic in situ hybridization) to ascertain the degree of chromosome homology between the two genera. Mitotic cells of T. dactyloides were simultaneously probed with total genomic DNA from Z. mays ssp .mays (2n = 20) and with rDNA (pTA71). A disperse pattern of hybridization signal among all 72 chromosomes, corresponding to maize total DNA, and six strong fluorescent signals due to the rDNA probe hybridizing on 3 chromosome pairs of T. dactyloides were observed. Mitotic chromosomes from Z. mays ssp. mays (2n = 20 + 5 B) were hybridized with a maize line that lacked B chromosomes and knobs and with total DNA from T. dactyloides. The knobless line of maize hybridized intensely on all chromosomes except for some regions where the probe bound less. Tripsacum dactyloides bound intensely on one terminal region of each B chromosome and to some regions of chromosome pairs 2, 6, and 8. These regions are DAPI positive and coincide with regions that displayed lower affinity with the probe from the knobless maize line. The possible significance of these results is discussed briefly.Key words: Tripsacum dactyloides, Zea mays ssp. mays, maize B chromosomes, genomic in situ hybridization, GISH.

Localization of the genes controlling B chromosome transmission rate in maize (Zea mays ssp. mays, Poaceae)

In previous papers we found that the frequency of B chromosomes in native races of maize varies considerably in different populations. Moreover, we found genotypes that control high and low transmission rates (TR) of B chromosomes in the Pisingallo race. In the present work crosses were made to determine whether the genes controlling B-TR are located on the normal chromosome set (As) or on the B chromosomes (Bs). We made female f.0B × male m.2B crosses between and within high (H) and low (L) B-TR groups. The Bs were transmitted on the male side in all cases. The mean B-TR from the progeny of f.0B (H) × m.2B (H) and f.0B (H) × m.2B (L) crosses was significantly higher than that from f.0B (L) × m.2B (L) and f.0B (L) × m.2B (H) crosses. The results show that the B-TR of the crosses corresponds to the H or L B-TR of the 0B female parents irrespective of the Bs of the male parent. This indicates that B-TR is genetically controlled by the 0B female parent and that these genes are located on the A chromosomes.

Genome size and numerical polymorphism for the B chromosome in races of maize (Zea mays ssp. mays, Poaceae)

Twenty-one native populations (1120 individuals) of maize from Northern Argentina were studied. These populations, which belong to 13 native races, were cultivated at different altitudes (80-3620 m). Nineteen of the populations analyzed showed B chromosome (Bs) numerical polymorphism. The frequency of individuals with Bs varied from 0 to 94%. The number of Bs per plant varied from 0 to 8 Bs, with the predominant doses being 0, 1, 2, and 3. Those populations with varying number of Bs showed a positive and statistically significant correlation of mean number of Bs with altitude. The DNA content, in plants without Bs (A-DNA)(2n = 20), of 17 populations of the 21 studied was determined. A 36% variation (5.0-6.8 pg) in A-DNA content was found. A significant negative correlation between A-DNA content and altitude of cultivation and between A-DNA content and mean number of Bs was found. This indicates that there is a close interrelationship between the DNA content of A chromosomes and doses of Bs. These results suggest that there is a maximum limit to the mass of nuclear DNA so that Bs are tolerated as long as this maximum limit is not exceeded.

Cytogenetic studies in the genus Zea : 3. DNA content and heterochromatin in species and hybrids

The nuclear DNA amount and the heterochromatin content in species and hybrids of Zea were analyzed in telophase nuclei (2C) of the root apex of germinating seeds. The results revealed significant differences among taxa and also among lines and races of maize. The hybrids between Z. mays ssp. mays x Z. mays ssp. mexicana (2n=20), Z. diploperennis x Z. perennis (2n=30), and Z. diploperennis x Z.perennis (2n=40) showed DNA content intermediate between that of the parents. The number of chromosomal C-bands and the proportion of the genome comprising C-band heterochromatin were positively related to genome size. In the different lines and races of maize studied, there was a positive correlation between genome size and the interval from germination to flowering. Octoploid Z. perennis (2n=40) showed the smallest DNA content per basic genome and the smallest heterochromatic blocks, suggesting that the DNA lost by this species consisted mainly of repetitive sequences. Considering that the extant species of Zea are tetraploid (2n=20) and octoploid (2n=40) and that the ancestral diploids are extinct, any consideration of the direction (increase or decrease) of the DNA change would be entirely speculative. The extant species could be the product of natural and artificial selection acting on different genotypic and nucleotypical constitutions at the diploid and/or tetraploid levels.

Cytogenetic studies in the genus Zea : 2. Colchicine-induced multivalents

Premeiotic colchicine treatment brings about the production of one to five quadrivalents in Zea mays ssp. mays (maize, 2n=20) and an increase in the number of quadrivalents from five to ten in Zea perennis (2n=40). The results confirm the allotetraploid nature of maize and suggest that the species possesses two homoeologous genomes (A2A2 B2B2) that fail to pair, probably due to the presence of Ph-like genes. Moreover, the autoallooctoploid nature of Zea perennis, with a genome formula A'1A'1 A″1A″1 C1C1 C2C2, is supported by the present results.

CYTOGENETICS OF SOME SPECIES AND NATURAL HYBRIDS IN PROSOPIS (LEGUMINOSAE)

Cytological results on 12 species and 4 putative hybrids of Prosopis are presented. Of these, 5 species and 4 hybrids have been hitherto unknown cytologically. The following species proved to be diploid (2n = 28) and constitute new chromosome number determinations for the genus: P. algarobilla Griseb., P. hassleri Harms, P. nigra (Griseb.) Hieron., P. patagonica Speg., P. tamarugo Phil. The diploid nature of some races of P. juliflora (Sw.) DC. is established; apparently under this taxon there are also tetraploid populations. The following putative interspecific hybrids showed regular meiosis with formation of 14 bivalents: P. vinalillo Stuck. (P. ruscifolia × P. alba?), P. alba × P. nigra? and P. hassleri × P. ruscifolia?.So far 28 taxa of the genus have been studied cytologically; 27 of these are diploid. The scarcity of polyploidy in the genus (3.5%) might be a consequence of the almost general lack of means of vegetative reproduction and of the absence of chromosome repatterning in primary speciation. Results of other authors concerning cytological data are also discussed.