Trochosira polychaeta: a colonial diatom from the late Cretaceous exhibiting two contrasting chain-linking mechanisms and a wide range of preservation

The fossil species Trochosira polychaeta Strelnikova, exhibits a wide range of preservational states that has led to contrasting interpretations with regard to its resting stage or vegetative cell status. Within shallow-buried, well preserved diatomites from the Alpha Ridge of the Arctic Ocean, a continuum of dissolution effects are documented and a vegetative cell status is clearly indicated. The chains are formed by a central linking process but complex marginal structures also constitute a complementary linking mechanism. The double linkage may have supported the integrity of the colonial chains and provided a mechanism for enhanced nutrient uptake. The presence of two distinct types of linking might also represent a stage in a transition from the Cretaceous when central linking structures were common, through the Cenozoic to the modern with more common linking through marginal structures

POSSIBILITIES OF EARLY DIAGNOSIS OF PRIMARY CILIARY DYSKINESIA

Despite the manifestations of primary ciliary dyskinesia (PCD) in the neonatal period or in the first year of life, the diagnosis of this rare disease is usually established at the age of 4–7 years. The aim of the study was to search for reserves for early diagnosis of PCD. Materials and methods of research: 17 patients were observed with PCD, confirmed on the basis of the PICADAR scale, high-speed light video microscopy (all patients) and transmission electron microscopy (in 3 patients) of the mucous biopsy of the respiratory membrane using a genetic study (in one patient). Results: all patients were born full-term; neonatal respiratory distress syndrome (RDS) was observed in 71% of patients; the median duration of mechanical ventilation/oxygen therapy was 14 [7; 21] days; lateralization abnormalities were found in 35% of patients; all patients had persistent nasal congestion and/or rhinorrhea, 94% had chronic or recurrent sinusitis, otitis, recurrent pneumonia, chest x-ray and computed tomography (CT) scans in 71% had atelectasis with constant localization in the middle lobe, 12 of 15 patients, traced in the follow-up, – bronchiectasis (BE), also mainly in the middle lobe (in 9 patients). The average age at diagnosis was 5 [1.75; 7] years, patients with an established diagnosis over the age of 3 years were more often diagnosed with BE. The median of PICADAR scores was 7 [6; 8] points. Conclusions: to establish early diagnosis of PCD, it is important to consider neonatal RDS, lateralization of organs, difficulty in nasal breathing, starting from the first half of life. © 2022, Pediatria Ltd. All rights reserved