Impact of age-associated increase in 2′-O-methylation of miRNAs on aging and neurodegeneration in Drosophila

MicroRNAs (miRNAs) are 20- to ∼24-nucleotide (nt) small RNAs that impact a variety of biological processes, from development to age-associated events. To study the role of miRNAs in aging, studies have profiled the levels of miRNAs with time. However, evidence suggests that miRNAs show heterogeneity in length and sequence in different biological contexts. Here, by examining the expression pattern of miRNAs by Northern blot analysis, we found that Drosophila miRNAs show distinct isoform pattern changes with age. Surprisingly, an increase of some miRNAs reflects increased 2′-O-methylation of select isoforms. Small RNA deep sequencing revealed a global increase of miRNAs loaded into Ago2, but not into Ago1, with age. Our data suggest increased loading of miRNAs into Ago2, but not Ago1, with age, indicating a mechanism for differential loading of miRNAs with age between Ago1 and Ago2. Mutations in Hen1 and Ago2, which lack 2′-O-methylation of miRNAs, result in accelerated neurodegeneration and shorter life span, suggesting a potential impact of the age-associated increase of 2′-O-methylation of small RNAs on age-associated processes. Our study highlights that miRNA 2′-O-methylation at the 3′ end is modulated by differential partitioning of miRNAs between Ago1 and Ago2 with age and that this process, along with other functions of Ago2, might impact age-associated events in Drosophila.     

Long-Term Results after Video-Assisted Thoracic Surgery for Spontaneous Pneumothorax

Objective: Analysis of the long-term results of video-assisted thoracic surgery (VATS) for spontaneous pneumothorax in patients treated in two surgical centres from May 1994 until December 2000.

Methods: A cohort of 86 patients was studied retrospectively. For final analysis, 74 patients undergoing 76 VATS procedures were included.

Results: Sixty-three procedures for primary spontaneous pneumothorax (PSP) and 13 procedures for secondary spontaneous pneumothorax (SSP) were performed. In 78.9% (n = 60) blebs or bullae were resected with an endostapler device. In 2.6% (n = 2) an apical fibrotic zone was resected. In 71.1% (n = 54) a subtotal pleurectomy was performed combined with an abrasion in 41 cases. In 21.1% (n = 16) a total pleurectomy and in 7.8% (n = 6) an abrasion was performed. Operative mortality was 1.3% (n = 1) and total operative morbidity 25.4% in the PSP group and 76.9% in the SSP group. Mean follow-up was 36 months. The global recurrence rate was 5.3% (n = 4), being 4.8% (n = 3) in the PSP group and 7.7% (n = 1) in the SSP group. Recurrences occurred at 1 (n = 2), 2 (n = 1) and 16 (n = 1) months after the initial operation. The incidence of postoperative neuralgia was 17.1% (n = 13). One patient needed analgesics for the neuralgia.

Conclusion: VATS treatment of spontaneous pneumothorax proves to be effective. In cases of SSP, VATS treatment is feasible but a higher morbidity rate should be anticipated.     

The role of mast cells in neuroinflammation

Mast cells (MCs) are densely granulated perivascular resident cells of hematopoietic origin and well known for their pathogenetic role in allergic and anaphylactic reactions. In addition, they are also involved in processes of innate and adaptive immunity. MCs can be activated in response to a wide range of stimuli, resulting in the release of not only pro-inflammatory, but also anti-inflammatory mediators. The patterns of secreted mediators depend upon the given stimuli and microenvironmental conditions, accordingly MCs have the ability to promote or attenuate inflammatory processes. Their presence in the central nervous system (CNS) has been recognized for more than a century. Since then a participation of MCs in various pathological processes in the CNS has been well documented. They can aggravate CNS damage in models of brain ischemia and hemorrhage, namely through increased blood–brain barrier damage, brain edema and hemorrhage formation and promotion of inflammatory responses to such events. In contrast, recent evidence suggests that MCs may have a protective role following traumatic brain injury by degrading pro-inflammatory cytokines via specific proteases. In neuroinflammatory diseases such as multiple sclerosis, the role of MCs seems to be ambiguous. MCs have been shown to be damaging, neuroprotective, or even dispensable, depending on the experimental protocols used. The role of MCs in the formation and progression of CNS tumors such as gliomas is complex and both positive and negative relationships between MC activity and tumor progression have been reported. In summary, MCs and their secreted mediators modulate inflammatory processes in multiple CNS pathologies and can thereby either contribute to neurological damage or confer neuroprotection. This review intends to give a concise overview of the regulatory roles of MCs in brain disease.     

The impact of circulation in a heart–lung machine on function and survival characteristics of red blood cells

Extracorporeal circulation is accompanied by changes in red blood cell morphology and structural integrity that affect cell function and survival, and thereby may contribute to the various side effects of heart–lung machine-assisted surgery. Our main objectives were to determine the effect of circulation of red blood cells in a stand-alone extracorporeal circuit on several parameters that are known to be affected by, as well as contribute to red blood cell aging. As a source of RBCs, we employed blood bank storage units of different ages. In order to assess the relevance of our in vitro observations for the characterization of extracorporal circulation technology, we compared these changes in those of patients undergoing extracorporeal circulation-assisted cardiac surgery. Our results show that circulation in a heart–lung machine is accompanied by changes in red blood cell volume, an increase in osmotic fragility, changes in deformability and aggregation behavior, and alterations in the exposure of phosphatidylserine and in microvesicle generation. RBCs from 1-week-old concentrates showed the highest similarities with the in vivo situation. These changes in key characteristics of the red blood cell aging process likely increase the susceptibility of red blood cells to the various mechanical, osmotic, and immunological stress conditions encountered during and after surgery in the patient’s circulation, and thereby contribute to the side effects of surgery. Thus, aging-related parameters in red blood cell structure and function provide a foundation for the validation and improvement of extracorporeal circulation technology.