Correlation of dynamic membrane fluctuations in red blood cells with diabetes mellitus and cardiovascular risks

Membrane fluctuations of human red blood cells investigated by the current signal noise in scanning ion conductance microscopy

Human red blood cells show submicron membrane fluctuations (CMFs) that have been mainly studied with optical microscopies. Although the functional role of this phenomenon is still uncertain, the amplitude of membrane fluctuations is considered as an indicator of mechanical resilience to the stress encountered in the capillary beds. We investigate here the membrane fluctuations in red blood cells using the scanning ion conductance microscopy (SICM), a scanning probe technique that avoids the probe-sample contact. The ion current noise was recorded at a fixed distance from the cell and converted in terms of membrane fluctuation amplitude using as a converting factor the slope of the current-distance curve. We found that CMF amplitude was irreversibly reduced by membrane cross-link. Both whole cell and local increase of membrane tension induced a reduction of CMF amplitude. As for the biochemical regulation of membrane dynamics, we observed that the activation of the noradrenergic transduction pathway, via β-receptors, increased the CMF amplitude. We conclude that the CMFs recorded by SICM and those optically recorded on red blood cells share the main features. In addition SICM provides high spatial and temporal resolution as well as the possibility to apply through the glass pipette acting as probe chemical or physical stimuli to the membrane area where the CMFs are recorded.

Dysregulated CREB3 cleavage at the nuclear membrane induces karyoptosis-mediated cell death

Cancer cells often exhibit resistance to apoptotic cell death, but they may be vulnerable to other types of cell death. Elucidating additional mechanisms that govern cancer cell death is crucial for developing new therapies. Our research identified cyclic AMP-responsive element-binding protein 3 (CREB3) as a crucial regulator and initiator of a unique cell death mechanism known as karyoptosis. This process is characterized by nuclear shrinkage, deformation, and the loss of nuclear components following nuclear membrane rupture. We found that the N-terminal domain (aa 1-230) of full-length CREB3 (CREB3-FL), which is anchored to the nuclear inner membrane (INM), interacts with lamins and chromatin DNA. This interaction maintains a balance between the outward force exerted by tightly packed DNA and the inward constraining force, thereby preserving INM integrity. Under endoplasmic reticulum (ER) stress, aberrant cleavage of CREB3-FL at the INM leads to abnormal accumulation of the cleaved form of CREB3 (CREB3-CF). This accumulation disrupts the attachment of CREB3-FL to the INM, resulting in sudden rupture of the nuclear membrane and the onset of karyoptosis. Proteomic studies revealed that CREB3-CF overexpression induces a DNA damage response akin to that caused by UVB irradiation, which is associated with cellular senescence in cancer cells. These findings demonstrated that the dysregulation of CREB3-FL cleavage is a key factor in karyoptotic cell death. Consequently, these findings suggest new therapeutic strategies in cancer treatment that exploit the process of karyoptosis.

Nailfold video-capillaroscopy in the study of cardiovascular disease: a systematic review

OBJECTIVES

Nailfold video-capillaroscopy (NVC) is an inexpensive method of assessing microcirculation. We reviewed the literature to assess whether changes to the nailfold capillaries exist in patients with cardiovascular disease (CVD).

METHODS

We searched PubMed, Scopus and Cochrane Library databases for original research articles relating to the use of noninvasive microvascular assessment in patients with CVD. Methodological quality was assessed with the 'Quality Assessment Tool for Observational Cohort and Cross-sectional Studies.' The results obtained from NVC were analysed qualitatively and compared with other forms of microvascular assessment.

RESULTS

In total 2759 articles were screened, of which 22 studies involving 562 patients (~40% women) with CVD were included. Mean age ranged between 3.7-68.4 years (cases) and 4.0-58.0 years (controls). Reduced capillary density and increased capillary dimensions were seen in patients with pulmonary arterial hypertension (PAH). Among patients with systemic sclerosis, advanced scleroderma patterns can be used to identify patients with or at risk of developing PAH. Functional nailfold changes precede structural changes in patients with hypertension. However, the studies were heterogeneous in the diagnosis of disease and the measurement of nailfold parameters. Most studies did not exclude conditions with altered nailfold features, and only one study performed a power calculation. Furthermore, abnormal nailfold findings are present in patients without systemic disease.

CONCLUSIONS

Structural and functional changes to the nailfold are a feature of established CVD and precede the development of PAH. However, heterogeneity in measurement and abnormal findings in healthy participants limit their use in the wider population.

High hemoglobin fluctuation was a protective factor for cardiovascular-related death in peritoneal dialysis (PD) patients: A retrospective analysis of 232 patients with PD

Objectives

This study aimed to investigate the effect of hemoglobin (Hb) fluctuation after dialysis on the prognosis of cardiovascular‐related and all‐cause deaths in peritoneal dialysis (PD).

Methods

According to the Hb fluctuation, patients were divided into low fluctuation group, moderate fluctuation group, and high fluctuation group, and then, the effects of Hb fluctuation after dialysis on the prognosis of cardiovascular‐related and all‐cause death in PD were analyzed by regression analysis.

Results

A total of 232 patients were selected in this study. Compared with the low Hb fluctuation group, the moderate and high fluctuation groups had lower body mass index (BMI), estimated glomerular filtration rate (eGFR), and baseline Hb, and the moderate fluctuation group had less erythropoietin (EPO) and dialysis dose. Compared with survivors, patients with cardiovascular‐related and all‐cause deaths had lower mean Hb and Hb fluctuation (all p < 0.05). Cox regression analysis showed that before and after adjusting for confounding factors, Hb fluctuation was still independently correlated with cardiovascular prognosis, and higher Hb fluctuation was still a protective factor for cardiovascular‐related death in the Hb‐substandard group, but there was no significant correlation between Hb fluctuation and all‐cause death. Multivariate linear regression analysis revealed that Hb fluctuation was positively correlated with Kt/V and EPO dosage, but negatively correlated with the baseline Hb.

Conclusion

High Hb fluctuation was a protective factor for cardiovascular‐related death in PD with substandard Hb. Compared with Hb fluctuation, correction of anemia timely and making Hb reaches the standard level had a greater impact on reducing cardiovascular‐related death in PD.