Low ozone concentrations stimulate cytoskeletal organization, mitochondrial activity and nuclear transcription

Ozone therapy is a modestly invasive procedure based on the regeneration capabilities of low ozone concentrations and used in medicine as an alternative/adjuvant treatment for different diseases. However, the cellular mechanisms accounting for the positive effects of mild ozonization are still largely unexplored. To this aim, in the present study the effects of low ozone concentrations (1 to 20 µg O₃/mL O₂) on structural and functional cell features have been investigated in vitro by using morphological, morphometrical, cytochemical and immunocytochemical techniques at bright field, fluorescence and transmission electron microscopy. Cells exposed to pure O₂ or air served as controls. The results demonstrated that the effects of ozone administration are dependent on gas concentration, and the cytoskeletal organization, mitochondrial activity and nuclear transcription may be differently affected. This suggests that, to ensure effective and permanent metabolic cell activation, ozone treatments should take into account the cytological and cytokinetic features of the different tissues.

Internalized chitosan nanoparticles persist for long time in cultured cells

Chitosan-based nanoparticles (chiNPs) are considered to be potentially good carriers for the sustained intracellular delivery of specific molecules. However, scarce attention has been paid to the long-lasting permanence of these NPs in the intracellular milieu, as well as to their intracellular fate (i.e., distribution, interaction with cell organelles, and degradation) in the long term. In the present study, the presence and subcellular location of FITC-labelled chiNPs were monitored in HeLa cells up to 14 days post-administration using multicolorfluorescence confocal microscopy and diaminobenzidine photo-oxidation at transmission electron microscopy. The main result of the present study is the demonstration that internalized chiNPs persist inside the cell up to two weeks, occurring in both the cytoplasm and nucleus; accordingly, chiNPs are able to pass from mother to daughter cells through several mitotic cycles. The cells did not show increased mortality or structural damage up to 14 days after chiNP exposure.

Correlates of low testosterone in men with chronic spinal cord injury

Although high rates of serum testosterone deficiency have been reported in men with spinal cord injury (SCI), its determinants and attributes are not yet established. The aim of this study was to recognize, among putative determinants and attributes of androgen deficiency, those significantly associated to low testosterone after adjustment for confounders recognizable in men with chronic SCI. A biochemical androgen deficiency (total testosterone <300 ng/dL) was exhibited by 18 of 51 patients (35.3%). Significant correlates of testosterone levels were as follows: weekly leisure time physical activity (LTPA) explored by the LTPA Questionnaire for people with SCI, body mass index (BMI), homeostatic model assessment of insulin resistance (HOMA-IR), triglycerides and sexual symptoms, explored by the aging males' symptom (AMS) questionnaire. At the multiple linear regression analysis, among putative determinants of low testosterone, only weekly LTPA and BMI exhibited a significant association with testosterone levels, explaining 54.2 and 9.0% of testosterone variability respectively. At the linear regression models, among various putative attributes of androgen deficiency, only lower sexual desire and, at a lesser extent, higher HOMA-IR, exhibited significant associations with lower testosterone levels, after adjustment for BMI, age, comorbidities and weekly LTPA. In conclusion, poor LTPA, high BMI and low sexual desire are independent predictors of low testosterone in men with chronic SCI. This is relevant to clinical practice, as all these features are routinely assessed in rehabilitation settings for SCI. As poor LTPA and high BMI are modifiable life-style related risk factors, prospective studies could clarify whether life-style modification could increase the level of testosterone and improve the low sexual desire, relevant clinical attribute of low testosterone in men with SCI.

Tracing nanoparticles and photosensitizing molecules at transmission electron microscopy by diaminobenzidine photo-oxidation

During the last three decades, diaminobenzidine photo-oxidation has been applied in a variety of studies to correlate light and electron microscopy. Actually, when a fluorophore is excited by light, it can induce the oxidation of diaminobenzidine into an electron-dense osmiophilic product, which precipitates in close proximity to the fluorophore, thereby allowing its ultrastructural detection. This method has very recently been developed for two innovative applications: tracking the fate of fluorescently labeled nanoparticles in single cells, and detecting the subcellular location of photo-active molecules suitable for photodynamic therapy. These studies established that the cytochemical procedures exploiting diaminobenzidine photo-oxidation represent a reliable tool for detecting, inside the cells, with high sensitivity fluorescing molecules. These procedures are trustworthy even if the fluorescing molecules are present in very low amounts, either inside membrane-bounded organelles, or at the surface of the plasma membrane, or free in the cytosol. In particular, diaminobenzidine photo-oxidation allowed elucidating the mechanisms responsible for nanoparticles internalization in neuronal cells and for their escape from lysosomal degradation. As for the photo-active molecules, their subcellular distribution at the ultrastructural level provided direct evidence for the lethal multiorganelle photo-damage occurring after cell photo-sensitization. In addition, DAB photo-oxidized samples are suitable for the ultrastructural detection of organelle-specific molecules by post-embedding gold immunolabeling.

Simultaneous ultrastructural analysis of fluorochrome-photoconverted diaminobenzidine and gold immunolabelling in cultured cells

Diaminobenzidine photoconversion is a technique by which a fluorescent dye is transformed into a stably insoluble, brown, electrondense signal, thus enabling examination at both bright field light microscopy and transmission electron microscopy. In this work, a procedure is proposed for combining photoconversion and immunoelectron microscopy: in vitro cell cultures have been first submitted to photoconversion to analyse the intracellular fate of either fluorescent nanoparticles or photosensitizing molecules, then processed for transmission electron microscopy; different fixative solutions and embedding media have been used, and the ultrathin sections were finally submitted to post-embedding immunogold cytochemistry. Under all conditions the photoconversion reaction product and the target antigen were properly detected in the same section; Epon-embedded, osmicated samples required a pre-treatment with sodium metaperiodate to unmask the antigenic sites. This simple and reliable procedure exploits a single sample to simultaneously localise the photoconversion product and a variety of antigens allowing a specific identification of subcellular organelles at the ultrastructural level.

Absence of an independent association between serum uric acid and left ventricular mass in Caucasian hypertensive women and men

BACKGROUND AND AIM

Experimentally uric acid may induce cardiomyocyte growth and interstitial fibrosis of the heart. However, clinical studies exploring the relationship between serum uric acid (SUA) and left ventricular (LV) mass yielded conflicting results. The aim of our study was to evaluate the relationships between SUA and LV mass in a large group of Caucasian essential hypertensive subjects.

METHODS AND RESULTS

We enrolled 534 hypertensive patients free of cardiovascular complications and without severe renal insufficiency. In all subjects routine blood chemistry, including SUA determination, echocardiographic examination and 24 h ambulatory blood pressure (BP) monitoring were obtained. In the overall population we observed no significant correlation of SUA with LV mass indexed for height(2.7) (LVMH(2.7)) (r = 0.074). When the same relationship was analysed separately in men and women, we found a statistically significant correlation in female gender (r = 0.27; p < 0.001), but not in males (r = -0.042; p = NS). When we grouped the study population in sex-specific tertiles of SUA, an increase in LVMH(2.7) was observed in the highest tertiles in women (44.5 ± 15.6 vs 47.5 ± 16 vs 55.9 ± 22.2 g/m(2.7); p < 0.001), but not in men. The association between SUA and LVMH(2.7) in women lost statistical significance in multiple regression analyses, after adjustment for age, 24 h systolic BP, body mass index, serum creatinine and other potential confounders.

CONCLUSIONS

Our findings do not support an independent association between SUA and LV mass in Caucasian men and women with arterial hypertension.

Muscleblind-like1 undergoes ectopic relocation in the nuclei of skeletal muscles in myotonic dystrophy and sarcopenia

Muscleblind-like 1 (MBNL1) is an alternative splicing factor involved in postnatal development of skeletal muscles and heart in humans and mice, and its deregulation is known to be pivotal in the onset and development of myotonic dystrophy (DM). In fact, in DM patients this protein is ectopically sequestered into intranuclear foci, thus compromising the regulation of the alternative splicing of several genes. However, despite the numerous biochemical and molecular studies, scarce attention has been paid to the intranuclear location of MBNL1 outside the foci, although previous data demonstrated that in DM patients various splicing and cleavage factors undergo an abnormal intranuclear distribution suggestive of impaired RNA processing. Interestingly, these nuclear alterations strongly remind those observed in sarcopenia i.e., the loss of muscle mass and function which physiologically occurs during ageing. On this basis, in the present investigation the ultrastructural localization of MBNL1 was analyzed in the myonuclei of skeletal muscles from healthy and DM patients as well as from adult and old (sarcopenic) mice, in the attempt to elucidate possible changes in its distribution and amount. Our data demonstrate that in both dystrophic and sarcopenic muscles MBNL1 undergoes intranuclear relocation, accumulating in its usual functional sites but also ectopically moving to domains which are usually devoid of this protein in healthy adults. This accumulation/delocalization could contribute to hamper the functionality of the whole splicing machinery, leading to a lower nuclear metabolic activity and, consequently, to a less efficient protein synthesis. Moreover, the similar nuclear alterations found in DM and sarcopenia may account for the similar muscle tissue features (myofibre atrophy, fibre size variability and centrally located nuclei), and, in general, for the aging-reminiscent phenotype observed in DM patients.

Diaminobenzidine photoconversion is a suitable tool for tracking the intracellular location of fluorescently labelled nanoparticles at transmission electron microscopy

Chitosan-based nanoparticles (NPs) deserve particular attention as suitable drug carriers in the field of pharmaceutics, since they are able to protect the encapsulated drugs and/or improve their efficacy by making them able to cross biological barriers (such as the blood-brain barrier) and reach their intracellular target sites. Understanding the intracellular location of NPs is crucial for designing drug delivery strategies. In this study, fluorescently-labelled chitosan NPs were administered in vitro to a neuronal cell line, and diaminobenzidine (DAB) photoconversion was applied to correlate fluorescence and transmission electron microscopy to precisely describe the NPs intracellular fate. This technique allowed to demonstrate that chitosan NPs easily enter neuronal cells, predominantly by endocytosis; they were found both inside membrane-bounded vesicles and free in the cytosol, and were observed to accumulate around the cell nucleus.

Diaminobenzidine photoconversion is a suitable tool for tracking the intracellular location of fluorescently labelled nanoparticles at transmission electron microscopy

Chitosan-based nanoparticles (NPs) deserve particular attention as suitable drug carriers in the field of pharmaceutics, since they are able to protect the encapsulated drugs and/or improve their efficacy by making them able to cross biological barriers (such as the blood-brain barrier) and reach their intracellular target sites. Understanding the intracellular location of NPs is crucial for designing drug delivery strategies. In this study, fluorescently-labelled chitosan NPs were administered in vitro to a neuronal cell line, and diaminobenzidine (DAB) photoconversion was applied to correlate fluorescence and transmission electron microscopy to precisely describe the NPs intracellular fate. This technique allowed to demonstrate that chitosan NPs easily enter neuronal cells, predominantly by endocytosis; they were found both inside membrane-bounded vesicles and free in the cytosol, and were observed to accumulate around the cell nucleus.

Discrete foci containing RNase A are found in nucleoli of HeLa cells after aging in culture

We have studied by means of ultrastructural immunocytochemistry the localization of RNase A in nuclei of HeLa cells in control conditions and following cell ageing in culture. We have found that roundish, electron dense foci, which contain a significant amount of RNase A, can be detected within nucleoli of aged cells. These bodies also contain RNA and lack ribosomal S3 proteins, and may represent either simple storage sites or areas where RNA degradation takes place.

Relationships between metabolic syndrome and left ventricular mass in hypertensive patients: does sex matter?

Several studies documented an association between metabolic syndrome (MetS) and left ventricular (LV) hypertrophy. However, only in a few of these studies the impact of MetS on left ventricular mass (LVM) was separately analysed by gender, with conflicting results. The aim of our study was to verify, in a wide sample of essential hypertensive patients, the influence of gender, if any, on the relationship between MetS and LVM. We enrolled 475 non-diabetic subjects (mean age: 46 +/- 11 years), with mild-to-moderate essential hypertension, of whom 40% had MetS, defined on the basis of Adult Treatment Panel III (ATPIII) criteria. All the patients underwent a 24-h ambulatory blood pressure monitoring and an echocardiogram. LVM indexed for height (2.7) (LVMH (2.7)) was significantly (P < 0.001) higher in women with MetS (n=83) than in those without it (n=97; 54+/-17 vs 42+/-11 g m(-2.7)). An equally significant difference in LVMH (2.7) was documented also in male gender between the two groups with (n=105) and without MetS (n=190; 51+/-14 vs 43+/-11 g m(-2.7); P < 0.001). The relationship between MetS and LVMH (2.7) remained statistically significant (P < 0.001) in both sexes, in multiple regression analyses, even after adjustment for potential confounding factors. Our results seem to suggest that the relationship between MetS and LVM is not significantly affected by gender, being LVM increased in both hypertensive women and men with MetS.

Bone regeneration: in vitro evaluation of the behaviour of osteoblast-like MG63 cells placed in contact with polylactic-co-glycolic acid, deproteinized bovine bone and demineralized freeze-dried bone allograft

Insufficient bone density of the alveolar crests, caused by loss of the dental elements, sometimes impedes the primary stability of an integrated bone implant. The techniques of bone regeneration allow to obtain a sufficient quantity of alveolar bone to permit the implant rehabilitation of the edentulous crests. Today several grafting materials are available and they have different characteristics, according to their structure, which influence the different behaviour of the grafting materials to the bone and the implant surface. The aim of this study is to evaluate the interaction between a human osteosarcoma MG63 cell line and three different biomaterials: polylactic-co-glycolic acid (PLAGA), deproteinized bovine bone and demineralised freeze-dried bone allograft (DFDBA). From this study a different behaviour emerges of the osteoblast-like MG63 cells in relation to the sublayer on which these cells were placed in culture. The results of the study, in fact, demonstrate that the most osteoconductive material of the three analysed is the DFDBA, followed by DPBB. On the contrary, the PLGA, because of its roughness, does not seem to represent a valid support for cell growth, and does not encourage any morphologic modification in tumor cells. Furthermore, deproteinized bovine bone shows a differentiating effect which could lead to hypothesise an osteoconductive capacity of this biomaterial. Further studies should be carried out with the aim of explaining the results obtained.

Inverse relationship between ambulatory arterial stiffness index and glomerular filtration rate in arterial hypertension

BACKGROUND

Arterial stiffness and mild-to-moderate renal dysfunction are predictors of cardiovascular (CV) morbidity and mortality. Recently, the ambulatory arterial stiffness index (AASI) has been proposed as a surrogate index of arterial stiffness. It has been associated with an enhanced risk of stroke. The aim of our study was to assess the relationship between AASI and glomerular filtration rate (GFR) in a group of hypertensive patients with no CV complications.

METHODS

A total of 143 untreated hypertensive subjects (mean age: 44 +/- 12 years; men 57%), with serum creatinine <1.5 mg/dl, were enrolled. AASI was calculated as one minus the regression slope of diastolic on systolic blood pressure (BP) obtained by individual 24-h BP recordings. GFR was computed from the scintigraphic determination of the technetium-99m diethylenetriaminepentaacetic acid uptake within the kidneys, by the Gates' method.

RESULTS

Hypertensive patients with AASI above the median value (n = 71) had lower GFR than those with AASI below the median (n = 72) (98.3 +/- 31 vs. 122.4 +/- 32 ml/min/1.73 m(2); P < 0.001). This difference held even after adjustment for age and gender. The linear regression analysis disclosed a significant inverse correlation between GFR and AASI (r = -0.30; P < 0.001), that was replicated (beta = -0.19; P = 0.02) in a multiple regression model including, as independent variables (besides AASI), age, gender, high-density lipoprotein cholesterol, body mass index, 24-h pulse pressure (PP) and nocturnal reduction in BP.

CONCLUSIONS

AASI is inversely related to GFR in arterial hypertension. This may help to explain the increased CV risk associated with mild-to-moderate renal dysfunction.