Dyslipidemia and heart failure: current evidence and perspectives of use of statins

Heart failure (HF) is a condition with growing morbidity and mortality. Dyslipidemia in HF is not concentrated around hypercholesterolemia as in coronary artery disease. As a corollary, the robust benefits seen with statins across the spectrum of CAD have not been replicated in HF. Multiple potential pleiotropic effects of statins include anti-inflammatory, antioxidant, endothelial stabilization, antiapoptotic, anti-thrombotic, and modulation of the autonomic system apart from lipid lowering. These benevolent actions need to be counterbalanced with the potential derangement of ubiquinone, selenoprotein and endotoxin pathways. While small randomized and non-randomized studies demonstrated a multitude of benefits in clinical and surrogate endpoints, two large RCTs failed to demonstrate unequivocal benefits. However, multiple large meta-analyses do demonstrate definite improvement in clinical endpoints including death and heart failure hospitalization. The clinical likelihood of benefit was higher in younger patients with less advanced HF and use of lipophilic statins.

Role of nutrients in modulating microbiota and immunity in COVID-19 disease

COVID-19 is a novel disease with a broad range of clinical patterns. Several patients show dysbiosis in the intestinal tract, with evidence of reduced beneficial bacteria, such as Bifidobacteria and Lactobacilli. It is well established that human gut microbiota dysbiosis is associated with several clinical conditions, including respiratory tract diseases due to the gut-lung axis. This narrative review discusses the role of nutrients in the relationship between the gut microbiota and the immune response in SARS-CoV-2 infection. In particular, we will focus on the benefits offered by vitamins and micronutrients on different aspects of COVID-19 disease while also discussing which diets seem to provide the most advantages.

The role of MTHFR polymorphisms in the risk of lipedema

OBJECTIVE

This study examines the role of MTHFR gene polymorphism (rs1801133) in women with lipedema (LIPPY) body composition parameters compared to a control group (CTRL).

SUBJECTS AND METHODS

We carried out a study on a sample of 45 LIPPY and 50 women as a CTRL. Body composition parameters were examined by Dual-energy X-ray Absorptiometry (DXA). A genetic test was performed for the MTHFR polymorphism (rs1801133, 677C>T) using a saliva sample for LIPPY and CTRL groups. Mann-Whitney tests evaluated statistically significant differences between four groups (carriers and non-carriers of the MTHFR polymorphism for LIPPY and CTRL groups) on anthropometric/body composition parameters to identify patterns.

RESULTS

LIPPY showed significantly higher (p<0.05) anthropometric parameters (weight, BMI, waist, abdominal, hip circumferences) and lower waist/hip ratio (p<0.05) compared to the CTRL group. The association between the polymorphism alleles related to the rs1801133 MTHFR gene and the body composition values LIPPY carriers (+) showed an increase in fat tissue of legs and fat region of legs percentage, arm's fat mass (g), leg's fat mass (g), and leg's lean mass (g) (p<0.05) compared to CTRL (+). Lean/fat arms and lean/fat legs were lower (p<0.05) in LIPPY (+) than in CTRL (+). In the LIPPY (+), the risk of developing the lipedema disease was 2.85 times higher (OR=2.85; p<0.05; 95% confidence interval = 0.842-8.625) with respect to LIPPY (-) and CTRL.

CONCLUSIONS

The presence or absence of MTHFR polymorphism offers predictive parameters that could better characterize women with lipedema based on the association between body composition and MTHFR presence.

Drag Reduction in Turbulent Wall-Bounded Flows of Realistic Polymer Solutions

Suspensions of DNA macromolecules (0.8 wppm, 60 kbp), modeled as finitely extensible nonlinear elastic dumbbells coupled to the Newtonian fluid, show drag reduction up to 27% at friction Reynolds number 180, saturating at the previously unachieved Weissenberg number ≃10^{4}. At a large Weissenberg number, the drag reduction is entirely induced by the fully stretched polymers, as confirmed by the extensional viscosity field. The polymer extension is strongly non-Gaussian, in contrast to the assumptions of classical viscoelastic models.

Social inequalities and nutritional disparities: the link between obesity and COVID-19

OBJECTIVE

Cohort studies, clinical audits of patients with COVID-19 in hospital and routine primary care records provided evidence-based insights on the relationship between excess weigh, obesity and COVID-19. The purpose of this umbrella review is to highlight the relationship between nutritional quality and social inequalities related to CDNCD, obesity and SARS-CoV-2 infection.

MATERIALS AND METHODS

Only articles published from 2008 to the present were included in the search to show an updated picture of the topic. The search for published studies was conducted in February 2021 in the scientific databases PubMed (MEDLINE). The terms used for the search were "COVID-19", "Obesity", "Disparities", "Nutritional inequalities", "Chronic degenerative non-communicable diseases" and "review" OR "systematic review" OR "meta-analysis" separated by the Boolean operator AND.

RESULTS

1874 reviews were found, but only 99 met the objective. Obese or dysmetabolic patients are those who had a worse course of disease following COVID-19. This data was observed not only for Chinese and Caucasians, but also and above all among Africans, African Americans, Latinos and indigenous people. Plausible mechanisms to explain the association between obesity and COVID-19 outcomes, included the role of excess adipose tissue on respiratory function, metabolic dysfunction, the cardiovascular system, enhanced inflammatory response and impaired response to infection.

CONCLUSIONS

Today, chronic non-communicable degenerative diseases (CDNCDs) are responsible for 70% of public health expenditure, affecting 30% of the population (one or more chronic diseases). Unfortunately, given the health emergency due to SARS-CoV-2, infectious diseases are currently more at the center of attention. However, the spread of infectious communicable diseases and CDNCDs is facilitated in situations of social disparity. In fact, in the poorest countries there are the highest rates of malnutrition and there is a greater risk of contracting viral infections, as well as, paradoxically, a risk of comorbidity, due to access to cheaper food and qualitatively poor, with high caloric density.

Obesity, bariatric surgery and periodontal disease: a literature update

Obesity is linked to other systemic diseases, such as diabetes mellitus, dyslipidemia, and arterial hypertension. These comorbidities increase the risk of developing cardiovascular disease risk. Adipose tissue is a true endocrine organ and releases various pro-inflammatory cytokines. Periodontal disease (PD) is a chronic inflammatory disorder of the gingiva and bone support (periodontal tissues) that surrounds the teeth. The relationship between obesity and an increased risk of developing PD is already known in the literature. Many studies correlated the cardiometabolic risk with periodontal disease. Bariatric surgery is a way to reduce the adipose tissue in obese patients, that meet specific criteria. It has been observed that this type of surgery usually reduces both the systemic inflammation and the cardiometabolic risk. Some authors have hypothesized that, as a result, the progression of periodontal disease is also reduced. Five articles are analyzed in this systematic review. In these papers, the periodontal health before and after the bariatric surgery was compared. However, the conclusion of the previous studies demonstrated a scarce literature and did not confirm the reduction of periodontal disease after bariatric surgery, but a reduction of cardiometabolic risk. Therefore, periodontal disease in no way influences the reduction of cardiovascular risk after bariatric surgery.

FTO rs9939609 influence on adipose tissue localization in the Italian population

OBJECTIVE

Among the genes involved in obesity, the Fat mass and obesity-associated gene (FTO) is certainly one of the most known and the relation between FTO rs9939609 and BMI is highly discussed; nevertheless, data about its influence on body composition are limited.

MATERIALS AND METHODS

We carried out a study on a sample of 1066 Italian subjects, whose body composition and FTO rs9939609 were analyzed.

RESULTS

We found significant relations between FTO with arm (p=0.01), abdomen (p=0.00), and trunk circumferences (p=0.00), BMI (p=0.01), FM% (p=0.00), and android FM% (p=0.01), whereas no relations were found between FTO and both gynoid fat and lean mass.

CONCLUSIONS

To conclude, the relation between FTO and BMI is confirmed and is related specifically with android FM%. These results indicated that FTO rs9939609 may be a genetic etiological factor for obesity. Indeed, the specificity for the android FM% would indicate FTO as an etiological factor in the development of cardiovascular diseases.

The role of IL-6 gene polymorphisms in the risk of lipedema

OBJECTIVE

Lipedema is a disorder of adipose tissue characterized by abnormal subcutaneous fat deposition, leading to swelling and enlargement of the lower limbs and trunk. The aim of this study was to evaluate the lipedema phenotype by investigating the role of polymorphisms related to IL-6 (rs1800795) gene in people with diagnosis of lipedema. The second aim was to identify indicators of body composition, useful for a differential analysis between subjects with lipedema and the control group.

PATIENTS AND METHODS

Two groups are involved in the study, 45 women with lipedema (LIPPY) and 50 women randomly chosen from the population as Control (CTRL). Clinical and demographical variables recorded include weight, height, body mass index (BMI) and circumference measurements. Body composition (Fat mass, FM; lean mass, LM) was assessed by Dual-energy X-ray Absorptiometry (DXA). The genetic tests for IL-6 (rs18oo795) gene were performed for both groups, using a saliva sample.

RESULTS

The study of the relationship between the IL-6 (rs1800795) gene polymorphism, the anthropometric values and the body composition indices has provided the following significant results: subjects with diagnosis of lipedema present statistically significant increased values with regard to weight, BMI, waist, abdomen and hip circumferences, arms, legs and whole FM (% and kg), gynoid FM (kg), legs LM (kg) and ASMMI. Moreover, the value of the waist hip ratio was found to be decreased.

CONCLUSIONS

For the first time, we suggested that IL-6 gene polymorphism could characterize subjects with lipedema respect to Normal Weight Obese and obese subjects. The intra-group comparisons (LIPPY carriers vs. LIPPY non-carriers and CTRL carriers vs. CTRL non-carriers) showed no statistically significant values. In contrast, the inter-group comparisons (LIPPY non-carriers vs. CTRL non-carriers and LIPPY carriers vs. CTRL carriers) resulted statistically significant. We have identified other indices, such as leg index, trunk index, abdominal index, total index, that could be promising clinical tools for diagnosis of the lipedema phenotype and for predicting the evolution of the disease.

The Fluid-Dynamics of Endo Vascular Aneurysm Sealing (EVAS) System failure

Purpose

The main objective of this work is to investigate hemodynamics phenomena occurring in EVAS (Endo Vascular Aneurysm Sealing), to understand if and how they could lead to type 1a endoleaks and following re-intervention. To this aim, methods based on computational fluid mechanics are implemented as a tool for checking the behavior of a specific EVAS configuration, starting from the post-operative conditions. Pressure and velocity fields are detailed and compared, for two configurations of the Nellix, one as attained after correct implantation and the other in pathological conditions, as a consequence of migration or dislocation of endobags.

Methods

The computational fluid dynamics (CFD) approach is used to simulate the behavior of blood within a segment of the aorta, before and after the abdominal bifurcation. The adopted procedure allows reconstructing the detailed vascular geometry from high-resolution computerized tomography (CT scan) and generating the mesh on which the equations of fluid mechanics are discretized and solved, in order to derive pressure and velocity field during heartbeats.

Results

The main results are obtained in terms of local velocity fields and wall pressures. Within the endobags, velocities are usually quite regular during the whole cardiac cycle for the post-implanted condition, whereas they are more irregular for the migrated case. The largest differences among the two cases are observed in the shape and location of the recirculation region in the rear part of the aorta and the region between the endobags, with the formation of a gap due to the migration of one or both of the two. In this gap, the pressure fields are highly different among the two conditions, showing pressure peaks and pressure gradients at least four times larger for the migrated case in comparison to the post-implanted condition.

Conclusions

In this paper, the migration of one or both endobags is supposed to be related to the existing differential pressures acting in the gap formed between the two, which could go on pushing the two branches one away from the other, thus causing aneurysm re-activation and endoleaks. Regions of flow recirculation and low-pressure drops are revealed only in case of endobag migration and in presence of an aneurysm. These regions are supposed to lead to possible plaque formation and atherosclerosis.

Developing and cross-validation of new equations to estimate fat mass in Italian population

OBJECTIVE

Obesity is a global burden that involves more than 500 million people. The objective of this work is to develop and cross-validate the new sex-specific equations to estimate fat mass, based on anthropometric parameters and to compare with other equations.

PATIENTS AND METHODS

We evaluated 38762 subjects by dual-energy X-ray absorptiometry (DXA) and enrolled 1434 women and 640 men, aged between 18 and 65 years. Then, we randomized 480 men and 1080 women in developing set and 160 men and 354 women in the cross-validation set. Statistical analysis as multiple regression and Bland-Altman methods were performed.

RESULTS

Sex-specific equations were created based on developing set. Then, based on the cross-validating set, these equations were validated and were observed to agree with fat mass by DXA, better than other equations, such as BAI and RFM.

CONCLUSIONS

These new sex-specific equations represent an easy tool, since they require only two circumferences, to be used in clinical practice. In the next future, these equations could be validated and refine on specific Italian sub-populations, divided by gender and age, such as the military.

Dental agenesis and evaluation of body composition through bioelectrical impedance analysis. Observational study on a sample of paediatric subjects

AIM

The aim of the present study was to evaluate the anthropometric parameters and the body composition through bioelectrical impedance analysis on paediatric subjects with dental agenesis.

MATERIALS AND METHODS

The study was conducted on 144 subjects (58.3% females and 41.7% males), aged 7-14 years (average age 10.22±2.53 years). Each patient underwent a dental check-up at the Paediatric Dentistry Unit, University of Rome Tor Vergata (Italy) and a nutritional evaluation, aimed at analysing the anthropometric characteristics and evaluating the indices of body composition through bioelectrical impedance analysis (BIA) at the Human Nutrition Unit, University of Rome Tor Vergata. The sample was divided into three groups: a group with single agenesis (Group 1), a group with multiple agenesis (Group 2) and a control group (Group A). Using the predictive equations, the following values were evaluated: resistance (R), reactance (Xc), phase angle (PHA), body cell mass index (BCMI), body cell mass (BCM), total body water (TBW), intracellular water (ICW), extracellular water (ECW), fat mass (FM), fat free mass (FFM).

STATISTICS

The Excel environment and the SAS System, version 9.3, were used for statistical analysis, providing a descriptive and parametric analysis of the sample. The values of the anthropometric parameters were expressed as mean ± standard deviation. For the statistical analysis of anthropometric parameters and body composition, analysis of variance (1-way ANOVA) was used, which allowed us to find differences and the Student's t-test to compare Groups 1, 2, and A.

RESULTS

There is a significant difference in the resistance R value between the case group with single agenesis (Group 1) and the control group (Group A) (R, 710.28±72.46 vs 667.4±104.16, p=0.028), and the phase angle PHA between the case group with multiple agenesis (Group 2) and the control group (Group A) (PHA, 5.18±0.48 vs 5.85±1.05, p=0.028). The BCM% value shows a significant difference between both Group 1 and Group A (BCM%, 50.53 ± 3.29 vs 52.68 ± 4.74, p=0.016) and between Group 2 and Group A (BCM%, 49.25± 2.86 vs 52.68 ± 4.74, p=0.035). The TBW, ICW, ECW, FM, FFM values showed no significant differences between the various groups analysed.

CONCLUSION

Body composition in subjects with dental agenesis presents a higher R, a consequently lower PHA and a lower BCM% compared to the control group. For the first time, the results highlighted the possible relationship between dental agenesis and body composition, measured through BIA.

Lean body mass: reference values for Italian population between 18 to 88 years old

OBJECTIVE

Body's lean mass compartment is a strong predictor of morbidity and mortality risk in various clinical conditions. This paper proposes a simple and easily applied reference table for lean body mass (LBM) and lean body mass index (LBMI) for the Italian population.

PATIENTS AND METHODS

Retrospective analysis of a database containing anthropometric and DXA body composition measurements obtained from a cross-sectional study conducted between 2002 and 2009 with Italian individuals. Parametric and nonparametric tests were performed using R 3.1.1 and SPSS 22.0 software packages.

RESULTS

The 3712 study participants, 37.3% men and 62.7% women, aging from 18 to 88 years. Individuals with normal weight, overweight and obesity were evenly distributed in the sample. LBM and LBMI measures were significantly higher in males. In both genders, there was a significant and progressive decline in these measures associated with aging. Significant differences in LBMI between genders were found in all age groups except for individuals over 75 years.

CONCLUSIONS

Based on the participants LBM profile, a reference table for LBM values was proposed. This reference will be useful to detect changes in the LBM compartment of individuals from the South Central Region of Italy, supporting health professionals during the process of diagnosing sarcopenia.

Exact regularized point particle (ERPP) method for particle-laden wall-bounded flows in the two-way coupling regime

The Exact Regularized Point Particle (ERPP) method is extended to treat the interphase momentum coupling between particles and fluid in the presence of walls by accounting for the vorticity generation due to the particles close to solid boundaries. The ERPP method overcomes the limitations of other methods by allowing the simulation of an extensive parameter space (Stokes number, mass loading, particle-to-fluid density ratio and Reynolds number) and of particle spatial distributions that are uneven (few particles per computational cell). The enhanced ERPP method is explained in detail and validated by considering the global impulse balance. In conditions when particles are located close to the wall, a common scenario in wall-bounded turbulent flows, the main contribution to the total impulse arises from the particle-induced vorticity at the solid boundary. The method is applied to direct numerical simulations of particle-laden turbulent pipe flow in the two-way coupling regime to address the turbulence modulation. The effects of the mass loading, the Stokes number and the particle-to-fluid density ratio are investigated. The drag is either unaltered or increased by the particles with respect to the uncoupled case. No drag reduction is found in the parameter space considered. The momentum stress budget, which includes an extra stress contribution by the particles, provides the rationale behind the drag behaviour. The extra stress produces a momentum flux towards the wall that strongly modifies the viscous stress, the culprit of drag at solid boundaries.

Efficacy and safety of very-low-calorie ketogenic diet: a double blind randomized crossover study

OBJECTIVE

To verify safety respect to weight loss, cardiometabolic diseases of short-term Very low-calorie ketogenic diets (VLCKDs, <800 kcal day-1).

PATIENTS AND METHODS

Randomized cross-over trial with placebo. The study had no. 2 dietary treatment (DT), conducted in two arms: (1) VLCKD1 in which 50% of protein intake is replaced with synthetic amino acids; (2) VLCKD2 with placebo. The VLCKDs (<800 kcal day-1) were different in term of protein content and quality each arm lasted three weeks (wks). Between the two arms a 3-wks washout period was performed to avoid additive effects on DT to follow. At the baseline, at start and end of each arm, all the subjects were evaluated for their health and nutritional status, by anthropometric analysis, body composition (Dual X-ray Absorptiometry (DXA), Bioimpedentiometry, biochemical evaluation, and Peroxisome Proliferator-Activated Receptor γ (PPAR) γ expression by transcriptomic analysis.

RESULTS

After VLCKD1 were reduced: Body Mass Index (BMI) (Δ%=-11.1%, p=0.00), Total Body Water (TBW) (p<0.05); Android Fat Percentage (AFP) (Δ%=-1.8%, p=0.02); Android Fat Mass (AFM) (Δ%=-12.7%, p=0.00); Gynoid Fat Mass (GFM) (Δ%=-6.3%, p=0.01); Intermuscular Adipose Tissue (IMAT) (Δ%= -11.1%, p=0.00); Homeostasis Model Assessment of Insulin Re-sistance (HOMA-IR) (Δ%=-62.1%, p=0.01). After VLCKD1 a significant increase of uricemia, cre-atinine and aspartate aminotransferase (AST) (respectively Δ%=35%, p=0.01; Δ%=5.9%, p=0.02; Δ%=25.5%, p=0.03). After VLCKD2 were reduced: BMI (Δ%=-11.2%, p=0.00); AFM (Δ%=-14.3%, p=0.00); GFM (Δ%=-6.3%, p=0.00); Appendicular Skeletal Muscle Mass Index (ASMMI) (Δ%=-17.5%, p=0.00); HOMA-IR (Δ%=-59,4%, p=0.02). After VLCKD2, uricemia (Δ%=63.1%, p=0.03), and Vitamin D levels (Δ%=25.7%, p=0.02) were increased. No significant changes of car-diovascular disease (CVD) indexes were observed after DTs. No significant changes of PPARγ lev-el in any DTs.

CONCLUSIONS

21-days VLCKDs not impair nutritional state; not cause negative changes in global measurements of nutritional state including sarcopenia, bone mineral content, hepatic, renal and lipid profile.

Post-prandial effects of hazelnut-enriched high fat meal on LDL oxidative status, oxidative and inflammatory gene expression of healthy subjects: a randomized trial

OBJECTIVE

Postprandial oxidative stress is characterized by an increased susceptibility of the organism towards oxidative damage after consumption of a meal rich in lipids and/or carbohydrates. Micronutrients modulate the immune system and exert a protective action by reducing low-density lipoproteins oxidation (ox-LDL) via induction of antioxidant enzymes.

SUBJECTS AND METHODS

The clinical study was a randomized and cross-over trial, conducted through the CONSORT flowchart. We evaluated the gene expression of 103 genes related to oxidative stress (HOSp) and human inflammasome pathways (HIp), and ox-LDL level at fasting and after 40 g raw "Tonda Gentile delle Langhe" hazelnut consumption, in association with a McDonald's® Meal (McDM) in 22 healthy human volunteers.

RESULTS

Ox-LDL levels significantly increased comparing no dietary treatment (NDT) vs. McDM, and decreased comparing McDM vs. McDM + H (p<0.05). Percentage of significant genes expressed after each dietary treatment were the follows: (A) NDT vs. McDM: 3.88% HIp and 17.48% HOSp; (B) NDT vs. McDM + H: 17.48% HIp and 23.30% HOSp; (C) McDM vs. McDM + H: 17.48% HIp and 33.98% HOSp.

CONCLUSIONS

Hazelnut consumption reduced post prandial risk factors of atherosclerosis, such as ox-LDL, and the expression of inflammation and oxidative stress related genes. Chronic studies on larger population are necessary before definitive conclusions.

Very-low-calorie ketogenic diet with aminoacid supplement versus very low restricted-calorie diet for preserving muscle mass during weight loss: a pilot double-blind study

OBJECTIVE

Obesity plays a relevant pathophysiological role in the development of health problems, arising as result of complex interaction of genetic, nutritional and metabolic factors. We conducted a dietary intervention case-control randomized trial, to compare the effectiveness on body composition of two nutritional protocols: a very-low-carbohydrate ketogenic diet (VLCKD), integrated by an aminoacid supplement with whey protein, and very low restricted-calorie diet (VLCD).

PATIENTS AND METHODS

The clinical study was conducted with a randomized case-control in which twenty-five healthy subjects gave informed consent to participate in the interventional study and were evaluated for their health and nutritional status, by anthropometric, and body composition evaluation.

RESULTS

The results of this pilot study show that a diet low in carbohydrates, associated with a decreased caloric intake, is effective in weight loss. After VLCKD, versus VLCD, no significant differences in body lean of the trunk, body lean distribution (android and gynoid), total body lean were observed (p > 0.05). After VLCKD, no increasing of sarcopenia frequency, according ASSMI, was observed.

DISCUSSION

Many studies have shown the effectiveness of the ketogenic diet on weight loss; even if not know how to work effectively, as some researchers believe that the weight loss is due to reduced calorie intake, satiety could also be induced by the effect of the proteins, rather than the low-carbohydrates.

CONCLUSIONS

Our pilot study showed that a VLCKD was highly effective in terms of body weight reduction without to induce lean body mass loss, preventing the risk of sarcopenia. Further clinical trials are needed on a larger population and long-term body weight maintenance and risk factors management effects of VLCKD. There is no doubt, however, that a proper dietary approach would impact significantly on the reduction of public expenditure costs, in view of prospective data on increasing the percentage of obese people in our nation.

Scaling properties in the production range of shear dominated flows

In large Reynolds number turbulence, isotropy is recovered as the scale is reduced and homogeneous-isotropic scalings are eventually observed. This picture is violated in many cases, e.g., wall bounded flows, where, due to the shear, different scaling laws emerge. This effect has been ascribed to the contamination of the inertial range by the larger anisotropic scales. The issue is addressed here by analyzing both numerical and experimental data for a homogeneous shear flow. In fact, under strong shear, the alteration of the scaling exponents is not induced by the contamination from the anisotropic sectors. Actually, the exponents are universal properties of the isotropic component of the structure functions of shear dominated flows. The implications are discussed in the context of turbulence near solid walls, where improved closure models would be advisable.

Double scaling and intermittency in shear dominated flows

The nature of intermittency in shear dominated flows changes with respect to homogeneous and isotropic conditions since the process of energy transfer is affected by the turbulent kinetic energy production associated with the Reynolds stresses. For these flows, a new form of refined similarity law is able to describe the increased level of intermittency. Ideally a length scale associated with the mean shear separates the two ranges, i.e., the classical Kolmogorov-like inertial range, below, and the shear dominated range, above. In the present paper we give evidence of the coexistence of the two regimes and we support the conjecture that the statistical properties of the dissipation field are practically insensible to the mean shear. This allows for a theoretical prediction of the scaling exponents of structure functions in the shear dominated range based on the known intermittency corrections for isotropic flows. The prediction is found to closely match the available numerical and experimental data. The analysis shows that the larger anisotropic scales of shear turbulence display universality, and determines the modality by which the dissipation field fixes the properties of turbulent fluctuations in the shear dominated range.

Morphology of photoreceptor systems in microalgae

The polyphyletic artificial assemblage of O(2)-evolving, photosynthetic organisms, collectively referred to as algae, include a highly diverse array of organisms from large seaweeds (macroalgae) to unicellular microalgae. Phycology, the study of algae, focuses on morphological, ecological, physiological and molecular biological aspects of these organisms. Most microalgae show a photo-behaviour, i.e. they sense light and move towards it; in this review we will describe morphological similarities and differences in the photoreceptive system of microalgae.

First identification and localization of a visual pigment in Hydra (Cnidaria, Hydrozoa)

The cnidarian Hydra does not possess identified photoreceptive structures or specialized cells for light detection; nevertheless, it shows a marked photosensitivity. So far no evidence has been previously reported about the localization of the proteins involved in the photoresponse. We used polyclonal antibodies and immunofluorescence microscopy on whole-mount Hydra to identify a putative rhodopsin-like protein. Our results show an immunoreactivity in the ectodermal layer of Hydra, which corresponds in position to the nervous epidermal sensory cells. These data provide the first identification of a rhodopsin-like protein in a phylogenetically old invertebrate and give a new insight into the Hydra photoreceptive response.

Ultrastructure of the pellicle of Euglena gracilis

Deep-etching technique was used to investigate the organization of the pellicle complex of Euglena gracilis. The interpretation of the images was further supported by SEM and TEM investigations. Our results mainly validate data obtained by previous freeze-fracture studies on the E and P faces of the outer cortical membrane. At the level of the ridges, the outer E fracture face is highly organized in a regular striated pattern, whereas the P inner face shows a particulate structure. However, our images reveal that this particulate organization of the P face is not limited to the ridges, but it is displayed also by the grooves. Moreover, this face shows two distinct layers, a particulate layer facing the cytoplasm and a striated layer facing the E face; these layers represent different true fracture levels of the same P face.

The photoreceptor protein of Euglena gracilis

We isolated the photoactive protein Erh, isolated from the photoreceptor of the unicellular photosynthetic flagellate Euglena gracilis. It is a 27 kDa protein with a photocycle resembling that of sensory rhodopsin, but with at least one stable intermediate. We recorded the absorption spectrum of the parent form of this protein both under native form and in the presence of hydroxylamine and sodium borohydride, and the fluorescence spectra of both the parent and intermediate forms. We suggest that Erh is a rhodopsin-like protein and propose a simple photocycle. This protein shows optical bistability, without thermal deactivation.

Morphology and spectral sensitivities of retinal and extraretinal photoreceptors in freshwater teleosts

Fish eyes possess a complicated morphological and neural organisation of retinal and extra-retinal receptors. Features such as photoreceptor mosaic array and photoreceptor grouping are unique among vertebrates. Spectral sensitivities of these photoreceptors range from UV to the red portion of the visible spectrum. Moreover, these sensitivities can change with the age of the animals. In this review we will examine thoroughly the morphology, and the spectral sensitivities of retinal and extra-retinal receptors and the influence upon them of factors such as hormones, ageing, season, habitat light conditions, and migration.

A complex photoreceptive structure in the cyanobacterium Leptolyngbya sp

Among the terrestrial epilithic cyanobacteria isolated from Roman hypogea at extremely low light intensity, a non-heterocystous strain, belonging to the genus Leptolyngbya, showed a marked photobehavior. These red cyanobacteria possess an orange spot at the tip of the apical cell. Micro-spectrophotometric analysis of this tip showed an absorption spectrum with two bands, centered at 456 and 504 nm, respectively. Experiments on photo-orientation impairment of these cells, and micro-spectrophotometric analysis of the tip of impaired trichomes showed that a rhodopsin-like protein might be present in this structure. All these data could support the hypothesis of the presence of a complex photoreceptive system in this prokaryote.

Retinal identification in Pelvetia fastigiata

Unidirectional blue light directs the rhizoid-thallus axis in the apolar zygote of the brown alga Pelvetia fastigiata. This effect is mediated by an increase in the intracellular concentration of cGMP. Here, we show the extraction, purification and identification of 1 microgram of all-trans retinal from 1.2 x 10(6) Pelvetia zygotes. The number of retinal molecules per cell was about 4 x 10(9). Since retinal, wherever present, is exclusively associated with an opsin to form a light sensitive complex (rhodopsin-like proteins), and since the physiological response originated by this protein produces a variation of cGMP concentration, this new finding suggests that a rhodopsin-like protein could be the photoreceptor in this brown alga.

In vivo photocycle of the Euglena gracilis photoreceptor

We present the light-induced photocycle of the paraflagellar swelling of Euglena gracilis. The kinetics of this process was reconstructed by sampling its fluorescence emission and switching the excitation light from 365 nm to 436 nm. Stable intermediates in the photocycle were manifested. The measured millisecond resolution kinetics best fits a Michaelis-Menten equation. The data provide strong evidence that the paraflagellar swelling, a three-dimensional natural crystal of a light-detecting protein, is the true Euglena photoreceptor.

Effects of hydroxylamine, digitonin and triton X-100 on photoreceptor (paraflagellar swelling) and photoreception of Euglena gracilis

We present experiments that test the effects of agents commonly used in visual pigment investigations, namely hydroxylamine (NH2OH), digitonin and triton X-100, on the photoreceptor and photoreception of Euglena. Hydroxylamine reacts with free and opsin-bound retinal, in aqueous solution, to form stable oximes, whereas digitonin and triton X-100 are the most common extractants of rhodopsin. Since previous data indicate that the chromophore present in Euglena photoreceptor is retinal, we investigated the influence of these chemicals on this organelle. The effects of these agents were studied by means of phase contrast, fluorescence and transmission electron microscopy and photobehaviour experiments. Hydroxylamine inhibited the formation of the Euglena photoreceptor. Photoaccumulation experiments on hydroxylamine-treated cells showed that they are unable to perceive light. Digitonin solubilized the crystalline structure of the photoreceptor, whereas the triton effect was limited to the membranous structures of the cell, leaving the photoreceptor unimpaired.

Identification of a rhodopsin photoreceptor in Euglena gracilis

Visual pigments are a class of receptor proteins that absorb light and trigger sensory signals. Retinal-containing proteins are used in nature as photoreceptors mainly in animals vision. Mammalian rhodopsin is the best studied example of a light sensor which couples photon absorption to a cascade of biochemical reactions amplifying the input signal. A surprising discovery was to find rhodopsin also in Archaebacteria and in unicellular eukaryotes. On the basis of absorption microspectroscopic measurements and of inhibition experiments on pigment biosynthetic pathways, we have recently suggested that a rhodopsin could be the functional receptor of the visual process in Euglena gracilis, a flagellate which can use light directly to promote photosynthetic reactions, or as an incident flux of information to adjust its swimming orientation. We here report purification and identification of all-trans-retinal by column chromatography, HPLC and GC-MS in E. gracilis; these findings indicate with absolute certainty that rhodopsin is the photoreceptor molecule of this microorganism.

Ultrastructure of the apical zone of Euglena gracilis: photoreceptors and motor apparatus

Euglena is an organism that every student of biology has observed; its morphology has been a subject of interest since the early microscopic literature for its enigmatic role of "plant-like" or "animal-like" organism. Therefore, this review has no pretensions to absolute novelty, but, like a journey to the centre of the earth, will attempt to arouse the reader's curiosity by taking him inside the cell Euglena, through the canal opening into the reservoir chamber. In light of the most recent knowledge, though much remains to be clarified, the aim is to provide information from ultramicroscopical studies on the apical zone of Euglena and possible functional meanings of the structures present therein. The survey of these structures is carried on as a study in correlation: TEM of cells after various treatments is correlated with SEM of cells fixed by means of different techniques. Notes on locomotion and other features of cytological and biological interest are added to assist with the comprehension of this microorganism.

An algorithm comparing the two mononuclear curves of choice reaction times in pigeons

A simple and fast algorithm allowing the matching between frequency distributions is developed. The procedure consists in a class by class mapping of two distributional curves in order to derive a class transformation function that specifies how a class from one distribution is modified to produce a class in another distribution. Being interested in investigating the equivalence between the eyes, we have compared left and right monocular curves of choice reaction times to three different visual discrimination tasks in intact and surgically manipulated pigeons by means of the present technique of analysis. The results indicate that RTs distributions of the eyes belong to the same family of functions. It is possible, however, to demonstrate a difference in the range of time responses between the two monocular curves during one of the three visual discriminations used, particularly in the lesioned group.

A procedure for the extraction of object features in microscope images

A program for a detailed and fast feature extraction procedure on objects from a digitized microscope image is presented. The single-pass algorithm labels the pixels of the image that are above a selected threshold, and connects those which belong to the same object. A data structure addressable as an associative memory is created, thus avoiding the use of any recursive procedures. A detailed description of the procedure, which extracts features such as integrated optical density, area and baricenter coordinates, is presented.

Chitosan as flocculant for concentrating Euglena gracilis cultures

The practical criteria for the usefulness of an algal separation process for laboratory routine being effectiveness and time consumption, we tested the feasibility of a flocculation procedure to harvest large volumes of Euglena gracilis in culture. This procedure turned out to be a technically viable system which avoided tedious centrifugation and preserved E. gracilis flagellar apparatus integrity. E. gracilis cultures were treated with chitosan, a by-product derived from chitin from the exoskeleton of crustaceans. Since this polymer carries a positive charge, it functions as a polycationic coagulating agent by adsorbing onto particles in suspension and by bridging together into agglomerates, or flocs. A 96-98% reduction of suspended cells in cultures with 200 mg/l of chitosan, at pH 7.5, was obtained.

Tryptophan phosphorescence and the conformation of liver alcohol dehydrogenase in solution and in the crystalline state

Information on the effects of crystallization upon the structure of liver alcohol dehydrogenase from horse is obtained from a comparison of the phosphorescence properties of its tryptophan residues in solution and in the crystalline state. In the crystalline state the red shift in the phosphorescence spectrum of the solvent-exposed Trp-15 attests to a decreased polarity of its environment consistent with its shielding away from the aqueous solvent probably through its involvement in an intermolecular contact. On the other hand, the triplet-state lifetime of Trp-314 which is buried deeply in the coenzyme-binding domain demonstrates that the flexibility of this region of the macromolecule is unaffected by crystallization; a conclusion supported also by the similarity in the rate of oxygen quenching of its phosphorescence. Given that lattice constraints strongly inhibit large-scale conformational changes these results allow us to identify the average solution structure with the 'open' conformer determined crystallographically.

Microorganism track reconstruction: an image processing approach

This paper presents an automatic system for the analysis of microorganism behaviour. The movements of free swimming microorganisms are videotaped by means of a television camera mounted on a microscope. The analysis is performed off-line by digitizing the video signal through the use of an image processor unit. Microorganism tracks are reconstructed spatially and chronologically by means of image processing techniques. From these tracks cell movement parameters are obtained. The results of our experiment in testing photoinduced movements follow.

Identification of cellular and subcellular features by means of digital microscopy

This paper presents two examples of the application of quantitative digital microscopy to two different fields of biological analysis: DNA content determination in microstructures and the study of the behaviour of microorganisms. In both cases the application of segmentation and labelling procedures was found to be essential in order to obtain the desired results, because it made it possible to overcome the measurement limits of traditional instrumentation and to obviate drawbacks normally present when analysis is placed in the hands of the human operator.

Kinetics of the reaction of intraerythrocytic haemoglobin by single cell microspectroscopy: effect of shape and osmolarity

The kinetics of the reaction of CO with intraerythrocytic haemoglobin has been studied in single red blood cells (RBC) using a scanning microspectrophotometer and a photochemical perturbation method. Measurements have been carried out using red blood cells from man and camel (Camelus dromedarius), the latter at different osmotic pressures. Camel RBC, which are smaller and different in shape compared to human RBC, are known to remain intact even at an osmolarity 6-times lower than physiological (280-290 mosm/l), swelling up to twice their normal volume. The results show that the recombination time course is affected by diffusion of CO through a stagnant layer of solvent around the cell membrane, but that it is also influenced by other parameters such as intracellular diffusion of ligand and haemoglobin.