Biochemistry of the induction and prevention of lipoperoxidative damage in human spermatozoa

Lipid peroxidation occurs in human sperm cells with damage to the cell plasma membrane, leading to loss of cytosolic components and hence to cell 'death'. The peroxidation may be induced at high rates in the presence of Fe2+ and ascorbate. It occurs at slower rates under physiological conditions as spontaneous lipid peroxidation, which has the following characteristics. The rate is constant over the time required for complete loss of motility in the cells of the sperm sample; one can thus use the time to complete loss of motility (TLM) as a ready measure of the rate. Loss of motility occurs at a characteristic extent of lipid peroxidation, assayed in terms of production of the peroxidative breakdown product, malonaldehyde (MA), that is independent of peroxidation rate. For human sperm, this extent corresponds to 0.1 nmol MA/10(8) cells. Human spermatozoa possess the anti-lipoperoxidative defence enzymes, superoxide dismutase (SOD) and glutathione peroxidase plus glutathione reductase (GPX/GRD). The SOD activity is highly variable between human sperm samples while the activities of GPX and GRD are rather more constant. The rates of production of superoxide anion, O2-, and hydrogen peroxide, H2O2, from human spermatozoa are variable, but their sum calculated in O2- equivalents as O2- + 2H2O2 is quite constant. The variability arises from the variability in SOD activity: all H2O2 produced is from O2- due to the action of SOD. The essential role of SOD as defence enzyme is inferred from the observation that TLM of a given sperm sample is directly proportional to the SOD activity of that sample. The essential role of GPX/GRD is inferred from the observation that inhibition of GPX, either with mercaptosuccinate or with complete oxidation of intracellular reduced glutathione, results in a 20-fold increase in peroxidation rate. The capacity of the GPX/GRD system appears to be limited by the glucose-6-phosphate dehydrogenase-catalysed rate of production of NADPH, the required reductive substrate for GRD. Human spermatozoa appear to have enough anti-lipoperoxidative defensive capacity for lifetimes long enough for fertilization but still short enough for ready removal from the female reproductive tract in good time. Too low a defence capacity could lead to male infertility.      

The role of the sagittal view of the ductal arch in identification of fetuses with conotruncal anomalies using 4-dimensional ultrasonography.

OBJECTIVE: Conotruncal anomalies represent one fifth of all congenital heart defects (CHDs) detected in the fetus. However, the spatial relationship of the great vessels is incorrectly defined in about 20% of these cases. The sagittal view of the ductal arch is considered a standard ultrasonographic view in fetal echocardiography and can be easily visualized using 4-dimensional (4D) ultrasonography. This study was designed to determine the role of this ultrasonographic plane for the prenatal diagnosis of conotruncal anomalies. METHODS: We reviewed 4D volume data sets, acquired with the spatiotemporal image correlation technique, from fetuses with and without confirmed conotruncal anomalies. The visualization rate of the sagittal view of the ductal arch was compared among groups using standardized multiplanar views. RESULTS: This study included 183 volume data sets from fetuses in the following groups: (1) normal echocardiographic findings (n = 130); (2) conotruncal anomalies (n = 18); and (3) other CHDs (n = 35). Volumes of poor image quality were excluded from analysis (8.2% [15/183]). The visualization rate of the sagittal view of the ductal arch was significantly lower in fetuses with conotruncal anomalies (5.6% [1/18]) than that in fetuses without abnormalities (93.1% [108/116]) and that in fetuses with other CHDs (79.4% [27/34]; P < .01). Absence of visualization of the sagittal view of the ductal arch was associated with a likelihood ratio of 9.44 (95% confidence interval, 5.8-15.5) to have conotruncal anomalies. CONCLUSIONS: The sagittal view of the ductal arch may play an important role in the screening and prenatal diagnosis of conotruncal anomalies in 4D ultrasonography.     

Transcatheter closure of patent foramen ovale (PFO) in patients with paradoxical embolism. Periprocedural safety and mid-term follow-up results of three different device occluder systems.

AIMS: Interventional PFO closure has previously been reported to reduce the risk for recurrent thromboembolic events. The aim of the present study was to evaluate three different occluder systems in respect to (a) the safety and practicability and (b) the mid-term risk of recurrent thromboembolic events. METHODS AND RESULTS: Since 08/98 until 12/02, 307 consecutive patients (138 women, 169 men, mean age 43 years) with a symptomatic PFO underwent PFO closure using the PFO-Star ( n=177), Amplatzer PFO occluder ( n=69) and CardioSeal/Starflex ( n=61 ). Implantation was successful in all patients. Periinterventional complications occurred in 9 patients (5x ST-segment elevations, 1x arteriovenous fistula, 2x TIA, 1x device dislodgement). All of them were reversible and not associated with a specific type of device. During the median follow-up of 24 months (25/75th percentiles: 14/37 months), the annual risk of recurrence was 0.6% for TIA, 0% for stroke and 0.2% for peripheral embolism (PFO-Star: 0.8%, Amplatzer PFO occluder: 0.7% and CardioSeal/Starflex: 1.0%). CONCLUSION: Interventional PFO closure appears to be safe and a promising technique in symptomatic PFO patients with a low incidence of periinterventional complications and recurrent thromboembolic events using three different devices (PFO-Star, Amplatzer PFO occluder or the CardioSeal/Starflex).     

Knowledge,attitude and behaviour regarding dietary salt intake among medical students in Angola

High salt (sodium chloride) consumption is an important determinant of high blood pressure and cardiovascular risk. According to World Health Organisation (WHO) statistics, over 80% of cardiovascular disease (CVD) deaths take place in low-and middle-income countries, and elevated blood pressure levels were a major cause of these CVD deaths in those countries.1 Lifestyle factors such as unhealthy diet, physical inactivity, tobacco use and harmful use of alcohol have been considered the most important behavioural risk factors for heart disease and stroke.2Among dietary factors, high salt intake has been the most strongly associated with raised blood pressure and increased risk of stroke and CVD.3 Therefore dietary sodium restriction has been recommended as a non-pharmacological approach to blood pressure lowering,4-6 and for the prevention and control of non-communicable diseases at the population level.7,8Cumulative evidence has shown that even a modest reduction in salt intake was associated with blood pressure lowering and therefore with a significant reduction in incidence of cardiovascular events.9-12 Furthermore, data from the most recent systematic review and meta-analyses has shown the benefit of lowering sodium intake in apparently healthy adults and children,13 and in both hypertensive and normotensive individuals, irrespective of gender and ethnic group.9Since hypertension is associated with CVD worldwide, a public health intervention to reduce high blood pressure must target the role of lifestyle, particularly reduced sodium intake.7 Therefore, several countries have initiated strategies to reduce dietary salt intake in the general population by a combination of various procedures such as public education, food labelling, and collaboration with the food industry to reduce the salt content of processed food.14Among sub-Saharan African countries, only Nigeria and South Africa have developed dietary guidelines regarding salt intake.15 Recently, the South African government implemented important specific legislation towards decreasing salt intake in the population by reducing sodium content of processed foods by industries.16 Therefore, the current public health recommendation is that countries should launch national initiatives to reduce the over-consumption of salt as part of non-communicable disease prevention and healthy nutrition policies for limiting salt intake to less than 5 g/day for the general population including children.7 Despite of this guideline, however, high sodium intake remains prevalent around the world, with average daily salt intake varying from 5 to 18 g/day per person.17Although processed foods have been found to be the principal source of excessive dietary salt intake,18 sources of dietary sodium vary largely worldwide and may be influenced by cultural context and dietary habits of the population.19 In sub-Saharan African countries experiencing demographic and epidemiological transition, the rapid rise in prevalence of CVD (chiefly hypertension) has been attributed to lifestyle change, including high dietary sodium intake.20,21 However, consistent data from studies on risk factors are lacking for the majority of these countries.With regard to Angola, available data from a cross-sectional study reported a high prevalence of multiple cardiovascular risk factors, such as hypertension, sedentary lifestyle, electrocardiographic left ventricular hypertrophy,22 and high rate of the metabolic syndrome23 in an apparently healthy middle-aged population of university public employees living in urban and peri-urban areas.Determining the level of sodium intake in the population is crucial to establish intervention strategies and policy on reduction of sodium intake. For medical students in particular, it is very important to assess their awareness regarding dietary salt intake, since they are the future providers of healthcare information for the counselling of people about the need to reduce salt consumption. The aim of this study was to determine salt intake and to assess the knowledge, attitude and behaviour regarding dietary salt among medical students.     

A respiratory hemocyanin from an insect

Insects possess an elaborate tracheal system that enables transport of gaseous oxygen from the atmosphere directly to the inner organs. Therefore, the presence of specialized oxygen-transport proteins in the circulatory system of insects has been considered generally unnecessary. Here, we show for the first time, to our knowledge, the presence of an ancestral and functional hemocyanin (Hc) in an insect. In the hemolymph of nymphs and adults of the stonefly Perla marginata, a hexameric Hc was identified, which consists of two distinct subunit types of 659 and 655 amino acids. P. marginata Hc displays cooperative oxygen binding with a moderately high oxygen affinity [(half-saturation pressure, P(50) approximately 8 torr (1 torr = 133 Pa)]. No evidence was found for the presence of Hcs in the more evolutionarily advanced holometabolan insects, suggesting that this type of respiratory protein was lost later in insect evolution. However, our results demonstrate that, in contrast to the accepted paradigm, certain basal insects have retained an ancestral blood-based mechanism of gas exchange.