Changes of membrane fluidity in erythrocytes of obese children: a spin label study

Red blood cells depend on circulating lipoproteins for the turnover of membrane phospholipids. Thus abnormalities in lipid and lipoprotein metabolism are frequently associated with changes in composition and fluidity of erythrocyte membranes. Using the electron spin resonance technique we studied the physical state of erythrocyte membranes from 15 obese children with a body mass index ranging from 22.8 to 34 kg . m-2 and slight alterations of plasma lipids. The spin labels used, 5-doxylstearate and 16-doxylstearate, have shown an increase of the order parameter and of the correlation time, respectively. These observations indicate a decrease of fluidity at the surface and in the hydrophobic core of erythrocyte membranes from obese subjects. The results are statistically significant and they are discussed in relation to clinical aspects of childhood obesity. Studies on erythrocyte membrane molecular organization could represent a sensitive way to find out small metabolic alterations hardly detectable with compositional studies.

Effects of exercise on maximal instantaneous muscular power of humans

The maximal instantaneous anaerobic power (w), as determined during a high jump off both feet on a force platform, was measured on eight subjects starting from a resting base line; a base line of steady-state cycloergometric exercise requiring 30, 50, and 70% of individual maximum O2 consumption (VO2max); and a base line of maximal and supramaximal exercise (100 and 120% of VO2max). In addition, w was also measured during the VO2 transients from rest to each of the above work loads. Blood lactate concentration ([Lab]) was determined before and 8 min after the end of each priming load. After the onset of any priming load, w decreases with time reaching in 2 min a steady level that is lower the higher the VO2. For the three lowest work rates, the steady w level is unchanged by increasing the duration of the priming exercise up to 30 min. For low work levels, the decrease of w as a function of VO2 is essentially parallel to that of estimated muscle concentration of ATP ([ATP]). For work levels greater than 60% of VO2max involving a substantial accumulation of lactate, the decrease of w becomes smaller than the estimated drop of muscle [ATP]. This finding is tentatively attributed to an increase of either the mechanical equivalent or of the velocity constant of ATP splitting brought about by the lowering of intracellular muscle pH after lactate accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Ca2+ on structure and fluidity of microvillus membranes of human placenta

This investigation shows the effect of a Ca2+ addition on the structural and physiochemical properties of microvillus plasma membranes obtained from human placenta. Ca2+ addition induces an increase in microviscosity, as shown by the increase of order parameter and rotational correlation time of 5- and 16-doxylsterate derivatives and by the increase of fluorescence polarization of diphenylhexatriene. All the effects were obtained in a wide temperature range. The morphometric analysis of the ultrastructural images shows that the vesicle profiles of syncytiotrophoblast membranes decrease both area and form factor (FF) in the presence of Ca2+ with respect to the controls. The freeze-fracture results also show that Ca2+ induces an enhanced tendency to IMP clusterization. The Ca2+-induced changes were observed in both E and P faces. Our results underline the important role of Ca2+ in the cell membrane structure per se and in modulating interactions between cytoplasmic and extracellular microenvironments. The results of morphometric analysis of the ultrastructural images agree with biochemical data showing an increased stability induced by calcium on plasma membranes.

Effect of chronic ethanol abuse on the physico-chemical properties of erythrocyte membranes in man

Chronic alcoholics (greater than 150 g/day) showing minor serum and histological changes have been studied, compared to healthy non alcoholic subjects, and the following parameters have been considered: S. (Serum)cholesterol (CH), S.phospholipids (PH), S.folate level, and mean corpuscular volume (MCV). Erythrocyte ghosts have been studied for CH and PH content and membrane fluidity using diphenylhexatriene as a probe. All alcoholics showed decreased fluidity of red cell membrane with increased CH/PH ratio, even in patients showing normal MCV or minimal alterations of functional tests, suggesting that changes in red cell membrane fluidity represent an early sign of ethanol abuse. These likely reflect the diffuse interaction of ethanol with biological membranes. The administration of N5-Methyltetrahydrofolate produced an increase of membrane fluidity over the 3 weeks considered, associated with modest changes of MCV. The latter were delayed with respect to changes in fluidity. If changes of red cell membrane fluidity are a sensitive index of alcohol abuse, they could be a useful marker for detection and follow-up of chronic alcoholism.

[Budd-Chiari syndrome. Description of 2 cases]

The causes of Budd-Chiari syndrome are quickly reviewed with reference to the pathology described in series from various parts of the world. In the West the syndrome is caused by obstruction of the Inferior Vena Cava in its retrohepatic course with or without concomitant obstruction of the suprahepatic veins attributable to fibrous regression of the vessel wall and subsequent endoluminal thrombosis. In the Far East and South Africa the syndrome is caused by the presence of a thin fibrous septum obstructing the vein immediately upstream of the right atrium. Of the two cases of Budd-Chiari syndrome described, one presented high grade stenosis of the Vena Cava caused by fibrous regression of the vessel wall and the other a fibrous septum situated transversally to the lumen. The description of the first case is particularly interesting because before the clinical picture was correctly understood, a succession of major complications induced incorrect diagnosis and treatment. In contrast the second was a classic case of rapid diagnosis and successful treatment. The discussion of the two cases highlights the primary role currently played by abdominal echography with Doppler ultrasound, examination with lower cavography using a contrast medium in documenting a caval flow pathology of this kind. CAT scanning, arteriography of the Celiac tripod and closed hepatic needle biopsy appear to be much less decisive.

Echo-Doppler velocimetry in the diagnosis of renal artery stenosis on transplanted kidney

Renal artery stenosis is one of the most important complications in the natural history of kidney transplantation. Particular care has to be taken in the use of angiography techniques because of the invasiveness and of the potential toxicity of radiopaque contrast material, even in the less invasive radiological tests, like endovenous sequential angiourography with image subtraction (SAU) and digital subtraction angiography (DSA). Fifty-one patients have been examined with echo-Doppler velocimetry (EDV) and also with SAU in order to verify the previous status of the artery. EDV exhibits a 100% sensitivity: all SAU detected stenosis have been formerly identified via EDV. The non-invasiveness and possibility of early repetition allows an early diagnosis capability for all transplanted patients. In this way, a surgical intervention may quite often be prevented by a precocious use of endoluminal angioplasty.

Physiological profile of world-class high-altitude climbers

The functional characteristics of six world-class high-altitude mountaineers were assessed 2-12 mo after the last high-altitude climb. Each climber on one or several occasions had reached altitudes of 8,500 m or above without supplementary O2. Static and dynamic lung volumes and right and left echocardiographic measurements were found to be within normal limits of sedentary controls (SC). Muscle fiber distribution was 70% type I, 22% type IIa, and 7% type IIb. Mean muscle fiber cross-sectional area was significantly smaller than that of SC (-15%) and of long-distance runners (LDR, -51%). The number of capillaries per unit cross-sectional area was significantly greater than that of SC (+ 40%). Total mitochondrial volume was not significantly different from that of SC, but its subsarcolemmal component was equal to that of LDR. Average maximal O2 consumption was 60 +/- 6 ml X kg-1 X min-1, which is between the values of SC and LDR. Average maximal anaerobic power was 28 +/- 2.5 W X kg-1, which is equal to that of SC and 40% lower that that of competitive high jumpers. All subjects were characterized by resting hyperventilation both in normoxia and in moderate (inspired O2 partial pressure = 77 Torr) hypoxia resulting in higher oxyhemoglobin saturation levels in hypoxia. The ventilatory response to four tidal volumes of pure O2 was similar to that of SC. It is concluded that elite high-altitude climbers do not have physiological adaptations to high altitude that justify their unique performance.

S-100 protein-induced changes in the physical state of synaptosomal particulate fractions as monitored by spin labels

This report documents changes in the physical state of synaptosomal particulate fractions (SYN) upon binding of S-100 protein, as monitored by spin labels. Studies were conducted on SYN labeled with either 5-doxylstearic acid or 16-doxylstearic acid, which probe the polar region and the hydrophobic core of the lipid bilayer, respectively. S-100 perturbs to some extent both the polar surface and the hydrophobic core of SYN in a time- and temperature-dependent manner. Ca2+ is essential for S-100 to perturb the membranes. K+ almost completely inhibits the S-100 perturbing effect if present in the incubation medium, but fails to reverse the S-100-induced changes if added after S-100 has interacted with SYN. At room temperature and below, the overall S-100 effect registered after about 30 min of association of the protein with SYN is an increase in the fluidity of both the surface and the interior of the membranes. Spectra registered at intervals at room temperature indicate that the S-100 perturbing effect on the membrane surface is practically monophasic, consisting of an increase in fluidity, while that on the membrane interior is multiphasic, consisting of a decrease in fluidity during the first 10 min of association, followed by an increase in fluidity during the subsequent 20 min and a return to starting values during the second 30 min of association. Around 37 degrees C, on the contrary, a decrease in fluidity is registered in both regions. The data suggest that S-100 induces a spatial rearrangement of membrane components (proteins) involved in the specific binding and/or partially penetrates into the lipid bilayer.

Hydatidosis in Sardinia: review and recommendations

In Sardinia, hydatidosis due to Echinococcus granulosus is endemic and constitutes a current and important problem in the economy and public health. This paper reviews the epidemiological aspects, including the geographical distribution, and the socio-cultural factors involved in the dissemination of hydatidosis. Hospital data indicate that about 200 people undergo surgery for hydatid cysts every year with an average of 8.8 deaths annually. An average of 80% of the sheep are infected, constituting a livestock loss estimated as over 20 billion liras per year. The benefits expected from a hypothetical control programme amount to approximately 32 billion liras against an investment of 17 billion liras in a control programme extending over a period of 10 years. The eradication campaign should result in a gradual reduction of infection rate from 80% to 10% in sheep, from 30% to 3-5% in dogs and in a reduction of human morbidity from 200 to 15 cases, equal to a prevalence rate of 1 per 100,000 inhabitants.

Neuropsychological assessment of a case of early right hemiplegia: qualitative and quantitative analysis

Evidence for normal development of linguistic but poor visuo-perceptual skills has been obtained with the neuropsychological assessment of a case of early left-brain injury. Data suggest the transfer of linguistic functions from the left to the right hemisphere at the expense of visuo-perceptual capacities for which the right hemisphere is potentially specialized.

Energy cost of and energy sources for alpine skiing in top athletes

O2 uptake (VO2) during exercise and at 2 min of the recovery along with blood lactate concentration 5 min after exercise were measured in an all-out special slalom (SS) and giant slalom (GS) performed by eight top male athletes and five controls in a field study. Heart rate (HR) was continuously monitored before, during, and after each task. On the basis of an energy equivalent of 3.15 ml O2 X kg body wt-1 for 1 mmol X 1-1 lactate accumulation and the assumption that the amount of O2 consumed in recovery is used to reconstitute approximately phosphates used during the exercise, the total energy cost (delta VO2 tot) could be calculated and subdivided into aerobic, lactic, and alactic fractions. In top athletes, delta VO2 tot was equal during SS and GS [7.28 +/- 1.14 (SD) and 7.47 +/- 0.89 liters for about 55- and 70-s performances, respectively]. When referred to time, the O2 expenditure rate was 2 and 1.6 times VO2max in SS and GS, respectively. In SS and GS, the energy sources were about 40% aerobic, 20% alactic , and 40% lactic metabolism. In control skiers, delta VO2 tot of GS was 6.12 +/- 1.45 liters for 77 s, amounting to about 1.3 VO2max, with the contribution of the different energy sources being roughly the same as in top skiers. HR reached maximal values in 30-40 s in all subjects for all conditions.

Duchenne muscular dystrophy: alterations in lymphocyte fluidity

We have studied lymphocyte membrane from 7 patients with Duchenne Muscular Dystrophy (DMD) and 8 normal controls using fluorescence polarization of 1,6-diphenyl-hexatriene (DPH). The microviscosity of lymphocytes membrane is significatively higher in DMD patients than in normal controls. Our results support the hypothesis of a generalized membrane defect in Duchenne Muscular Dystrophy.

Electron spin resonance studies of the effects of lipids on the environment of proteins in mitochondrial membranes

The physical state of mitochondrial membranes has been investigated by means of stearic acid spin labels and of a maleimide spin label covalently bound to protein sulfhydryl groups. Stearic acid spin labels 5-NS and 16-NS show that n-butanol enhances the lipid fluidity of mitochondrial membranes in the whole temperature range between 4 and 37 degrees C; the effects in the hydrophobic membrane core, probed by 16-NS, are already apparent at 10 mM butanol. In liposomes formed of mitochondrial phospholipids, a fluidizing effect appears only at much higher concentration. Such results are compatible with the idea that butanol destabilizes lipid-protein interactions. On the other hand, the ratio between weakly and strongly immobilized SH groups probed by maleimide spin label is only slightly affected in the temperature range of 4-37 degrees C by addition of high concentrations of n-butanol, indicating that the environments probed are stable to agents inducing fluidity changes in the lipids. There are, however, indications that the environment probed by maleimide is affected by lipids, since the spin label, when bound to lipid-depleted mitochondria, becomes more immobilized, reconstitution of such lipid-depleted membranes with phospholipids restores the original spectra.

The intrinsic fluorescence characteristics of sarcoplasmic reticulum membranes

The fluorescence characteristics of tryptophan in sarcoplasmic reticulum, were investigated to gain information concerning its location and environment within the intact membrane system. With an excitation of 295 nm, tryptophan has an emission maximum of 330 nm characteristic of tryptophan in a buried hydrophobic environment. At the wavelength studied only a faint contribution of tyrosine is present. The changes observed in the presence of urea 8 M suggest only a partial exposition of the aromatic residues.

Superficial shell insulation in resting and exercising men in cold water

From measurements of subcutaneous fat temperature (Tsf) at known depths below the surface, skin surface temperature (Tsk), and direct skin heat flux (H), the superficial shell isulation (Iss) of the thigh (fat + skin) was calculated as Iss (degrees C.m2.w-1) = (Tsf - Tsk)/H in nine male subjects immersed head out in a well-stirred water bath. Also, at critical water temperature (CWT = 28-33 degrees C), eight of the subjects rested for 3 h, enabling overall maximal tissue insulation (It,max) to be calculated as It,max (degrees C.m2.W-1) = (Tre - Tw)/(0.92 M +/- delta S), where Tre is rectal temperature, Tw is water temperature, M is metabolic rate, and s is loss or gain of body heat. Five subjects performed up to 2 h of mild leg cycling, preceded and followed by 60 min of rest, and both thigh Iss and overall It were measured during exercise. Iss increased from minimal values in Tw greater than 33 degrees C to maximal values (Iss,max) at CWT or below. Iss,max was linearly related to tissue thickness (d) in millimeters of fat plus skin, Iss,max (degrees C.m2.W-1) = 0.0048d-0.0052; r = 0.95, n = 37, and was not influenced by leg exercise up to a metabolic rate of 150 W.m-2 in CWT despite large increases in Tsf and H and large decreases in overall It. The slope of Iss,max vs. depth, 0.0048 degrees C.m2.W-1.mm-1, is almost identical to thermal resistivity of fat in vitro, suggesting that the superficial shell is unperfused in CWT at rest or during mild exercise. When maximal superficial shell insulation (It,ss,max) for the whole body was calculated with allowance for differing fat thicknesses and surface areas of body regions, it could account for only 10-15% of overall It,max at rest and 35-40% of overall It in mild exercise. We suggest that the poorly perfused muscle shell plays a more important role as a defense against cooling at CWT than does the superficial shell (fat + skin), particularly at rest.