Glycation as an atherogenic modification of LDL

PURPOSE OF REVIEW: To highlight the potential importance of glycation as an atherogenic modification of LDL in both diabetic and nondiabetic people. RECENT FINDINGS: Small dense LDL which is known to be most closely associated with atherogenesis is more susceptible to glycation than more buoyant LDL. Glycation and oxidation of LDL appear to be intimately associated. SUMMARY: Glycation of LDL occurs chiefly due to the nonenzymatic reaction of glucose and its metabolites with the free amino groups of lysine in which LDL is rich. Higher concentrations of glycated LDL are present in diabetic than in nondiabetic individuals, but even in the latter, there is generally more circulating glycated LDL than oxidatively modified LDL. Probably, oxidation and glycation of LDL are at least partially interdependent, but both prevent LDL receptor-mediated uptake and promote macrophage scavenger receptor uptake. The recognition that LDL glycation is at least as important as oxidation in atherogenesis may lead to improvements in our understanding of its mechanism and how to prevent it.     

Paraoxonase and arylesterase activities in fibromyalgia

We aimed to evaluate the association of serum paraoxonase and arylesterase activities and oxidative/antioxidative status in patients with fibromyalgia. Forty-two patients with fibromyalgia and 53 healthy controls were included in the study. Serum paraoxonase and arylesterase activities were measured spectrophotometrically. Oxidative and antioxidative status were evaluated by measuring serum lipid hydroperoxide (LOOH) levels, total antioxidant status (TAS) and free sulfhydryl groups (-SH = total thiol). Lipid parameters were determined by routine laboratory methods. Serum paraoxonase and arylesterase activities, and TAS were lower in patients with fibromyalgia than in controls (P < 0.001, for all), and the -SH level was also lower in the patient group (P = 0.03). LOOH levels were higher in the patient group than in controls (P = 0.01). Our results suggest that patients with fibromyalgia were exposed to oxidative stress, and paraoxonase and arylesterase activities were decreased in these patients. Patients with fibromyalgia might be prone to development of atherosclerosis with reduced paraoxonase and arylesterase activities.     

Über die Wirkung von ADP und einigen Kationen auf die Rotationsströmung in den Wurzelhaaren der Gerste (Hordeum vulgare L.)

Zusammenfassung In getrennten Versuchen wurde die Wirkung von ADP, Ca⁺⁺, Mg⁺⁺, K⁺ und Cu⁺⁺ auf die Rotationsströmung in den Wurzelhaaren der Gerste (Hordetim vulgare L.) untersucht. Das in verschiedenen Konzentrationen fortdauernd verabreichte ADP bedingte eine Stimulation der Plasmaströmung. Die Beschleunigung der Rotationsströmung war der ADP-Konzentration gegenüber umgekehrt proportional (Abb. 3).Von den untersuchten Kationen hatte nur Ca⁺⁺ (1·10^–3 Mol) eine Stimulationswirkung. Diese Stimulationswirkung wird der Aktivierung eines Enzyms bzw. eines kontraktilen Proteins mit ATPase-Eigenschaften zugeschrieben.Die Rolle von ADP und einigen Kationen bei der Stimulation der Rotation wurde dann mit Hilfe einer gemischten Behandlung untersucht. Diese bestand in der gleichzeitigen Verabreichung von ADP (1·10^–6 Mol) und CaCl₂, MgCl₂, KCl (1 · 10^–3 Mol) oder CuCl₂ (1·10^–6 Mol). Es wurde festgestellt, daß Mg⁺⁺ und Ca⁺⁺ eine antagonistische Wirkung ausüben. Ca⁺⁺ hebt die durch ADP induzierte Stimulation auf und reduziert die Rotationsgeschwindigkeit plötzlich bis auf den Kontrollwert. Die Mg⁺⁺-Wirkung bewirkt, nach einer zeitweiligen Beibehaltung der Stimulation, ebenfalls eine Abnahme der Geschwindigkeit. K⁺ hat eine ähnliche Wirkung wie Ca⁺⁺. Cu⁺⁺ beeinträchtigt die ADP-induzierte Stimulation in geringem Maße.Die gleichzeitige Einwirkung von ADP und einigen Kationen erlaubt die Aufstellung folgender Hypothese. Die Rotationsstimulation erfolgt dank dem ATP, das auf Kosten des von außen absorbierten ADP in den Mitochondrien synthetisiert wird. Die zusätzliche ATP-Synthese kann durch gleichzeitige Ca⁺⁺-Behandlung unterbunden werden. NachHanson und Mitarb, sollen Ca⁺⁺ und ADP um ein phosphoryliertes Zwischenprodukt in Kompetition treten, so daß es zu einer Ansammlung von Ca⁺⁺ und P_a in der Zelle kommt. Andererseits könnte teilweise auch die aktive, energieverbrauchende Salzabsorption die Geschwindigkeitsabnahme der Rotation bei gemischter Behandlung erklären.

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The effect of ADP and some cations on rotational streaming in barley (Hordeum vulgare L.) root hairs

Summary The effect of ADP, Ca⁺⁺, Mg⁺⁺, K⁺, and Cu⁺⁺ upon rotational streaming within barley (Hordeum vulgäre L.) root hairs was separately studied. It was shown that various solutions of ADP may stimulate the streaming after continuous treatment. The rate increase of the rotational streaming was inverse proportional to ADP concentration (Fig. 3).From the investigated cations only Ca⁺⁺ (1·10^–3M) caused a stimulation of streaming after continuous treatment. This effect is probably due to enzymic activation of a contractile proteine which has ATPase feature.The role of ADP and of the investigated cations in the stimulation of the rotational streaming was studied by means of mixed treatment. This kind of treatment consists in a simultaneous administration of ADP (1 · 10^–6M) and CaCl₂, MgCl₂, KCl (1 · 10^–3M), or CuCl₂ (1 · 10^–6M) solutions. Ca⁺⁺ and Mg⁺⁺ showed an antagonistic action. Ca⁺⁺ brings about an immediately suppress of ADP induced stimulation. Suddenly the rate of streaming comes back to control. Mg⁺⁺ after a temporary maintaining of stimulation, also causes the lowering of the streaming. The action of K⁺ was very similar to those of Ca⁺⁺. Cu⁺⁺ changes to a little extent the stimulation caused by ADP.The simultaneous action of ADP and of the investigated cations allow us to express the following hypothesis. The stimulation of the rotational streaming after ADP treatment probably is due to ATP synthetized in mitochondria on the account of ADP. The additional synthesis of ATP can be prevented by simultaneous administration of Ca⁺⁺. According toHanson and his coworkers Ca⁺⁺ would compete with ADP for a phosphorylated intermediate product. From a such competition would result the Ca⁺⁺ and P_i accumulation. The active uptake of salts which require energy would also explain the lowering of the rotational streaming rate after the mixed treatment.

     

Responses of the digestive tract of the omnivorous northern brown bandicoot, Isoodon macrourus (Marsupialia: Peramelidae), to plant- and insect-containing diets

The gastrointestinal tract of omnivores such as bandicoots (Marsupialia: Peramelidae) must be able to process foods as different as invertebrates, fungi and plant material. We studied the mechanisms involved in the utilisation by captive northern brown bandicoots (Isoodon macrourus) of insect larvae and milled lucerne (Medicago sativa) hay incorporated into a basal diet of a commercial small carnivore mix. Animals on the plant-basal mix digested less dry matter, energy, lipid, fibre and total nitrogen, but consumed 79% more dry matter than those on the insect-basal mix. Consequently intake of digestible energy (i.e. energy absorbed) was not significantly different between diets. Mean retention time (MRT, the mean time a marker remains in the tract) of a large particle marker was shorter on the plant-basal mix, reflecting its higher intake, but MRT of a solute marker was not significantly different between diets. Consequently the solute marker was retained longer than the particle marker on the plant-basal mix, indicating selective retention of solutes and very small particles in the caecum on this diet. This was confirmed by a higher proportion of small particles in the caecum than the distal colon of road-killed I. macrourus. Thus the main responses by I. macrourus to the plant-basal mix appeared to be an increase in gastrointestinal tract capacity (from radiographic evidence), selective retention of solutes and very small particles in the caecum, and facilitated passage of less tractable large particles through the colon. As a consequence, food intake was higher on the plant-basal mix, which compensated for its lower digestibility, and intake of digestible energy was similar to that on the insect-basal mix. This considerable flexibility of the morphologically rather simple digestive tract of northern brown bandicoots helps to explain their ability to cope with naturally variable diets consisting of mainly invertebrates in summer to much more plant and fungal material in winter, and to survive in nutritionally dynamic environments such as heathlands where there can be dramatic changes in food type and availability following periodic wildfires. Accepted: 14 April 1999     

Yellow nail syndrome: treatment of lymphedema using low pressure compression

The present report describes a case with the triad of yellow nail syndrome (YNS) and the use of low-pressure compression pump as treatment of lymphedema in YNS. A 71-year-old woman presented with bilateral lower extremity lymphedema, yellow nails, and recurrent bilateral pleural effusion. In this case, we specifically focused on lymphedema treatment of the legs besides other recommendations for YNS.     

Association of eNOS gene intron 4 a/b VNTR polymorphisms in children with nephrotic syndrome

To investigate the association of endothelial nitric oxide synthase gene intron 4 (eNOS4) polymorphisms with nephrotic syndrome, the eNOS4 genotypes were assessed in 161 children with nephrotic syndrome in comparison with 78 healthy subjects. We classified the children with nephritic syndrome into 2 groups: as steroid-sensitive nephrotic syndrome (SSNS) (n = 125) and steroid-resistant nephrotic syndrome (SRNS) (n = 36). The eNOS4 polymorphisms were analyzed by polymerase chain reaction. The frequencies of eNOS4 aa, ab and bb genotypes were 3%, 31%, and 66% in all the nephrotic syndrome groups, and 1%, 23%, and 76% in the control group (x² = 2.87, p > 0.05). In addition, the frequencies of eNOS4 aa, ab and bb genotypes were 2%, 33%, and 65% in SSNS group, and 5%, 28%, and 67% in the SRNS group (x² = 1.13, p = 0.567). The present study is the first to investigate eNOS4 gene polymorphisms in children with SSNS and SRNS. Our data show that the eNOS4 gene polymorphisms were not associated with the development, frequent relapse and response to steroid in nephritic syndrome.     

Assessment of paraoxonase activities in patients with knee osteoarthritis

The objective of this study was to investigate serum paraoxonase and arylesterase activities, and lipid hydroperoxide (LOOH) and total thiol (total free sulfhydryl groups, -SH) levels along with lipid parameters in patients with knee osteoarthritis. Thirty-six patients with knee osteoarthritis and 30 healthy individuals were enrolled in the study. Serum paraoxonase and arylesterase activities were measured spectrophotometrically. LOOH levels were measured by ferrous oxidation with xylenol orange assay (FOX-2). Serum high-density lipoprotein-cholesterol (HDL-C), -SH levels, paraoxonase and arylesterase activities were significantly lower in the patient group than those in the controls (P < 0.05, for all), while LOOH and low-density lipoprotein (LDL) levels were significantly higher. In conclusion, paraoxonase and arylesterase activities were decreased significantly in patients with knee osteoarthritis. Lower serum paraoxonase-1 activity and lower level of HDL-C seem to be related to increased oxidative stress and inflammatory condition in these patients. It is known that paraoxonases reduce oxidative stress in serum and tissues thereby protecting against cardiovascular disease, particularly atherosclerosis. Thus, decreased paraoxonase and arylesterase activities play a role in the pathogenesis of atherosclerosis through increased susceptibility to lipid peroxidation in patients with osteoarthritis.