Original and generic preservation solutions in organ transplantation. A new paradigm?

Abstract Solid organ transplantation is a very complex process, in which the storage of the graft in a preservation solution is mandatory in order to extend ischemic times and contain further damage. The condition in which the organ is transplanted is critical for the outcome of the organ recipient. The recent emergence of generic versions of organ preservation solutions (solutions with the same composition and under the same legislation as the original versions, but with different brands) compelled us to study whether the standards are maintained when comparing the original and its generic counterpart. Along these lines, we discuss and comment on some aspects concerning this issue of general interest in the organ transplantation field.

Glutathione: Glutathione Sulfide Redox Imbalance in Early Impaired Fasting Glucose.

Aim: The current study aims to examine the balance between glutathione and glutathione sulfide and how this was disturbed in patients with impaired fasting glucose (IFG) level. The study also included 8-hydroxy-2’-deoxyguanosine to provide a more comprehensive picture of the overall redox state. Methodology: A cross-sectional analysis of ninety medication free participants without reported history of cardiovascular disease and/or diabetes mellitus was undertaken with data collected from the Diabetes Complications Research Initiative database at Charles Sturt University. Fasting blood glucose, HbA1c and cholesterol as standard markers for diabetes mellitus and associated complications were measured in addition to the emerging biomarkers glutathione (GSH), glutathione disulfide (GSSG), and urinary 8- hydroxy-2’-deoxyguanosine (8OHdG). Results: The IFG group had a mean blood glucose level above 6.1mmol/L being significantly higher compared to control (P<0.001). Traditional clinical markers were all within the normal range for both groups. However the GSH/GSSG ratio (8.53±5.4 vs 6.62±2.2, P=.04) was significantly lower in the IFG group. GSH and 8OHdG, being markers for oxidative stress, were not significantly different between the two groups. Conclusion: The free radical related changes in metabolic redox pathways are linked to oxidative stress and related pathologies but may not be associated with disease progression, providing an explanation why conflicting results are presented in the literature concerning any individual biomarkers and risk of diabetes. Our study included individuals with no medication use and mild hyperglycemia (impaired fasting glucose) and indicates a pro-oxidant response to mild-moderate hyperglycemia with a moderate rise in oxidative DNA damage.

Anti-hyperglycemic and anti-oxidative effect of aqueous extract of Momordica charantia pulp and Trigonella foenum graecum seed in alloxan-induced diabetic rats.

Diabetes is an oxidative stress disorder and oxidative damage to tissues such as heart, kidney, liver and other organs may be a contributory factor to several diabetic complications. Momordica charantia (family: Cucurbitaceae) and Trigonella foenum graecum (family: Fabaceae) are used traditionally in Indian folk medicine to manage diabetes mellitus. In the present study, the anti-hyperglycemic and anti-oxidative potential of aqueous extracts of M. charantia pulp and seed powder of T. foenum graecum were assessed in alloxan (150 mg/kg body weight) induced diabetic rats. Alloxan treatment to the rats could induce diabetes as the fasting blood glucose (FBG) levels were >280 mg/dl. Treatment of diabetic rats for 30 days with M. charantia and T. foenum graecum could significantly (p<0.001) improve the FBG levels to near normal glucose levels. Antioxidant activities (superoxide dismutase, catalase, reduced glutathione content and glutathione-s-transferase) and lipid peroxidation levels were measured in heart, kidney and liver tissues of normal, diabetic and experimental animals (diabetics + treatment). TBARS levels were significantly (p<0.001) higher and anti-oxidative activities were found low in diabetic group, as compared to the control group. Significant (p<0.001) improvement in both the TBARS levels and antioxidant activities were observed when M. charantia and T. foenum graecum were given to diabetic rats. Our results clearly demonstrate that M. charantia and T. foenum graecum are not only useful in controlling the blood glucose levels, but also have antioxidant potential to protect vital organs such as heart and kidney against damage caused due to diabetes induced oxidative stress.

possible role of peroxisome proliferator-activated receptors agonists in the vascular reactivity and myocardial changes induced by long-term blockade of nitric oxide synthesis in the rat

Peroxisome proliferator-activated receptors [PPARs] are a family of ligand-activated nuclear transcription factors. PPAR alpha and gamma are the most extensively key modulators of lipid and glucose homeostasis. They are predominantly expressed in adipose tissues, some non adipose tissues including heart, kidney, spleen, and all relevant cells of the vasculature: endothelial cells, smooth muscle cells, and macrophages. The vascular distribution suggests their involvement in the control of cardiovascular function. The present experimental work was designed to study the effects of fenofibrate and rosiglitazone treatment on blood pressure, antioxidant enzymes, vascular reactivity and cardiac hypertrophy in N[G]-nitro-L-arginine methyl ester [L-NAME] induced hypertension in rats. Fifty male albino rats weighing from 150-200 g were included in this study. Rats were divided into two main groups. Group 1, [10 rats] served as a control group for group II, and was received 1 ml of physiological saline [0.9%], orally for seven weeks.Group II: hypertensive group [40 rats] was given daily L-NAME in a dose of 40 mg/kg orally for seven weeks. Rats were further subdivided into A, B, C, and D, each of ten rats. Group- A, received 1ml of 2% gum acacia daily orally for six weeks, starting one week after L-NAME administration.Groups B,C and D treated with daily fenofibrate [30 mg / kg.b.wt. orally] and rosiglitazone [3 mg / kg.b.wt.], alone or together for six weeks. Blood pressure, serum tumor necrosis factor- alpha [TNF- alpha], body weight [BW] and heart weight [HW] were measured. Malondialdehyde [MDA] and reduced glutathione [GSH] were estimated in cardiac tissues. Thoracic aorta was isolated and the aortic rings were allowed to achieve maximal tension by cumulative addition of phenylephrine [PE] [10[-9]-10[-5] M] to the bath solution. Fenofibrate and rosiglitazone, alone or together produced significant decreases in blood pressure and TNF- alpha. Higher oxidative stress accompanying hypertension was significantly reduced by fenofibrate and rosiglitazone treatment. The results showed that both drugs significantly attenuated the augmented contractile response to PE in hypertensive rats. In addition, they inhibited the cardiac hypertrophy [reduction in HW/BW ratio]. These data suggest that PPAR alpha and gamma activation contribute to normal regulation of blood pressure and exert protective actions in hypertension via inhibition of generation of free radicals

Electrochemical studies of glucose oxidase immobilized on glutathione coated gold nanoparticles.

Glutathione (L-gamma-glutamyl-L-cysteinyl-L-glycine; GSH) forms a surface monolayer on gold nanoparticles by tethering via sulfur bonds (Au:GSH). In the present study, glucose oxidase (GOx; EC 1.1.3.4) was immobilized by covalent chemical coupling reactions on to Au:GSH nanoparticles and the enzyme coupled nanoparticles formed a stable colloid (stable for several weeks) in water. The immobilized enzyme was investigated for electrochemical characteristics to monitor the FAD (prosthetic group of the GOx) redox potentials. Various concentrations of substrate (glucose) were added to check the oxidation characteristics. It was observed that with increase in substrate concentrations, the oxidation rate increased proportionally with the current. The present study demonstrated that GOx was effectively coupled to the gold nanoparticle (Au:GSH). The coupled nanoparticle system could be used in a potential biosensor application. Similarly, other enzymes (e.g., horseradish peroxidase) could be immobilized to the Au:GSH nanoparticles via the peptide arm (GSH) to achieve the desired characteristics needed for a specific application in biosensor.

Kinetics and mechanism of reduction of ferricytochrome c by glutathione and L-cysteine: a comparative study.

The kinetics and mechanism of the reduction of ferricytochrome c [Cyt c(III)] by substrates namely glutathione (GSH) and L-cysteine (L-cys) have been investigated spectrophotometrically employing [substrate]T > [Cyt c(III)]T. The reaction exhibits first order dependence in [substrate]T and [Cyt c(III)]T. The pseudo-first order rate constant increases with an increase in pH, indicating that the conjugate base form of the HCyt c(III) is a better oxidant than the parent HCyt c(III). The electron transfer rate constants between the oxidants and GSH for both the k1 and k2 paths are found to be greater than that with L-cysteine. Hence, GSH is a better reductant of Cyt c(III) as compared to L-cysteine. A suitable mechanism has been proposed on the basis of experimental findings. The deprotonation constant for HCyt c(III) and the second order rate constants of k1 and k2 paths for the present reaction at 25 degrees C have been determined.

Ultraestructura de la retinopatía causada por la hiperoxia en ratas en desarrollo / Ultra structure of retinopathy induced by hyperoxia in developing rats

In order to evaluate the effect of postnatal hyperoxia on retinal structure, newborn rats were exposed to different oxygenation intervals (80 ± 1%) with three interruptions of 21% (30 min each). Four groups of rats were exposed from birth to the 6th, 9th, 12th and 14th postnatal day, respectively and another group was placed under normoxia. After this period all oxygenated groups and the controls remained under normoxia until they were 30 days old for the structural analysis of retina. Retinal histology was carried out using conventional techniques for transmission electron microscopy (TEM). In the ganglion cell layer of the retina from rats exposed for 9 days to hyperoxia, capillaries with large projections toward the lumen, were observed as a possible consequence of cellular edema of endothelium. The most severe damage was observed in rats exposed to hyperoxia during 12 and 14 days, showing mitochondrias swollen up and without crests in the areas surrounding the capillaries, necrosis and apoptosis processes, dense bodies, cells with swollen cytoplasms and rupture of the plasmatic membrane. The results suggest that postnatal hyperoxia causes severe damages to the retina in developing rats with a direct relationship between the time exposed to oxygen and ultra structural damages.

Con el propósito de evaluar el efecto de la hiperoxia posnatal sobre la estructura retiniana se analizaron retinas de ratas recién nacidas expuestas a diferentes periodos de oxigenación (80 ±1%), con tres interrupciones de 21% (30 min c/u). Cuatro grupos de ratas fueron expuestas desde su nacimiento hasta el 6to, 9no, 12mo y 14to días de vida y otro grupo fue mantenido en normoxia. Después de este periodo tanto los grupos expuestos a la hiperoxia como los controles permanecieron en normoxia hasta una edad de 30 días para el análisis estructural de la retina. La histología se hizo usando técnicas convencionales para microscopía electrónica de transmisión (MET). En la capa de células ganglionares de la retina de ratas expuestas a nueve días de hiperoxia, se observaron capilares con notables proyecciones hacia la luz, posiblemente como consecuencia de edema celular del endotelio. El daño más intenso fue observado en las ratas expuestas a hiperoxia durante 12 y 14 días, mostrando mitocondrias hinchadas y sin crestas en las áreas circundantes a los capilares, procesos de necrosis y apoptosis, cuerpos densos, células con citoplasmas hinchados y con ruptura de la membrana plasmática. Los resultados sugieren que la hiperoxia posnatal causa graves daños a la retina en las ratas en desarrollo, con una relación directa entre el tiempo de exposición al oxígeno y los daños ultraestructurales.

Effect of cholesterol and 7-beta hydroxycholesterol on glutathione status and nitric oxide production in murine peritoneal macrophages.

Present study was conducted to observe the effect of cholesterol and oxidized cholesterol (7beta-hydroxycholesterol,7beta-OH) on the nitric oxide (NO) production and the redox ratio by lipopolysaccharide-stimulated macrophages. Dose-dependent decrease in NO levels was seen with both cholesterol and 7beta-OH at different incubation intervals (6,12,18,24 hr) and concentrations (2.5,5,7.5microg/ml). On comparison, a significant decrease in the NO was observed at 24 hr interval in 7beta-OH exposed cells with all respective concentrations of cholesterol. Incubation with 7beta-OH also resulted in significant increase in levels of oxidized glutathione (GSSG) and decrease in reduced glutathione (GSH), while cholesterol showed no effect on GSSG levels. Moreover, GSH levels were lowered only at highest concentration (7.5microg/ml), and at longer incubation intervals (18,24 hr) with cholesterol exposure. This altered the redox status in both cholesterol/7beta-OH treated macrophages. Increased redox ratio and decreased NO levels indicated increased oxidative stress and decreased vasodilation by 7beta-OH compared to cholesterol.

Complejos de vanadio (III) con glutatión en disolución acuosa / Vanadium (III) complexes with glutathione in aqueous solution

Se presentan los resultados del estudio de los complejos de vanadio(III) con glutatión (GSH, H3L) a 25 °C y en KCl3,0 M mediante medidas de fuerzas electromotrices, emf(H). El análisis de los datos mediante el programa de mínimos cuadrados generalizados LETAGROP indica la formación de cantidades significativas de los complejos VH4l4+, VH3L3+, V(H3L)23+ yv(L)(3L)2+, cuyas constantes de estabilidad fueron determinadas.

The formation of the vanadium(III) complexes with glutathione (GSH, H3L) was studied in 3.0 M KCl at 25 °C by means of electromotive forces measurements, emf (H). The analysis of the potentiometric data by means of the least-squares program LETAGROP indicates the formation of significant quantities of the complexes VH4l4+, VH3L3+, V(H3L)23+ yv(L)(3L)2+, whose stability constants were determined.