Nutritional management in renal transplant recipients: A transplant team opportunity to improve graft survival

AIMS

The nutritional management of renal transplant recipients (RTR) represents a complex problem either because the recovery of renal function is not complete and for the appearance of "unavoidable" metabolic side effects of immunosuppressive drugs. Nevertheless, it remains a neglected problem, whereas an appropriate dietary intervention could favorably affect graft survival.

DATA SYNTHESIS

Renal transplantation is associated with steroids and calcineurin inhibitors administration, liberalization of diet after dialysis restrictions, and patients' better quality of life. These factors predispose, from the first months after surgery, to body weight gain, enhanced post transplant diabetes, hyperlipidemia, metabolic syndrome, with negative consequences on graft outcome. Unfortunately, specific guidelines about this topic and nutritional counseling are scarce; moreover, beyond the low adherence of patients to any dietary plan, there is a dangerous underestimation of the problem by physicians, sometimes with inadequate interventions. A prompt and specific nutritional management of RTR can help prevent or minimize these metabolic alterations, mostly when associated with careful and repeated counseling.

CONCLUSIONS

A correct nutritional management, possibly tailored to enhance patients' motivation and adherence, represents the best preventive maneuver to increase patients' life and probably improve graft survival, at no cost and with no side effects.

The impact of a nutritional intervention based on egg white for phosphorus control in hemodialyis patients

BACKGROUND AND AIMS

Here we describe a dietary intervention for hyperphosphatemia in dialysis patients based on the partial replacement of meat and fish, which are one of the main sources of alimentary phosphorous, with egg white, a virtually phosphorous-free protein source. This intervention aims to reduce phosphorous intake without causing protein wasting.

PATIENTS AND METHODS

As many as 23 hyperphosphatemic patients (15 male and 8 female, mean age 53.0 ± 10.0 years) on chronic standard 4 h, three times weekly, bicarbonate hemodialysis were enrolled in this open-label, randomized controlled trial. Patients in the intervention group were instructed to replace fish or meat with egg white in three meals a week for three months whereas diet was unchanged in the control group.

RESULTS

Serum phosphate concentrations were significantly lower in the intervention group than in controls after three (4.9 ± 1.0 vs 6.6 ± 0.8; p < 0.001) but not after one month of treatment. Phosphate concentrations decreased more from baseline in the intervention than in the control group both after one (-1,2 ± 1,1 vs 0,5 ± 1,1; p = 0.004) and after three (-1,7 ± 1,1 vs -0,6 ± 1,1; p < 0.001) months of follow-up. No change either in body weight or in body composition assessed with bioelectrical impedance analysis or in serum albumin concentration was observed in either group.

CONCLUSION

The partial replacement of meat and fish with egg white induces a significant decrease in serum phosphate without causing protein malnutrition and could represent a useful instrument to control serum phosphate levels in hemodialysis patients. CLINICALTRIALS.

GOV IDENTIFIER

NCT03236701.

Dietary phosphate restriction in dialysis patients: a new approach for the treatment of hyperphosphataemia

BACKGROUND AND AIM

Elevated serum phosphate and calcium-phosphate levels play an important role in the pathogenesis of vascular calcifications in uraemic patients and appear to be associated with increased cardiovascular mortality. We aimed to evaluate the effects of a partial replacement of food protein with a low-phosphorus and low-potassium whey protein concentrate on phosphate levels of dialysis patients with hyperphosphataemia.

METHODS AND RESULTS

Twenty-seven patients undergoing chronic haemodialysis were studied for a 3-month period. In the intervention group (n = 15), food protein were replaced by 30 or 40 g of low-phosphorus and low-potassium protein concentrate aimed at limiting the phosphate intake. In the control group (n = 12) no changes were made to their usual diet. Anthropometric measurements, biochemical markers and dietary interviews were registered at baseline and during the follow-up period. From baseline to the end of the study, in the intervention group, serum phosphate and circulating intact parathyroid hormone levels lessened significantly (8.3 ± 1.2 mg/dL vs 5.7 ± 1.4 mg/dL and 488 ± 205 pg/ml vs 177 ± 100 pg/ml respectively; p < 0.05) with decreasing of phosphate and potassium intake. No significant differences were found in the control group. No significant changes were observed in serum albumin, calcium, potassium, Kt/V, body weight and body composition in both the intervention and control groups.

CONCLUSION

Dietary intake of phosphate mainly comes from protein sources, so dietary phosphorus restriction may lead to a protein/energy malnutrition in a dialysis patient. A phosphorus-controlled diet plan including a nutritional substitute resulted in serum phosphate and intact parathyroid hormone decrease without nutritional status modifications in dialysis patients.

The ascidian homolog of the vertebrate homeobox gene Rx is essential for ocellus development and function

The tadpole larvae prosencephalon of the ascidian Ciona intestinalis contains a single large ventricle, along the inner walls of which lie two sensory organs: the otolith (a gravity-sensing organ) and the ocellus (a photo-sensing organ composed of a single cup-shaped pigment cell, about 20 photoreceptor cells, and three lens cells). Comparison has been drawn between the morphology and physiology of photoreceptor cells in the ascidian ocellus and the vertebrate eye. The development of vertebrate and invertebrate eyes requires the activity of several conserved genes and it is regulated by precise expression patterns and cell fate decisions common to several species. We have isolated a Ciona homeobox gene (Ci-Rx) that belongs to the paired-like class of homeobox genes. Rx genes have been identified from a variety of organisms and have been demonstrated to have a role in vertebrate eye formation. Ci-Rx is expressed in the anterior neural plate in the middle tailbud stage and subsequently in the larval stage in the sensory vesicle around the ocellus. Loss of Ci-Rx function leads to an ocellus-less phenotype that shows a loss of photosensitive swimming behavior, suggesting the important role played by Ci-Rx in basal chordate photoreceptor cell differentiation and ocellus formation. Furthermore, studies on Ci-Rx regulatory elements electroporated into Ciona embryos using LacZ or GFP as reporter genes indicate the presence of Ci-Rx in pigment cells, photoreceptors, and neurons surrounding the sensory vesicle. In Ci-Rx knocked-down larvae, neither basal swimming activity nor shadow responses develop. Thus, Rx has a role not only in pigment cells and photoreceptor formation but also in the correct development of the neuronal circuit that controls larval photosensitivity and swimming behavior. The results suggest that a Ci-Rx "retinal" territory exists, which consists of pigment cells, photoreceptors, and neurons involved in transducing the photoreceptor signals.

IGF-II/IGF-I receptor pathway up-regulates COX-2 mRNA expression and PGE2 synthesis in Caco-2 human colon carcinoma cells

Nonsteroidal anti-inflammatory drugs reduce the risk of colon cancer and this effect is mediated in part through inhibition of type 2 prostaglandin endoperoxide synthase/ cyclo-oxygenase (COX-2). In the present study, we demonstrate that COX-2 expression and PGE2 synthesis are up-regulated by an IGF-II/IGF-I receptor autocrine pathway in Caco-2 colon carcinoma cells. COX-2 mRNA and PGE2 levels are higher in proliferating cells compared with post-confluent differentiated cells and in cells that constitutively overexpress IGF-II. Up-regulation of COX-2 expression by IGF-II is mediated through activation of IGF-I receptor because: (i) treatment of Caco-2 cells with a blocking antibody to the IGF-I receptor inhibits COX-2 mRNA expression; (ii) transfection of Caco-2 cells with a dominant negative IGF-I receptor reduces COX-2 expression and activity. Also, the blockade of the PI3-kinase, that mediates the proliferative effect of IGF-I receptor in Caco-2 cells, inhibits IGF-II-dependent COX-2 up-regulation and PGE2 synthesis. Moreover, COX-2 expression and activity inversely correlate with the increase of apoptosis in parental, IGF-II and dominant-negative IGF-I receptor transfected cells. This study suggests that induction of proliferation and tumor progression of colon cancer cells by the IGF-II/IGF-I receptor pathway may depend on the activation of COX-2-related events.

Surfactant-induced leakage from liposomes: a comparison among different lecithin vesicles

The interactions, at sublytic concentration, of Triton X-100 and sodium cholate with sonicated and extruded liposomes of egg and soya lecithins were considered to analyze the integrity and/or the barrier efficiency of liposomal membranes. Results are discussed in terms of surfactant partition between the aqueous and the lipid phases and of the release of a fluorescent hydrophilic probe. Phospholipid nature and liposome size influence detergent partition, whereas the content release is mainly affected by the surfactant mole fraction in the bilayer, and by the liposome size.

Cell cycle block at G1-S or G2-M phase correlates with differentiation of Caco-2 cells: effect of constitutive insulin-like growth factor II expression

BACKGROUND & AIMS

We have previously shown that autocrine insulin-like growth factor (IGF)-II synthesis through IGF-I receptor stimulates proliferation and inhibits differentiation of Caco-2 cells. To demonstrate whether differentiation of Caco-2 cells is dependent on cell growth status, we analyzed the effect of cell cycle arrest on differentiation of wild-type and IGF-II-overexpressing cells.

METHODS

Cells were treated with drugs that inhibit the progression either to S phase (l-b-D-arabinofuranosylcytosine or M phase (nocodazole). Cell differentiation was analyzed by assessing apolipoprotein A-1 and sucrase-isomaltase expression. Cell proliferation and DNA content were assessed by thymidine incorporation and fluorescence-activated cell sorter analysis, respectively. Cell cycle regulatory molecules were analyzed by assessing p21 and retinoplasma protein (pRb) expression and pRb phosphorylation.

RESULTS

Cell cycle block at G1-S phase was associated with increased expression of differentiation markers in both parental and IGF-II-transfected cells. On the contrary, cell cycle arrest at G2-M phase correlated with the expression of differentiation markers in parental but not in IGF-II-transfected cells. Constitutive IGF-II-expressing cells actively incorporated thymidine and showed an increase in the proportion of cells with >4N DNA ploidy in the presence of nocodazole. Nocodazole treatment of constitutive IGF-II-expressing cells stimulated p21 expression in the presence of hyperphosphorylated pRb.

CONCLUSIONS

The data show that cell cycle arrest increases differentiation of Caco-2 cells. IGF-II-mediated proliferation may prevent cell differentiation through effects on control cell checkpoint proteins.

Effects of surfactants on the spectral behaviour of calcein (II): a method of evaluation

The spectral behavior of calcein, a water-soluble self quenching fluorescent marker often used in biomedical analysis, can be considerably affected by the presence of surfactants. With this study we intend to obtain further information on the photophysical properties of calcein, in the presence of surfactants and in the concentration range commonly used to investigate the release of such marker from vesicle dispersions. The experiments were carried out both in water and in a physiological buffer (HEPES, pH 7.5), in the presence of Triton X-100, sodium dodecyl sulphate and centyltrimethylammonium bromide, both below and above their critical micelle concentration (c.m.c.). The obtained results confirm that calcein fluorescence can be affected by the presence of surfactants. Thus, environmental conditions must always be carefully checked for the actual quantitative evaluation of this dye. Furthermore, this study sheds some light on the nature and mechanism of calcein quenching.

Helicobacter pylori up-regulates cyclooxygenase-2 mRNA expression and prostaglandin E2 synthesis in MKN 28 gastric mucosal cells in vitro

Helicobacter pylori has been suggested to play a role in the development of gastric carcinoma in humans. Also, mounting evidence indicates that cyclooxygenase-2 overexpression is associated with gastrointestinal carcinogenesis. We studied the effect of H. pylori on the expression and activity of cyclooxygenase-1 and cyclooxygenase-2 in MKN 28 gastric mucosal cells. H. pylori did not affect cyclooxygenase-1 expression, whereas cyclooxygenase-2 mRNA levels increased by 5-fold at 24 h after incubation of MKN 28 cells with broth culture filtrates or bacterial suspensions from wild-type H. pylori strain. Also, H. pylori caused a 3-fold increase in the release of prostaglandin E2, the main product of cyclooxygenase activity. This effect was specifically related to H. pylori because it was not observed with Escherichia coli and was independent of VacA, CagA, or ammonia. H. pylori isogenic mutants specifically lacking picA or picB, which are responsible for cytokine production by gastric cells, were less effective in the up-regulation of cyclooxygenase-2 mRNA expression and in the stimulation of prostaglandin E2 release compared with the parental wild-type strain. This study suggests that development of gastric carcinoma associated with H. pylori infection may depend on the activation of cyclooxygenase-2-related events.

Effect of aspirin on cell proliferation and differentiation of colon adenocarcinoma Caco-2 cells

Several lines of evidence suggest that long-term treatment with non-steroidal anti-inflammatory drugs may reduce the risk of colon cancer and the size and number of colonic polyps in patients with familial adenomatous polyposis. Aspirin has also been shown to inhibit cell proliferation in human tumor cell lines and to induce apoptosis in colonic mucosa of familial polyposis patients. To elucidate the molecular mechanisms of the antiproliferative action of aspirin, we studied the effects of aspirin on cell growth and differentiation of the human colon carcinoma Caco-2 cell line. These cells represent a useful tool for studying the mechanisms involved in the regulation of cell growth and differentiation of intestinal epithelial cells since they spontaneously differentiate into polarized cells, expressing brush border enzymes. We show in this study that aspirin (0.1-10 mM) induces a profound inhibition of cell replication as assessed either by cell counts or thymidine incorporation. Moreover, aspirin concentrations of 5 and 10 mM induce apoptosis, whereas concentrations of 1 and 2 mM do not. The inhibition of growth is associated with a dose-dependent reduction in insulin-like growth factor II mRNA expression and with an increase in sucrase activity (a brush border enzyme) and apolipoprotein A-I mRNA expression, 2 specific markers of the differentiative status of this cell line. Our data thus show that aspirin-dependent inhibition of cell growth is associated with the enterocyte-like differentiation of Caco-2 cells.

Effects of surfactants on the spectral behaviour of calcein

The spectral behaviour of calcein, a water-soluble self-quenching molecule that is often used as a marker in biomedical analysis, can be considerably affected by the presence of surfactants. The aim of this work was to investigate the spectral properties of calcein under conditions that are particularly significant in liposome studies. For this purpose the fluorescence and absorbance of this dye were determined in solutions of ionic and non-ionic surfactants (cetyltrimethylammonium bromide, sodium dodecyl sulphate and Triton X-100), at different concentrations below and above their critical micelle concentrations (c.m.c.) as well as in the presence of phospholipids in the form of liposomes and/or mixed micelles. Cationic surfactants induced changes in lambda max, absorbance and fluorescence but these changes were less noticeable in the phospholipid dispersions. The anionic and the non-ionic surfactants induced mainly changes in fluorescence intensity.

Hepatitis B virus infection among health care workers at an urban teaching hospital in southern Italy: a low occupational hazard?

A prevalence study of HBV serologic markers was carried out among hospital employees of ten departments of the Second School of Medicine in Naples, an urban area with a high prevalence of HBV infection. Departments and occupational categories were selected to represent a spectrum of different exposure to B virus infection. Workers in a large electronic plant in the same geographical area were screened as controls. HBsAg prevalence was 4.8% in the hospital community and 4.0% in control group. It rises to 4.3% in the Campania Region, where all screened workers live, and in some specific areas of the same region it rises to 12%. But no significant difference among seropositivities for at least 1 marker of HBV, considered to be a better indicator of occupational hazard, was found among personnel of different departments or belonging to different occupational categories. None of the occupational and non-occupational risk factors studied was found to be significantly associated with HBV infection. Two years later, an incidence study was carried out among susceptible subjects. Seropositivity for 1 marker was 2.2% among hospital workers and 2.8% in the control group. These figures are lower than the annual attack rate (5%) required for an acceptable cost-benefit ratio of vaccination against hepatitis B. Our results indicate that in a geographical area with HBV endemicity the occupational hazard for B virus infection is low in hospital workers because of the high number of the high number of immunized subjects and the contacts with infected people out of the hospital.

Prevention of molecular self-association by sodium salicylate: effect on insulin and 6-carboxyfluorescein

The effect of sodium salicylate on the concentration-dependent self-association of insulin and 6-carboxyfluorescein (CF), as expressed by metachromasy, fluorescence, and changes in aqueous solubility, was learned. By decreasing the CF concentration from 12 to 0.48 microgram.ml-1, lambda max peaks shift from the shorter wavelengths (451, 474 nm), indicating the presence of oligomers, toward the monomer wavelength region (484 nm). Sodium salicylate shifts the peaks of a 12 micrograms.mL-1 CF solution towards the monomer region, eliminating the peak at the lower wavelengths and generating a spectrum with one peak at 490 nm, the effect being concentration dependent. The fluorescence of insulin and CF solutions increases with their concentration. Quenching of these solutions was observed, up to complete elimination of fluorescence, when various concentrations of salicylate were added. The water solubility of both molecules, CF and insulin, was considerably increased with the addition of increasing concentrations of salicylate to the solutions: at 37 degrees C, 2.5 M sodium salicylate solution increases the CF solubility 532 times from 12.2 to 6.5 mg.mL-1, and 1.5 M salicylate increases the solubility of insulin 7875 times, thus an aqueous solution containing 630 mg.mL-1 of insulin may be prepared. The results obtained here, together with our previously reported data, indicate that the interference between sodium salicylate and drug self-association behavior, by increasing drug solubility, may substantially contribute to the improved drug bioavailability mediated by salicylate.

Cholic acids/salts as barriers to diffusing species: effect of pH

Bile acids have been absorbed on a microporous polypropylene membrane and the diffusion of ionic and non-ionic compounds through the barriers obtained has been studied at different pH values. Results indicate that permeation rates are affected by environmental pH conditions and an explanation of this behaviour is proposed. This study represents an approach for a pH-controlled drug delivery system.