Renal physiological regenerative medicine to prevent chronic renal failure: should we start at birth?

With the incidence of end-stage renal disease increasing dramatically during the last ten years, its prevalence rising about 8% per year, chronic kidney disease (CKD) represents one of the most problematic public health problems worldwide. CKD represents a growing clinical problem that, in its terminal stages, requires renal replacement therapy. Kidney transplant has been proposed as the definitive therapy able to address the growing clinical, social and economic problems related to the increasing prevalence of end-stage kidney disease (ESKD). Traditional stem cell-based regenerative medicine, when applied to kidneys disrupted by end-stage renal disease, has been shown to be unable to regenerate the damaged organ. The theme of this work is to hypothesize a new approach to the prevention of CKD, based on the management of the huge amount of stem/progenitor cells physiologically present in the kidney of preterm babies at birth. Here a new concept of primary prevention of renal disease is suggested: a true primary prevention, starting in the perinatal period aimed at increasing the number of functioning glomeruli. This approach has been defined as "physiological regenerative medicine", in order to underline the use of physiological tools, including endogenous renal stem cells and stem cell stimulators physiologically expressed in our cells.

Paratiroidectomía en pacientes renales crónicos en Argentina: estudios prequirúrgicos, tipos de cirugía, recurrencia y persistencia / Parathyroidectomy in chronic kidney disease patients in Argentina: pre surgical studies, types of surgery, recurrence and persistence

La paratiroidectomía (PTx) es el tratamiento de elección en pacientes con HPT 2º severo, refractario al tratamiento médico. Se cuenta con muy poca información en Argentina de este procedimiento, por lo cual se realizó este estudio. Material y Métodos: Se incluyeron 255 pacientes con PTx entre el año 2003 al 2007 de un registro voluntario. Se evaluaron los estudios de localización prequirúrgicos, de laboratorio de metabolismo fosfocálcico previo y posterior a la cirugía y el tipo de técnica quirúrgica utilizada. Se analizó la persistencia y recidiva del HPT postcirugía. Resultados: La tasa de PTx fue de 2,7/1000 pacientes año. 83% de los pacientes tuvieron ecografía de cuello y 59% Sesta Mibi con Tc 99. Hubo una correlación positiva (p<0.001) entre el número de glándulas detectadas por ecografía y Sesta Mibi. La paratiroidectomía realizada fue: subtotal en 77%, total con autoimplante en 14% y total sin autoimplante en 9%. Hubo descensos significativos de Ca y P, fosfatasa alcalina y PTH (1744 ± 788 pg/ml a 247 ±450 pg/ml; p<0.0001) postcirugía. A los 2,4 ±2,5 meses de la PTx, el 72% de los pacientes tenía PTH <250 pg/ml, 19,8% tenía persistencia y 8,3% había recidivado. De acuerdo al tipo de cirugía la persistencia y recidiva fueron para PTx subtotal 22% y 8,3%, PTx total con implante 11% y 11% y PTx total sin autoimplante 13% y 4% respectivamente. La realización de Sesta Mibi no influyó en los resultados de la PTx. No se observaron diferencias entre los centros en relación con persistencia y recidiva. Conclusiones: La tasa de PTx fue muy baja, la ecografía fue el método de localización prequirúrgico preferido y la PTX subtotal la técnica quirúrgica más utilizada. La PTx fue exitosa en la mayoría de los pacientes y la persistencia y recidiva no estuvieron relacionadas con la técnica.

Parathyroidectomy (PTx) is the selecte treatment for patients with severe secondary hyperparathyroidism, refractory to medical treatment. There is not enough information about this procedure in Argentina, that is the reason why we performed this study. Material and Methods: 255 patients with PTx were included from the year 2003 to 2007 on a voluntary register. Studies of pre-surgical localization, phosphocalcic metabolism laboratories before and after surgery were evaluated, and the type of surgical technique used. The persistence and recurrence of post-surgical hyperparathyroidism was analyzed. Results: The PTx rate was 2,7/1000 patients year. 83% of the patients had neck echography and 59% Sestamibi scans with Tc 99. There was a positive correlation (p<0,001) between the number of detected glands by echography and Sestamibi. The parathyroidectomy performed was: subtotal in 77%, total with self-implant in 14% and total without self-implant in 9%. There were significant falls of Ca and P, Alkaline Phosphatase and PTH (1744±788 pg/ml to 247±450 pg/ml; p<0.0001) post-surgical. 2.4 ±2,5 months after the PTx, 72% of patients had PTH <250 pg/ml, 19,8% had persistence and 8,3% had recurrence. According to the type of surgery, the persistence and recurrence were for subtotal PTx 22% and 8,3%, total PTx with implant 11% and 11%, and total PTx without selfimplant 13% and 4% respectively. The performance of the Sestamibi scan did not affect the PTx results. No noticeable differences were observed among the centers for persistence and recurrence. Conclusions: The PTx rate was very low, echography was the preferred method of pre-surgical localization, and subtotal PTx was the most used surgical technique. PTx was successful in most of the patients, and persistence and recurrence were not related to the technique.

Hipovitaminosis D en pacientes hemodiálizados (HD): factores relacionados e influencia sobre la fuerza muscular / Hypovitaminosis D in patients on hemodialysis (HD): related factors and influence on muscle strength

Introducción: La deficiencia de 25 (OH) vitamina D es una alteración prevalente en los pacientes con enfermedad renal crónica (ERC) , sin embargo en nuestro medio no es medida de manera rutinaria y por ende no suele hacerse reposición vitamínica. Nuestro objetivo fue determinar la prevalencia y los factores relacionados a deficiencia de 25 (OH) D en pacientes con ERC en hemodiálisis (HD), particularmente la relación con la función y masa muscular. Métodos: Efectuamos un estudio prospectivo, multicéntrico, en pacientes adultos en HD crónica que no estuvieran recibiendo ningún derivado de la vitamina D. Se midieron en sangre los niveles de 25(OH) D, Hemoglobina, PCR, Albúmina, Ca, P, FAL, PTHi. Se realizó la medición de la fuerza del puño con dinamómetro, y la prueba de sentado-parado. Se aplicó el índice de Karnofsky para clasificar el estado funcional., Se realizó una bioimpedanciometría (BCM; Frese nius Medical Care) en aquellos pacientes sin, contraindicación. Resultados: Se incluyeron 138 pacientes. La 25(OH) vitamina fue de 20.43 ± 10.5 ng/ml, la prevalencia de insuficiencia /defi ciencia 87% (37% con menos de 15 ng/ml). Las concentraciones de vitamina D/deficiencia mostraron correlación/relación significativa con la edad, la presencia de diabetes, los niveles de hemoglobina y albúmina, la fuerza y la masa muscular y la clase funcional (p<0.05) . Conclusión: Alta prevalencia de hipovitaminosis D en pacientes hemodializados particularmente gerontes y diabéticos. Esto estaría relacionado con la desnutrición, anemia, clase funcional y la fuerza/masa muscular de los pacientes, estos últimos dos factores no reportados hasta ahora. Todos estos factores deben ser considerados al momento de la sustitución vitamínica y en la evaluación de la efectividad de la misma.

Background: 25 (OH) vitamin D deficiency is a prevailing alteration in patients with chronic kidney disease (CKD); however, in our environment, it is not routinely measured and, therefore, vitamin replacement is unusual. Our purpose was assessing the prevalence of and the factors related to 25 (OH) vitamin D deficiency in patientswith CKD in hemodialysis (HD), especially the relation to function and muscle mass. Methods: We conducted a prospective, multicenter study in adult patients on chronic HD who were not receiving any vitamin D derivative. Blood levels of 25 (OH) D, Hemoglobin, CRP, Albumin, Ca,P, ALP and PTHi were measured. The handgrip strength was measured with a dynamometer and the sitting-rising test was carried out. A bioimpedance analysis (BCM; Fresenius Medical Care) was conducted in the patients who had no contraindications. Results: 138 patients were included. The levels of 25 (OH) vitamin D were 20.43±10.5 ng/ml; the insufficiency/deficiency had 87% prevalence (and 37% prevalence with less than 15 ng/ml). Vitamin D concentrations/ deficiency showed a significant correlation with/ relation to age, diabetes, hemoglobin and albumin levels, muscle strength and mass, and functional class (p<0.05). Conclusion: High prevalence of hypovitaminosis D in patients on hemodialysis, particularly in the elderly and in patients with diabetes. This should be related to undernutrition, anemia, the functional class and the muscle strength/mass of patients, the latter two being unreported factors until now. All these factors should be considered when vitamin replacement is conducted and when its effectiveness is assessed.

Protooncogene methylation and expression in regenerating liver and preneoplastic liver nodules induced in the rat by diethylnitrosamine: effect of variations of S-adenosylmethionine:S-adenosylhomocysteine ratio.

S-adenosylmethionine:S-adenosylhomocysteine (SAM/SAH) ratio, 5-methylcytosine (5mC) DNA content, and methylation and expression of c-myc, c-Ha-ras and c-Ki-ras have been studied in liver nodules, induced by diethylnitrosamine according to the 'resistant hepatocyte' model, and in regenerating liver (RL) between 0.5 and 72 h after partial hepatectomy (PH). Nodules, 11, 13 and 21 weeks after initiation, grew actively, showed a low tendency to remodel (persistent nodules), and did not exhibit carcinomatous changes. They underwent extensive remodeling after a 1-week SAM treatment (64 mumol/kg/day), and decreased in size and number after a 3-11-week treatment. A low SAM/SAH ratio was coupled, in nodules, with a high labeling index (LI), 2-fold fall in 5mC DNA content, increase in c-myc, c-Ha-ras and c-Ki-ras expression and hypomethylation of CCGG sequences in the DNA hybridizing with the three protooncogenes. In RL a low SAM/SAH ratio, overall DNA hypomethylation and enhanced c-myc expression were first observed 0.5 h after PH, reached a peak at 5 h and progressively returned to pre-PH levels later on. Maximum expression of c-Ha-ras and c-Ki-ras occurred 24-30 h after PH, roughly coincident with the LI peak. However, no great modifications of the methylation pattern of protooncogene CCGG sequence occurred at any time after PH, indicating the presence of hypomethylated genes and/or DNA sequences different from those investigated in this paper. SAM injection to nodule-bearing rats, for 1-11 weeks before killing, and to hepatectomized rats, 2 days before PH and then up to killing, largely prevented decrease in the SAM/SAH ratio and overall DNA methylation and inhibited LI and protooncogene expression. In nodules these effects were proportional to the treatment length and coupled with methylation of CpG residues in the CCGG sequence of the three protooncogenes studied. SAM treatment left the methylation pattern of these genes unchanged in RL. Kinetics of increase in protooncogene expression suggest a role in the regulation of cell cycle in RL. However, decrease in the SAM/SAH ratio, protooncogene hypomethylation and enhanced expression are apparently stable in nodules 11-21 weeks after initiation and could be implicated in continuous nodule growth and progression. Control of DNA methylation and gene expression by exogenous SAM could be a mechanism of the SAM anti-progression effect.

Inhibition of promotion and persistent nodule growth by S-adenosyl-L-methionine in rat liver carcinogenesis: role of remodeling and apoptosis.

The resistant hepatocyte model (initiation/selection) and the triphasic model (initiation/selection followed by phenobarbital, for a maximum of 16 weeks) were compared for their ability to generate enzyme-altered foci (EAF) and nodules in the liver of Wistar rats initiated by diethylnitrosamine. The effects of S-adenosyl-L-methionine (SAM) on the development of preneoplastic tissue was tested in these experimental models. In the absence of phenobarbital (PB), EAF and early nodules (EN) went through a phase of rapid growth, between 4 and 9 weeks after initiation, to a phase in which progressive decrease in number and size occurred. By the 26th week only a few remodeling EAF and nodules were found. In PB-treated rats a rapid increase in the percentage of liver occupied by EAF and EN, up to the 9th week after initiation, was followed by a period of slow growth (from the 9th to the 20th week) and then, after PB withdrawal (20th week), by a drop in the number and size of EAF and EN. However, at the 26th week actively growing nodules with a low tendency to spontaneous remodeling (persistent nodules) developed. EAF and EN showed a high DNA synthesis 5 weeks after initiation. Thereafter, progressive decline in DNA synthesis, coupled with remodeling and decrease in number of biochemical markers, was seen both in the absence and, even though to a lesser extent, in the presence of PB, indicating that preneoplastic lesions became increasingly insensitive to PB. Relatively few apoptotic bodies could be observed in EAF and EN during PB treatment. After PB withdrawal, decrease in growth potential was coupled with increase in apoptotic bodies. In contrast, in persistent nodules relatively high apoptosis occurred which partially counterbalanced high DNA synthesis. Administration of SAM for a maximum of 16 weeks, starting at the 4th week after initiation, caused a great decrease in number and size of EAF and EN, associated with inhibition of DNA synthesis, high cell death by apoptosis, high remodeling, and loss of biochemical markers, in preneoplastic lesions of both PB-treated and untreated rats. A 1-8-week SAM treatment, started after the development of persistent nodules, caused a great regression of nodular lesions, coupled with a sharp fall in DNA synthesis and increase in apoptosis. It is suggested that inhibition by SAM of the development of preneoplastic tissue is linked to a shift of the equilibrium between cell production and cell death in favor of cell death.(ABSTRACT TRUNCATED AT 400 WORDS)

Reversal by ribo- and deoxyribonucleosides of dehydroepiandrosterone-induced inhibition of enzyme altered foci in the liver of rats subjected to the initiation--selection process of experimental carcinogenesis.

The effect of dehydroepiandrosterone (DHEA) on the activity of NADPH-producing enzymes and the development of enzyme-altered foci has been investigated in the liver of female Wistar rats subjected to an initiating treatment (a necrogenic dose of diethylnitrosamine) followed, 15 days later, by a selection treatment [a 15-day feeding of a diet containing 0.03% 2-acetylaminofluorene (2-AAF), with a partial hepatectomy at the midpoint of this feeding]. At the end of the selection treatment all rat groups received, for 15 days, a basal diet containing, when indicated, 0.05% phenobarbital (PB) and/or 0.6% DHEA. The effect of DHEA on the activity of NADPH-producing enzymes was also studied in normal rats fed, for 15 days, a diet containing 0.6% DHEA and in their pair-fed controls. DHEA caused a 43-58% inhibition of glucose-6-phosphate dehydrogenase (G6PD) and, respectively, 338-420% and 21-24% increases in malic enzyme (ME) and isocitric dehydrogenase activities in all rat groups. This was coupled with a great fall in the production of ribulose-5-phosphate, while no change in NADP+/NADPH ratio occurred. Hepatocytes, isolated from DHEA-treated rats, exhibited a very low activity of hexose monophosphate shunt (HMS), which was not stimulated by methylene blue, an exogenous oxidizing agent that markedly stimulated HMS activity in control hepatocytes. DHEA caused a great fall in the percentage of liver occupied by gamma-glutamyltranspeptidase (GGT)-positive foci, in the rats subjected to the initiation-selection treatments. PB enhanced the development of these foci, an effect which was completely overcome by DHEA. In addition, focal cells no longer expressed a G6PD activity higher than that of surrounding liver in DHEA-treated rats, but exhibited a high histochemical reaction for ME. DHEA also caused a great fall in labelling index of GGT-positive foci. Starting at the end of 2-AAF feeding, a mixture of ribonucleosides (RNs) of adenine, cytosine, guanine and uracil and of deoxyribonucleosides (DRNs) of adenine, cytosine, guanine and thymine were injected i.p. every 8 h for 12 days to the rats subjected to the initiation-selection treatments plus PB. Rats were killed 3 days after the end of RN and DRN treatments. These treatments completely overcome the DHEA effect on the development of GGT-positive foci and DNA synthesis by the focal cells, without affecting G6PD activity of both whole liver and putative preneoplastic foci. Experiments with labeled nucleosides revealed that RNs and DRNs produced derivatives that were incorporated into liver DNA.(ABSTRACT TRUNCATED AT 400 WORDS)