carlos ruben zayas - Academia.edu (original) (raw)

Papers by carlos ruben zayas

Journal of the American Society of Nephrology, 1999

Clinical transplantation, 2018

Racial disparities persist in access to kidney transplantation. Racial differences in preemptive ... more Racial disparities persist in access to kidney transplantation. Racial differences in preemptive referral, or referral prior to dialysis start, may explain this discrepancy. Patient-level data on kidney transplant referrals (2005-2012) from all Georgia transplant centers were linked to the United States Renal Data System to examine racial disparities in preemptive referral, waitlisting, and living donor transplant. Adjusted logistic regression and Cox proportional hazard models determined the associations between race (African American vs white) and preemptive referral, and placement on the waitlist and receipt of a living donor kidney, respectively. Among 7752 adults referred for transplant evaluation, 20.38% (n = 1580) were preemptively referred. The odds of African Americans being preemptively referred for transplant evaluation were 37% (OR = 0.63; [95% CI: 0.55 0.71]) lower than white patients. Among preemptively referred patients, there was no racial difference (African America...

BMC nephrology, Jan 15, 2018

The Reducing Disparities in Access to kidNey Transplantation Community Study (RaDIANT) was an End... more The Reducing Disparities in Access to kidNey Transplantation Community Study (RaDIANT) was an End-Stage Renal Disease (ESRD) Network 6-developed, dialysis facility-level randomized trial testing the effectiveness of a 1-year multicomponent education and quality improvement intervention in increasing referral for kidney transplant evaluation among selected Georgia dialysis facilities. To assess implementation of the RaDIANT intervention, we conducted a process evaluation at the conclusion of the intervention period (January-December 2014). We administered a 20-item survey to the staff involved with transplant education in 67 dialysis facilities randomized to participate in intervention activities. Survey items assessed facility participation in the intervention (fidelity and reach), helpfulness and willingness to continue intervention activities (sustainability), suggestions for improving intervention components (sustainability), and factors that may have influenced participation and...

Clinical transplantation, Jan 20, 2018

Clinical outcomes are generally worse for black vs nonblack renal allograft recipients. In BENEFI... more Clinical outcomes are generally worse for black vs nonblack renal allograft recipients. In BENEFIT and BENEFIT-EXT, recipients were randomized to belatacept more intense-based, belatacept less intense-based, or cyclosporine-based immunosuppression. At year 7, belatacept was associated with superior graft survival vs cyclosporine in BENEFIT (recipients of living or standard criteria deceased donor kidneys); belatacept was associated with similar graft survival vs cyclosporine in BENEFIT-EXT (recipients of extended criteria donor kidneys). In both studies, renal function was superior for belatacept-treated vs cyclosporine-treated patients. Seven-year outcomes were examined by race post hoc in each study. The effect of race and treatment on time to death or graft loss was compared using Cox regression. The interaction between treatment and race was also considered. Glomerular filtration rate (GFR) was estimated from months 1 to 84 using a repeated-measures model. In total, 8.3% (55/666...

Pedagogia Universitaria, 1996

Pedagogia Universitaria, 1997

Sugar Tech, 2008

For the first time both priming and biopriming approaches have been integrated into the sugarcane... more For the first time both priming and biopriming approaches have been integrated into the sugarcane micropropagation technology by temporary immersion bioreactors (TIBs). Sugarcane micropropagation in CO 2-rich TIBs induces a mixotrophic condition adequate for the production of natural phenolic metabolites. Scaling up has been conducted in the C86-56 and C90-317 commercial genotypes. While phenolics demonstrate to act as priming molecules during the in vitro culture, vitroplantlets growing and shooting in the presence of phenolic metabolites display an enhanced vigour (measure as plant size), emitted functional roots and increase adaptability to the natural environment. Additionally, when combined with the inoculation of the endophytic Gluconacetobacter diazotrophicus during transplanting, a significant improvement of the percentage of survival has been attached through this critical step. Altogether, results indicate a promising potential for diversification of the sugarcane micropropagation industry by the production of useful metabolites as byproducts.

Plant Science, 2012

The relation between the oxidative burst and phenylpropanoid pathways has been studied using the ... more The relation between the oxidative burst and phenylpropanoid pathways has been studied using the sugarcane cultivar C86-56, which does not release phenolics in agar-base micropropagation systems. In stationary liquid culture, a significant production of phenolic compounds and plant survival were determined in sugarcane plants treated with 5 mM H 2 O 2. The spectrophotometer determinations and the gene expression analysis corroborated that releasing of phenolics and soluble Â-quinones was induced during the first 24 h of treatment. In comparison with the control treatments, sugarcane plants treated with H 2 O 2 demonstrated differences in the micropropagation-related variables when multiplied in Temporary Immersion Bioreactors (TIBs) supplemented with polyethyleneglycol (PEG 20%). Expression of selected genes related to photosynthesis, ethylene, auxins, oxidative burst, and defense pathways were confirmed during the entire PEG 20% stress in the plants coming from the 5 mM H 2 O 2 treatment; whereas, much more heterogeneous expression patterns were evidenced in plants stressed with PEG but not previously treated with H 2 O 2. RT-PCR expression analysis supports the hypothesis that while H 2 O 2 induces the oxidative burst, the phenylpropanoids pathways elicit and maintain the defensive response mechanism in micropropagated sugarcane plants.

Plant Science, 2008

The genomic characterization of sugarcane plants has been achieved by suppressing key genes of th... more The genomic characterization of sugarcane plants has been achieved by suppressing key genes of the phenylpropanoid pathway; as a result, a new function of phenolic metabolites has been characterized during micropropagation in TIBs. Genes related to cell metabolism and development (10), plant defenses (9), phenylpropanoids (7), methyl jasmonate response (5), ethylene (5), oxidative burst (3) and, auxins (3) pathways, among others (8) were found to be induced in sugarcane plants micropropagating in TIBs with phenolic metabolites, supporting that phenylpropanoids might act as elicitor molecules of others biochemical pathways. During adaptation to natural conditions, plants micropropagated in TIBs with highest levels of phenolics displayed an increased number of functional roots, a high growth rate and, an early ability to be colonized by the natural sugarcane endophytic Gluconacetobacter diazotrophicus.

Kidney International, 1999

MK-591 acutely restores glomerular size selectivity and reduces disease (ESRD) [1]. Despite an in... more MK-591 acutely restores glomerular size selectivity and reduces disease (ESRD) [1]. Despite an increasing understanding proteinuria in human glomerulonephritis. of the pathogenetic mechanisms that mediate immune Background. Leukotrienes are 5-lipoxygenated (5-LO) meglomerular damage, the treatment of glomerulonephritis tabolites of arachidonic acid that mediate some of the glomeruis still unsatisfactory. The treatment of glomerulonephrilar hemodynamic and structural changes in experimental and tis with nonselective immunosuppression, mostly with human glomerulonephritis. Methods. We conducted an open-label, pilot study of the cytotoxic agents, has yielded encouraging results in some short-term effects of leukotriene biosynthesis inhibition using forms of glomerulonephritis such as lupus nephritis [2], an orally active 5-LO activating protein (FLAP) antagonist but is associated with significant morbidity [2-4]. In the (MK-591) on glomerular function in patients with glomerulonelast 10 to 15 years, there have been significant advances phritis. Eleven adult patients (seven women, median age 38 in the understanding of the pathogenesis of glomerular years) with glomerulonephritis (5 lupus nephritis, 2 IgA nephropathy, 1 membranoproliferative, 1 membranous, 1 C1qinflammation, mostly gathered from experimental moddeficiency, and 1 idiopathic crescentic) and moderate renal els [5-8]. In animals with experimentally induced glomerinsufficiency [glomerular filtration rate (GFR) 62 Ϯ 9 ml/min/ ulonephritis, an initial deposition of immune complexes 1.73 m 2 ] were given MK-591 at a dose of 100 mg orally twice in the glomerulus is followed by recruitment and activaa day for four days. Results. MK-591 reduced proteinuria (albumin and IgG ex-tion of blood polymorphonuclear leukocytes (PMNs), cretion rates) from 3233 Ϯ 1074 to 1702 Ϯ 555 g/min and followed by influx of lymphocytes, macrophages, and from 196 Ϯ 78 to 148 Ϯ 55 g/min for albumin and IgG, platelets. These in turn generate a cascade of immune respectively (P Ͻ 0.05 for both). This was not accompanied mediators-interleukins, prostanoids, complement, oxyby a reduction in systemic arterial pressure, GFR, or renal gen radicals, etc.-that promotes further cellular events plasma flow. By analysis of the fractional clearance of polydisperse dextrans, baseline proteinuria resulted from a loss of size Key words: leukotrienes, glomerular inflammation, dextran sieving, transglomerular protein trafficking. filtration rate (GFR). Furthermore, an acute blockade of LTD 4 in models of nephrotoxic serum nephritis [10],

Kidney International, 2001

Early glomerular dysfunction in human renal allografts. In the last two decades, major advances i... more Early glomerular dysfunction in human renal allografts. In the last two decades, major advances in immunosup-Background. The long-term outcome of renal allografts is pressive management have resulted in excellent (Ͼ90%) characterized by a progressive deterioration of renal function one-year survival of kidney transplants [1]. Despite this and graft loss. Our aim was to determine early glomerular funcsuccess in early graft survival, the long-term outcome of tional abnormalities, before they become clinically apparent. renal transplantation is characterized by renal dysfunc-Methods. Glomerular hemodynamics and dextran sieving were characterized in 21 well-functioning cadaveric renal allotion and graft loss. At ten years post-transplantation only graft recipients [normal glomerular filtration rate (GFR) and about 50% of cadaveric grafts are still functioning and albumin excretion rate (AER), who also had a kidney biopsy most of them have evidence of damage as assessed by with normal or minimal histological changes] and in 15 unina high serum creatinine [2, 3]. Histologically, the term ephrectomized kidney donors. Both groups were one to three chronic transplant nephropathy has been coined to charyears after transplantation or uninephrectomy. Results. The GFR and renal plasma flow (RPF) were similar acterize this loss of kidney function and is characterized in both groups (62 Ϯ 3 vs. 63 Ϯ 4, and 343 Ϯ 26 vs. 334 Ϯ by a combination of vascular, glomerular and tubulo-21 mL/min/1.73 m 2 for GFR and RPF, in cadaveric recipients

Journal of the American Society of Nephrology, 2006

Patients with sickle cell anemia (SCA) may develop a glomerulopathy with proteinuria and progress... more Patients with sickle cell anemia (SCA) may develop a glomerulopathy with proteinuria and progressive renal insufficiency, leading to ESRD. Albuminuria is a sensitive marker of glomerular damage in this population and precedes the development of renal insufficiency. For determination of the prevalence of glomerular damage in SCA and the clinical correlates of renal insufficiency, 300 adult patients with SCA were studied (hemoglobin SS ‫؍‬ 184; and 116 with other sickling hemoglobinopathies: SC, SD, and S-␤ thalassemia); albumin excretion rates (AER) and renal function (Cockroft-Gault formula) were determined, and clinical and hematologic evaluations were conducted. In hemoglobin SS disease, increased AER (micro-and macroalbuminuria) occurred in 68% of adult patients, and macroalbuminuria occurred in 26%. In other sickling disorders, increased AER occurs in 32% of adults, and macroalbuminuria occurs in 10%. The development of graded albuminuria was age dependent, so at 40 yr, 40% of patients with SS disease had macroalbuminuria. There were no differences in hematologic parameters (hemoglobin levels, white blood cell count, percentage of reticulocytes, platelet counts, or lactate dehydrogenase levels) between patients with normoalbuminuria and those with micro-or macroalbuminuria. By multivariate analysis, albuminuria correlated with age and serum creatinine in SS disease but not with BP or hemoglobin levels. In other sickling disorders, albuminuria tended to be associated with age but not with hemoglobin or BP levels. The diastolic BP was lower in patients with SCA than in African American control subjects, and the development of renal insufficiency, which was present in 21% of adults with SS disease, was not accompanied by significant hypertension. It is concluded that glomerular damage in adults with SCA is very common, and a majority of patients with SS disease are at risk for the development of progressive renal failure. The development of micro-and macroalbuminuria is not related to the degree of anemia, suggesting that sickle cell glomerulopathy is not solely related to hemodynamic adaptations to chronic anemia. In contrast to other glomerulopathies, the development of systemic hypertension is uncommon in SS disease with renal insufficiency.

In Vitro Cellular & Developmental Biology - Plant, 2010

The production of phenolic metabolites has been optimized in parallel to sugarcane micropropagati... more The production of phenolic metabolites has been optimized in parallel to sugarcane micropropagation in temporary immersion bioreactors (TIBs). Culturing micropropagated plants in 0.4% CO 2-rich air induced their photosynthetic activity by enhancing the change from a heterotrophic to a photomixotrophic metabolic stage. Under 0.4% CO 2 enrichment, the transcript levels of both phenylalanine ammonia-lyase (PAL EF189195) and ribulose-1,5-biphosphate carboxylase/oxygenase (Rubisco CF576750) increased and were correlated to a 4.6-and 6.3fold increase in the phenolic levels when plants were multiplied in 20 or 30 g/l sucrose, respectively. A novel application of plant phenolic metabolites as elicitors of resistance to tomato bacterial wilt in the Solanum lycopersicum-Ralstonia solanacearum pathosystem has been identified. The culture media was collected, and the phenolics were sprayed onto tomato plants infected with R. solanacearum, eliciting and/or maintaining an early defense signaling mechanism that resulted in the protection of the plant against the tomato bacterial wilt disease. RT-PCR analyses confirmed that selected genes from defense-related pathways were differentially expressed between plants treated with sugarcane metabolites, non-treated pathogenfree plants, and non-treated plants inoculated with R. solanacearum.