[Liver and intestinal transplant in paediatric population]

Our organizational model allows an annual 1,000 liver transplants. Pediatric liver transplantation constitutes 5% of such activity and provides, in children with severe, progressive and irreversible liver disease, a 1 year-survival of 90% and more than 80% after 15 years of follow-up. The main indication is biliary atresia followed by metabolic liver disease and acute liver failure. Around half of the procedures are performed in children under two years and 25-30% in the first year of life. The waiting list remains at around 35 patients, with an average of 100 patients enrolled annually and 60 of them finally transplanted after an average of 136.3 days on the waiting list. The prioritization of the candidates uses the PELD as an objective tool for decision-making. However, the progressive aging of donors, with a profile increasingly different from the requirements of the pediatric patients included in the waiting list, requires strategies such as living donor liver transplantation and the split liver transplantation, to increase the probability of transplant while reducing both time and mortality on the waiting list at the same time. Pediatric intestinal transplantation registers a low indication but involves strict requirements that outline a very uncommon donor in our country which, together with the absence of alternatives that outweigh the impact of these difficulties, penalizes the chances of transplant for these patients.

Benchmarking in the process of donation after brain death: a methodology to identify best performer hospitals

A benchmarking approach was developed in Spain to identify and spread critical success factors in the process of donation after brain death. This paper describes the methodology to identify the best performer hospitals in the period 2003-2007 with 106 hospitals throughout the country participating in the project. The process of donation after brain death was structured into three phases: referral of possible donors after brain death (DBD) to critical care units (CCUs) from outside units, management of possible DBDs within the CCUs and obtaining consent for organ donation. Indicators to assess performance in each phase were constructed and the factors influencing these indicators were studied to ensure that comparable groups of hospitals could be established. Availability of neurosurgery and CCU resources had a positive impact on the referral of possible DBDs to CCUs and those hospitals with fewer annual potential DBDs more frequently achieved 100% consent rates. Hospitals were grouped into each subprocess according to influencing factors. Hospitals with the best results were identified for each phase and hospital group. The subsequent study of their practices will lead to the identification of critical factors for success, which implemented in an adapted way should fortunately lead to increasing organ availability.

Continuously evaluating performance in deceased donation: the Spanish quality assurance program

The Spanish Quality Assurance Program applied to the process of donation after brain death entails an internal stage consisting of a continuous clinical chart review of deaths in critical care units (CCUs) performed by transplant coordinators and periodical external audits to selected centers. This paper describes the methodology and provides the most relevant results of this program, with information analyzed from 206,345 CCU deaths. According to the internal audit, 2.3% of hospital deaths and 12.4% of CCU deaths in Spain yield potential donors (clinical criteria consistent with brain death). Out of the potential donors, 54.6% become actual donors, 26% are lost due to medical unsuitability, 13.3% due to refusals to donation, 3.1% due to maintenance problems and 3% due to other reasons. Although the national pool of potential donors after brain death has progressively decreased from 65.2 per million population (pmp) in 2001 to 49 pmp in 2010, the number of actual donors after brain death has remained at about 30 pmp. External audits reveal that the number of actual donors could be 21.6% higher if all potential donors were identified and preventable losses avoided. We encourage other countries to develop similar comprehensive approaches to deceased donation performance.

Liver retransplantation in HIV-infected patients: a prospective cohort study

Information regarding liver retransplantation in HIV-infected patients is scant. Data from 14 HIV-infected patients retransplanted between 2002 and 2011 in Spain (6% retransplantation rate) were analyzed and compared with those from 157 matched HIV-negative retransplanted patients. In HIV-infected patients, early (≤30 days) retransplantation was more frequently indicated (57% vs. 29%; p = 0.057), and retransplantation for HCV recurrence was less frequently indicated (7% vs. 37%; p = 0.036). Survival probability after retransplantation in HIV-positive patients was lower than in HIV-negative patients, 42% versus 64% at 3 years, although not significantly (p = 0.160). Among HIV-infected patients, those with undetectable HCV RNA at retransplantation and those with late (>30 days) retransplantation showed better 3-year survival probability (80% and 67%, respectively), similar to that in their respective HIV-negative counterparts (72% and 70%). In HIV-infected and HIV-negative patients, 3-year survival probability in those with positive HCV RNA at retransplantation was 22% versus 65% (p = 0.008); in those with early retransplantation, 3-year survival probability was 25% versus 56% (p = 0.282). HIV infection was controlled with antiretroviral therapy after retransplantation. In conclusion, HIV-infected patients taken as a whole have unsatisfactory survival after liver retransplantation, although patients with undetectable HCV RNA at retransplantation or undergoing late retransplantation show a more favorable outcome.

Outcome of HCV/HIV-coinfected liver transplant recipients: a prospective and multicenter cohort study

Eighty-four HCV/HIV-coinfected and 252-matched HCV-monoinfected liver transplant recipients were included in a prospective multicenter study. Thirty-six (43%) HCV/HIV-coinfected and 75 (30%) HCV-monoinfected patients died, with a survival rate at 5 years of 54% (95% CI, 42-64) and 71% (95% CI, 66 to 77; p = 0.008), respectively. When both groups were considered together, HIV infection was an independent predictor of mortality (HR, 2.202; 95% CI, 1.420-3.413 [p < 0.001]). Multivariate analysis of only the HCV/HIV-coinfected recipients, revealed HCV genotype 1 (HR, 2.98; 95% CI, 1.32-6.76), donor risk index (HR, 9.48; 95% CI, 2.75-32.73) and negative plasma HCV RNA (HR, 0.14; 95% CI, 0.03-0.62) to be associated with mortality. When this analysis was restricted to pretransplant variables, we identified three independent factors (HCV genotype 1, pretransplant MELD score and centers with <1 liver transplantation/year in HIV-infected patients) that allowed us to identify a subset of 60 (71%) patients with a similar 5-year prognosis (69%[95% CI, 54-80]) to that of HCV-monoinfected recipients. In conclusion, 5-year survival in HCV/HIV-coinfected liver recipients was lower than in HCV-monoinfected recipients, although an important subset with a favorable prognosis was identified in the former.

Differential uptake and transport of trivalent and hexavalent chromium by tumbleweed (Salsola kali)

Experiments were conducted to determine the differential absorption of Cr species by tumbleweed (Salsola kali) as well as the effect of this heavy metal on plant growth and nutrient uptake. Tumbleweed seeds were grown in an agar-based media containing different concentrations of either Cr(III) or Cr(VI). The results demonstrated that the uptake of Cr was influenced by the Cr concentration in the growth medium and the speciation of this heavy metal. When supplied in the hexavalent form, the concentration of Cr in the different plant parts (2900, 790, and 600 mg kg(-1) for roots, stems, and leaves, respectively) was between 10 and 20 times higher than the amounts found when Cr was supplied in the trivalent form. In addition, it was found that in most of the experiments, Cr(III) exhibited more toxic effects on tumbleweed plants than Cr(VI). The size of roots of plants grown in 20 mg L(-1) Cr(III) were significantly smaller (p < 0.05) than those grown in 20 mg L(-1) Cr(VI). Plants exposed to 20 mg L(-1) Cr(III) produced shoots significantly shorter (p < 0.05) compared with the size of control plants and with those grown in 20 mg L(-1) Cr(VI). In addition, the absorption of macronutrients and microelements was in general lower when the plants were grown in the medium containing Cr(III). The amounts of Cr concentrated in the aerial plant parts under experimental conditions may indicate tumbleweed as a new option for the phytoremediation of Cr-contaminated soil.

Chemistry and nanoparticulate compositions of a 10,000 year-old ice core melt water

Particulates extracted from a single section of a 10,000 year-old ice core melt sample exhibited characteristics of contemporary, airborne fine particulates: a majority were microcrystalline particulates and aggregated microcrystals, including some mixtures of microcrystals and carbonaceous matter. Particularly significant were the presence of carbon nanotubes and fullerene nanocrystals composing aggregated particulates reflecting global combustion products similar to contemporary, airborne carbon nanocrystal aggregates. ICP elemental analysis of the melt water showed significant concentrations of Ca, K and especially Na (corresponding to K, NaCl), S, Si, Se, and Zn. Overall, the elemental analysis of the melt water is similar to local tap water. However, lead was absent in the local tap water and only half the concentration of selenium was present in the tap water in contrast to the ice core water. While these observations cannot be generalized, the methodology illustrates the potential to characterize and compare airborne particulate regimes and water chemistries in antiquity.

Bioaccumulation of cadmium, chromium and copper by Convolvulus arvensis L.: impact on plant growth and uptake of nutritional elements

The remediation of heavy metal-contaminated sites using plants presents a promising alternative to current methodologies. In this study, the potential accumulation of Convolvulus arvensis L. for Cd(II), Cr(VI), and Cu(II) was determined using an agar-based medium. The shoots of C. arvensis plants exposed to 20 mgl(-1) of these heavy metals, demonstrated capability to accumulate more than 3800 mg of Cr, 1500 mg of Cd, and 560 mg of Cu per kg of dry tissue. The outcome of this study and the field data previously reported corroborate that C. arvensis is a suitable candidate for the phytoremediation of Cd(II), Cr(VI), and Cu(II) contaminated soils. Furthermore, the concentration of Cr determined in the dry leaf tissue (2100 mgkg(-1)) indicates that C. arvensis could be considered as a potential Cr-hyperaccumulator plant species.

Use of silica-immobilized humin for heavy metal removal from aqueous solution under flow conditions

Humin extracted from Sphagnum peat moss was immobilized in a silica matrix and column experiments were performed in order to evaluate the removal and recovery of metal ions from aqueous solution under flow conditions. These experiments also allowed testing the recycling capacity of the column. Single-element solutions of Cu(II) and Pb(II), and a multi-metal solution containing Cd(II), Cu(II), Pb(II), Ni(II), and Cr(III) were passed through the columns at a flow rate of 2 ml/min. A 0.5 M sodium citrate solution was used as the stripping agent in the metal-ion recovery process. Humin immobilized in the silica matrix exhibited a similar, and in some cases, even a higher capacity than other biosorbents for the removal of metal ions from aqueous solutions under flow conditions. The sodium citrate was effective in removing Cu(II), Pb(II), Cd(II), and Ni(II) from the metal saturated column. The selectivity of the immobilized biomass was as follows: Cr(III)>Pb(II)>Cu(II)>Cd(II)>Ni(II). This investigation provides a new, environmentally friendly and cost-effective possibility to clean up heavy-metal contaminated wastewaters by using the new silica-immobilized humin material.

Utilization of ICP/OES for the determination of trace metal binding to different humic fractions

In this study, the use of inductively coupled plasma/optical emission spectrometry (ICP/OES) to determine multi-metal binding to three biomasses, Sphagnum peat moss, humin and humic acids is reported. All the investigations were performed under part per billion (ppb) concentrations. Batch pH profile experiments were performed using multi-metal solutions of Cd(II), Cu(II), Pb(II), Ni(II), Cr(III) and Cr(VI). The results showed that at pH 2 and 3, the metal affinity of the three biomasses exposed to the multi-metal solution that included Cr(III) presented the following order: Cu(II), Pb(II)>Ni(II)>Cr(III)>Cd(II). On the other hand, when Cr(VI) was in the heavy metal mixture, Sphagnum peat moss and humin showed the following affinity: Cu(II), Pb(II)>Ni(II)>Cr(VI)>Cd(II); however, the affinity of the humic acids was: Cu(II)>Pb(II), Cr(VI)>Ni(II)>Cd(II). The results demonstrated that pH values of 4 and 5 were the most favorable for the heavy metal binding process. At pH 5, all the metals, except for Cr(VI), were bound between 90 and 100% to the three biomasses. However, the binding capacity of humic acids decreased at pH 6 in the presence of Cr(VI). The results showed that the ICP/OES permits the determination of heavy metal binding to organic matter at ppb concentration. These results will be very useful in understanding the role of humic substances in the fate and transport of heavy metals, and thus could provide information to develop new methodologies for the removal of low concentrations of toxic heavy metals from contaminated waters.

Regulatory role of tetraspanin CD9 in tumor-endothelial cell interaction during transendothelial invasion of melanoma cells

Heterotypic interaction among tumor cells (TCs) and endothelial cells (ECs) may play a critical role during the vascular dissemination of neoplastic cells and during pathologic angiogenesis in tumors. To identify molecules involved in these processes, the distribution of vascular junctional proteins was first studied by immunofluorescence at sites of heterologous intercellular contact using TC-EC mosaic monolayers grown on 2-dimensional collagen. Several members of the tetraspanin superfamily, including CD9, CD81, and CD151, were found to localize at the TC-EC contact area. The localization of tetraspanins to the TC-EC heterologous contact area was also observed during the active transmigration of TCs across EC monolayers grown onto 3-dimensional collagen matrices. Dynamic studies by time-lapse immunofluorescence confocal microscopy showed an active redistribution of endothelial CD9 to points of melanoma insertion. Anti-CD9 monoclonal antibodies were found to specifically inhibit the transendothelial migration of melanoma cells; the inhibitory effect was likely caused by a strengthening of CD9-mediated heterotypic interactions of TCs to the EC monolayer. These data support a novel mechanism of tetraspanin-mediated regulation of TC transcellular migration independent of TC motility and growth during metastasis and a role for these molecules in the formation of TC-EC mosaic monolayers during tumor angiogenesis.

The genetic structure of Mexican Mestizos of different locations: tracking back their origins through MHC genes, blood group systems, and microsatellites

Mexican Mestizos, who are the result of the admixture of Spanish, Indian, and Black genes, were analyzed for different systems. Three populations from geographical distinct areas were studied: the north (State of Nuevo Leon ), the center (State of Guanajuato), and the highlands (mainly Mexico City). Ten blood group systems (N = 229), STRs (N = 107), HLA-A*, B*, C* (N = 116-167), and DRB1, DQA1, and DQB1 (N = 40, 101, 160, respectively) were analyzed in the samples of the highlands. The three groups cluster together in the same branch: Mestizos from Venezuela, Mediterranean and Jews close to the cluster of Orientals, followed by Amerindians. All markers demonstrate that Indian genes are strongly represented in the highlands: Di(a), O, D(-)(+), s, A*0201, *0206, B*1539 (*1541), *3902, *3905, *3512, *3517, *4002, *4005, Cw*0801, *0304, *0401 among others. Cw*0501, *1203, *1204, and *1601 are of White ancestry. The most frequent haplotypes *0407-*03011-*0302 and *0802-*0401-*0402 are of Indian descent as well. The center and mainly the north show a more Caucasian and Semitic profile. The results demonstrate the high variability resulting from interethnic admixture, suggesting that this mechanism is the main factor responsible for the large diversity found in urban populations.

Molecular analysis of HLA class I alleles in the Mexican Seri Indians: implications for their origin

The molecular analysis of HLA class I loci has demonstrated that, although, the genetic profile is restricted in Amerindians, several micropolymorphisms may be important in conferring a biological advantage. We analyzed the HLA-A and B genetic profile of Seris, a Mexican Indian tribe living in northwestern Mexico in the state of Sonora. There are presently only 619 individuals. Our study included 100 Seris belonging to nine families. HLA-A and -B loci typing was performed by polymerase chain reaction using an amplification refractory mutation system (PCR-ARMS) on a select group of samples; all of them were typed by polymerase chain reaction using sequence-specific oliogonuoleotide probes (PCR-SSOP) at a low-intermediate resolution level. The correlation between the techniques was 100%. Only five HLA-A alleles and seven HLA-B alleles were found. A*0201, A*68, A*31, A*24, B*3501, B*40, B*51, B*3512 and B*15 were present in over 5% of the individuals. B*27052 was detected in 2%. B27 is absent in any other Mexican Indian groups previously studied. The presence of B27 may be the result of a founder effect due to different waves of southward migrations. The B-locus is more diverse and the prevalent haplotypes were: A*0201-B*3501, A*0201-B*40, A*0201-B*3512, A*31-B*51, A*68-B*3501 and A*68-B*40. This genetic profile is different from the pattern of other Mexicans. The phylogenetic tree suggests that Seris are more closely related to the Warao Indians from Venezuela, who live in a similar ecosystem, and to some groups of Argentina, than they are to the Mexican Lacandones who live in the jungle. These data emphasize the relevance of the interaction between genes and environment.

MHC class II sequences of susceptibility and protection in Mexicans with autoimmune hepatitis

BACKGROUND/AIMS

Autoimmune hepatitis has a genetic background associated with different HLA DRB1 alleles depending on the ethnic group. The aim of this study was to analyse the immunogenetics of type I autoimmune hepatitis in Mexicans.

METHODS

Thirty Mexican Mestizo patients and 175 healthy controls were HLA typed as follows: class I antigens were determined by microlymphocytotoxicity and class II typing was done on DNA samples using PCR-SSO and PCR-SSP for DRB1, DQA1 and DQB1 loci.

RESULTS

A significant association of autoimmune hepatitis with DRB1*0404 was found, (chi2Y=19.95, pc=0.002, RR=7.71), suggesting the presence of a susceptibility gene located at the DRB1 locus. Resistance was at least partially due to a DQB1 gene, since a significant decrease in DQB1*0301 was also detected (chi2Y=8.21, pc=0.04). Analysis of subgroups according to age at onset showed an association with DRB1*0404 (chi2Y=4.31, p=0.04) in patients with late onset (after 30 years), while DQA1*0501 (chi2Y=5.12, p=0.02) was increased in the early onset group.

CONCLUSIONS

The possible mechanism of HLA association is due to "shared epitopes", since DRB1*0404, and those found in other populations namely, DRB1*0401, *0405 and *0301 share almost the same sequence at position 67-72 (LLEQRR, R or K at 71). Valine-86 is also relevant to the age at onset because DRB1*0404 is increased in the patients with an average age at onset of 32. These findings are relevant in determining which peptides in the liver are targets for T cells.

Relevant residues of DRbeta1 third hypervariable region contributing to the expression and to severity of rheumatoid arthritis (RA) in Mexicans

Rheumatoid arthritis (RA) is a chronic autoimmune disease leading to destruction of the joints. Residues at positions 67-74 of the DRB1 third hypervariable region are involved in susceptibility (S) and resistance (P) to RA. DNA from 83 patients and 175 controls, all of them Mexican Mestizos were oligotyped using PCR-SSOP and PCR-SSP. The (S) alleles are DRB*0404 (p = 0.000004), *0401 (p = 0.007) and *1001 (p = 0.008). Those associated with P are DRB1*0701 (p = 0.0001); *1101 (p = 0.01); *1503 (p = 0.02); *0801 (p = 0.04); *1401 (p = 0.04). Susceptibility/protection are recessive traits; SS genotypes are increased in the patients (p = 0.0003) while PP genotypes are decreased in them (p = 0.00004). The motif at 67-74 and the valine or glycine at position 86 are relevant in the development and severity of RA in Mexicans. The associations suggest that residues 67, 70, 71 are central for susceptibility. The P alleles have D-70 or carry V-86 in the absence of D-70. Thus, susceptibility/protection depends on the combination of basic residues at these positions and a non-polar aa at 86 contributes to resistance. Severity is also HLA influenced. DQA1*03011-DQB1*0302 are associated to severe lesions in the presence of any DR4 subtype. Analyzing different ethnic groups is essential to elucidate the etiopathogenesis of RA.

[High- and low-risk molecular sequences in autoimmune diseases. An analysis of type I diabetes in Latin America]

Type I diabetes is an autoimmune and a polygenic disease, in which MHC-class II genes contribute to 48% of the disease. The aim of the present study, is to provide a guideline to understanding the molecular association of these genes, through the immunogenetic analysis of 3 Latin american mestizo populations. We included 606 individuals, 349 patients with DMDI and 257 healthy controls coming from 3 geographical areas: Mexico City, Mexico; Caracas, Venezuela and Medellin, Colombia. The results clearly indicate that in mestizo groups, the diabetogenic haplotypes are from mediterranean ancestry, while protection is due to Amerindian genes. It was demonstrated that the relevant sequences for IDDM expression are located to DRB1 and DQB1 loci with a minimal contribution of DQA1 residues. The sequences determining peptide recognition and the induction of TH1 cells mediating the cellular autoimmune response are in positions DRB1-57 and 74 (an aspartic acid and a glutamic acid respectively, confer protection), modulated by D-57 in the DQ, 8 chain. These data show that DRB1-DQB1 haplotypes are central for IDDM expression and open new pathways for the disease management.

An HIV/AIDS prevention project for Mexican homosexual men: an empowerment approach

In this intervention, participants design and implement an HIV/AIDS prevention project for Mexican homosexual men. The intervention is consistent with, and contributes to, empowerment theory because it enhances collective action, provides opportunities to develop knowledge and skills, creates needed resources, and includes shared control with professional and among participants. The intervention described provides an illustration of an empowering process and distinguishes itself from empowerment outcomes. An evaluation of the project is also described, but the outcomes were HIV/AIDS-related behaviors rather than psychological empowerment of the participants. The results suggest that the participants' HIV/AIDS knowledge and preventive behavior improved when compared to individuals who did not participate in the intervention. In addition, the intervention generated community change initiated by participants. Implications for designing interventions using an empowerment approach are discussed.

[Valve prostheses and transesophageal echocardiography]

The aim of this paper is to inform about the experience of the Echocardiography Department of the National Institute of Cardiology Ignacio Chávez, in the assessment of prosthetic valves dysfunction by transesophageal echocardiography. Sixty patients with a total of 75 prosthetic valves: 19 bioprostheses and 56 mechanical valves were studied. Forty four were in mitral position, 27 in aortic position and 4 in tricuspid position. All patients were evaluated using 5 MHz monoplane or biplane transesophageal transducers. The 52% (39) of the studied prosthetic valves were found normally functioning. However, 48% (36) of these showed signs of dysfunction. The causes of dysfunction in the mechanical valves were: obstruction, pannus, infectious endocarditis and periprosthetic leak, and in relation with bioprostheses rupture of the leaflets, stenosis and calcification, partial dehiscence, infectious endocarditis and periprosthetic leak were identified. The obtained percentage and type of prosthetic valves dysfunction in our results agree with those reported in the literature and confirm the great utility of transesophageal research in the detection of the valvular prosthetic dysfunction.

AIDS knowledge and sexual behavior among Mexican gay and bisexual men

Little knowledge exists about AIDS and Human Immunodeficiency Virus (HIV) infection among Latin American gay males. In Latin America, sexual transmission from man to man is the leading cause of HIV infection. In Mexico, which ranks third in number of AIDS cases in the Americas, more than three-quarters of the cases are due to sexual transmission; among these cases, 35% and 23.7% are due to homosexual and bisexual male practices, respectively. A sample of 200 individuals from Juarez, Mexico, a city on the U.S. border, was interviewed. Information about their AIDS knowledge, sexual behavior, and condom use was obtained. Factory workers and individuals who meet sexual partners in the streets reported more sexual partners than workers in service or professional occupations and those who meet their partners in bars and discos. Number of sexual partners and respondents' age were inversely associated with condom use. Implications for HIV prevention are discussed.