Abundance and distribution of plant derived leaf waxes (long chain n-alkanes & fatty acids) from lake surface sediments along the west coast of southern South America: Implications for environmental and climate reconstructions.

Southern South America is the only large landmass that extends through the core of the Southern Westerly Winds (SWW), controlling hydrological and ecosystem variability in the region. In fact, the vegetation along the west coast changes from Temperate and Valdivian Rain Forest to the North Patagonian Evergreen Forest (ca. 42°S) due to the latitudinal influence of the SWW. Climate is an important driver of organic matter accumulation in lakes, hence changes in vegetation would be recorded in lacustrine sedimentary archives. This study evaluated leaf waxes contained in lake surface sediments as indicators of climate change along the west coast of southern South America, providing a biogeochemical dataset for ongoing and future (paleo)climate and environmental research. The fatty acid and n-alkane sediment leaf wax datasets are compared with latitudinal, orographic, and climatic (Mean Annual air Temperature [MAT] & Precipitation [MAP]) trends extracted from a monthly gridded reanalysis product of the Climate Forecast System Reanalysis. Fatty acids are more abundant than n-alkanes, with high abundances characterizing the transition between seasonal and year-round precipitation along the coast (ca. 42°S). The abundance of both leaf wax groups increases with MAP, suggesting precipitation as the main control on sedimentary leaf wax delivery to the lake sediments in the study area. The Carbon Preference Index (CPI) of the two groups show opposite trends, but both highlight the climate transition at ca. 42°S, and have a linear relationship with MAP. The opposite significant trends between n-alkane CPI and fatty acid CPI with MAP are interpreted as higher n-alkane production at much higher precipitation because leaf wax fatty acids are the precursors of n-alkanes. Hence, past periods during which these leaf waxes show opposite trends in CPI might be interpreted as a precipitation change, especially if additional information such as pollen, diatoms, chironomids and stable isotopes is available.

Low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope: Monte Carlo treatment planning and dose measurements in a postmortem subject.

Objective.The goal of this study was to use Monte Carlo (MC) simulations and measurements to investigate the dosimetric suitability of an interventional radiology (IR) c-arm fluoroscope to deliver low-dose radiotherapy to the lungs.Approach.A previously-validated MC model of an IR fluoroscope was used to calculate the dose distributions in a COVID-19-infected patient, 20 non-infected patients of varying sizes, and a postmortem subject. Dose distributions for PA, AP/PA, 3-field and 4-field treatments irradiating 95% of the lungs to a 0.5 Gy dose were calculated. An algorithm was created to calculate skin entrance dose as a function of patient thickness for treatment planning purposes. Treatments were experimentally validated in a postmortem subject by using implanted dosimeters to capture organ doses.Main results.Mean doses to the left/right lungs for the COVID-19 CT data were 1.2/1.3 Gy, 0.8/0.9 Gy, 0.8/0.8 Gy and 0.6/0.6 Gy for the PA, AP/PA, 3-field, and 4-field configurations, respectively. Skin dose toxicity was the highest probability for the PA and lowest for the 4-field configuration. Dose to the heart slightly exceeded the ICRP tolerance; all other organ doses were below published tolerances. The AP/PA configuration provided the best fit for entrance skin dose as a function of patient thickness (R2 = 0.8). The average dose difference between simulation and measurement in the postmortem subject was 5%.Significance.An IR fluoroscope should be capable of delivering low-dose radiotherapy to the lungs with tolerable collateral dose to nearby organs.

Guía de recomendación ACCHED-SCHGE para el funcionamiento de las unidades de endoscopia durante el brote de coronavirus (COVID-19) / Guideline recommendations ACHED-SCHGE for the endoscopy units during the Coronavirus outbreak (COVID-19)

The outbreak of COVID-19 disease has recently spread from its original place in Wuhan, Hubei province, China, to the entire world, and has been declared to be a pandemic by the World Health Organization in March 2020. All countries in America, in particular Chile, show an important increase in COVID-19 cases and deaths. The clinical manifestations of COVID-19 are a broad spectrum, from asymptomatic mild disease, to severe respiratory failure, shock, multiorgan dysfunction and death. Thus, high clinical suspicion and appropriate structure risk stratification are needed. Health care teams in endoscopy units, are at an increased risk of infection by COVID-19 from inhalation of droplets, mucosae contact, probably contamination due to contact with stools. Endoscopic aerosolized associated infections have also been reported. Different societies' recommendations, have recently placed digestive endoscopy (especially upper) among the high risk aerosol generating procedures (AGPs). In addition, live virus has been found in patient stools. On top of this, the infected health professionals may transmit the infection to their patients. Health care infection prevention and control (HCIPC), has been shown to be effective in assuring the safety of both health care personnel and patients. This is not limited to the correct use of personal protective equipment (PPE), but is based on a clear, detailed and well communicated HCIPC strategy, risk stratification, use of PPE, and careful interventions in patients with moderate and high risk of COVID-19. A conscientious approach regarding limited resources is important, as the simultaneous outbreak in all countries heavily affects the availability of health supplies. The Chilean Gastroenterology Society (SChGE) and Digestive Endoscopy Association of Chile (ACHED) are joining to provide continued updated guidance in order to assure the highest level of protection against COVID-19, for both patients and health care workers. This guideline will be updated online as needed.

El brote de la enfermedad denominada COVID-19, se ha extendido desde su origen en Wuhan, provincia de Hubei, China, a todo el mundo. La Organización Mundial de la Salud lo declaró pandemia en marzo de 2020. Todos los países de América, en especial Chile, presentan incremento de casos y fallecidos. Las manifestaciones clínicas de COVID-19 van desde una enfermedad leve, hasta insuficiencia respiratoria severa, shock, disfunción orgánica y muerte. Se necesita una alta sospecha clínica y una adecuada estratificación del riesgo. El equipo de salud en las unidades de endoscopia, tiene un mayor riesgo de COVID-19 que otras unidades clínicas y de apoyo diagnóstico, dada la mayor exposición a inhalación de gotas, contacto posible con mucosas y contaminación por contacto con deposiciones. Recomendaciones de diferentes sociedades colocan la endoscopia digestiva (especialmente la esofagogastroscopia o endoscopia digestiva alta, EDA) entre los procedimientos generadores de aerosoles (PGA) de alto riesgo. Además, se han encontrado virus viables en las deposiciones de los pacientes. Potencialmente, los profesionales de la salud infectados podrían contagiar a los pacientes. Se ha demostrado que la prevención y control de infecciones asociadas a la atención de salud (IAAS), son efectivos para garantizar la seguridad tanto del personal de salud, como de los pacientes. Esto no es solamente el correcto uso del equipo de protección personal (EPP), sino que se basa en una clara estrategia de IAAS, bien comunicada, con estratificación de riesgo, uso de EPP e intervenciones correctas en pacientes con riesgo moderado y alto. Es relevante un enfoque sobre los limitados recursos, dado la simultaneidad del brote en todos los países, que afecta la disponibilidad de insumos. La Sociedad Chilena de Gastroenterología (SChGE) y la Asociación Chilena de Endoscopia Digestiva (ACHED) publican esta guía actualizada para apoyar las buenas prácticas contra COVID-19, tanto para pacientes como para el equipo de salud. Esta guía podrá tener actualizaciones según avance la información disponible.

Hepatotoxicidad grave inducida por sertralina / Sertraline-induced severe hepatotoxicity

We report the case of a 19-year-old patient, with a history of traumatic liver damage, but with a normal liver profile at her first discharge; 1 month after the event, with post-traumatic stress disorder, treatment with 25 mg of sertraline was started every day; one month later, she develops severe hepatotoxicity without a specific etiology. According to the Naranjo algorithm, it is attributed as a probable case of sertraline hepatotoxicity. Management is carried out with support measures and suspension of the medication, and the patient recovers until she is asymptomatic, currently has normal liver tests

Reportamos el caso de una paciente de 19 años, con antecedentes de daño hepático traumático, pero con un perfil hepático normal en su primer alta; después de 1 mes del evento, con trastorno de estrés postraumático se inició tratamiento con 25 mg diarios de sertralina; un mes después, desarrolla una hepatotoxicidad severa sin etiología determinada. De acuerdo con el algoritmo de Naranjo, se atribuye como caso probable de hepatotoxicidad por sertralina. El manejo se realiza con medidas de apoyo y suspensión del medicamento, y la paciente se recupera hasta que se encuentra asintomática, actualmente tiene pruebas hepáticas normales

[Update on celiac disease]. / Enfermedad celíaca.Revisión.

The prevalence of Celiac disease in the general population is approximately 1% and remains undiagnosed in a significant proportion of individuals. Its clinical presentation includes the classical malabsorption syndrome, unspecific and extra-intestinal manifestations, and silent celiac disease. The serologic diagnosis has an elevated sensitivity and specificity and, at least in adult population, it must be confirmed by biopsy in every case. Diagnosis in subjects already on gluten free diet includes HLA typing and gluten challenge with posterior serologic and histologic evaluation. The core of the treatment is the gluten free diet, which must be supervised by an expert nutritionist. Monitoring must be performed with serology beginning at 3-6 months, and with histology two years after the diagnosis, unless the clinical response is poor. Poor disease control is associated with complications such as lymphoma and small bowel adenocarcinoma. In the future, it is likely that new pharmacologic therapies will be available for the management of celiac disease.

Enfermedad celíaca: revisión / Update on celiac disease

The prevalence of Celiac disease in the general population is approximately 1% and remains undiagnosed in a significant proportion of individuals. Its clinical presentation includes the classical malabsorption syndrome, unspecific and extra-intestinal manifestations, and silent celiac disease. The serologic diagnosis has an elevated sensitivity and specificity and, at least in adult population, it must be confirmed by biopsy in every case. Diagnosis in subjects already on gluten free diet includes HLA typing and gluten challenge with posterior serologic and histologic evaluation. The core of the treatment is the gluten free diet, which must be supervised by an expert nutritionist. Monitoring must be performed with serology beginning at 3-6 months, and with histology two years after the diagnosis, unless the clinical response is poor. Poor disease control is associated with complications such as lymphoma and small bowel adenocarcinoma. In the future, it is likely that new pharmacologic therapies will be available for the management of celiac disease.

Enfermedad celíaca: revisión / Celiac disease: a review

La Enfermedad Celiaca (EC) tiene una prevalencia cercana al 1% de la población general y se considera que hay un número importante de pacientes asintomáticos no diagnosticados. Su presentación clínica es variable comprendiendo el clásico síndrome de malabsorción, formas menores y la EC silente. El diagnóstico serológico tiene una elevada sensibilidad y especificidad y siempre debe confirmarse con biopsia. El diagnóstico en pacientes en dieta libre de gluten incluye test de tipificación de HLA y prueba de dieta con gluten con estudio serológico e histológico posterior. El pilar del tratamiento es la dieta libre de gluten, que debe ser supervisada por un nutriólogo con experiencia. La monitorización de la terapia debe realizarse con serología. La EC mal controlada puede determinar complicaciones como linfoma y adenocarcinoma de intestino delgado. En el futuro es probable que nuevas terapias farmacológicas sean de utilidad en el manejo de la EC.

Celiac disease has a prevalence near to 1% of general population and there is an important amount of asymptomatic people not yet diagnosed. Clinical presentation includes the classical malabsorption syndrome, minor and silent celiac disease. Serologic diagnosis has an elevated sensitivity and specificity, and must be confirmed by biopsy. Diagnosis in those on gluten free diet includes HLA type and gluten challenge with posterior serologic and histologic evaluation. The core of the treatment is the gluten free diet that must be supervised by an expert nutritionist. Monitoring is with serology. Poor disease control can determine complications such as lymphoma and small bowel adenocarcinoma. In the future, it is likely that new pharmacologic therapies will be available for the management of celiac disease.

Experiencia del uso de terapia biológica en pacientes con enfermedad inflamatoria intestinal en un hospital público / Experience in the use of biological therapy in IBD patients in a public hospital

Biological therapy plays an important role in the treatment of inflammatory bowel disease (IBD). However, the use of these drugs is limited due to fears about their side effects. Aim: To report the experience with the use of infliximab/adalimumab in IBD patients in a public hospital. Material and Methods: Descriptive study of a historical cohort of IBD patients treated with infliximab and adalimumab between April 2012 and July 2014. The clinical response was considered favourable when general, intestinal and extra intestinal symptoms subsided after the induction therapy. In addition, endoscopic and/or imaging response was evaluated at three and six months of treatment. Results: Fifteen out of 162 patients, aged 17 to 52 years (7 women) were included. Seven had Crohn´s Disease, 7 had ulcerative colitis and one had non-classifiable IBD. Biological therapy was indicated due to conventional refractory disease in all patients. All patients received combined treatment with immunosuppressive medications. A favorable clinical response was observed in 93 percent after induction therapy and 73 percent showed endoscopic/imagining remission after 3-6 months. Only one patient experienced side effects associated to the biological therapy, which did not result in discontinuation or treatment interruption. Conclusions: In this cohort of IBD patients treated in a public hospital, the use of infliximab/adalimumab was associated with favorable clinical and endoscopic evolution, post induction therapy with no major side effects.

La terapia biológica tiene un papel fundamental en el tratamiento de la enfermedad inflamatoria intestinal (EII). Sin embargo, el uso de estos fármacos es escaso debido a los costos y los temores sobre los efectos secundarios. Objetivo: Dar a conocer la experiencia en el uso de infliximab/adalimumab en pacientes con EII atendidos en un hospital público de nuestro país. Material y Métodos: Estudio descriptivo de una cohorte histórica de pacientes con EII tratados con infliximab y adalimumab entre abril de 2012 y julio de 2014. La respuesta clínica fue considerada favorable cuando los síntomas generales, intestinales y extra-intestinales desaparecieron después de la terapia de inducción. Además se evaluó la respuesta endoscópica/radiológica a los 3 y 6 meses de tratamiento. Resultados: De un total de 162 pacientes con EII, 15 fueron tratados con terapia biológica, con edad entre 17-52 años (7 mujeres). Siete presentaban el diagnóstico de enfermedad de Crohn, siete colitis ulcerosa y uno EII no clasificable. En todos se inició terapia biológica debido a la presencia de refractariedad a la terapia convencional. Todos recibieron terapia combinada con inmunosupresores. Se observó una respuesta clínica favorable en 93 por ciento después de la terapia de inducción y 73 por ciento tuvo una mejoría endoscópica después de 3-6 meses. Sólo un paciente presentó un evento adverso a terapia biológica, el cual no motivó la interrupción del tratamiento. Conclusiones: En esta cohorte de pacientes con EII tratados en un hospital público, el uso de infliximab/adalimumab se asoció con mejoría clínica y endoscópica post terapia de inducción, sin mayores efectos secundarios.

Trasplante de microbiota fecal en paciente con colitis ulcerosa e infección refractaria por: revisión de la literatura a partir de un caso clínico / Fecal microbiota transplantation in patient with ulcerative colitis and refractory infection due to: review of the literature based on a clinical case

Infection (CDI) is increasing both in the hospital environment as in the outpatient setting, and is associated with prior use of antibiotics, hospitalizations and inflammatory bowel disease (IBD), among others. It is also characterized by a high rate of recurrence with the usual antibiotic treatment, which increases with greater number of episodes, reaching up to 65 percent. In this context, the transplantation of fecal microbiota (FMT) emerges as recurrent CDI therapy, achieving success rates exceeding 90 percent, including in IBD patients, with minimum rates of recurrence. To achieve such efficiency, the colonization by the donated microbiota in the recipient is critical. The role of FMT is still unclear in IBD therapy not associated with CDI. Although there are great differences in the methodology of FMT, the process has been standardized even creating banks of frozen fecal samples, without reducing its effectiveness. FMT is a safe procedure, without serious adverse events, and accepted by the potential beneficiary population. There are few reported cases of refractory CDI management with FMT. Since 2012, the FMT in CDI and IBD publications have increased significantly, but in our country there are only few reports of this therapeutic strategy. We present a patient with ulcerative colitis and conventional antimicrobial management resistant CDI, which was successfully treated with FMT in a public hospital in Chile.

La infección por Clostridium difficile (ICD) está en aumento tanto en el ambiente hospitalario como ambulatorio, y se asocia a uso previo de antibióticos, hospitalización y enfermedades inflamatorias intestinales (EII), entre otros. Se caracteriza además por su alta tasa de recurrencia con el tratamiento antimicrobiano habitual, que aumenta con el mayor número de episodios alcanzando hasta 65 por ciento. En este contexto, el trasplante de microbiota fecal (TMF) surge como terapia para la ICD recurrente, logrando tasas de éxito superiores a 90 por ciento, incluyendo pacientes con EII, con mínimas tasas de recurrencia. Para lograr esa eficacia, la colonización por la microbiota donada en el receptor es fundamental. Aún no está claro el rol del TMF en la terapia de EII no asociada a ICD. Aunque existe gran heterogeneidad en la metodología del TMF, el proceso se ha ido estandarizando incluso hasta llegar a la creación de bancos de muestra fecal congelada, sin disminuir su efectividad. El TMF es un procedimiento seguro, sin eventos adversos graves y aceptado por la población potencialmente beneficiaria de él. Existen pocos casos publicados de manejo de ICD refractaria con TMF. Desde el 2012 el número de publicaciones sobre TMF en ICD y en EII ha aumentado considerablemente, sin embargo, en nuestro país los reportes sobre esta estrategia terapéutica son escasos. Presentamos el caso de un paciente con colitis ulcerosa e ICD refractaria al manejo antimicrobiano habitual, que se trató exitosamente con TMF en un hospital público de Chile.

HLA in Jaidukama: an Amerindian secluded Colombian population with new haplotypes and Asian and Pacific-shared alleles.

America first inhabitants and peopling are still debated. In order to increase knowledge about these questions, we have aimed to detect HLA genes of an Amerindian secluded community: Jaidukama, who lives in North Colombia Equatorial forest. HLA genotyping and extended haplotype calculations were carried out in 39 healthy individuals belonging to 13 families. HLA frequencies were compared to other Amerindians and worldwide populations by calculating genetic distances, relatedness dendrograms and correspondence analyses. Only four DRB1 alleles were found (*0404, *0407, *1402 and *1602); however a total of 17 Amerindian different extended class I-class II HLA haplotypes were directly counted from the family studies, nine of them were specific of Jaidukamas. Some of the alleles or group of alleles within an extended haplotype (i.e. DQB1-DRB1) were also found in Asians and Pacific Islanders, further supporting existence of Asian and Pacific gene flow with Amerindians or a common founder effect. It is further supported that HLA extended haplotypes vary faster than alleles in populations. It is concluded that this unique model of Amerindian secluded families study suggests that rapid HLA haplotype variation may be more important than allele variation for survival (starting immune responses). This work may also be useful for future transplant programs in the area.

HLA genes in Uros from Titikaka Lake, Peru: origin and relationship with other Amerindians and worldwide populations.

Uros population from the Titikaka Lake live in about 42 floating reed ('totora') islands in front of Puno City (Peru) at a 4000 m high altiplano. They present both an mtDNA and a human leucocyte antigen (HLA) profile different from the surrounding populations: mtDNA A2 haplogroup is common to Uros and Amazon forest lowland Amerindians. HLA genetic distances between populations have been calculated and neighbour-joining dendrograms and correspondence analyses were carried out. Approximately 15 006 HLA chromosomes from worldwide populations have been used for comparisons. Only eight HLA-A alleles have been found, three of them accounting for most of the frequencies. The same phenomenon is seen for HLA-B, HLA-DRB1 and HLA-DQB1 alleles: a few alleles (3, 4 and 3, respectively) are present in most individuals. The presence of HLA-B*4801 and HLA-DRB1*0901 alleles in a relatively high frequency (although not the most frequent alleles found) is a characteristic shared with Asians and some populations from the Andean altiplano. Three specific Uros haplotypes have been found among the most frequent ones: HLA-A*680102-B*3505-DRB1*0403-DQB1*0302; HLA-A*2402-B*1504-DRB1*1402-DQB1*0301; and HLA-A*2402-B*4801-DRB1*0403-DQB1*0302. The present study suggests that Uros may have been one of the first populations from the shores of the Titikaka Lake coming from the Amazonian forest, which might have given rise to other later differentiated ethnic group (i.e. Aymaras). Uros HLA profile is also useful to study genetic epidemiology of diseases linked to HLA and to construct a future transplant waiting list by adding up regional lists in order to get a bigger pool for transplanting with better HLA matching.

The peopling of Madeira Archipelago (Portugal) according to HLA genes.

The Madeira-Porto Santo Archipelago was officially colonized in 1420 by Portuguese settlers. Its importance in Columbus' information for the American discovery and for slave traffic across the Atlantic is unquestionable. Thus, a complex peopling may have given rise to a present-day high admixture of ethnicities according to HLA genes. A sample of 173 healthy unrelated Madeirans was analysed and compared with 6986 HLA chromosomes from other worldwide populations. Genetic distances, neighbour-joining dendrograms and correspondence analyses were used for comparisons. Southern European, North African (including Canary Islands), Jewish and Mediterranean typical HLA alleles were found and genetic distances from Madeirans to these populations were the closest ones. In addition A*24-B*65-DRB1*0102-DQB1*0501 and A*68-B*08-DRB1*0301-DQB1*0201 haplotypes were newly found in Madeira and not found in any other population. Jewish-Armenian-Middle East haplotype (A*33-B*65-DRB1*0102-DQB1*0501) is one of the most common haplotypes; this haplotype is also present in Spaniards and North Africans. Quantitatively, Portuguese, North Africans (Algerians), Spaniards and Canary Islanders (in this order) are the most important parental populations to Madeirans. Results are discussed on the basis of the recorded historical peopling which does not show a noticeable African gene input in present-day Madeiran population according to our data; one of the closest related populations found is the Canary Islanders, suggesting that Guanche (Canary Islands first inhabitants) slaves gene flow is still noticed at present, both in Madeira and in Canary Islands populations.

[Latin-American Dialysis and Kidney Transplantation Registry: data on the treatment of end-stage renal disease in Latin America]. / Registro latino-americano di dialisi e trapianto: dati relativi al trattamento dell'insufficienza renale cronica terminale nell'America Latina.

Latin America, a region composed of a series of neighboring countries that share their history, Latin ancestry and language (Spanish or Portuguese), includes Mexico, Central America, the Spanish Caribbean islands, and South America. The Latin-American Dialysis and Kidney Transplantation Registry, which has been operative since 1991, collects data from 20 countries (Argentina, Brazil, Bolivia, Chile, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, Dominican Republic, Venezuela and Uruguay), where 97% of Latin Americans live. The prevalence of renal replacement therapy (RRT) has increased from 119 patients per million (pmp) in 1991 to 478.2 in 2005 (147,158 patients [57%] on chronic hemodialysis, 58,251 [23%] on peritoneal dialysis and 52,565 [20%] living with a functioning kidney graft). The incidence rate also increased from 27.8 pmp in 1992 to 167 in 2005. The increment in prevalence and incidence occurred in all Latin- American countries. The transplantation rate increased from 3,7 pmp in 1987 to 15 pmp in 2005 (7,968 kidney transplants performed this year, the cumulative number being 98,415). Access to RRT was available for every patient diagnosed with end-stage renal disease only in Argentina, Brazil, Chile, Cuba, Puerto Rico, Venezuela and Uruguay. In Latin America, the incidence and prevalence of RRT increased year by year. Only in some countries is access to RRT available to 100% of diagnosed patients. Detection and prevention programs for chronic kidney disease are needed in the region. Meanwhile, access to RRT has to be improved for everybody who needs it.

A novel allele, HLA-G*010114, with a non-coding DNA base change in exon 2.

The non-classical human leucocyte antigen (HLA) class I locus, HLA-G, shows a low protein polymorphism and a more varied DNA (eight proteins and 28 alleles). HLA-G DNA polymorphism accounts mainly for changes at third codon bases of the protein coding exons; this does not imply amino acid change in most cases. This relatively high HLA-G DNA polymorphism in comparison with their protein polymorphism suggests that evolutionary forces are acting upon HLA-G for invariance. This may be related to the immunotolerogenic function postulated for HLA-G.

Killer immunoglobulin receptor gene and allele frequencies in Caucasoid, Oriental and Black populations from different continents.

Parallel to the growth in interest in the past few years in the killer immunoglobulin-like receptor (KIR) genes has been the elucidation of the presence/absence of these genes and to a very limited extent, the frequency of alleles of these genes in many populations. In the present study, we have chosen seven populations to investigate the presence/absence of the KIR genes and their alleles, i.e. Cuban, Brazilian, Oman, Hong Kong Chinese, Singapore Chinese, South African Xhosa and South African San. The populations were chosen to represent different continents of the world. We show the divergence in the frequencies of these genes, and their alleles, in the different populations. Many new sequence-specific oligonucleotide probe patterns represent new alleles, each occurred in only one of the populations. The KIR gene frequencies of these seven populations were calculated and genetic distances were represented by neighbour-joining dendrograms and correspondence analyses. Also, the presence or absence of 17 KIR loci in the presently studied populations was compared with the presence or absence of the same loci in 56 worldwide populations (available on the website www.allelefrequencies.net). In total, 5134 individuals were analysed and the populations grouped, with some exceptions, according to a geographical gradient.

A novel HLA-G allele (HLA-G*0108) with an alpha-3 domain amino acid change.

HLA-G non classical class I locus shows a comparatively low polymorphism. It encodes for tolerogenic HLA molecules that may be important in autoimmunity and transplant (and foetal) rejection control. HLA-G molecules give negative signals to Natural Killer and T lymphocytes. In the present paper, a new allele, HLA-G*08, is described, which may be useful for monitoring transplants and for HLA and disease studies.

HLA-E polymorphism in Amerindians from Mexico (Mazatecans), Colombia (Wayu) and Chile (Mapuches): evolution of MHC-E gene.

Human leukocyte antigen (HLA)-E is a nonclassical class I (Ib) gene with a restricted polymorphism. Only eight DNA alleles and three proteins of this gene have been described and their frequencies analyzed in Caucasian, Oriental, Asian Indian, and Negroid populations. In the present study, HLA-E polymorphism has been analyzed in six Amerindian and Mestizo populations from North and South America and compared with previously described populations. HLA-E*0101 is the most frequent allele found in all populations except in Afrocolombian and Wayu Amerindians, in which blood group analyses show a high admixture with Caucasian and African populations. Mazatecan and Mapuche (two Amerindian groups from North and South America, respectively) presented similar HLA-E frequencies, whereas Wayu Indians are more similar to the Afrocolombian population. The Mexican and Colombian Mestizo show similar allele frequencies to Amerindians with high frequencies of HLA-E*0101 and HLA-E*010302 alleles. Also, frequencies in Negroids and Asian Indians present a similar distribution of HLA-E alleles. These data are in agreement with worldwide restricted polymorphism of HLA-E because no new allele was detected in the six populations studied. The allelic frequencies show differences among Caucasian, Oriental, Mestizo and Indian populations. Ape major histocompatibility complex-E allelism is also very restricted: common chimpanzee (one allele); bonobo (two alleles); gorilla (two alleles); orangutan (one allele); rhesus monkey (eight alleles); cynomolgus monkey (two alleles); and green monkey (two alleles).

MHC-F polymorphism and evolution.

The major histocompatibility complex (MHC)-F class Ib locus shows a limited polymorphism, and the function of its mainly intracellular protein is not clear. We have identified human leukocyte antigen (HLA)-F orthologous DNA sequences in Pongidae in order to study the MHC-F gene evolution and its products' function. HLA-F orthologous complementary DNA transcripts are found in chimpanzee and in the new primate species studied (bonobo, gorilla and orangutan). Analyses of the predicted amino acid sequences and their comparison with other primate MHC-F proteins show that MHC-F may be a protein with a typical class I structure and that the key residues of the peptide-binding region are highly conserved in MHC-F in all studied primates species. Thus, MHC-F conservation along the primate evolution suggests an important role in cellular physiology. It is possible that the MHC-F protein could be involved, together with MHC-G and MHC-E, in the natural killer cell activity regulation, although rhesus macaque cannot express complete surface MHC-G orthologue molecules.

HLA-G polymorphism and evolution.

Six proteins, one null allele and 22 human leukocyte antigen (HLA)-G alleles were found in humans. Bonobo, chimpanzee and gorilla only show one allele and orangutan shows five alleles. All Cercopithecus alleles show stop codons at position 164 (Macaca mulatta with seven DNA alleles, Macaca fascicularis with seven DNA alleles and Cercopithecus aethiops with three DNA alleles). Cotton-top tamarin New World monkeys showed 20 DNA and protein alleles; the major histocompatibility complex (MHC)-G New World sequences seem to be closer to MHC-E and lack typical MHC-G primates intron 2-specific deletion. This seems to suggest that MHC-G genes in New World primates are not orthologous and that their function may be similar to that of classical presenting MHC genes.