Population structure and paternal admixture landscape on present‐day Mexican‐Mestizos revealed by Y‐STR haplotypes

Mestizos currently represent most of the Mexican population (>90%); they are defined as individuals born in the country having a Spanish‐derived last name, with family antecedents of Mexican ancestors back at least to the third generation. Mestizos are result of 500 years of admixture mainly among Spaniards, Amerindians, and African slaves. Consequently, a complex genetic pattern has been generated throughout the country that has been scarcely studied from the paternal point of view. This fact is important, taking into account that gene flow toward the New World comprised largely males. We analyzed the population structure and paternal admixture of present‐day Mexican‐Mestizo populations based on Y‐STRs. We genotyped at least 12 Y‐STRs in DNA samples of 986 males from five states: Aguascalientes (n = 293); Jalisco (n = 185); Guanajuato (n = 168); Chiapas (n = 170); and Yucatán (n = 170). AmpF?STR Y‐filer and Powerplex‐Y® kits were used. Inclusion of North and Central Y‐STR databases in the analyses allowed obtaining a Y‐STR variability landscape from Mexico. Results confirmed the population differentiation gradient previously noted in Mestizos with SNPs and autosomal STRs throughout the Mexican territory: European ancestry increments to the Northwest and, correspondingly, Amerindian ancestry increments to the Center and Southeast. In addition, SAMOVA test and Autocorrelation Index for DNA Analysis autocorrelogram plot suggested preferential gene flow of males with neighboring populations in agreement with the isolation‐by‐distance model. Results are important for disease‐risk studies (principally male‐related) and for human identification purposes, because Y‐STR databases are not available on the majority of Mexican‐Mestizo populations. Am. J. Hum. Biol., 2010. © 2009 Wiley‐Liss, Inc.     

Test of association: which one is the most appropriate for my study?

BACKGROUND

Hypothesis tests are statistical tools widely used for assessing whether or not there is an association between two or more variables. These tests provide a probability of the type 1 error (p-value), which is used to accept or reject the null study hypothesis.

OBJECTIVE

To provide a practical guide to help researchers carefully select the most appropriate procedure to answer the research question. We discuss the logic of hypothesis testing and present the prerequisites of each procedure based on practical examples.     

Changes in cellular proliferation and plasma products are associated with liver failure

AIMTo study the differences in immune response and cytokine profile between acute liver failure and self-limited acute hepatitis.METHODSForty-six patients with self-limited acute hepatitis (AH), sixteen patients with acute liver failure (ALF), and twenty-two healthy subjects were involved in this study. The inflammatory and anti-inflammatory products in plasma samples were quantified using commercial enzyme-linked immunoassays and quantitative real-time PCR. The cellular immune responses were measured by proliferation assay using flow cytometry. The groups were divided into viral- and non-viral-induced self-limited AH and ALF. Thus, we worked with five groups: Hepatitis A virus (HAV)-induced self-limited acute hepatitis (HAV-AH), HAV-induced ALF (HAV-ALF), non-viral-induced self-limited acute hepatitis (non-viral AH), non-viral-induced acute liver failure (non-viral ALF), and healthy subjects (HC). Comparisons among HAV and non-viral-induced AH and ALF were performed.RESULTSThe levels of mitochondrial DNA (mtDNA) and the cytokines investigated [interleukin (IL)-6, IL-8, IL-10, interferon gamma, and tumor necrosis factor] were significantly increased in ALF patients, independently of etiology (P < 0.05). High plasma mtDNA and IL-10 were the best markers associated with ALF [mtDNA: OR = 320.5 (95%CI: 14.42-7123.33), P < 0.0001; and IL-10: OR = 18.8 (95%CI: 1.38-257.94), P = 0.028] and death [mtDNA: OR = 12.1 (95%CI: 2.57-57.07), P = 0.002; and IL-10: OR = 8.01 (95%CI: 1.26-50.97), P = 0.027]. In the cellular proliferation assay, NK^bright, NKT and regulatory T cells (TReg) predominated in virus-specific stimulation in HAV-induced ALF patients with an anergic behavior in the cellular response to mitotic stimulation. Therefore, in non-viral-induced ALF, anergic behavior of activated T cells was not observed after mitotic stimulation, as expected and as described by the literature.CONCLUSIONmtDNA and IL-10 may be predictors of ALF and death. TReg cells are involved in immunological disturbance in HAV-induced ALF.     

Creating a global rare disease patient registry linked to a rare diseases biorepository database: Rare Disease-HUB (RD-HUB)

A movement to create a global patient registry for as many as 7,000 rare diseases was launched at a workshop, "Advancing Rare Disease Research: The Intersection of Patient Registries, Biospecimen Repositories, and Clinical Data." http://rarediseases.info.nih.gov/PATIENT_REGISTRIES_WORKSHOP/. The workshop was sponsored by the Office of Rare Diseases Research (ORDR). The focus was the building of an infrastructure for an internet-based global registry linking to biorepositories. Such a registry would serve the patients, investigators, and drug companies. To aid researchers the participants suggested the creation of a centralized database of biorepositories for rare biospecimens (RD-HUB)http://biospecimens.ordr.info.nih.gov/ that could be linked to the registry. Over two days of presentations and breakout sessions, several hundred attendees discussed government rules and regulations concerning privacy and patients' rights and the nature and scope of data to be entered into a central registry as well as concerns about how to validate patient and clinician-entered data to ensure data accuracy. Mechanisms for aggregating data from existing registries were also discussed. The attendees identified registry best practices, model coding systems, international systems for recruiting patients into clinical trials and novel ways of using the internet directly to invite participation in research. They also speculated about who would bear ultimate responsibility for the informatics in the registry and who would have access to the information. Hurdles associated with biospecimen collection and how to overcome them were detailed. The development of the recommendations was, in itself, an indication of the commitment of the rare disease community as never before.     

Traumatic coronary arteriovenous fistula communicating the left main coronary artery to pulmonary artery, associated with pulmonary valvular insufficiency and endocarditis: case report

The authors present a case of a seventeen-year-old white male who suffered from a knife chest wound and secondarily developed a traumatic coronary arteriovenous fistula communicating the left main coronary artery to the pulmonary artery, associated with pulmonary valvular insufficiency and endocarditis.     

Health providers' knowledge on transfusion-transmitted viral hepatitis

OBJECTIVE: Training health providers is a strategy for improving health care quality that need to be technically correct and comply with the conceptual universe of the trainees. A pilot study was carried out to explore the consistency of knowledge on blood transmission of viral hepatitis among primary care providers. METHODS: A non-identified questionnaire was applied to 190 providers attending a public health training program in 2003 and 2004. Answers were compared according to two groups: physicians, nurses and dentists (115 subjects) and other health providers (66 subjects). Frequencies of correct and incorrect answers were compared through Chi-square test (chi2). Nine respondents did not inform their occupation. RESULTS: The study population mainly comprised women (80%) aged 20 to 60 years from Northeastern (27.4%), Southeastern (35.3%), and Midwestern (37.3%) regions. Blood transfusion was associated with hepatitis B and C for 57.5% of the respondents; hemophilia was associated with hepatitis B and C for 55.7% of the respondents, while 74% considered to be incorrect the statement: "viral hepatitis cannot be transmitted through blood" and 16.4% considered it correct. The number of correct answers regarding blood transfusion was greater in the group of physicians, nurses and dentists than other providers (chi2=1.2; p=0.2741). CONCLUSIONS: These findings were compared with current data on viral hepatitis transmission and the consistency of the answers concerning different risk factors was evaluated. These providers' knowledge on blood transmission of these conditions shows inconsistencies that may jeopardize the effectiveness of prevention and control programs.     

Severe hyperkalemic type 4 renal tubular acidosis after kidney transplantation: a case report

BACKGROUND: Hyperkalemia after transplantation is a common event, occurring in up to 70% of patients. It is usually asymptomatic but sometimes manifests as muscle weakness or cardiac arrhythmias. METHODS: Case report. RESULTS: At 102 days after a second cadaveric kidney transplantation, a 15-year-old boy, was admitted to the emergency room with severe muscle weakness. His examinations showed a serum potassium of 9.8 mEq/L; blood pH 7.1; serum bicarbonate 7.6 mmol/L; and creatinine 2.5 mg/dL. He was initially treated with sodium bicarbonate, calcium gluconate, and furosemide. Subsequent investigation showed hyperchloremic metabolic acidosis, urinary pH <5.5, positive urinary anion gap, reduced transtubular potassium gradient (TTKG, 1.5) and low levels of aldosterone (0.7 ng/mL), suggesting the presence of type 4 renal tubular acidosis (RTA). Other causes of hyperkalemia were excluded in the present case. Serum levels of potassium returned to normal when fludrocortisone was added to the bicarbonate supplementation. This case of severe hyperkalemic secondary to type 4 RTA after kidney transplantation only responded to the combination of alkali and mineralocorticoid therapies.