Population amalgamation and genetic variation: observations on artificially agglomerated tribal populations of Central and South America.

The interpretation of data on genetic variation with regard to the relative roles of different evolutionary factors that produce and maintain genetic variation depends critically on our assumptions concerning effective population size and the level of migration between neighboring populations. In humans, recent population growth and movements of specific ethnic groups across wide geographic areas mean that any theory based on assumptions of constant population size and absence of substructure is generally untenable. We examine the effects of population subdivision on the pattern of protein genetic variation in a total sample drawn from an artificial agglomerate of 12 tribal populations of Central and South America, analyzing the pooled sample as though it were a single population. Several striking findings emerge. (1) Mean heterozygosity is not sensitive to agglomeration, but the number of different alleles (allele count) is inflated, relative to neutral mutation/drift/equilibrium expectation. (2) The inflation is most serious for rare alleles, especially those which originally occurred as tribally restricted "private" polymorphisms. (3) The degree of inflation is an increasing function of both the number of populations encompassed by the sample and of the genetic divergence among them. (4) Treating an agglomerated population as though it were a panmictic unit of long standing can lead to serious biases in estimates of mutation rates, selection pressures, and effective population sizes. Current DNA studies indicate the presence of numerous genetic variants in human populations. The findings and conclusions of this paper are all fully applicable to the study of genetic variation at the DNA level as well.

Comparison of two strategies for the treatment of acute myocardial infarction: In-hospital outcomes analysis

A strategy of pre-hospital reduced dose fibrinolytic administration coupled with urgent coronary intervention (PCI) for patients with STEMI (FAST-PCI) has been found to be superior to primary PCI (PPCI) alone. A coordinated STEMI system-of-care that includes FAST-PCI might offer better outcomes than pre-hospital diagnosis and STEMI team activation followed by PPCI alone. We compared the in-hospital outcomes for patients treated with the FAST-PCI approach with outcomes for patients treated with the PPCI approach during a pause in the FAST-PCI protocol. In-hospital data for 253 STEMI patients (03/2003–12/2009), treated with FAST-PCI protocol were compared to 124 patients (12/2009–08/2011), treated with PPCI strategy alone. In-hospital mortality was the primary endpoint. Stroke, major bleeding, and reinfarction during index hospitalization were secondary endpoints. Comparing the strategies used during the two time intervals, in-hospital mortality was significantly lower with FAST-PCI than with PPCI (2.77% vs. 10.48%, p = 0.0017). Rates of stroke, reinfarction and major bleeding were similar between the two groups. There was a lower frequency of pre- PCI TIMI 0 flow (no patency) seen in patients treated with FAST-PCI compared to the PPCI patients (26.7% vs. 62.7%, p<0.0001). Earlier infarct related artery patency in the FAST-PCI group had a favorable impact on the incidence of cardiogenic shock at hospital admission (FAST-PCI- 3.1% vs. PPCI- 20.9%, p<0.0001). The FAST-PCI strategy was associated with earlier infarct related artery patency and the lower incidence of cardiogenic shock on hospital arrival, as well as with reduced in-hospital mortality among STEMI patients.^