How many populations set foot through the Patagonian door? Genetic composition of the current population of Bahía Blanca (Argentina) based on data from 19 Alu polymorphisms

The city of Bahía Blanca occupies a strategic place in Argentina south of the Pampean region in the north-east corner of the Patagonia. Since 1828, this city has been the historical and political border between Amerindian lands in the south, and the lands of European colonists. Nowadays, Bahía Blanca is an urban population mainly composed by descendents of immigrants from Spain and other European countries with apparently low admixture with Amerindians. In view of the unexpectedly high Amerindian admixture levels (about 46.7%) suggested by mtDNA data, and protein markers (19.5%), we analyzed a set of 19 Alu polymorphisms (18 autosomal, 1 of Chromosome Y) in a well-documented genealogical sample from Bahía Blanca. The genotyped sample was made up of 119 unrelated healthy individuals whose birth place and grandparent origins were fully documented. According to available genealogical records, the total sample has been subdivided into two groups: Bahía Blanca Original (64 individuals with all 4 gandparents born in Argentina) and Bahía Blanca Mix (55 individuals with one to three grandparents born out of Argentina). Allele frequencies and gene diversity values in Bahía Blanca fit well into the European ranges. Population relationships have been tested for 8 Alu markers, whose variation has been described in several Amerindian and European samples. Reynolds genetic distances underline the significant genetic similarity of Bahía Blanca to Europeans (mean distance 0.044) and their differentiation from Amerindians (0.146). Interestingly enough, when the general sample is divided, Bahía Blanca Original appears slightly closer to Amerindians (0.127) in contrast to Bahía Blanca Mix (0.161). Furthermore, the genetic relationships depicted through a principal components analysis emphasize the relative similarity of Bahía Blanca Original to Amerindians. A thorough knowledge of the sample origins has allowed us to make a subtle distinction of the genetic composition of Bahía Blanca.

Role of intrapartum hypoxia in carnitine nutritional status during the early neonatal period

We analyze markers of carnitine insufficiency and deficiency, lysine (LYS) and methionine (MET), in 39 neonates with intrapartum hypoxia (selection criteria: umbilical artery pH <7.20, lactate >1.8 mmol/l and PaO2 <25 mm Hg), and in 35 healthy newborn infants (control group) in the early neonatal period (1-7 days of life). Free (FC), total (TC) carnitine and acylcarnitines (AC=short-chain+long-chain acylcarnitines) were measured using a radioisotopic micromethod; LYS and MET were determined by high-pressure liquid chromatography. AC and TC plasma concentrations and AC/FC ratio were higher while FC/TC ratio was lower in the hypoxic neonates than in the control group. Hypoxic newborn infants (59%) presented "carnitine deficiency" (FC/TC <0.7) and 60% of them "carnitine insufficiency" (AC/FC ratio >0.4) vs. 31% and 28%, respectively, for the neonates of the control group (p<0.05). In the healthy neonates group, MET correlated with FC/TC and the AC/FC ratio. FC, TC, AC, AC/FC and umbilical artery pH (pHua) were inversely correlated. FC/TC and MET correlated with pHua. We conclude that: (1) an important percentage of newborn infants with intrapartum hypoxia suffer carnitine deficiency and carnitine insufficiency in the early neonatal period, related to MET plasma levels; (2) the carnitine deficiency or insufficiency in the neonate is determined by the degree of intrapartum acidosis.

High heterogeneity of apolipoprotein E gene frequencies in South American Indians

The apolipoprotein E (APOE) polymorphism was investigated in 186 individuals from six South American Indian tribes, and the results integrated with those previously presented for this ethnic group. The three APOE alleles commonly reported in other populations were also observed in South Amerindians with a highly heterogeneous distribution. As in other populations, APOE*3 was the most common allele (51-98%) followed by APOE*4 (2-47%). These two isoforms were identified in all tribes, but APOE*2 was observed among the Wai Wai (2%) and Mataco (4%) only. No previous indications of inter-ethnic admixture were observed among the Wai Wai, but the introduction of this allele among the Mataco through non-Indian sources cannot be excluded.

Low-dosage prophylactic vancomycin in central-venous catheters for neonates

Neonatal infectious pathology remains one of the main causes of morbidity and mortality in this age group. The introduction of plasticized catheters for the administration of medication, fluidotherapy and parenteral nutrition was a significant advance in treatment of patients at risk, but also led to the appearance of infectious complications. Negative coagulase staphylococcus is the principal pathogen in most neonatal intensive care units. Recent studies have examined the prophylactic use of vancomycin in preterm babies receiving parenteral nutrition. We have evaluated the efficacy of this procedure, applied via the central venous catheters employed for all neonates, within the intensive care unit over a period of one year. Prophylactic vancomycin administered via the catheters significantly reduced the incidence of Gram-positive infections, despite the presence within this group of a greater number of septic risk factors than in the control group.