1,721,086 research outputs found
Body size, composition, and blood pressure of high-altitude Quechua from the Peruvian Central Andes
No full textAlthough much information is available about the effects of high altitude on physiological characteristics, less is know about its effect on body composition. In the present study, anthropometric and body composition variables were investigated in a sample of 77 adult Quechua males from the Peruvian Central Andes (Huancavelica, 3,680 m). The subjects are shorter in relation to body weight than other ethnic groups, whereas body proportions are macrocormic (indicating a long trunk relative to the lower extremities), with intermediate values of the acromial-iliac index. All skinfold thicknesses are low (Ο 15th percentiles of NHANES reference values for the triceps and subscapular skinfolds), but tend to be higher than in the other Quechua populations. Similar results are obtained when percentage fat is estimated. Somatotypes are dominant in mesomorphy with very low ectomorphy. Comparison with a sample of high-altitude Kirghiz (3,200 m), previously studied with the same methods, shows higher values in the Peruvian sample for all variables related to adiposity. The presence of low adiposity in the Quechua population could be associated with stresses of the high-altitude environment. Mean values of blood pressure are very low and there is no correlation with age. © 2001 Wiley-Liss, Inc
Reconstruction of prehistory on the basis of genetic data
No full textIn their letter, Torroni et al. (2000) express a radical
disagreement with the assumptions, methods, and conclusions
of Simoni et al.’s (2000) article. We think that
their many criticisms can be reduced to four points:
1. Haplogroups have been incorrectly defined, and
therefore the spatial autocorrelation analysis (SAAP) of
their frequencies is flawed;
2. Aside from these errors, the frequencies of haplogroup
J and of superhaplogroup JT do not match previous
reports;
3. Only 22 polymorphic sites have been considered,
and therefore the results of AIDA are flawed;
4. Meaningful patterns of mtDNA diversity can only
be identified by the analysis of the distributions of recent
mutations
Patterns of gene flow inferred from genetic distances in the Mediterranean region
No full textThe analysis of population structure may lead to inferences about demographic phenomena. In particular, regions of sharp genetic differentiation suggest the existence of factors that impaired gene flow and increased the evolutionary role of genetic drift. Here, we present an analysis of a data set of 10 allele frequencies in 39 populations of the Mediterranean region. As a preliminary step, we describe spatial patterns of allele frequencies using spatial autocorrelation analysis. We then construct a network connecting localities and estimate genetic distances along the edges of the network. By applying specific algorithms, we locate on the map the areas of sharpest genetic differentiation, or genetic boundaries. The main boundaries separate the northern and the southern coasts, especially in their western portions; in addition, several localities appear genetically isolated. The comparatively high genetic differentiation across the western Mediterranean, where the sea distances between localities are shorter, strongly suggests that the sea distance by itself can hardly be regarded as a major isolating factor among these populations. On the contrary, the decrease in genetic resemblance between populations of the 2 coasts as one proceeds westward may reflect an increased genetic exchange in the eastern Mediterranean basin or independent human dispersal along the 2 coasts or both
Geographic patterns of mtDNA diversity in Europe
No full textGenetic diversity in Europe has been interpreted as a
reflection of phenomena occurring during the Paleolithic
(»45,000 years before the present [BP]), Mesolithic
(»18,000 years BP), and Neolithic (»10,000 years BP)
periods. A crucial role of the Neolithic demographic
transition is supported by the analysis of most nuclear
loci, but the interpretation of mtDNA evidence is controversial.
More than 2,600 sequences of the first hypervariable
mitochondrial control region were analyzed
for geographic patterns in samples from Europe, the
Near East, and the Caucasus. Two autocorrelation statistics
were used, one based on allele-frequency differences
between samples and the other based on both sequence
and frequency differences between alleles. In the
global analysis, limited geographic patterning was observed,
which could largely be attributed to a marked
difference between the Saami and all other populations.
The distribution of the zones of highest mitochondrial
variation (genetic boundaries) confirmed that the Saami
are sharply differentiated from an otherwise rather homogeneous
set of European samples. However, an area
of significant clinal variation was identified around the
Mediterranean Sea (and not in the north), even though
the differences between northern and southern populations
were insignificant. Both a Paleolithic expansion
and the Neolithic demic diffusion of farmers could have
determined a longitudinal cline of mtDNA diversity.
However, additional phenomena must be considered in
both models, to account both for the north-south differences
and for the greater geographic scope of clinal
patterns at nuclear loci. Conversely, two predicted consequences
of models of Mesolithic reexpansion from glacial
refugia were not observed in the present study
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Relationships between blood pressure, anthropometric characteristics and blood lipids in high- and low-altitude populations from Central Asia
No full textWe studied the relationships between blood pressure, anthropometric characteristics and blood lipids in 72 low altitude (LA) Uighurs (600 m), 91 LA-Kirghizs (900 m), 117 medium altitude (MA) Kazakhs (2100 m) and 94 high altitude (HA) Kirghizs (3200 m). All subjects were male and had a similar age (p = ns, ANOVA; range for all 374 subjects: 18-66 yr). Body weight (Wt), body mass index (BMI) and the sum of four skinfolds (4SF) were significantly lower in HA-Kirghizs than the remaining groups (p < 0.0005, p < 0.0005 and p < 0.05 respectively, ANOVA). However, no difference was found in body fat distribution as detected by waist:hip circumference (WHR) and triceps:subscapular skinfold ratios (TSR; p = ns, ANOVA). Stage 1 hypertension was detected in 18% of LA-Uighurs, 2% of LA-Kirghizs, 4% of MA-Kazakhs and 1% of HA-Kirghizs; stage 2 hypertension was detected in 2% of LA-Uighurs and none of the remaining groups; no subject had stage 3 hypertension (The Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure 1997). Blood cholesterol (CH) and triglycerides (TG) did not differ between groups (p = ns, ANOVA). The relationships between systolic (SBP) or diastolic (DBP) blood pressure and age, Wt, BMI, 4SF, WHR, TSR, CH and TG were independent from altitude (p = ns, ANCOVA). In the pooled sample (n = 374), age explained 1 and 3% of SBP (p < 0.05) and DBP (p < 0.005) variance respectively, Wt was the best predictor of SBP and DBP explaining 11 and 10% of their variance respectively (p < 0.0001) and CH explained 5% of DBP variance (p < 0.0001). In conclusion, hypertension is more frequent in LA- than MA- and HA-subjects from Central Asia. However, anthropometric characteristics and blood lipids do similarly contribute to explain blood pressure in these subjects
A Mediterranean melting pot. Excavating uni-parental genetic strata in Sicily and Southern Italy
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