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Biomedical subjects

R Soria

Publications and source records attributed to R Soria.

At least 19 recordsLinked to original sources
PubMed2002

[Submental abscess by Lactobacillus acidophilus/jensenii].

The different species of Lactobacillus genus are bacteria of a low pathogenicity. They are found in the gastrointestinal tract, the female genitourinary tract, and also as part of the anaerobic flora in the mouth. Due to this low pathogenicity, they are generally related with infections together with other with more virulent microorganisms, or in immunocompromised patients. In our case, Lactobacillus appears alone as an etiological agent in an immunocompetent patient with a submental abscess.

Abscess↗
PubMed2000

Higher arterial oxygen saturation during submaximal exercise in Bolivian Aymara compared to European sojourners and Europeans born and raised at high altitude.

Arterial oxygen saturation (SaO(2)) was measured at 3,600-3,850 m by pulse oximetry at rest and during submaximal exercise in three study groups: 1) highland Aymara natives of the Bolivian altiplano (n = 25); 2) lowland European/North American sojourners to the highlands with at least 2 months of acclimatization time to 3,600 m (n = 27); and 3) subjects of European ancestry born and raised at 3,600 m (n = 22). Aymara subjects maintained approximately 1 percentage point higher SaO(2) during submaximal work up to 70% of their maximal work capacity, and showed a smaller rate of decline in SaO(2) with increasing work compared to both European study groups. The higher-exercise SaO(2) of Aymara compared to Europeans born and raised at 3,600 m suggests genetic adaptation. The two European study groups, who differed by exposure to high altitude during their growth and development period, did not show any significant difference in either resting or exercise SaO(2). This suggests that the developmental mode of adaptation is less important than the genetic mode of adaptation in determining exercise SaO(2). A weak correlation was detected (across study groups only) between the residual forced vital capacity (FVC) and the residual SaO(2) measured at the highest level of submaximal work output (P = 0.024, R = 0.26). While firm conclusions based on this correlation are problematic, it is suggested that a part of the higher SaO(2) observed in Aymara natives is due to a larger lung volume and pulmonary diffusion capacity for oxygen. Results from this study are compared to similar studies conducted with Tibetan natives, and are interpreted in light of recent quantitative genetic analyses conducted in both the Andes and Himalayas.

Adaptation, Physiological↗
PubMed1999

Percent of oxygen saturation of arterial hemoglobin among Bolivian Aymara at 3,900-4,000 m.

A range of variation in percent of oxygen saturation of arterial hemoglobin (SaO2) among healthy individuals at a given high altitude indicates differences in physiological hypoxemia despite uniform ambient hypoxic stress. In populations native to the Tibetan plateau, a significant portion of the variance is attributable to additive genetic factors, and there is a major gene influencing SaO2. To determine whether there is genetic variance in other high-altitude populations, we designed a study to test the hypothesis that additive genetic factors contribute to phenotypic variation in SaO2 among Aymara natives of the Andean plateau, a population geographically distant from the Tibetan plateau and with a long, separate history of high-altitude residence. The average SaO2 of 381 Aymara at 3,900-4,000 m was 92+/-0.15% (SEM) with a range of 84-99%. The average was 2.6% higher than the average SaO2 of a sample of Tibetans at 3,800-4,065 m measured with the same techniques. Quantitative genetic analyses of the Aymara sample detected no significant variance attributable to genetic factors. The presence of genetic variance in SaO2 in the Tibetan sample and its absence in the Aymara sample indicate there is potential for natural selection on this trait in the Tibetan but not the Aymara population.

Adaptation, Physiological↗
PubMed1999

Developmental components of resting ventilation among high- and low-altitude Andean children and adults.

This paper evaluates the age-associated changes of resting ventilation of 115 high- and low-altitude Aymara subjects, of whom 61 were from the rural Aymara village of Ventilla situated at an average altitude of 4,200 m and 54 from the rural village of Caranavi situated at an average altitude of 900 m. Comparison of the age patterns of resting ventilation suggests the following conclusions: 1) the resting ventilation (ml/kg/min) of high-altitude natives is markedly higher than that of low-altitude natives; 2) the age decline of ventilation is similar in both lowlanders and highlanders, but the starting point and therefore the age decline are much higher at high altitude; 3) the resting ventilation that characterizes high-altitude Andean natives is developmentally expressed in the same manner as it is at low altitude; and 4) the resting ventilation (ml/kg/min) of Aymara high-altitude natives is between 40-80% lower than that of Tibetans.

Adaptation, Physiological↗
PubMed1999

Effect of developmental and ancestral high-altitude exposure on VO(2)peak of Andean and European/North American natives.

Peak oxygen consumption (VO(2)peak) was measured in 150 adult males (18-35 years old) in Bolivia, using a complete migrant study design to partition developmental from ancestral (genetic) effects of high-altitude (HA) exposure. High-altitude natives (HANs, Aymara/Quechua ancestry, n = 75) and low-altitude natives (LANs, European/North American ancestry, n = 75) were studied at high altitude (3,600-3,850 m) and near sea level (420 m). HAN and LAN migrant groups to a nonnative environment were classified as: multigeneration migrants, born and raised in a nonnative environment; child migrants who migrated to the nonnative environment during the period of growth and development (0-18 years old); and adult migrants who migrated after 18 years of age. Variability in VO(2)peak due to high-altitude adaptation was modeled by covariance analysis, adjusting for fat-free mass and physical activity (training) differences between groups. A trend for increased VO(2)peak with increasing developmental high-altitude exposure in migrant groups did not reach statistical significance, but low statistical power may have limited the ability to detect this effect. HANs and LANs born, raised, and tested at high altitude had similar VO(2)peak values, indicating no genetic effect, or an effect much smaller than that reported previously in the literature. There was no functional correlation between forced vital capacity and VO(2)peak, within or across groups. These results do not support the hypothesis that Andean HANs have been selected to express a greater physical work capacity in hypoxia.

Adaptation, Physiological↗
PubMed1998

Hemoglobin concentration of high-altitude Tibetans and Bolivian Aymara.

Elevated hemoglobin concentrations have been reported for high-altitude sojourners and Andean high-altitude natives since early in the 20th century. Thus, reports that have appeared since the 1970s describing relatively low hemoglobin concentration among Tibetan high-altitude natives were unexpected. These suggested a hypothesis of population differences in hematological response to high-altitude hypoxia. A case of quantitatively different responses to one environmental stress would offer an opportunity to study the broad evolutionary question of the origin of adaptations. However, many factors may confound population comparisons. The present study was designed to test the null hypothesis of no difference in mean hemoglobin concentration of Tibetan and Aymara native residents at 3,800-4,065 meters by using healthy samples that were screened for iron deficiency, abnormal hemoglobins, and thalassemias, recruited and assessed using the same techniques. The hypothesis was rejected, because Tibetan males had a significantly lower mean hemoglobin concentration of 15.6 gm/dl compared with 19.2 gm/dl for Aymara males, and Tibetan females had a mean hemoglobin concentration of 14.2 gm/dl compared with 17.8 gm/dl for Aymara females. The Tibetan hemoglobin distribution closely resembled that from a comparable, sea-level sample from the United States, whereas the Aymara distribution was shifted toward 3-4 gm/dl higher values. Genetic factors accounted for a very high proportion of the phenotypic variance in hemoglobin concentration in both samples (0.86 in the Tibetan sample and 0.87 in the Aymara sample). The presence of significant genetic variance means that there is the potential for natural selection and genetic adaptation of hemoglobin concentration in Tibetan and Aymara high-altitude populations.

Adaptation, Physiological↗
PubMed1998

Jasmonic acid stimulates the expression of nod genes in Rhizobium.

Jasmonates and salicylic acid are considered to be signal molecules that induce a variety of plant genes involved in wound or defence response, as well as affecting nos promoter activity. In this paper we examined whether these chemicals could also affect nod genes from isogenic rhizobia strains. Isogenic strains contain the Rhizobium leguminosarum nodA promoter fused to the lacZ gene of Escherichia coli and differ only in the source of the regulatory nodD gene. Naringenin, jasmonic acid and methyl jasmonate induced expression of nod genes in strain RBL1284 and salicylic acid showed no activity alone or when used in combination with other compounds; addition of naringenin + jasmonic acid produced a synergistic effect. Results obtained with strain RBL5284 were similar to those for RBL1284 albeit the combination of naringenin with the other compounds markedly inhibited nod gene expression. Whereas RBL5283 responded to naringenin with a strong induction, jasmonic acid, methyl jasmonate or salicylic acid showed no significant responses. The inhibitory effect of salicylic acid on nod gene expression indicates that the induction mechanism of jasmonic acid, methyl jasmonate, N-propyldihydrojasmonate and naringenin is probably different from that of salicylic acid.

Acyltransferases↗
PubMed1997

Ventilation and hypoxic ventilatory response of Tibetan and Aymara high altitude natives.

Newcomers acclimatizing to high altitude and adult male Tibetan high altitude natives have increased ventilation relative to sea level natives at sea level. However, Andean and Rocky Mountain high altitude natives have an intermediate level of ventilation lower than that of newcomers and Tibetan high altitude natives although generally higher than that of sea level natives at sea level. Because the reason for the relative hypoventilation of some high altitude native populations was unknown, a study was designed to describe ventilation from adolescence through old age in samples of Tibetan and Andean high altitude natives and to estimate the relative genetic and environmental influences. This paper compares resting ventilation and hypoxic ventilatory response (HVR) of 320 Tibetans 9-82 years of age and 542 Bolivian Aymara 13-94 years of age, native residents at 3,800-4,065 m. Tibetan resting ventilation was roughly 1.5 times higher and Tibetan HVR was roughly double that of Aymara. Greater duration of hypoxia (older age) was not an important source of variation in resting ventilation or HVR in either sample. That is, contrary to previous studies, neither sample acquired hypoventilation in the age ranges under study. Within populations, greater severity of hypoxia (lower percent of oxygen saturation of arterial hemoglobin) was associated with slightly higher resting ventilation among Tibetans and lower resting ventilation and HVR among Aymara women, although the associations accounted for just 2-7% of the variation. Between populations, the Tibetan sample was more hypoxic and had higher resting ventilation and HVR. Other systematic environmental contrasts did not appear to elevate Tibetan or depress Aymara ventilation. There was more intrapopulation genetic variation in these traits in the Tibetan than the Aymara sample. Thirty-five percent of the Tibetan, but none of the Aymara, resting ventilation variance was due to genetic differences among individuals. Thirty-one percent of the Tibetan HVR, but just 21% of the Aymara, HVR variance was due to genetic differences among individuals. Thus there is greater potential for evolutionary change in these traits in the Tibetans. Presently, there are two different ventilation phenotypes among high altitude natives as compared with sea level populations at sea level: lifelong sustained high resting ventilation and a moderate HVR among Tibetans in contrast with a slightly elevated resting ventilation and a low HVR among Aymara.

Acclimatization↗
PubMed1996

Subjective and cardiovascular effects of intravenous nicotine in smokers and non-smokers.

The present study assessed the subjective and cardiovascular effects of intravenous nicotine in smokers and nonsmokers. Nonsmokers (n = 5) and smokers (n = 5) were administered a single dose of nicotine (0.75 or 1.5 mg) or saline on each of 3 days. The nicotine doses were given in ascending order in a double-blind fashion. Although smokers and nonsmokers manifested significant increases in systolic and diastolic blood pressure and heart rate 1 min after administration of all active test doses, the difference between peak heart rate and that measured at later times was greater in nonsmokers than in smokers. Nonsmokers and smokers also differed in subjective self-reports. In response to items on visual analogue scales indicative of positive effects (e.g., "good effects," "like drug," "use again," and "feel energetic"), smokers but not nonsmokers reported high scores (> 40) after nicotine injection. In addition, responses on the MBG and LSD subscales of the Addiction Research Center Inventory indicated that smokers experienced positive subjective effects after the test doses, whereas nonsmokers experienced disorientation. The fact that intravenous nicotine was not associated with positive subjective effects in nonsmokers indicates that repeated exposure is required to establish positive reinforcing effects of nicotine.

Adult↗
PubMed1996

Event-related potential scalp fields during parallel and serial visual searches.

Event-related potential (ERP) scalp fields generated during parallel and serial searches were compared using a bootstrap resampling technique. Two different parallel search tasks required the detection of a single feature either color or orientation. A serial search task required the detection of the feature conjunction target: color and orientation. Identical stimuli were used for both parallel searches and a similar stimulus for the serial search. No evidence for scalp field differences earlier than 150 ms were discovered, suggesting that "low-level' visual processing is the same in both types of searches. ERP scalp fields that distinguished parallel from serial searches were identified between 150 and 250 ms. It is proposed that these different scalp fields represent timing and/or magnitude differences in the regions of cortex activated during parallel and serial searches.

Adult↗
PubMed1995

Developmental, genetic, and environmental components of aerobic capacity at high altitude.

The aerobic capacity of 268 subjects (158 males and 110 females) was evaluated in La Paz, Bolivia situated at 3,750 m. The sample included 1) 39 high altitude rural natives (all male); 2) 67 high altitude urban natives (32 male, 35 female); 3) 69 Bolivians of foreign ancestry acclimatized to high altitude since birth (37 male, 32 female); 4) 50 Bolivians of foreign ancestry acclimatized to high altitude during growth (25 male, 25 female); and 5) 42 non-Bolivians of either European or North American ancestry acclimatized to high altitude during adulthood (25 male, 18 female). Data analyses indicate that 1) high altitude urban natives, acclimatized to high altitude since birth or during growth, attained higher aerobic capacity than subjects acclimatized to high altitude during adulthood; 2) age at arrival to high altitude is inversely related to maximum oxygen consumption (VO2 max) expressed in terms L/min or ml/min/kg of lean body mass, but not in terms of ml/min/kg of body weight; 3) among subjects acclimatized to high altitude during growth, approximately 25% of the variability in aerobic capacity can be explained by developmental factors; 4) as inferred from evaluations of skin color reflectance and sibling similarities, approximately 20 to 25% of the variability in aerobic capacity at high altitude can be explained by genetic factors; 5) except among the non-Bolivians acclimatized to high altitude during adulthood, the aerobic capacity of individuals with high occupational activity level is equal to the aerobic capacity of high altitude rural natives; and 6) the relationship between occupational activity level and aerobic capacity is much greater among subjects acclimatized to high altitude before the age of 10 years than afterwards. Together these data suggest that the attainment of normal aerobic capacity at high altitude is related to both developmental acclimatization and genetic factors but its expression is highly mediated by environmental factors, such as occupational activity level and body composition.

Acclimatization↗
PubMed1991

[Left bifascicular block and percutaneous mitral valvuloplasty].

In some patients, the inflation of balloons through the mitral orifice during percutaneous mitral valvuloplasties may impair intraventricular conduction. In some cases, this appears to correspond to a block of the anterior and middle network within the left branch of the bundle of His. This left "biblock" is characterized by extreme left axial deviation of AQRS, of about -60 to -70 degrees, with a QS aspect on D2 and D3, RS on V1 and R on V6 with no major prolongation of ventricular activation time. If this hypothesis is correct, it would support the "trifascicular" concept of the left branch of the bundle of His.

Adult↗
PubMed1989

[The natural history of 270 cases of Wolff-Parkinson-White syndrome in a survey of the general population].

Among 226,464 ambulatory subjects who underwent medical check-ups over a 15-year period, 270 were found to have Wolff-Parkinson-White syndrome (1.2 case in 1,000). The syndrome was more frequent in men (181 cases, 1.4 p. 1,000) than in women (89 cases, 0.9 p. 1,000). 222 subjects were aged from 20 to 49 years (1.4 p. 1,000) and only 48 were between 50 and 80 years of age (0.7 p. 1,000). 197 subjects were re-evaluated: 119 (60.4 p. 100) complained of palpitations and 78 (39.6 p. 100) were asymptomatic. Palpitations began at all ages, even after 50 years, and usually proceeded in short attacks lasting a few seconds or minutes, with a mean recurrence rate of 5 attacks per annum (76.4 p. 100). This constant pattern sometimes was interrupted for months or years. Conversely, in a minority of cases (23.5 p. 100) an unexpected accentuation occurred which lasted for hours or days. As years went by, palpitations tented to decrease and disappear. The pre-excitation area and its degree of fusion with the normal ventricular activation had no influence on the origin and frequency of palpitations. In contrast, sustained tachycardia seemed to be more frequent in cases with lateral and posterior left pre-excitation. Among 270 subjects with pre-excitation syndrome, 7 died including 4 whose death was not due to a cardiac disease, 2 who died suddenly and 1 who succumbed to ventricular tachycardia after a road accident. None of these patients had an associated heart disease. These last 3 cases might contribute to alter the usually favourable prognosis of Wolff-Parkinson-White syndrome.

Adult↗
PubMed1987

[Dilated cardiomyopathy: electrocardiographic forms].

The shape of the QRS complex was analyzed in 90 cases of dilated cardiomyopathy and was divided into 6 electrocardiographic types which may be interpreted as follows: A predominant S wave in V2, V3 and V4 leads, surrounded by a reduced QRS voltage in the other leads was the most frequent characteristic pattern, being found in 31 cases (34.4%). This pattern coexisted with a lack of R wave progression from V1 to V4, with primary disorders of ST-T and with alterations in P wave. The deep S wave is probably due to a growth of vectors in the base of the left ventricle and in the septum in response to lesions in the rest of the myocardium. Second in frequency (22.2%) came left bundle branch block, with 20 cases. If to these are added the 19 cases of left anterior half-block observed, dilated cardiomyopathy appears as the major cause of the cardiac pathology that partially or completely interrupts the left branch. These cases also show that the lesions predominate in the left ventricle. The 14 cases (15.5%) of QS with elevated and convex ST-T betray extensive areas of fibrosis or necrosis. This pattern is characteristically located at the apex of the heart and associated with ventricular tachycardia. In 11 cases (12.2%) the QRS complex was normal in shape but associated with depressed ST-T and atrial disorders. This shows that the ventricular myocardium which produces QRS is neither badly damaged nor hypertrophic, but that repolarization is highly sensitive to the constant alterations of the subendocardial layers observed in dilated cardiomyopathy. Left ventricular hypertrophy was seen in 9 cases (10%).(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1985

[Prevalence and course of Wolf-Parkinson-White syndrome in a population of 138,048 subjects].

The prevalence of the Wolff-Parkinson-White (WPW) syndrome, frequency of arrhythmias and their evolution were studied in a group of volunteers consisting in 79,978 men and 59,070 women, aged from 20 to over 70. The higher prevalence of WPW in men than in women (p less than 0.001) decreased significantly with age, much more in men (p less than 0.001) than in women (p less than 0.05). Ventricular pre-excitation was intermittent in 6.7 p. 100 of men and in 16 p. 100 of women. The probable site of pre-excitation, determined on the orientation of the delta wave was more often left than right (104 vs 66, p less than 0.02). The frequency of paroxysmal tachycardia increased with age: 10 p. 100 of the cases from 20 to 39 years of age, 29 p. 100 from 40 to 59, 36 p. 100 at 60 and over (p = 0.05). It was 1.7 times more frequent in cases of left pre-excitation. A hundred and fifty-one patients were followed-up from 1 to 11 years (4.6): 5 patients died, 3 of non-cardiac and 2 of undetermined causes, with one sudden death in a 29 year old man. Fifty-three patients were reviewed 4.5 years after the initial examination: 9 pre-excitations (7 right, 2 left) had disappeared. In conclusion, the higher prevalence of WPW in men decreases with age. This decrease appears to be essentially due to the disappearance of the ventricular pre-excitation and not to an increased mortality. Arrhythmias are more frequent in older patients with left-sided pre-excitation.

Adult↗
PubMed1984

[Coexistence of left branch block and ectopic rhythm simulating alternating block].

During the acute phase of diaphragmatic myocardial infarction with septal extension, the ECG of a patient with a chronic left bundle branch block changed in a period of seconds from complete left bundle branch block to incomplete right bundle branch block then to narrow QRS complexes followed by incomplete and then complete left bundle branch block: the same QRS changes then occurred in reverse order; the atrial rhythm was absolutely stable during the recording. These appearances are explained by fusion of sinus and of an ectopic rhythm arising distal to the zone of block, the rate of which (sometimes faster and sometimes slower than the sinus rhythm) could have been influenced by an electrotonic effect after retrograde activation of the right bundle and concealed conduction in the left bundle. Appearances of bundle branch block may be recorded when the ventricle is partially activated from the point of breakthrough of the blocked branch.

Aged↗