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Biomedical subjects

A Loría

Publications and source records attributed to A Loría.

At least 19 recordsLinked to original sources
PubMed1980

Red cell indices in normal adults residing at altitude from sea level to 2670 meters.

Hemoglobin (Hb), packed cell volume (PCV), red blood cells (RBCs), mean cell volume (MCV), and mean cell hemoglobin concentration (MCHC) were measured by a single operator in a single laboratory by means of an electronic particle counter in 942 healthy adults (491 females and 451 males) residing at five altitudes: 0, 1000, 1860, 2220, and 2670 meters above sea level. The subjects were carefully screened clinically, and subjects with low transferrin saturation (less than 15%) were excluded. In both sexes there was a differential behavior as a function of altitude, of Hb and PCV on the one hand, and number of RBCs on the other. The findings suggest the presence of two sequential mechanisms of adaptation to progressively lower atmosphere oxygen pressure: One operating from sea level to 1860 meters, which leads to a progressively increasing number of relatively microcytic RBC; and a second one -- from 1860 to 2670 meters -- in which there is an increased but constant number of progressively more normocytic RBC, so that a simplistic model of equal magnitude increases in the three parameters and is seen at 2670 meters, but not at the intermediate altitudes. The middle group's comparativity, essential to these interpretations, apparently was achieved with regard to time elapsed between sampling and testing and with regard to the people integrating the groups.

Adolescent↗
PubMed1979

Serum ferritin in an elderly population.

Serum ferritin was assayed by an immunoradiometric method in 82 people above 60 years of age. For comparison purposes, the same assay was performed in 71 younger normal adults. The serum ferritin distribution in the elderly had a larger variance than in the younger adults and in addition, there was a clear shift to higher values in the elderly. The latter was more notable in females than in males but there was still a statistically lower mean in elderly females than in elderly males. Ten out of 55 elderly subjects with evidence of iron deficiency (response to oral iron therapy) had a normal or high serum ferritin which suggests that variables unrelated to iron status may operate in determining serum ferritin levels in the elderly. The shift to higher values appears to occur upon reaching grossly 70 years of age. Whether the shift is a physiologically normal event is at present an open question.

Aged↗
PubMedDate not supplied

[Intestinal hemorrhage for 21 years in a case of blue nevus syndrome].

OBJECTIVE: To report a case of gastrointestinal bleeding due to a blue rubber bleb nevus syndrome undiagnosed for 21 years. CASE: A woman of 28 years of age suffered chronic gastrointestinal bleeding starting at seven years of age. During these 21 years she received various treatment with oral and parenteral iron and, in addition, four blood transfusions. We found her to be anemic with 7.8 g/dL of hemoglobin (HB), iron deficient and with skin lesions in tongue, right hand and lower extremities. A skin biopsy diagnosed the lesions as cavernous hemangiomas. Multiple intestinal hemangiomas seen by radiologic, endoscopic and colonoscopic studies, established the diagnosis. She was treated with oral iron; three months later she was asymptomatic and with higher levels of HB (9.1 g/dL). CONCLUSION: The rarity of the syndrome and the fact that, as far as we know, it is the first case reported in Mexico, probably led to a delay in its diagnosis and to potentially dangerous therapy in this patient in spite of the fact that the diagnosis was not difficult.

Adult↗
PubMedDate not supplied

[A model for evaluating internal accuracy].

OBJECTIVE: To provide an evaluation model of internal accuracy illustrating its use in a quality control program of clinical chemistry. METHODS: The model uses data transformed to percentage of assigned value (%AV) that allows the pooling of different controls. Precision is evaluated by the mean of the intracontrol coefficients of variation, and accuracy by the mean of means of the %VAs and its standard deviation. The model was used in 17,280 measurements of 23 analytes assayed in seven pairs of controls (medium and high concentration) during four years in two automated clinical chemistry analyzers. RESULTS: The model established inaccuracy of 5% to 25% in seven analytes, five of them enzymes. It also detected interanalyzer differences in accuracy of five analytes (22%) and an erroneous assigned value in 19 of 304 controls (6%). CONCLUSIONS: The model showed its capacity to dissect the sources of variation of accuracy. There was inaccuracy in 30% of the analytes but further studies are needed to validate these inaccuracies with controls of other sources. The model can be useful for control programs of any quantitative assay system. A summary description of the model's operation is given.

Chemistry, Clinical↗
PubMedDate not supplied

[Evaluation of pipetting systems. II. Precision and accuracy of precision dispensers].

OBJECTIVE: To evaluate the precision and accuracy of the liquid dispensers being used in our institution. MATERIAL: A total of 15 dispensers (8 micro and 7 macro) of automatic, semiautomatic or manual types were evaluated. They had been in use from 0.5 to 7 years. METHODS: The volume dispensed was established by gravimetry using an analytical balance (Chio JP-160) and deionized distilled water as previously described. The microdispensers were evaluated using volumes of 20 and 100 microL, and the macrodispensers with 1 and 5 mL. Each dispenser was evaluated using 10 replicates: the mean and the CV (coefficient of variation) were calculated with the 10 replicates. The mean was transformed to per cent of the theoretical volume. Thus a 100% ratio of accuracy corresponds to a perfect accuracy. An important methodological aspect was that the 10 dispensing replicates were performed personally by the habitual user of the dispenser. RESULTS: The mean and CV are shown in table 2 for the microdispensers, and in table 3 for the macrodispenser. In the total 25 evaluation in tables 2 and 3 there were 8 instances in which precision was poor (CV above 3%) and also 8 cases of sizable inaccuracy (ratio outside of 100 +/- 5%). In 4 (2 micro and 2 macro) of these 8 inaccuracies, the error ranged from 10% to 22%. A minority was within the specifications of precision and accuracy claimed by the manufacturers of the dispensers with the exception of the manual microdispensers which were within specifications in most instances. We attribute the latter to the lack of a mechanical device in the manual dispensers. CONCLUSIONS: As in a previous evaluation of automatic micropipettes, we detected a high proportion of pipetting systems out of specifications in both precision and accuracy. The magnitude of error in the accuracy of 4 dispensers (10 to 22%) would be catastrophic in methods demanding good pipetting.

Calibration↗