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A Villena

Publications and source records attributed to A Villena.

At least 37 records · Page 2Linked to original sources
PubMed1997

Quantitative morphological changes in neurons from the dorsal lateral geniculate nucleus of young and old rats.

BACKGROUND: We studied the morphological changes occurring in neurons from the dorsal lateral geniculate nucleus (dLGN) during aging by analysing the size and shape of cell bodies and nuclei. METHODS: Male albino Wistar rats, aged 3, 18, 24, and 30 months, were used. After appropriate tissue preparation and following the usual histological procedure, the profiles of 1,920 neuronal bodies and nuclei were drawn using a camera lucida. Data was later recorded and processed with a semiautomatic image analyser. RESULTS AND CONCLUSIONS: We observed that dLGN neurons do not change in size from the age of 3-24 months. Between 24 and 30 months, the soma and nucleus of the cell undergo hypertrophy, 32.8% and 35.6%, respectively, when compared to those from 3-month-old animals (P < 0.01). Furthermore, we found a high correlation between cell body size/nucleus size, which does not disappear with age. The r values (correlation coefficient) were 0.7998, 0.8662, 0.8433 and 0.7304, and R2 (determination coefficient) was equal to 0.6397, 0.7504, 0.7112, and 0.5335. These latter values show that in 63.97%, 75.04%, 71.12%, and 53.35% of cases, respectively, modifications in somata size were accompanied by similar changes in nucleus size, and vice-versa. The study of the shape of the soma and nucleus of the cell revealed that both structures have a rounded-oval configuration that does not change in a significant way from adulthood to old age.

Aging↗
PubMed1997

Influence of low corrected seminal fructose levels on sperm chromatin stability in semen from men attending an infertility service.

OBJECTIVE: To determine any correlation between sperm chromatin stability under sodium dodecyl sulfate (SDS), and SDS-ethylendiamine tetraacetic acid (SDS and EDTA) conditions with levels of corrected seminal fructose, obtained multiplying logarithm of sperm count by seminal fructose concentration, in men attending an infertility service. DESIGN: Cross sectional study to compare semen parameters of two groups (control and experimental), one with normal levels of corrected fructose (control) and the second with low levels of corrected fructose (experimental). Subjects were also grouped according to number, motility and morphology of sperm, and according to results of hypo-osmotic test. SETTING: Andrology laboratory at the Instituto de Investigaciones de la Altura, Lima, Perú. PATIENT(S): Two hundred and twenty five male partners in infertile couples attending the Andrology Laboratory. INTERVENTION(S): None MAIN OUTCOME MEASURE(S): semen analysis, hypo-osmotic swelling test, sperm chromatin stability after SDS, and SDS and EDTA, and seminal fructose. RESULT(S): Seminal volume, sperm motility, and seminal fructose were significantly lower in samples from subjects with low levels of corrected fructose. Subjects with low levels of corrected fructose had also high sperm chromatin stability under SDS, and SDS and EDTA treatment. After SDS treatment, sperm chromatin stability was similar in normal samples and in those with oligozoospermia, asthenozoospermia, teratozoospermia, or abnormal hypo-osmotic swelling test. After SDS and EDTA treatment, a high sperm stability was observed in samples with asthenozoospermia. This hyper-stability is observed in asthenozoospermic samples with low corrected fructose levels, but not in asthenozoospermic samples with normal corrected fructose levels. The logistic regression analysis applied to asthenozoospermic data showed that chronological age, seminal volume, acid phosphatase per ejaculate and percent of stable sperm after SDS and EDTA treatment were significantly associated to levels of corrected fructose. CONCLUSION(S): Low levels of corrected fructose were associated to low seminal volume, low sperm motility, and high sperm chromatin stability under SDS and EDTA treatment.

Adult↗
PubMed1996

Quantitative histochemical study of cytochrome oxidase in the dLGN of aging rats.

We carried out a quantitative histochemical study of the enzyme cytochrome oxidase (CO) in neurons of the dorsal lateral geniculate nucleus (dLGN) of male Wistar rats aged 3, 18, 24 and 28 months. The results show that the activity of cytochrome oxidase decreases significantly between 24 and 28 months. We also checked whether a correlation existed between neuronal size and enzymatic activity. Low correlation coefficients were obtained which were between 0.4139 at 3 months 0.2092 at 28 months. Nevertheless, we observed a certain relationship between both parameters, and therefore we classified the neurons as light, moderate and dark according to their optical density, which correlates with enzyme cytochrome oxidase activity, and as small, medium and large depending on their size. We found that light neurons were scarcely represented in the dLGN. At the age of 3 months, the most frequent neurons were moderate, medium-size ones, and dark, small ones. The population of moderate neurons increased with age, reaching 74.5% at the 28th month, 52.2% of which corresponded to medium-size neurons. In the same group dark neurons decreased, falling to a total of 15.3% made up of medium and large-size ones. These results could be interpreted as reflecting a decrease in the bioenergetic competence of the neurons of this nucleus in old age.

Aging↗
PubMed1996

The effect of ageing on neurones in the visual sector of the thalamic reticular nucleus.

This paper studies the quantitative morphological changes occurring during ageing in neurones of the dorsocaudal or visual sector of the thalamic reticular nucleus. Male Wistar rats aged 3, 6, 18, 24 and 30 months were used in this study which applied morphometric methods. We have observed an increase in the size of neurones from this sector between the 3rd and 24th month and a decrease between the 24th and 30th month. In all the ages studied the majority of neurones are fusiform.

Aging↗
PubMed1996

Tissue distribution and structure of barrier cells in the hematopoietic and lymphoid organs of salmonids.

BACKGROUND: Barrier cells have been recognized as a discrete group of fibroblastic- or myofibroblastic-like cells located in the lymphoid and hematopoietic organs of mammals. This paper reports the results of a morphological study of the main lymphoid organs of three salmonid species, in which cells structurally similar to the mammalian barrier cells were observed in healthy animals. METHODS: The spleen, kidney, and thymus of fingerlings of rainbow trout, Oncorhynchus mykiss, and Coho salmon, Oncorhynchus kisutch, and of adult brown trout, Salmo trutta fario, were processed for electron microscopy study using various fixation methods. Semithin sections were used for the Periodic Acid-Schiff (PAS) staining technique, and for the demonstration of the endogenous peroxidase activity. RESULTS: The kidney and spleen of all the species contained a variable, but usually low, number of electron-dense, elongated, and branched cells, ultrastructurally similar to the mammalian barrier cells. They also occurred in the thymus of some brown trout and Coho salmon, but not of rainbow trout. The electron density of this cell type was present after the various types of fixation procedures. They show numerous ribosomes, well-developed secretory organelles, electron-clear vesicles, large granules, and microfilaments. In all the salmonid species, barriers cells were positive for PAS staining and for endogenous peroxidase activity. A small number of barrier cells were in mitosis. In the different organs barrier cells appeared as isolated cells, or forming syncytial networks. They were found lining the blood sinusoids of the splenic red pulp and of the renal hematopoietic tissue, in the periellipsoidal sheaths, and closely associated with erythropoietic and plasmacytopoietic foci. CONCLUSIONS: Our results demonstrate the presence of cells closely resembling mammalian barrier cells in the hematopoietic and lymphoid organs of salmonids. The structure and tissue distribution of the salmonid barrier cells are discussed in relation to the functional roles described for this cell type in mammals.

Animals↗
PubMed1996

Critical anthropometry for menarche.

The objective of the study was to determine if any anthropometric measurements, including weight, height, and upper arm circumference, or the calculated body mass index observed at the time of menarche may be used as a threshold for menarche. The sample was randomly selected from 1133 girls aged 10-18 years from two groups, one residing in Lima, Peru, at 150 m above sea level, and the second in Cerro de Pasco, Peru, at 4340 m above sea level. For the purpose of this study, all girls who reached menarche at least 1 month before the study (n = 93) were considered as cases (girls at menarche); 88 girls without menarche at the time of the study were randomly matched by age and place of residence, and designated as controls. All subjects came from the same low socioeconomic status. Body weight at menarche was 44.6 +/- 5.09 kg (mean +/- SD; coefficient of variation [CV], 11.4%). Height at menarche was 151.6 +/- 5.5 cm (CV, 3.7%). Body mass index, defined as weight/height2.15, was 18.26 +/- 1.96 kg/m2.15 at menarche (CV, 10.7%). Upper arm circumference at menarche was 21.8 +/- 1.6 cm (CV, 7.3%). The logistic regression analysis showed that any of the four anthropometric measurements analyzed were critical for menarche; i.e., any of the four could be used as a threshold for menarche. Data from the present study do not support the hypothesis that there are anthropometric markers that are critical for menarche.

Adolescent↗
PubMed1996

Body mass index and age at menarche in Peruvian children living at high altitude and at sea level.

The present study was designed to determine the relationship between body mass index (BMI) and age at menarche in girls (aged 10-19 years) living in Lima (150 m) and in Cerro de Pasco (4340 m above sea level). The purpose of the study was to determine whether the relationships between BMI and both age at menarche and chronological age differ between girls living at low and at high altitude. The ratio weight/height (the Benn index) was used in the present study as a variant of BMI because the exponent minimizes the relationship with height and maximizes the relationship with weight. From 10 to 16 years of age the Benn index of highlander girls was lower than that for girls at sea level, but at 17-19 years the differences disappeared. A later age at menarche was observed at high altitude than at sea level after controlling for socioeconomic status and for the Benn index. The value of the Benn index at the time of menarche, after controlling for chronological age in the analysis, was significantly higher at high altitude than at sea level. It was also observed that the higher the chronological age, the lower the value of the Benn index at the time of menarche. Using the median ages at menarche in Lima and in Cerro de Pasco, we found that a higher Benn index at the time of menarche is still observed at high altitude compared with girls from sea level. In Lima body weight and height were directly related to age at menarche (p < 0.001 and p < 0.005, respectively), whereas in Cerro de Pasco only weight was related to age at menarche (p < 0.001). The value of body weight at the time of menarche, after controlling for height in the analysis, was significantly higher at high altitude than at sea level. The stepwise multiple regression analysis of data from 93 girls having menarche at the time of or at most one month before the study showed that weight and altitude x height are predictors of age at menarche. These data suggest that age at menarche has an effect on both age and the Benn index acting independently and that later age at menarche in girls from Cerro de Pasco is an independent effect of altitude. Because the Benn index for menarche was different at sea level and at high altitude, we conclude that regression equations to predict age at menarche must include altitude as an independent variable.

Adolescent↗
PubMed1995

Evolution of neuronal density in the ageing thalamic reticular nucleus.

In this paper we present an analysis of the visual sector of the Thalamic Reticular Nucleus (TRN) from 3, 6, 18, 24 and 30 month old Wistar rats using stereological methods. The volume density (Vv), the number of neurones per surface unit (Na) and the neurone numerical density (Nv) showed a progressive decrease between the 3rd and the 24th months as the animals aged, whereas a significant increase was observed between the 24th and the 30th month, the period at which these rodents have fully entered old age.

Age Factors↗
PubMed1995

Histopathology of the thymus in Saprolegnia-infected wild brown trout, Salmo trutta L.

A comparative analysis was made of the thymic cytoarchitecture of healthy and Saprolegnia-infected wild brown trout. In Saprolegnia-infected fish, even when the thymus was not invaded by fungal hyphae, the thymic architecture was lost without signs of regionalization. Intercellular oedema, some thymocytes, hypertrophic and degenerated epithelial cells and increased phagocytic activity were also observed. In thymi invaded by the fungus, hyphae occurred isolated or in close apposition to epithelial cells, and the thymic disorganization was more noticeable. Most thymocytes were pyknotic and both epithelial cells and macrophages contained engulfed dead cells. However, no inflammatory response to the fungal invasion was observed. These results confirm the immunodepressed condition of Saprolegnia-infected wild brown trout previously observed in peripheral lymphoid organs. We discuss the secretion of fungal products and/or the high levels of corticosteroids observed in these fish as possible origins of the condition.

Animals↗
PubMed1994

Cytochrome oxidase activity in the lateral geniculate nucleus of postnatal rats.

We have studied the cytochrome oxidase activity and its pattern of distribution in the dorsal lateral geniculate nucleus of the rat during postnatal development. Between the 1st and the 8th postnatal days, the geniculate nucleus is seen to have a homogeneous enzymatic pattern with high neuronal density and moderately reactive neuropil. On the 15th postnatal day, different levels of neuronal enzymatic activity are found, and adult morphology is attained as of the 21st. The densitometric study has revealed that moderate and lightly reactive neurons are predominant between the 1st and the 8th postnatal days, whereas dark neurons are more numerous and optical density maximum on the 15th postnatal day. No variation in the enzymatic pattern was observed between the 21st and the 42nd days.

Animals↗
PubMed1994

DNA determination of human hair bulbs in normal and androgenetic alopecia.

We carried out a cytophotometric study of the DNA content of matrix cells from normal hair follicles and those affected by androgenetic alopecia (early and established baldness), using the Feulgen technique. We thereby obtained a 2C reference value from lymphocyte nuclei from normal skin, from which we established a 2C-4C and 4C DNA content. The results obtained showed 71.75% of matrix cells in normal scalp to have a 2C content, while the remaining 28.25% was distributed between the values of 2C-4C and 4C. However, in early baldness, the number of 2C cells dropped to 48%, with a notable increase in cell populations with a 2C-4C and 4C content, which varied from 29.45% and 22.55% respectively. Finally, in established baldness, the 2C values decreased to as low as 29.56%, with the percentage of cells with a 2C-4C content reaching 38.71% and those of 4C, 31.73%.

Adult↗
PubMed1994

Relationship between body mass index, age, and serum adrenal androgen levels in Peruvian children living at high altitude and at sea level.

We have determined the relationship between body mass index (BMI) and serum adrenal androgen levels when age is controlled for in children, aged 7-12 years, living in Lima (150 m above sea level) and in Cusco (3400 m above sea level). The purpose of the study was to determine whether the relationship of serum adrenal androgen levels with both BMI and age differs between low and high altitude. The ratio weight/height2 is not an adequate marker of BMI because it correlates with height in children from Lima and Cusco. The ratio weight/height2.3 correlates with body weight but not with height and was used in the present study as the BMI. From age 7 to 12 years, the BMI increased significantly with age only in boys from sea level and in girls from high altitude. The study demonstrates that serum adrenal androgen levels are not related to BMI in either sea-level or high-altitude children when the effect of age is removed statistically. These data suggest that BMI in children is not related to serum levels of adrenal androgens and that delayed age of adrenarche observed in children at high altitude may be due to factors other than nutritional status.

Age Factors↗
PubMed1993

The in vitro infection of the hematopoietic stroma of trout kidney by hemorrhagic septicemia rhabdovirus.

Viral hemorrhagic septicaemia virus (VHSV) infected the hematopoietic stromal cells (7,8) derived from pronephritic tissue of the rainbow trout, Oncorhynchuss mykiss, W., at their ninth passage in vitro. Viral infection resulted in the development of lytic cytopathic effects on confluent in vitro tridimensional network stromal cell cultures. Replication of VHSV in the stromal cell cultures was demonstrated by the increase in infectivity by epithelioma papulosum cyprini (EPC) cell culture assays and by the increase of the nucleoprotein antigen of VHSV by ELISA. By using anti-VHSV monoclonal antibodies (MAbs), flow cytometry studies demonstrated that only the infected stromal cells contained cytoplasmic viral antigens. The lytic infection of trout hematopoietic stromal cells in vitro could be relevant to the hemorrhagic pathology seen in the kidney of fish infected with VHSV.

Animals↗
PubMed1993

Quantitative study of the human hair follicle in normal scalp and androgenetic alopecia.

We carried out a quantitative study of the matrix and dermal papilla of the human hair follicle of the scalp, both normal and in various degrees of androgenetic alopecia. A stereological study showed the measured parameters to decrease with increase in the degree of alopecia, particularly as regards the total volume of the matrix and its papilla. The ratio of the two volumes increased by 30%, indicating a much more marked decrease in size of the papilla than in the matrix size. The number of cell nuclei in the matrix and the papilla of alopecic scalp was found to be 30% and 50% smaller, respectively, than those of normal scalp. Finally, a morphometric study revealed enlarged nuclei in the matrix and papilla, as shown by their increased areas, perimeters, and maximal diameters.

Adult↗
PubMed1993

Serum levels of adrenal androgens up to adrenarche in Peruvian children living at sea level and at high altitude.

Serum levels of adrenal androgens were measured in children of both sexes living at sea level and at high altitude using a cross-sectional design. The levels were compared in relation to age at each altitude (150 m and 3400 m above sea level), and the first significant increase in mean levels compared with values at preceding ages was assessed and defined as adrenarche. A total of 118 boys and 95 girls aged 6-12 years living at low altitude and 95 boys and 104 girls aged 7-15 years living at high altitude, all of them attending public schools, were studied. Serum dehydroepiandrosterone, dehydroepiandrosterone sulphate and androstenedione were measured by radioimmunoassay and height and weight by standard anthropometric techniques. There were two significant increases in serum levels of adrenal androgens, the first observed in children between 6 and 8 years at sea level, and between 7 and 9 years at high altitude, and the second in children between 10 and 12 years at sea level and between 12 and 15 years at high altitude. Serum adrenal androgen levels increased earlier in children at sea level than at high altitude. It is concluded that adrenarche occurs later at high altitude than at sea level.

Adrenal Cortex↗
PubMed1993

Long-term myelopoietic cultures from the renal hematopoietic tissue of the rainbow trout, Oncorhynchus mykiss W.: phenotypic characterization of the stromal cells.

This study describes the conditions for the long-term culture of the renal hematopoietic tissue of the rainbow trout, Oncorhynchus mykiss, the characterization of the stromal cells, and their relationships with myelopoietic cells. The long-term cultures consisted of stromal cells, which supported active myelopoiesis. Stromal cells were analyzed by enzyme-cytochemical techniques and electron microscopy. Major stromal cell types in long-term cultures consisted of fibroblastic reticular cells and epithelioid cells. Myelopoietic cells differentiated in close association with the fibroblastic reticular cells, and mature granulocytes were released into the culture medium.

Animals↗
PubMed1993

Hematocrit levels in children at sea level and at high altitude: effect of adrenal androgens.

Hematocrit values are normally higher in natives living at high altitude than in natives living at sea level. Here, we have determined the hematocrit levels in relation to adrenal androgens in children living at altitudes of 150 m and 3400 m above sea level. The data demonstrate no association between serum adrenal androgens levels and hematocrit values. For all ages studied, hematocrit levels were higher in children at high altitude than in children at low altitude. Higher hematocrit values (> or = 54%) were observed in 15% of native boys at 3400 m. These data suggest that the higher hematocrit levels observed normally in children at high altitude are mainly related to altitude hypoxia and not to adrenal androgens.

Age Factors↗