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Biomedical subjects

V Flores

Publications and source records attributed to V Flores.

At least 19 recordsLinked to original sources
PubMed2000

Proteases with plasminogen activator activity in hamster oviduct.

At present the physiological role of most oviductal proteins remains unknown. In this work, we present evidence that the oviductal secretion as well as the crude oviductal tissue-extract show proteolytic-like esterase and amidase activity. The proteolytic activity of the oviductal enzymes was higher in the oviducts of superovulated hamster females than in those of normal ones, indicating that gonadotrophic hormones would stimulate the synthesis and secretion of these enzymes. Some of their properties were analyzed in the 15,600-g supernatant of both oviductal tissue extracts (OE) and oviductal fluid (OF). The enzymatic activity toward the synthetic substrates p-tosyl-l-arginine methyl ester-HCl (TAME) and alpha-N-benzoyl-dl-arginine-p-nitroanilide HCl (BAPNA) was activated by calcium ions, reached a maximum at pH 7.5, and was inhibited by soybean trypsin inhibitor (SBTI), N-alpha-p-tosyl-l-lysine chloromethyl ketone HCl (TLCK), phenyl methyl sulfonyl fluoride (PMSF), and benzamidine. The OE glycoprotein fraction recognized by WGA-Sepharose affinity columns (37% total proteins) showed proteolytic activity with properties similar to the OE and OF enzymes. The protease activity could be ascribed to a plasminogen activator (PA) detected in the Triton X-100 treated tissue crude membrane fraction (Triton-CMF) and in the oviductal secretion of the superovulated females. In the Triton-CMF fraction, 100% of the proteolytic activity was plasminogen-dependent. The use of amiloride, a selective urokinase-type plasminogen activator (uPA) inhibitor, shows that 90% of this activity was due to a tissue-type plasminogen activator (tPA) and 10% to uPA whereas in the uterus 100% of the activity was tPA. Only a small percentage of the OF proteolytic activity was plasminogen-dependent, probably due to the presence of PA inhibitors in this medium.

Amidohydrolases↗
PubMed2000

Steganoderma szidati n. sp. (Trematoda: Zoogonidae) from Galaxias maculatus (Jenyns) and G. platei Steindachner in Patagonia, Argentina.

Steganoderma szidati n. sp. is described from the intestine of two freshwater fishes, Galaxias maculatus and G. platei (Galaxiidae), from Andean lakes in Patagonia, Argentina. This freshwater zoogonid species fits in the genus Steganoderma (sensu Bray, 1987) because of the length of the caeca and the position of the vitelline follicles. The new species is characterised by possessing 6-13 vitelline follicles situated between the anterior margin of the ventral sucker and the posterior margin of the testis. The gonads are in the anterior hindbody and the ovary is anterior to the right testis. The cirrus has two conspicuous spines at its distal end, and the seminal vesicle always exhibits a constriction. The excretory vesicle never reaches the level of the posterior margin of the testes.

Animals↗
PubMed1998

Developmental pattern of plasminogen activator activity in chick brain hemispheres.

Plasminogen activators play key roles in several developmental events. In previous works we demonstrated the existence of typical developmental patterns of protease activity in the chick optic lobe and cerebellum. The aim of this work is to study the temporal pattern of development of plasminogen activator activity in the brain hemispheres. Plasminogen activator activity was assayed in soluble fractions derived by ultracentrifugation from Triton X-100 treated membrane fractions by using a radial fibrinolytic assay. Employing different inhibitors and anti-plasminogen activators antibodies we showed that developing brain hemispheres express only one type of enzyme which corresponds to the urokinase-type. Other results indicate that the protease activity displays a temporal pattern which completely differs from those of general parameters of development. This suggests that the plasminogen activator activity is developmentally regulated and could display specific functions during particular stages of development.

Aging↗
PubMed1998

Cutaneous aspergillosis: a report of six cases.

Skin invasion by Aspergillus is infrequent. We here describe six immunocompromised patients with skin manifestations caused by Aspergillus. A heart transplant recipient developed a primary cutaneous aspergillosis; two patients (one with chronic granulomatous disease and another treated with a high dose of corticosteroids) presented with nodular lesions secondary to haematogenous dissemination; and three patients with acute myelogenous leukaemia had skin dissemination by contiguity from orbit and sinus invasion. A. flavus was isolated in the three cases of leukaemia; the infection was due to A. fumigatus in the transplant recipient; A. fumigatus and A. versicolor were isolated in the patients with the secondary aspergillosis. In most cases, amphotericin B was useful, with clinical and mycological remission in four patients. A patient with leukaemia died without undergoing treatment, and a child carrier of chronic granulomatous disease died after only 12 days of treatment.

Aged↗
PubMed1998

Blue filter amblyopia treatment protocol for strabismic amblyopia: a prospective comparative study of 50 cases.

PURPOSE: Previous studies of monochromatic visual evoked potentials confirm the strong suppression of (the cortical representation of) paracentral retinal areas of functionally amblyopic eyes, by a flat response to a blue stimulus. A clinical trial stimulating these areas with blue light was encouraging, and justified a prospective comparison of this treatment with conventional classic treatment. SUBJECTS AND METHODS: In 50 strabismic children with amblyopia, the blue filter treatment protocol (flash stimulation with, and the wearing of, a blue filter during occlusion of the better eye for one hour daily) was compared with the classical treatment (full time total occlusion by patch) in a prospective matched and randomized study. Patients 3 to 7 years old without previous treatment and a visual acuity up to 0.3 were admitted to the study. Visual acuity and fixation behavior were used as the parameters of comparison. Visual Evoked Potentials by monochromatic flashes were also studied. Results of treatment were compared after 6 months. RESULTS: The visual acuity outcome for the blue filter treatment was "statistically significantly" better (p=0.005). The greatest improvement was seen in the subgroup of children with eccentric fixation (p=0.01). Fixation behavior also showed a better outcome from the blue filter treatment (p=0.05) favoring especially children between 3 and 5 years. In children of this age with a visual acuity better than 0.1 we found a very "statistically significant" difference between the two treatments (p=0.004). In children 3 to 5 years old with poorer visual acuity we also found a "statistically significant" difference in the two treatments (p=0.04). The interocular difference of amplitude on the Visual Evoked Potentials also demonstrated more improvement in children treated with the blue filter. This treatment improved especially the cortical response to blue flash stimulation, correlating to paracentral retinal areas. CONCLUSIONS: The blue filter treatment protocol provided better results for treating amblyopia than the conventional classic occlusion treatment method. We propose that stimulation of these paracentral retinal areas triggers a better disinhibition of a functionally amblyopic eye.

Amblyopia↗
PubMed1997

Evidence for heme-heme excitonic coupling in the Soret circular dichroism of hemoglobin.

In order to study interdimer heme-heme electronic interactions in human hemoglobin, the Soret circular dichroism spectrum of the carboxy adduct is measured as a function of protein concentration, the spectrum at the highest concentration representing primarily that of alpha2beta2 tetramers (93%) and the lowest concentration representing primarily alphabeta dimers (68%). The tetramer-dimer difference spectrum, obtained using singular value decomposition and linear least squares fitting from a matrix of CD spectra measured at ten concentrations, is roughly conservative, with a larger negative lobe at shorter wavelengths and a peak-to-trough magnitude that is 18% of the tetramer's maximum Soret CD magnitude. It is tentatively assigned to heme-heme excitonic interactions on the basis of theoretical predictions by R. W. Woody [(1985) in Optical Properties and Structure of Tetrapyrroles (Blauer, G., and Sund, H., Eds.), pp. 239-256, Walter de Gruyter, New York].

Carboxyhemoglobin↗
PubMed1997

Developmental pattern of plasminogen activator activity in chick optic lobe.

Plasminogen activators are serine proteases which play a key role in morphogenesis and tissue remodelling. Two different molecular types, tissue-type and urokinase-type, were identified and they were postulated to play a role in neural development. The developing chick optic lobe plays a central role in processing visual information. In previous studies we demonstrated the occurrence of high levels of plasminogen activator activity in this model. The aim of the present paper is to study the temporal pattern of expression of this activity and characterize the type of plasminogen activator expressed in the developing optic lobe. Using soluble fractions derived by ultracentrifugation from Triton X-100-treated membrane fractions we measured the protease activity with a radial fibrinolytic assay. Employing different inhibitors of fibrinolytic activity and a zymographic assay, we showed that the developing optic lobe expresses only one type of plasminogen activator which corresponds to an urokinase-type of 70 kDa. Our results indicate that peaks of protease activity temporally correlate with massive neuronal migration, neurite outgrowth and synapse formation and maturation. This suggests that a plasminogen activator could play a role in these developmental events. This consistent pattern of variability strongly suggests that it is developmentally regulated and, if so, it could be a reliable parameter to study neural plastic changes induced by modifications in the environmental stimulation.

Animals↗
PubMed1997

Temporal pattern of plasminogen activator activity in the developing chick cerebellum.

Plasminogen activators are considered to be involved in several developmental events. The present work aims at characterizing the developmental pattern of expression of plasminogen activators in the chick cerebellum. Soluble fractions derived by ultracentrifugation from Triton X-100 treated membrane fractions were used for determination of the enzyme activity with a radial fibrinolytic assay. By using specific inhibitors and different anti-plasminogen activators antibodies it is shown that only one type of the enzyme, the urokinase-type plasminogen activator, is expressed during the cerebellum ontogeny. Our results show the existence of a bimodal pattern of enzyme activity with two peaks that temporally coincide with the processes of massive neuronal migration, neurite outgrowth and synapse formation and plasticity. It is proposed that plasminogen activator could play a role in these developmental events and that its pattern of variability is developmentally regulated.

Animals↗
PubMed1995

Current Triton X-100 treatments do not allow a complete plasminogen activator extraction from developing nervous tissue.

Determinations of plasminogen activator (PA) activity are usually performed in Triton X-100-treated tissue homogenates or crude membrane fractions. Such preparations usually involve a single Triton X-100 treatment. In the present paper we describe the pattern of variability of PA activity measured in different fractions obtained from the developing chick CNS by a repetitive procedure of Triton X-100 treatment and ultracentrifugation. To further characterize this PA activity we have also performed zymographic analyses during the embryonic development and the early postnatal life. Our results show that: a) a single Triton X-100 treatment does not completely extract the enzyme and this lead to an underestimation of the total PA activity; b) the PA activity is associated with the particulate component of the total tissue homogenate requiring its complete solubilization more drastic Triton X-100 treatments; c) better estimations of total and specific activities are obtained by using soluble fractions derived by ultracentrifugation from Triton X-100-treated membrane fractions; d) the developing chick optic lobe expresses only one kind of PA molecule along the entire development; e) the level of PA activity vary characteristically during the ontogeny and the early postnatal life indicating the existence of a developmentally regulated mechanism of PA expression.

Aging↗
PubMed1995

Development of serotonergic innervation of the chick embryo tectum opticum.

This paper describes the development of the serotonergic innervation of the chick tectum opticum as revealed by an immunohistochemical methodology. The development of this innervation was previously described simply as the formation of an irregular network of serotonergic fibers that gradually invades the organ and increases in density. Our results show that the developmental pattern of serotonergic innervation differs significantly through the distinct tectal layers and that it progresses through a characteristic temporospatial pattern related to the lamination process. These findings support the idea that the concept of laminar segregation can be applied to describe the development of the serotonergic innervation. On the other hand, it is clear that the existence of a typical ordered developmental pattern of innervation makes it possible to detect embryonic or post-hatching alterations. Thus, the tectal serotonergic innervation could be used as a suitable model to investigate possible plastic changes in experimental conditions.

Animals↗
PubMed1995

Development of the laminated pattern of the chick tectum opticum.

Several ontogenetic studies have been devoted to the structural organization of the developing tectum opticum. They disagree in many respects because they are based on histological preparations performed with differently oriented planes of section. According to our results the differences found in the literature mainly result from the fact that the developmental gradient axis undergoes remarkable positional changes with respect to both optic lobe and neural tube longitudinal anatomical axes during the early stages of development. The present work is a dynamic description of the tectum opticum lamination based on sections coinciding with the developmental gradient. Since this latter displays a curved disposition, several slightly modified planes of section had to be used to obtain a complete picture along the developmental gradient. The development of the tectal architecture proceeds from a relatively simple organization through increasingly complex multilaminated patterns. A dynamic interpretation of successive images of a particular region observed at increasing developmental stages or of images observed at a particular stage along the entire length of the developmental gradient axis, allows us to propose that embryonic laminae are only transient spatial arrangements of cells actively migrating from the sites where they were generated to those where they will definitively reside. These considerations led us to define a nomenclature that establishes clear correlations between the early transient organizations and the definitive one of the fully developed optic tectum. This type of nomenclature could be usefully applied to describe dynamically the development of structures displaying multilaminated patterns such as other cortical zones of the central nervous system.

Animals↗
PubMed1993

Methods for removing endogenous factors from CNS membrane preparations: differences in [3H]GABA binding parameters and developmental-related effects.

The present report describes a systematic study comparing and combining methods currently used for the removal of endogenous factors known to affect the interaction of GABA with its receptor. The effects of these methods were analyzed by performing [3H]GABA binding studies, and by measuring the amount of residual GABA left in the different membrane preparations. The effectiveness of these methods were also applied to different developmental stages. The results show that: 1) an exhaustive buffer washing procedure is necessary to accurately measure the maximal binding capacity (Bmax) of the low-affinity GABA binding site, and 2) the use of more drastic methods, including freeze-thawing and Triton treatment allows a clear demonstration of receptor heterogeneity and a precise measurement of the Bmax of the high-affinity GABA binding site as well as increases the affinity of the low-affinity site. The analysis of the Bmax values obtained with these different procedures in relation to the values of GABA removal, strongly indicates that the exhaustive washing procedure removes some unknown endogenous substances required for Triton treatment to exhibit its maximal effectiveness. Finally, a detailed analysis of Kd and Bmax values obtained with these three methods in the developing nervous tissue shows the existence of significant differences with regard to their effectiveness in removing endogenous substances when applied in different developmental stages.

Animals↗
PubMed1993

Ultra-short topical treatment of pityriasis versicolor with 2.5% bifonazole cream.

The therapeutic efficacy of a preparation containing 2.5% bifonazole was investigated by comparing three different treatment modalities--A, B, and C. Group A used bifonazole only on Days 1, 2 and 3, and the Group C on Days 1, 3 and 5. Of the patients in Group A 56% had a negative mycological examination at the end of the study. The results obtained in Groups B and C were not significantly different: 92% of the patients had a negative mycological examination at the end of the study. Electron microscope (EM) studies showed morphological alterations such as loss of cytoplasmic organization with shrinkage and folding of the cell membranes after 1 week of treatment only in Groups B and C. We conclude that 2.5% bifonazole is a highly effective treatment for Pityrosporum ovale infection when applied using a 3-day schedule.

Administration, Topical↗
PubMed1992

The postnatal development of benzodiazepine receptor sites in the chick optic lobe is modulated by environmental lighting.

The present paper describes the ability of benzodiazepine receptor sites to undergo light mediated-plastic changes during the early postnatal development of the chick optic lobe. The postnatal development pattern of these receptors was studied under different levels of light stimulation, i.e. normal-, light-and dark-rearing. At hatching the specific binding of [3H]Flunitrazepam was 0.23 +/- 0.01 pmol/mg protein. The developmental profile shows a sharp and transient peak of receptor overexpression between the 1st and the 2nd postnatal day in three experimental groups. Between the 2nd and the 6th day significant differences were found between the three groups, being this difference maximal during the peak of overexpression. In fact, on the 2nd day the specific [3H]Flunitrazepam binding showed an increase of 17% (P < 0.0005) and a decrease of 34% (P < 0.0005) for light- and dark-reared animals as compared with normally-reared ones. The changes in receptor density were transient since from the 6th day onward they gradually disappeared, being almost identical in the three groups by the day 15. At this moment the number of benzodiazepine receptor sites stabilized at the adult level. Scatchard analysis at the 2nd postnatal day revealed that the differences observed in the high affinity benzodiazepine binding sites between the three groups were due to modifications in the total number of binding sites while the affinity remained unchanged. The maximal number of binding sites were: 2.76 +/- 0.03, 3.40 +/- 0.01 and 1.46 +/- 0.11 pmol/mg protein in normally-, light- and dark-reared chicks, respectively; while the apparent dissociation constants were unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1992

Serotoninergic reinnervation of regenerating tentacular sensory organs in a pulmonate snail, Cryptomphalus aspersa.

Several ontogenetic studies performed in different species suggest a developmental role for 5-HT neurons. The 5-HT system interconnecting the CNS and the tentacular sensory organs in pulmonates is a suitable model for studying the postulated developmental role of 5-HT neurons. In this paper we describe the behavior of the 5-HT fibers during the early stages of blastema reinnervation, primordium formation and differentiation of regenerating tentacular sensory organs in the pulmonate snail Cryptomphalus aspersa. Our results show that the regeneration process allows the development of a normal pattern of 5-HT innervation of the regenerated sensory organs and suggest that 5-HT could be involved in reciprocal developmental interactions with regenerating tentacular tissues.

Animals↗
PubMed1992

Fibre size and type adaptations to spinal isolation and cyclical passive stretch in cat hindlimb.

Impulse activity is known to have a strong influence in determining the characteristics that distinguish skeletal muscle fibres into types. The control of muscle proteins by the neural systems that innervate the muscles, however, is not complete (Edgerton et al. 1985, 1990). The purpose of the present study, therefore, was to determine the effects of inactivity for 6 months on the size and fibre type composition of selected cat hindlimb muscles. Inactivity was produced by isolating the lumbar region of the spinal cord, i.e. transecting the cord at T12-T13 and again at L7-.S1 and then performing a bilateral dorsal rhizotomy between the transection sites (SI). In each SI cat, one hindlimb was passively manipulated for 30 min per day through a range of motion at the ankle mimicking a step cycle. SI resulted in an atrophic response in most muscles, with predominantly slow extensors showing the largest effect. In general, the predominant fibre type, which also had the largest mean size, in each muscle atrophied the most. The mean fibre size of all fibre types were similar after SI, suggesting that there may be a minimal size for inactive intact fibres. In comparison with control animals, all muscles in the SI cats had a higher proportion of fast fibres. Further, the relative contribution of the slow fibres to the total cross-sectional area of the muscle was decreased following SI. Some slow fibres in each muscle, however, were resistant to change. These data demonstrate the extent to which size and myosin type of mammalian muscle fibres are independent of activation characteristics.

Adaptation, Physiological↗
PubMed1991

Effect of a simple visual pattern on the early postnatal development of GABA receptor sites in the chick optic lobe.

It is known that manipulation of the visual environment results in changes in the developmental pattern of several neurotransmitter receptors and that the GABA receptor shows a high degree of plasticity in differential illumination experiments. In the present paper we investigated whether exposure to a visual pattern has a developmental effect on GABA receptor expression during early postnatal life. Two groups of newly hatched chicks were used: one was exposed to a simple and specific visual pattern and the other was deprived of any visual pattern. GABA receptors at each developmental stage were determined by binding experiments performed in a crude membrane fraction. Saturation studies were carried out in a fraction enriched in synaptic membranes. The developmental pattern of both high and low affinity GABA binding sites was affected by the visual pattern. This effect displays its maximal expression by the end of the first postnatal week. The modification in receptor expression was due to a change in the receptor density while the affinity was not affected. The change in receptor density induced by the presence of a visual pattern was highest at the end of the first postnatal week suggesting that at that time there is a brief period of higher plasticity for GABA receptor expression in the visual system than at other times. Our results also suggest that variations in GABA receptor density could be instrumental in adaptative changes in the visual system in response to variations in the environmental stimulation.

Aging↗