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Biomedical subjects

C Santana

Publications and source records attributed to C Santana.

At least 37 records · Page 2Linked to original sources
PubMed1995

Arteriosclerotic histologic evaluation of the internal mammary artery in patients undergoing coronary artery bypass grafting.

During 1991, 52 patients undergoing myocardial revascularization had a biopsy of the distal internal left mammary artery (IMA) taken. There were 48 male and 4 female patients with a medium age of 58 years. Arteriosclerotic involvement of the IMA was assessed according to the scale of Kay. Using this index, grade 0 corresponds to a normal artery without atherosclerosis, grade 1 represents minimal disease, grade 2 a narrowing of less than 25% of the lumen, grade 3 narrowing between 25 and 50%, and grade 4 narrowing of 50% or greater of the lumen. Of the 52 IMA examined, the arteries with degree 0, 1, 2, 3, and 4 were: 19 (36.5%), 20 (38.4%), 9 (17.6%), 4 (7.6%) and zero. Thirty-three arteries (63.4%) had some degree of atherosclerosis. Considering the arteries with some atherosclerotic narrowing, 13 (25%) of the whole group had this pathological alteration. The IMA has a low but consistent incidence of arteriosclerosis involvement. Preoperative angiographic investigation of the IMA could be routinely performed.

Adult↗
PubMed1995

[Splenic lymphoma with circulating hairy lymphocytes lymphoma. Clinical cytological study of 4 patients].

PURPOSE: The splenic lymphoma with circulating villous lymphocytes (SLCVL) is an infrequent disease included within the low grade non Hodgkin's lymphoma, B-cell type. The results of the study of four patients are reported. PATIENTS AND METHODS: Clinical, cytological, immunophenotypic, ultrastructural, evolutive and therapeutic data have been revised in all the cases. RESULTS: Two males and 2 females of 76, 66, 68 and 62 years, respectively were diagnosed as having SLCVL. The initial symptoms were scarce, basically asthenia, and a big spleen without significant lymphadenopaty was the most relevant physical finding in each of them. In peripheral blood leukocyte count was normal with a slight lymphocytosis and a variable percentage of villous circulating lymphocytes. The immunophenotype of peripheral blood obtained by flow cytometry was according with a mature B-cell lymphocyte population, CD 5 and CD 25 negative. The cells were positive to acid phosphatase with a diffuse pattern of variable intensity; the reaction was inhibited by tartaric acid. All the patients had BM infiltration, studied with aspiration and biopsy. One case (M,66) had an IgM monoclonal gammopathy. The ultrastructural study, performed in 3 cases, showed thin and short villous prolongations. After splenectomy, a low degree lymphoma therapy has been employed in all the cases. The follow-up ranges between, 4 years and 4 months, all the patients being alive. CONCLUSIONS: The SLCVL is a definitive entity regarding the clinical, morphologic and immunophenotype features. A long clinical evolution and a good prognosis after splenectomy are common.

Aged↗
PubMed1994

Changes in tyrosine hydroxylase activity and melatonin synthesis in rat pineal glands throughout 72 hours of incubation.

Time-dependent modifications of N-acetyltransferase (NAT) activity, melatonin content, and tyrosine hydroxylase (TH) activity within the isolated rat pineal over a 72 h of incubation period were studied. Both pineal NAT activity and melatonin content displayed similar decreases after 12 h of incubation, and reached a maximal reduction of 82% or 93%, respectively, after 48 h. However, a maximal decrease of pineal TH activity was only 47% after 72 h of incubation. Neither the nuclear area of pinealocytes, nor lactate dehydrogenase (LDH) activity in the incubation medium showed any significant variation dependent on the incubation time. Treatment with isoproterenol caused an expected elevation of NAT activity and melatonin content but was unable to modify TH activity. Since a significant degree of pineal TH activity remained following 3 days of incubation, a non-sympathetic source of TH within the rat pineal gland is suggested.

Acetyltransferases↗
PubMed1994

Tyrosine ingestion during rat pregnancy alters postnatal development of dopaminergic neurons in the offspring.

It has been previously reported that tyrosine ingestion by the mother rat during gestation modifies different behavioral patterns in the adult offspring. In the present study, the action of maternal mother tyrosine ingestion on the postnatal development of the dopaminergic system of the offspring was evaluated. The offspring of tyrosine-treated mothers showed a decrease in dopamine (DA) levels during the first 15 days of postnatal life and an increase in DA levels from day 30 to adulthood. The DOPAC level and the DOPAC/DA index were higher in the tyrosine group from postnatal life to adulthood. These differences reach statistical significance in both forebrain and mesencephalon. During adulthood the DA concentration in both s. nigra and ventral tegmental area were higher in the tyrosine group than in the control group. The behavioral postsynaptic response to a DA receptor agonist (apomorphine) was higher in the offspring of tyrosine treated rats than in the control group. These data suggest that the bioavailability of the DA precursor tyrosine during gestation may modify during postnatal life DA synapsis at both pre- and postsynaptic level.

Administration, Oral↗
PubMed1994

Maternal ingestion of tyrosine during rat pregnancy modifies the offspring behavioral lateralization.

It was previously reported that oral administration of tyrosine (500 mg/kg) to pregnant rats increases tyrosine and monoamines level in the fetal brain and modifies locomotion during postnatal life. In the present study, it was found that this treatment alters behavioral lateralization in the offspring. Neonatal rats whose mothers received tyrosine during the second half of gestation showed a low level of absolute and population laterality in both tail and head movements. The alteration of behavioral lateralization was also found during postnatal development and during adulthood. The T-maze behavioral ontogeny was different for tyrosine-mother and sham-treated or untreated mother rats. During adulthood, the T-max lateralization after stress sessions (a procedure that decreases alternation behavior and facilitates the quantification of behavioral lateralization) was also different in control and tyrosine-mother groups. Neonatal and adult rats showed an increase in right-side movements probability. These data provide evidence that maternal ingestion of a catecholamine precursor during gestation may induce a long-lasting modification of the behavioral lateralization of the offspring.

Administration, Oral↗
PubMed1994

Ontogenic development of brain asymmetry in dopaminergic neurons.

In the present study the right-left brain asymmetry of central dopamine (DA) systems during postnatal brain development is evaluated. DA and dihydroxyphenylacetic acid (DOPAC) levels increased from neonatal to adult life in both the forebrain and mesencephalon. This increase was not similar in the right and left brain sides. From neonatal life to adulthood a fall was observed in (a) DA percentage in the DA high-brain side in the mesencephalon and (b) DOPAC percentage in the DOPAC high-brain side in both the forebrain and mesencephalon. The percentage of lateralized rats (more than 65% of DA or DOPAC levels in either brain side) also decreased during ontogeny. Thus, biochemical lateralization decreases during ontogeny. The right-left brain correlation for DA level and DA turnover was used to evaluate the inter-hemispheric regulation of dopaminergic systems. The correlation coefficient was near to 0 during postnatal life and around -0.8 during adulthood in both forebrain and mesencephalon. Taken together, these data suggest that the ontogenic decrease of in brain asymmetry for DA or DOPAC levels is related to the postnatal development of an inter-hemispheric regulatory system that control dopaminergic neurons activity.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Preparation of activated supports containing low pK amino groups. A new tool for protein immobilization via the carboxyl coupling method.

A method for the preparation of new aminated agarose gels containing monoaminoethyl-N-aminoethyl structures, MANA-agarose gels, has been developed. These gels contain primary amino groups with a very low pK value (6.8). In addition to that, we have been able to prepare very highly activated gels (e.g., 10% agarose gels containing up to 200 mu Eq of primary amines per milliliter). These two properties make these activated supports suitable for performing novel and interesting methods for protein immobilizations via very mild carbodiimide activation of carboxy groups. For example, very effective coupling reactions can be performed at pH 5.0-6.0 in the presence of low concentrations of activating agent, e.g., 1 mM. By using a model industrial enzyme, beta-galactosidase from Aspergillus oryzae, we have been able to demonstrate the excellent prospects of these novel activated supports.

Enzymes, Immobilized↗
PubMed1993

Neonatal lateralization of behavior and brain dopaminergic asymmetry.

Behavioral lateralization has previously been reported in adult animals. This work presents a study of behavioral laterality and spontaneous alternation behavior in 156 neonatal rats (39 litters with two males and two females per litter). The initial tail and head lateral movements (axis body-tail or head higher than 30 degrees) were recorded after neonatal rats were gently placed along a straight line drawn on a glass surface. This test was repeated 10 times. A leftward population lateralization was found for tail movement while head movement was rightward. The alternation behavior was lower (10-25%) than that previously reported for adult rats (80-90%) and than that expected if movement was made at random (50%). Males were more lateralized than females for head and tail movements. No sex differences were observed for behavioral alternation. In 2-day-old rats (10 litters with one male and one female per litter), the right brain side had a higher content in dopamine (mesencephalon) and DOPAC (proencephalon) than the left brain side. Thus, we concluded that behavioral and biochemical asymmetries in animals are conditioned by phenomena present during prenatal or early neonatal (first hours after birth) life and that spontaneous alternation behavior is not present during the earlier stages of postnatal development.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Dopaminergic neuron development in rats: biochemical study from prenatal life to adulthood.

Dopaminergic cell development has been studied mainly using morphological techniques and especially histofluorescence. However, the biochemical characteristics of dopamine (DA) neuron development and its physiological role during ontogeny are much less known. In the present article, the biochemical development of DA neurons, from day 13 of prenatal life to adulthood, is evaluated in Sprague-Dawley rats. DA was first detected on day 14 of gestation. The brain increase in this neurotransmitter begins on day 17 in the proencephalon and on day 18 in the mesencephalon, reaching on day 20 a level similar to that found during adulthood in the latter but not in the former. DA levels in the proencephalon rise slowly to adulthood level when compared to DA in the mesencephalon. The modifications observed in tyrosine levels are also largely similar to those reported for DA. Finally, the study of the first 48 h of life shows an increase in tyrosine levels and a decrease in dihydroxyphenylacetic acid levels (with a reduction of DA turnover) during the first 4-5 h of postnatal life. Since the serotonergic modification was completely different from DA modification, we conclude that the biochemical alteration of DA neurons during early postnatal development is specific. The present data suggest that DA neurons play different roles before and after reaching adult development.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Ovarian steroids block the isoproterenol-induced elevation of pineal melatonin production in the female rat.

Changes in pineal indole metabolism during the estrous cycle, as well as in response to estrogen administration, were studied in female rats. Tyrosine hydroxylase (TH) activity, norepinephrine (NE) and indoleamine levels were determined by high-performance liquid chromatography (HPLC). Pineal melatonin was measured by radioimmunoassay (RIA). Both 5-hydroxytryptamine (5-HT) and melatonin levels, but not TH activity or NE content, were reduced during proestrus. Ovarian hormones blocked the isoproterenol-induced elevation of pineal melatonin, and reduced 5-HT levels in ovariectomized rats. These results suggest that an estrogen-induced inhibition of the pineal response to adrenergic stimulation, could be responsible for the reduction in pineal melatonin production occurring during the proestrus stage of the rat estrous cycle.

Animals↗
PubMed1990

Treatment with forskolin for 8 hours during the day increases melatonin synthesis in the Syrian hamster pineal gland in organ culture: the long lag period is required for RNA synthesis.

The exposure of organ-cultured pineal glands of Syrian hamsters to forskolin, an adenylate cyclase activator, caused marked increases in melatonin levels when glands were collected in the second half of the dark period and incubated for 4 h. However, when glands were collected at the beginning of the dark period and incubated with the same drug, a significant increase in melatonin content was observed only after 6-8 h. Likewise, when glands were collected at the beginning of the light period, forskolin stimulated melatonin synthesis only after 6-8 h of incubation with the drug. These results support the existence of a relatively long lag period necessary for the induction of melatonin production in the Syrian hamster pineal gland. Experiments with actinomycin D indicate that RNA synthesis occurs during the lag period; thus, actinomycin D blocks the induction of melatonin synthesis by forskolin in glands collected at the beginning of the dark period and incubated for 8 h. In contrast, when pineal glands were collected from hamsters killed in the second half of the dark period, and incubated with forskolin for either 4 or 8 h, actinomycin D was unable to block the induction of melatonin production. These data suggest that RNA, presumably messenger RNA, which is necessary for increasing hamster pineal melatonin synthesis, is synthesized and accumulates during the first half of the night.

Animals↗
PubMed1990

Nocturnal increase in pineal melatonin production in two lemming species, Dicrostonyx hudsonius and D. groenlandicus.

Pineal N-acetyltransferase (NAT) activity and melatonin levels and thyroxine 5'-deiodinase (5'D) activity in brown adipose tissue (BAT) were compared during the day and night in two species of lemmings, Dicrostonyx hudsonius and D. groenlandicus. In both species, NAT and melatonin exhibited significant night-time increases in the pineal gland. Thyroxine 5'D activity in BAT did not show a statistically significant day-night difference in either species of lemming, suggesting the night-time rise in melatonin does not induce a similar increase in BAT 5'D.

Acetyltransferases↗
PubMed1990

Interferon-gamma modulates melatonin production in rat pineal glands in organ culture.

The effect of interferon-gamma (IFN-gamma) on melatonin production was determined in rat pineal glands in organ culture. IFN-gamma enhanced the production of melatonin in the glands incubated with either 10 nM or 1,000 nM isoproterenol (ISO, a beta-adrenergic receptor agonist) but decreased the 100 nM ISO response. The enhanced melatonin production was accompanied by either unchanged or a lower level of N-acetyltransferase (NAT) activity, whereas the suppression was accompanied by a reduced NAT activity. IFN-gamma did not change the activity of the enzyme hydroxyindole-O-methyltransferase (HIOMT) in the ISO-stimulated pineal glands. The results indicate that IFN-gamma has a dual action on the pineal gland: One is to increase melatonin production through yet unknown mechanisms, and the other is to suppress NAT activity. These results also suggest that the pineal gland, under physiological stimulation, is modulated by IFN-gamma to increase melatonin production. A hypothetical model is proposed to explain the delicate regulation of pineal function by the immune system.

Acetylserotonin O-Methyltransferase↗
PubMed1990

Type II thyroxine 5'-deiodinase activity in the rat brown adipose tissue, pineal gland, Harderian gland, and cerebral cortex: effect of acute cold exposure and lack of relationship to pineal melatonin synthesis.

The effect of acute cold exposure for 6 hours on nocturnal type II thyroxine 5'-deiodinase (5'-D) activity was studied in brown adipose tissue (BAT), Harderian gland, cerebral cortex, and pineal gland of the rat. Moreover, the effect of iopanoic acid (IOP), a potent inhibitor of 5'-D activity, on both pineal N-acetyltransferase (NAT) activity and melatonin content in rats maintained in a cold environment was also examined. Results show that acute cold exposure significantly increases 5'-D activity in BAT but not in either the pineal gland, Harderian gland, or cerebral cortex. In all tissues, the injection of IOP reduced dramatically 5'-D activity, while exposure of the animals to light at night reduced 5'-D activity in pineal gland but not in either the Harderian gland or BAT while light exposure at night increased cerebrocortical 5'-D activity. Cold exposure did not change either pineal NAT activity or the melatonin content of the gland. Finally, when pineal 5'-D activity was inhibited by IOP treatment, neither nocturnal pineal NAT activity nor melatonin content was affected.

Adipose Tissue↗
PubMed1990

Immunoreactive levels of pineal arginine vasopressin change during the rat estrous cycle.

It has been reported that mammalian pineal activity is influenced by reproductive hormones. However, even though a relationship between serum estrogen levels and pineal indole metabolism is well documented, little is known about other pineal components. Among peptides, arginine vasopressin (AVP) has been identified in the pineal gland of several species. In the present work, variations of immunoreactive (IR)-AVP in the rat pineal during the estrous cycle were studied by radioimmunoassay. Pineal IR-AVP levels increased significantly at the proestrus afternoon, and returned to basal levels by the end of estrus. These variations were partially related to those of serum estradiol concentration. Although the functional role of AVP in the rat pineal has not been clearly elucidated, these findings provide an additional indication that it might be involved in the reproductive function of the female rat.

Analysis of Variance↗
PubMed1990

In vivo stimulation of rat pineal type II thyroxine 5'-deiodinase activity by either norepinephrine or isoproterenol.

Herein we show, for the first time, a very marked increase in thyroxine 5'-deiodinase (5'-D) activity in rats injected with norepinephrine (NE) and desmethylimipramine, a drug which inhibits NE uptake by nerve terminals. The response to NE was greater in pineals collected from hypothyroid animals than in glands from euthyroid animals. NE was more effective in stimulating pineal 5'-D than was isoproterenol, suggesting that, in addition to beta-adrenergic receptors, alpha-adrenergic receptors might be involved in the 5'-D activation. However, phenylephrine, an alpha-adrenergic agonist, did not potentiate the effect of isoproterenol on pineal 5'-D activity. The nocturnal increase in pineal 5'-D activity was completely abolished by propranolol, a beta-adrenergic receptor blocker, while prazosin, an alpha-adrenergic receptor blocker, had minimal effect. These results show that the role of alpha-receptors in promoting the NE-mediated rise in rat pineal 5'-D activity is minor in contrast to the role of beta-adrenergic receptors.

Animals↗
PubMed1989

Effects of either forskolin, the 1,9-dideoxy derivative of forskolin, or 8-bromocyclic AMP on cyclic AMP and melatonin production in the Syrian hamster pineal gland in organ culture.

The possible involvement of cyclic AMP in the regulation of melatonin production was investigated in cultured Syrian hamster pineal glands. Addition of forskolin, an adenylate cyclase activator, to the incubation medium caused marked increases in both cyclic AMP and melatonin levels in glands collected in the second half of the dark period. 8-Bromocyclic AMP, an analogue of cyclic AMP, also increased melatonin production. The 1,9-dideoxy derivative of forskolin, which is unable to activate the cyclase, was ineffective in stimulating either cyclic AMP levels or melatonin production. These results support a primary role for cyclic AMP in the nocturnal increase of melatonin production in the Syrian hamster pineal gland.

8-Bromo Cyclic Adenosine Monophosphate↗