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J Burgos

Publications and source records attributed to J Burgos.

At least 55 records · Page 3Linked to original sources
PubMed1985

The binding of [3H]oestradiol-receptor complex to hypothalamic chromatin of male and female mice.

Histones and masking acidic proteins were removed from hypothalamic chromatin in order to evaluate/measure the number of available acceptor sites for the [3H]oestradiol-receptor complex. This number increases after dehistonizing and unmasking and is lower than published values for comparable preparations. No sex-related difference in [3H]oestradiol-receptor binding to hypothalamic chromatin in vitro was observed. Failure to observe such a difference suggests that sexual differentiation and steroid sensitivity cannot be attributed to marked differences in the degree of chromatin masking.

Animals↗
PubMed1985

[Effect of experimental subarachnoid hemorrhage on calcium incorporation and adrenergic innervation of the cerebral arteries of the cat].

The effect of experimental subarachnoid hemorrhage (SAH) on the adrenergic innervation and on the 45Ca2+ uptake of cat cerebral arteries was analyzed. Intracisternal injections of autologous blood reduced the noradrenaline content of perivascular nerve endings and 3H-noradrenaline uptake. These values returned to normal levels in a period of two weeks after SAH. The activity of dopamine-beta-hydroxylase was also reduced 3 and 7 days after SAH. Superior cervical gangliectomy and intracisternal injection of 6-hydroxydopamine also reduced these three parameters. The uptake of 45Ca2+ by arteries from animals submitted to SAH was greater than if the blood vessels were from untreated cats. Lantanum brought about a less 45Ca2+ displacement in the arterial segments from untreated animals than in those from cats after SAH. These results suggest that SAH induces a transient adrenergic denervation as well as changes in the membrane of smooth muscle cell which increase the quantity of Ca2+ bound to it. All these modifications might be involved in the cause of chronic cerebral vasospasm that appears after SAH.

Animals↗
PubMed1984

Further purification and characterization of diacetyl reducing enzymes from beef liver.

Two diacetyl reducing enzymes have been isolated from beef liver. One of them, a monomer of mol. wt 28-30,000 dalton and pI 6.2, corresponds to the low molecular weight diacetyl reductase formerly accounted for using preparations of this organ; it has been now identified as an L-glycol dehydrogenase. The other one, an oligomer of 78,000 dalton and pI 7.0, which matches the high molecular weight diacetyl reductase, is, in the authors' opinion, a new enzyme for which the systematic name L(+)-alpha-hydroxycarbonyl: NAD(P) oxidoreductase (EC 1.1.1...) and common name alpha-dicarbonyl reductase are proposed.

Acetoin Dehydrogenase↗
PubMed1984

Bovine skeletal muscle adenosine deaminase. Purification and some properties.

A low molecular weight form of adenosine deaminase from bovine skeletal muscle was purified about 930-fold. The enzyme had a mol. wt of 31,000, a Km value for adenosine of 2.37 X 10(-5) M and a pH optimum at 7.0. This enzyme is very resistant to heat inactivation and does not require metal activators or other dialysable cofactors. A possible role in the post-mortem metabolism of adenine nucleotide in skeletal muscle is discussed.

Adenosine Deaminase↗
PubMed1983

Kinetics of alpha-dicarbonyls reduction by L-glycol dehydrogenase from hen muscle.

Michaelis constants of L-glycol dehydrogenase from hen muscle (isozyme of pI 7.2) for the alpha-dicarbonyls tested (glyoxal, 2,3-pentanedione, methylglyoxal, and diacetyl) range from 35 microM for pentanedione to 0.41 mM for glyoxal. The enzyme shows a high affinity for NADPH, Km (2.2-3.1 microM), and Ks (1.2-1.9 microM) being so much lower than its tissue concentration that L-glycol dehydrogenase has to operate in vivo saturated with the coenzyme; this condition is very unfavorable to play a role in regulating the equilibrium oxidized/reduced forms of the pyridine nucleotides, as it has been proposed for some similar enzymes. Convergence of the double reciprocal plots and the pattern of inhibition by products and by acetone, a substrate analog, demonstrate that glyoxal reduction--and most likely that of diacetyl--proceeds via an ordered Bi-Bi mechanism in which NADPH is fixed before the addition of the carbonyl; the reduction of methylglyoxal and 2,3-pentanedione could follow the same model, but our experimental results are also consistent with that of Theorell-Chance.

Alcohol Oxidoreductases↗
PubMed1982

Diacetyl reductase.

Explore the source record for details and available documents.

Acetoin Dehydrogenase↗
PubMed1981

Purification and some properties of L-glycol dehydrogenase from hen's muscle.

1. An enzyme which catalyzes the NAD(P)H-linked reversible reduction of uncharged vicinal dicarbonyls and alpha-hydroxycarbonyls to L-(+)-glycols has been purified from hen's muscle. This enzyme has not been previously described. 2. According to the rules of the I.U.P.A.C.-I.U.B. Enzymes Commission, the systematic name of L-(+)-glycol:NAD(P) oxidoreductase and the trivial name of L-glycol dehydrogenase are proposed for the enzyme. 3. Three forms of this enzyme differing in pI have been isolated; two forms, which together represent about 90% of total recovered activity, and electrophoretically pure. 4. Molecular weight, pH profiles and affinity for substrates are also described.

Acetoin↗
PubMed1981

[Ackerman's verrucous carcinoma on the lower lip].

A patient with Ackerman's verrucous carcinoma located on the transitional epithelium of the lower lip is described. No previous cases have been reported with this location. The clinical course was similar to verrucous carcinoma arising on other areas of skin or mucosae. Viral particles were not found on ultrastructural studies. The response to conservative surgical treatment was excellent.

Adult↗
PubMed1980

Bilateral innervation of the cerebral arteries by the superior cervical ganglion in cats.

The effect of removal of the left superior cervical ganglion on the contractile response to norepinephrine (NE) and 5-hydroxytryptamine (5-HT, serotonin) was studied in isolated segments of the middle cerebral artery (MCA) and posterior communicating artery (PCoA) of the cat. Fifteen days after the excision, each dose of NE elicited a potentiated response in both the MCA and the PCoA, whichever side they originated. By contrast, 5-HT induced enhanced vasoconstriction at each dose only in the MCA and PCoA from the left side. When segments of MCA and PCoA from the right side were challenged against 5-HT, a significantly increased response was found only at the first three doses. On the other hand, the NE content of pools made of MCA, PCoA, and anterior cerebral artery from each side was reduced to the same level on both sides after ganglion removal. These results indicate that the excised superior cervical ganglion innervated the MCA and PCoA from both sides of the circle of Willis.

5-Hydroxytryptophan↗
PubMed1980

Effect of experimental subarachnoid hemorrhage on the adrenergic innervation of cerebral arteries.

The effect of subarachnoid hemorrhage (SAH) on the adrenergic innervation of cat cerebral arteries was analyzed. Intracisternal injections of autologous blood reduced the noradrenaline content from the perivascular nerves. Dopamine beta-hydroxylase and the uptake of 3H-noradrenaline were also decreased. These changes returned to normal in a period of 2 to 3 weeks after the SAH. Superior cervical ganglionectomy and intracisternal injections of 6-hydroxydopamine also reduced these three parameters. It is suggested that SAH induces a transient adrenergic denervation of the cerebral arteries that might be involved in the production of the chronic cerebral vasospasm.

Animals↗
PubMed1980

Cerebrovascular reactivity to noradrenaline and serotonin following experimental subarachnoid hemorrhage.

This study analyzes the time course of the changes induced by subarachnoid hemorrhage (SAH) in the sensitivity of cat cerebral arteries to noradrenaline and serotonin. Cerebral arteries to noradrenaline and serotonin. Cerebral arteries displayed a supersensitivity to these amines, which was most marked 3 days after the experiment and then gradually disappeared. The supersensitivity to serotonin was greater and longer than the response to noradrenaline. The increase in the vascular contractile response induced by SAH was similar to that seen after superior cervical ganglionectomy or intracisternal injections of 6-hydroxydopamine. It is suggested that supersensitivity to noradrenaline and serotonin induced by SAH may be involved in the production of chronic cerebral vasospasm.

Animals↗
PubMed1979

[Myoclonus in Alzheimer's disease. 2 anatomoclinical cases].

A few autopsy proved cases of Alzheimer's disease with myoclonus have been hitherto reported. We think that myoclonus is a frequent clinical feature in advanced cases of Alzheimer's disease. Our second case is such an example with a chronic evolution. In cases like our first one, with a short history, myoclonus, and atypical, diphasic, periodic complexes in the EEG, clinical differential diagnosis with Creutzfeldt-Jakob disease can be very difficult. Alzheimer disease has been considered an unitary clinico-pathological entity. However, transmission to the non human primates has been successfully achieved only in familiar cases but no in the sporadic ones. On the other hand some of his neuropathological features have been found in two cases of Creutzfeldt-Jakob disease, one of them successfully transmitted to the chimpanzee. All these points could eventually modify our present unitary concept on Alzheimer's disease.

Alzheimer Disease↗
PubMed1976

Pigeon liver diacetyl reductase. Effects of pH on the kinetic parameters of the reaction.

(1) The pH dependence of the kinetic parameters of the reaction catalyzed by pigeon liver diacetyl reductase (EC 1.1.1.5) was investigated in the pH range 5.1-8.6. (2) From the results obtained it is postulated that: (a), a group of pK around 7, active in the protonated form, participates in the interaction of the enzyme with NADH and NAD. (b), a second group with a pK of 8.4, active in the protonated form too, takes part in the binding of diacetyl to E-NADH. (c) A third group of pK about 4.7-5, active in the unprotonated form, is involved at least in the dissociation of the complex E-NAD and in the attachment of diacetyl to E-NADH.

Acetoin Dehydrogenase↗
PubMed1976

Effect of ultrasonic waves on the heat resistance of Bacillus spores.

The effect of ultrasonic treatment on the heat resistance of Bacillus spores differs widely both with the species and the strain tested. Ultrasonic waves do not affect the heat resistance of some strains, whereas they greatly reduce that of other strains of the same species. The heat-sensitizing effect of ultrasonic waves is more pronounced when short heating periods are used. Ultrasonic treatment does not seem to affect the "Z value".

Bacillus cereus↗