Ricardo Baeza

Influence of the estrous cycle and estradiol on the behavioral effects of amphetamine and apomorphine in rats

This experiment was designed to investigate the influence of hormonal status of the rat on the effects of two doses of an indirect-acting dopamine agonist (amphetamine 0.25 and 1.0 mg/kg, IP) and a direct-acting dopamine agonist (apomorphine 62.5 and 250 micrograms/kg, SC) on the acquisition of conditioning avoidance responses (CARs) and the performance of some spontaneous behaviors. Active conditioned avoidance was improved by amphetamine in all the groups except in females at diestrus; apomorphine improved this response only in females at estrus and in ovariectomized rats after estradiol replacement, but the avoidance response was deteriorated in males and females at diestrus and after ovariectomy without estradiol replacement. Both dopaminergic drugs had contrasting effects on motor activity, number of rearings, and number of head shakes according to the hormonal status of the rat. Only the time spent in grooming behavior decreased after the treatment with both dopamine agonists in all of the five groups studied. These results provided behavioral evidence for the hypothesis that dopaminergic activity in the CNS is affected distinctively by modifications in the sexual hormone status (gender, estrous cycle, ovariectomy, and estradiol replacement). Relationships between ovarian hormones and dopaminergic system are discussed.

The behavior of quadratic and differential forms under function field extensions in characteristic two

Abstract Let F be a field of characteristic 2. Let Ω n F be the F-space of absolute differential forms over F. There is a homomorphism ℘ :Ω n F →Ω n F / d Ω n−1 F given by ℘(x d x 1 /x 1 ∧⋯∧ d x n /x n )=(x 2 −x) d x 1 /x 1 ∧⋯∧ d x n /x n mod d Ω F n−1 . Let H n+1 (F)= Coker (℘) . We study the behavior of Hn+1(F) under the function field F(φ)/F, where φ=〈〈b1,…,bn〉〉 is an n-fold Pfister form and F(φ) is the function field of the quadric φ=0 over F. We show that ker (H n+1 (F)→H n+1 (F(φ)))= F· d b 1 /b 1 ∧⋯∧ d b n /b n . Using Katos isomorphism of Hn+1(F) with the quotient InWq(F)/In+1Wq(F), where Wq(F) is the Witt group of quadratic forms over F and I⊂W(F) is the maximal ideal of even-dimensional bilinear forms over F, we deduce from the above result the analogue in characteristic 2 of Knebuschs degree conjecture, i.e. InWq(F) is the set of all classes q with deg(q)⩾n.

Discriminants of polynomials and of quadratic forms

Abstract In this paper we describe the quadratic forms over any field k which admit a similarity with a given separable characteristic polynomial f(X) as the transfer of some binary quadratic form associated to the polynomial f(X). Using this description we show that the discriminant of the quadratic form is the discriminant of this polynomial.

On the Witt-equivalence of fields of characteristic 2

Let E, F be two fields of characteristic 2 and let W(E), W(F) be the Witt rings of non-singular symmetric bilinear forms over E and F. In this note it is proved that if dimE2 E = dimF2 F > 2, then E ≅ F is equivalent with W(E) ≅ W(F).

A note on generic splitting of quadratic forms

Let Fbe a field of any characteristic. For n≥ 0, let .The degree conjecture asserts that for each n≥0 Let pbe any n-fold quadratic Pfister form over Fand F(p) the function field of p. Then the function field conjecture asserts We prove that (DC) is equivalent to (FFC).

Behavioral effects of a LHRH antagonist in intact and ovariectomized rats

The effects of the LHRH antagonism on the acquisition of conditioned responses (CARs) and spontaneous motility were studied in intact and ovariectomized rats. A synthetic antagonist of LHRH, [N-acetyl-D-p-chloro-Phe1,2,D-Trp3,D-Arg6,D-Ala10]-LHRH, was injected in a single dose (10 micrograms/rat, SC) at noon on the day of proestrus in the normally cycling rat, and behavioral experiments were carried out on the morning of estrus or metestrus. Two procedures were followed in the ovariectomized rats: in the first, the antagonist was injected 1 h before estradiol, and in the second, at noon on the day after estradiol replacement. The experiments were carried out 24 and 48 h after estradiol, respectively. The LHRH antagonist facilitated the acquisition of CARs in both experimental groups, thus reversing the impairments observed during estrus and metestrus and those induced by estradiol replacement. The antagonist decreased the number of head shakes during estrus, whereas it induced an increase in total motility and rears in ovariectomized control animals. On the other hand, the antagonist increased the number of rears and reversed the decrease in grooming behavior induced by estradiol. The results led to the idea of a role of LHRH in behaviors not apparently related to sex, which could explain the behavioral changes observed across the estrous cycle and those induced by estradiol replacement in ovariectomized rats.

GENDER DIFFERENCES IN CARDIOVASCULAR RISK BY TWO DIFFERENT SCORES: A FIVE YEARS FOLLOW UP ANALYSIS OF A 1500-PATIENT DATABASE

We have previously shown that Framingham traditional risk score is not correlated with the presence of CAD in the female population. This may be attributed to the fact that traditional scores underscore risk in women. We sought to evaluate gender differences in all cause mortality between Global

On the arf invariant of quadratic forms and of knots

The purpose of this note is to make some remarks concerning the relations between the Arf-invariant and quadratic forms and the Berlekamp discriminant of some polynomials over a field F of characteristics 2. Using the relations we are then able to give a quick proof of a well known result of Levine concerning the Arf invariant of a topological knot.