A note on the attenuation of the sommerfeld effect of a non-ideal system taking into account a MR damper and the complete model of a DC motor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chlorination treatment of aqueous samples reduces, but does not eliminate, the mutagenic effect of the azo dyes Disperse Red 1, Disperse Red 13 and Disperse Orange 1

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

3-BODY COLLAPSE FOR TABAKIN POTENTIALS AND THE THOMAS EFFECT

A system constituted of three bosons interacting via two-body separable potentials with fixed two-boson binding is known to lead to bound-state collapse in the case where the potential parameters allow two-boson S-matrix poles close to (resonance) and on (continuum bound state) the real momentum axis. The collapse is shown to be accompanied by an increase in the average kinetic energy of the two-body bound state, which signals a decrease in the range of the two-body interaction for fixed two-body binding. The collapse is claimed to be a manifestation of the well-known Thomas effect which leads to a collapse of the three-body system when the range of the two-body interaction goes to zero for a fixed two-body binding.

PHARMACOLOGICAL EVALUATION OF THE INHIBITORY EFFECT OF EXTRACTS FROM ANCHIETIA-SALUTARIS ON THE HISTAMINE-RELEASE INDUCED IN THE RAT AND THE GUINEA-PIG

The tea made with leaves and stems of plant Anchietia salutaris is traditionally used in Brazil to treat allergies. We examined the effects of a crude aqueous extract and of purified fractions of this plant on the histamine release induced in rat and guinea pig tissues. The crude extract (3-10 mu g/ml) inhibits the histamine release induced by compound 48/80 (0.5 mu g/ml) and antigen in rat peritoneal mast cells. The inhibition is significant after 10 s of preincubation and is completed after 3 min. The crude extract dissolved in the perfusion fluid (1-30 mu g/ml) also inhibits the histamine release induced in guinea pig heart by cardiac anaphylaxis and in hearts from pretreated animals (10-100 mg/kg i.p.). In pretreated animals, the effect manifests after 3 h, is maximum after 12 h and disappears after 48 h. The histamine release induced in isolated guinea pig heart by ionophore A23187 is inhibited by similar doses as in antigen-induced histamine release. Extraction with solvents concentrated the active principle (s) in the hexane fractions, as demonstrated by the inhibition of the histamine release induced by antigen in isolated cells from guinea pig heart dispersed with collagenase. In subfractions produced by the fractionation of the hexane fraction, the active principle(s) concentrated in the subfractions obtained by extraction with hexane and ethyl acetate, which shows the low polarity of the compound(s). The same subfractions that inhibit the histamine release induced by antigen in cells from guinea pig heart also inhibit pulmonary cells. Our result show that A. salutaris contains low-polarity compound(s) that inhibit the histamine release induced by three different mechanisms in mast cells from two animal species. These facts suggest that the active principle(s) of A, salutaris could be useful in the treatment of allergies and/or as a tool for the study of mast cell secretions.

Repeated administration intensifies the reinforcing effect of fencamfamine in rats

1. In the present study, we evaluated the role of repeated administration on conditioning place preference (CPP) induced by fencamfamine (FCF) in male rats.2. Repeated FCF (3.5 mg/kg) or saline once or daily for ten consecutive days enhanced sniffing du ration and decreased locomotion and rearing duration.3. At the 3.5 mg/kg dose, FCF produced a significant place-preference effect.4. Repeated exposures to FCF intensified its reinforcing properties.5. These results suggest that repeated FCF administration sensitizes its rewarding effects, as with other addictive substances. GEN PHARMAC 29;2:265-261, 1997. (C) 1997 Elsevier B.V.

Nitric oxide and anglotensin II receptors mediate the pressor effect of angiotensin II: A study in conscious and zoletil-anesthetized rats

The circumventricular structures of the central nervous system and nitric oxide are involved in arterial blood pressure control, and general anesthesia may stimulate the central renin-angiotensin system. We therefore investigated the central role of angiotensin 11 and nitric oxide on the regulation of systemic arterial blood pressure in conscious and anesthetized rats. METHODS: Rats with stainless steel cannulae implanted into their lateral ventricle were studied. We injected the AT(1) and AT(2) angiotensin 11 receptor antagonists, losartan and PD123319, L-NAME, 7-nitroindazole (nitric oxide synthetase inhibitors), and FK409 (nitric oxide donor agent) into the lateral ventricles. Mean arterial blood pressure (MAP) was recorded in conscious and zoletil-anesthetized rats. RESULTS: Mean +/- (SEM) baseline MAP was 117.5 +/- 2 mm Hg. Angiotensin II injected into the brain lateral ventricle increased MAP from 136.5 +/- 2 min Hg to 138.5 +/- 4 mm Hg (Delta 16 +/- 3 mm Hg to Delta 21 +/- 3 mm Hg) for all experimental groups versus control from 116 +/- 2 mm Hg to 120 +/- 3 mm Hg (Delta 3 +/- 1 mm Hg to A5 +/- 2 mm Hg) (P < 0.05). L-NAME or 7-nitroindazole enhanced the angiotensin II pressor effect (P < 0.05). Prior injection of losartan and PD123319 decreased the angiotensin 11 pressor effect and the enhancement effect of L-NAME and 7-nitroindazole (P < 0.05). Zoletil anesthesia did not interfere with the effects of angiotensin 11, AT,, AT2 antagonists, or nitric oxide synthetase inhibitors. CONCLUSIONS: Endogenous nitric oxide functions tonically as a central inhibitory modulator of the angiotensinergic system. AT, and AT2 receptors influence the angiotensin 11 central control of arterial blood pressure. Zoletil anesthesia did not interfere with these effects. (Anesth Analg 2007;105:1293-7)

BACKGROUND THERMAL CONTRIBUTIONS IN TESTING THE UNRUH EFFECT

We consider inertial and accelerated Unruh-DeWitt detectors moving in a background thermal bath and calculate their excitation rate. It is shown that for fast moving detectors such a thermal bath does not affect substantially the excitation probability. Our results are discussed in connection with a possible proposal of testing the Unruh effect in high energy particle accelerators.

Antagonism produced by hypertonic nutrient solutions on the depressive effect of carbofuran on isolated guinea pig atria

The action of hyperosmotic nutrient solutions on the depressive effects of carbofuran was studied on spontaneously contracting guinea pig atria. The force and frequency of contraction were recorded using an isotonic lever. Carbofuran 33.0 mu g ml(-1) produced a gradual depressive effect. The time for stabilization of the depressive effect was 6.0+/-2.3 min. After the depressive effect of carbofuran was established, NaCI, mannitol, or urea were introduced into the organ bath to increase the osmolarity of the nutrient solution to about 100 mosmol kg(-1) of water. This resulted in a reversal of the contraction force and frequency to the initial levels. The addition of the osmotic agents at the same concentrations before the addition of 33.0 mu g ml(-1) carbofuran avoided its depressive effect on guinea pig atria. (C) 1996 the Italian Pharmacological Society.

Natural trans-crotonin: the antiulcerogenic effect of another diterpene isolated from the bark of Croton cajucara Benth.

The nor-clerodane diterpene trans-crotonin isolated from the bark of Croton cajucara BENTH. was investigated for its ability to prevent the formation of gastric-mucosa ulceration in different experimental models in mice. The results obtained from crotonin were compared with those obtained with another diterpene, DHC (trans-dehydrocrotonin) in the same models. When previously administered (p.o.) at the dose of 100 mg/kg, crotonin, as well as DHC, significantly reduced (p<0.05) gastric injury induced by stress (72, 67%), indomethacin/bethanechol (78, 29%) and pylorus ligature (35, 30%). In the HCl/ethanol-induced gastric ulcer model, at oral doses of 100 and 250 mg/kg, crotonin significantly prevented (p<0.05) the formation of gastric lesions by 51 and 56%, respectively, when compared to the control group. Gastric injury was also of significantly less magnitude in the DHC treatment group (p<0.05). In the pylorus-ligature model, crotonin (p.o.), like cimetidine, increased the volume of gastric juice when compared to the control group (p<0.05). No significant modifications where found in gastric parameters such as pH or total acid content after oral crotonin treatment. However, systemic alterations were observed when crotonin (100 mg/kg) was previously administered intraduodenally to mice. We observed significant changes (p<0.001) in gastric-juice parameters such as an increase in volume and a decrease in gastric acidity. Those pre-treated with crotonin as well as with DHC did not increase free mucus production (p>0.05). The results suggest that crotonin presents a significant anti-ulcer effect when assessed in these ulcer-induced models. As with DHC, the antiulcerogenic effects of crotonin are probably related to anti-secretory or/and gastroprotective properties of this substance. In light of results obtained with DHC and natural trans-crotonin in the present study, we concluded that the A-ring of both diterpenes is not directly involved in the antiulcerogenic activity.

ALPHA-ADRENERGIC PATHWAYS IN THE LATERAL HYPOTHALAMUS ARE IMPORTANT FOR THE DIPSOGENIC EFFECT OF CARBACHOL INJECTED INTO THE MEDIAL SEPTAL AREA

We studied the effect of the alpha(1)- and alpha(2)-adrenergic receptors of the lateral hypothalamus (LH) on the control of water intake induced by injection of carbachol into the medial septal area (MSA) of adult male Holtzman rats (250-300 g) implanted with chronic stainless steel cannulae into the LH and MSA. The volume of injection was always 1 mu l and was injected over a period of 30-60 s. For control, 0.15 M NaCl was used. Clonidine (20 nmol) but not phenylephrine (160 nmol) injected into the LH inhibited water intake induced by injection of carbachol (2 nmol) into the MSA, from 5.4 +/- 1.2 ml/h to 0.3 +/- 0.1 and 3.0 +/- 0.9 ml/h, respectively (N = 26). When we injected yohimbine (80 nmol) + clonidine (20 nmol) and prazosin (40 nmol) + clonidine (20 nmol) into theLH, water intake induced by injection of carbachol into the MSA was inhibited from 5.4 +/- 1.2 ml/h to 0.8 +/- 0.5 and 0.3 +/- 0.2 ml/h, respectively (N = 19). Water intake induced by carbachol (2 nmol) injected into the MSA was decreased by previous injection of yohimbine (80 nmol) + phenylephrine (160 nmol) and prazosin (40 nmol) + phenylephrine (l60 nmol) from 5.4 +/- 1.2 ml/h to 1.0 +/- 0.7 and 1.8 +/- 0.8 ml/h, respectively (N = 16). The cannula reached both the medial septal area in its medial portion and the lateral hypothalamus. It has been suggested that the different pathways for induction of drinking converge on a final common pathway. Thus, adrenergic stimulation of alpha(2),-adrenoceptors ofLH can influence this final common pathway.