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Biomedical subjects

S Ventura

Publications and source records attributed to S Ventura.

At least 19 recordsLinked to original sources
PubMed1992

In vivo quantification of cholesterol content in human carotid arteries by quantitative gamma-camera imaging after injection of autologous low density lipoproteins (LDL).

Low density lipoproteins (LDL) were isolated by immunoaffinity chromatography from 18 patients (31-70 years) suffering from primary hypercholesterolemia with angiographically proven atherosclerosis of either one or both carotid arteries. LDL were labeled with 123I (1 mCi/mg LDL) by the iodine monochloride method followed by purification with dialysis and immediately reinjected thereafter. Gamma-camera serial controls over carotid regions allowed visual detection of uptake of the radiocompound uptake in 12 out of the 18 patients. The lipid entry ratio (LER; counts over the vascular region/pixel as compared to the contralateral side after background subtraction) confirmed the visual findings. Whole body images performed until 20 h after reinjection showed 3 different kinetic types of LDL-influx into the vessel wall: decreasing (type I), increasing and then decreasing (type II) and continuously increasing (type III) with time. Four patients underwent endarterectomy within 2-7 weeks after gamma-camera imaging. Histological control revealed an extensive amount of "foam cells" in tissue samples derived during surgery and an absence of endothelial lining in samples belonging to patients with type II kinetics.

Adult↗
PubMed1992

Inhibition of field stimulation-induced contractions of rat cauda epididymis by purinoceptor agonists but not by adrenoceptor agonists.

1. Adenosine, AMP, ADP, and ATP were approximately equipotent in inhibiting contractions evoked by field stimulation (10 Hz, 60 V, 1 ms, 10 s) of isolated preparations of rat cauda epididymis. Adenosine had no significant effect on contractions induced by the exogenous application of either noradrenaline or ATP. 2. The effects of adenosine and AMP were markedly potentiated by the adenosine uptake inhibitor, dipyridamole. In contrast there was only a two-fold potentiation of the effects of ATP and no potentiation of the effects of ADP by dipyridamole. 3. Inhibitory responses to both adenosine and ATP were blocked by 8-phenyltheophylline. Neither the P2Y-purinoceptor antagonist, reactive blue 2, nor P2X purinoceptor antagonist alpha,beta-methylene ATP, blocked the inhibitory effects of ATP. 4. Several stable analogues of adenosine, namely 5'-(N-ethyl) carboxamidoadenosine (NECA), N6-cyclohexyl-adenosine (CHA), L-N6-(2-phenyl-isopropyl)adenosine (L-PIA), D-N6-(2-phenyl-isopropyl)adenosine (D-PIA) and 2-chloroadenosine (CADO) also inhibited nerve stimulation-induced contractions. NECA was the most potent. L-PIA and D-PIA were approximately equipotent, except in the presence of dipyridamole, when the potency of L-PIA exceeded that of D-PIA. 5. Field stimulation-induced contractions of the rat cauda epididymis were unaffected by the alpha 2-adrenoceptor agonists clonidine and xylazine; isoprenaline in high concentrations produced phentolamine-sensitive inhibition of contractions evoked by field stimulation and exogenous application of noradrenaline. 6. These findings taken together are consistent with the possibility that prejunctional purinoceptors, which are atypical in that they are directly activated by both ATP and adenosine, mediate inhibition of neurotransmission in this tissue. No evidence for the presence of functional alpha 2-adrenoceptors modulating neurotransmission was obtained.

Animals↗
PubMed1991

Sympathetic co-transmission to the cauda epididymis of the rat: characterization of postjunctional adrenoceptors and purinoceptors.

1. Electrical field stimulation (10 Hz, 60 V, 1 ms, for 10 s) produced monophasic contractions of isolated preparations of rat cauda epididymis which could be abolished by guanethidine, and attenuated by prazosin and alpha, beta-methylene ATP. 2. The rank order of potency of adrenoceptor agonists in causing contraction of the preparation in the presence of the neuronal uptake blocker, nisoxetine (0.1 microM) was: adrenaline greater than or equal to phenylephrine greater than or equal to noradrenaline greater than clonidine greater than methoxamine greater than metaraminol greater than dopamine greater than or equal to isoprenaline greater than xylazine. 3. Responses to the agonists were blocked by prazosin but not by propranolol or idazoxan. 4. The rank order of potency of purinoceptor agonists in causing contraction of the cauda epididymis was: alpha,beta-methylene ATP greater than beta,gamma-methylene ATP greater than or equal to 2-methylthio ATP greater than ATP greater than ADP. AMP and adenosine did not cause contractions. 5. Contractile responses to the purine nucleotide analogues were blocked by repeated application of alpha,beta-methylene ATP. 6. It is concluded that both ATP and noradrenaline may act as co-transmitters in the sympathetic nerves supplying the smooth muscle of the rat cauda epididymis, and that alpha 1-adrenoceptors and P2x-purinoceptors are present postjunctionally.

Animals↗
PubMed1990

DNA restriction fingerprint analysis of the soil bacterium Azospirillum.

Total DNAs of 18 strains of Azospirillum from different sources and geographical areas were compared by restriction endonuclease pattern analysis. Fragments obtained with HindIII or BglII were separated by PAGE and stained with silver nitrate. Each strain possessed a unique and reproducible fingerprint with each enzyme, thereby facilitating strain recognition. UPGMA analysis recovered clusters of band patterns that were compared to the distribution of species within the genus Azospirillum.

Bacteria↗
PubMed1990

Subsensitivity to ATP and some analogues in preparations of rat cauda epididymis and vas deferens after vasectomy.

1. The effects of ATP and some of its more stable analogues have been examined upon preparations of epididymal and prostatic halves of vasa deferentia and of cauda epididymides from rats that had undergone vasectomy by medial transection of the vas deferens. 2. After unilateral vasectomy, the potencies of ATP, beta, gamma-methylene ATP and 5'-adenylylimidodiphosphate (AppNHp) in tissues ipsilateral to the vasectomy were decreased compared to tissues from the contralateral unoperated side of the animal. 3. Tissues from bilaterally vasectomized rats were less responsive to ATP when compared to tissues taken from sham-operated rats. 4. Tissues taken from rats which had undergone vasovasostomies following unilateral vasectomy remained less responsive to these purines. 5. Responses of cauda epididymides and epididymal halves of vasa deferentia taken from unilaterally and bilaterally vasectomized rats to alpha, beta-methylene ATP usually did not differ from those of respective controls. 6. It is proposed that the subsensitivity which develops to ATP and some of its analogues on the epididymis and vas deferens following vasectomy may reflect increased breakdown, perhaps associated with changes in structural integrity of the tissues, rather than with the sympathetic denervation which is associated with vasectomy.

Adenosine Triphosphate↗
PubMed1990

Birth and fertility rates by education: 1980 and 1985.

Birth and fertility rates by educational attainment of mother are shown for the United States, geographic regions and divisions, and States for 1980 and 1985. The report focuses on differentials in childbearing among educational attainment groups and changes in fertility levels during the period, particularly for well-educated older mothers. The information presented is derived from entries on live-birth certificates from 47 states and the District of Columbia.

Adolescent↗
PubMed1989

Supersensitivity to noradrenaline in preparations of rat cauda epididymis after vasectomy.

Preparations of cauda epididymides were taken from rats unilaterally vasectomised by medial transection of the vas deferens. Responses of preparations from the operated side to field stimulation (10 pulses, 70 V, 1 ms, 0.1-20 Hz) declined in parallel with decreases in catecholamine fluorescence. There were leftward shifts in the mean cumulative concentration-response curves to noradrenaline on vasectomised cauda epididymides of 5-, 10-, and 12-fold at days 2, 7 and 28, respectively compared to unoperated cauda epididymides following vasectomy. Nisoxetine (0.1 mumol/l) enhanced the potency of noradrenaline upon unoperated but not upon vasectomised segments. There were leftward shifts of 7- and 8-fold in the mean cumulative concentration-response curves to acetylcholine in vasectomised cauda epididymides at days 2 and 7, respectively, following surgery. Responses to methoxamine and carbachol were unaffected by vasectomy. Thus neurotransmission to the smooth muscle of the rat cauda epididymis resembles that to the vas deferens, in that vasectomy results in the development of prejunctional supersensitivity to noradrenaline and acetylcholine.

Acetylcholine↗
PubMed1989

[Expression of the interleukin-2 receptor in T lymphocytes of the rheumatoid synovial membrane].

Indirect immunofluorescence was used to stain DR antigen and interleukin-2 receptor (Tac) of T-lymphocytes (Leu 4+). Tissue samples of synovial membrane were cut from arthroscopic biopsies of inflamed knees in four patients with active rheumatoid arthritis (RA). Consecutive cryostatic sections of rheumatoid sinovium were analysed using monoclonal antibodies. It was found that a high percentage of T-lymphocytes express DR antigen. In contrast the proportion of T cells expressing Tac was small. We conclude that T cell activation in synovial membrane is incomplete, and this disfunction may contribute to the chronic inflammation of RA.

Arthritis, Rheumatoid↗
PubMed1988

Plasma lipid lowering activity of acipimox in patients with type II and type IV hyperlipoproteinemia. Results of a multicenter trial.

A multicenter study was carried out in 130 out-patients to assess the plasma lipid lowering activity of acipimox in type IIa, IIb and IV hyperlipoproteinemia. The study consisted of two periods, an 8-week randomized, double-blind comparison of active drug versus placebo and a 16-week open follow-up with acipimox (400 mg and 250 mg t.i.d., respectively, in type II and IV patients). During the double-blind phase acipimox, compared to placebo, showed a highly significant triglyceride lowering effect in type IV patients (-43% vs. +4%, P less than 0.01), while reducing plasma cholesterol significantly in type II patients (-7% vs. -3%, P less than 0.05). Further reductions in plasma lipids were obtained in both types of hyperlipoproteinemia after the 16-week follow-up. In type II patients, total cholesterol fell by 9% in the former acipimox group and 17% in the former placebo group, whereas a 34% reduction in triglycerides was found in type IV patients previously treated with placebo. Treatment had to be discontinued in 4 patients during the double-blind phase and in 5 patients during follow-up, because of adverse events such as skin reactions and gastric disturbances. Statistical analysis of hematological and biochemical variables expressing safety did not show any significant change during treatment.

Adult↗
PubMed1980

[Delivery under general anesthesia with the sequence of althesin and lysine acetylsalicylate; a clinical contribution].

Personal experience in the use of Althesin in painless childbirth is reported. The anaesthetic is held to have no effect on the foetus and the technique using Althesin and acetylsalicylate of lysine is considered the correct one. If properly applied, it offers the foetus complete wellbeing during labour and enables the mother to overcome the psychophysical stress of an event which is too often accepted with inherited feelings of ancestral fear.

Adolescent↗