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A Rezvani

Publications and source records attributed to A Rezvani.

At least 37 records · Page 2Linked to original sources
PubMed1986

Comparative effects of dynorphin A(1-9) pyrrolidine analogs on isolated tissues.

Three dynorphin A(1-9) pyrrolidine analogs were synthesized by substituting isoleucine at position 8 with alanine (Ala), D-alanine (D-ala), and D-leucine (D-leu), and assayed for their effect on electrically induced twitches of the isolated guinea pig ileum and mouse vas deferens. All three dynorphin A(1-9) pyrrolidine analogs caused inhibition of the evoked twitches of the two preparations dose-dependently that was reversed by naloxone. However, the substitution by alanine or D-alanine resulted in a decrease in potency on guinea pig ileum when compared to dynorphin A(1-9) pyrrolidine and substitution by D-leucine caused a considerable loss of potency in both mouse vas deferens and guinea pig ileum. Although these substitutions reduced overall potency, a change of potency ratio towards more delta selectivity resulted.

Animals↗
PubMed1986

Opioids and rat erythrocyte deformability.

In previous studies from this laboratory, it was noted that opioids in vitro reduced human red blood cell deformability. The effect was found to be dose-dependent, naloxone reversible and preferentially selective kappa ligands exhibited the highest potency. To extend these findings studies were carried out using rat erythrocytes. The time required for erythrocytes to pass through a 5.0 um pore membrane was determined and used as an index of deformability. Opioids added in vitro produced inhibition of deformability in a dose-dependent, naloxone reversible manner. Injecting naive animals with morphine or nalbuphine also produced dose related reductions in red cell deformability. The degree of inhibition produced by nalbuphine correlated well with its plasma concentrations as measured by high performance liquid chromatography (HPLC). Chronic morphine treatment by pellet implantation resulted in the development of tolerance as evidenced by a loss in the ability of morphine in vitro to inhibit red cell deformability. Addition of naloxone resulted in a decrease in filtration time. Thus, the data confirm and extend previous findings on human red blood cells. In as much as previous data from this laboratory demonstrated that opioids inhibit calcium flux from erythrocytes by inhibiting calcium-ATPase and calcium efflux is necessary for normal deformability, it is concluded that opioids act to reduce red cell deformability by inhibition of the calcium pump.

Animals↗
PubMed1985

[Cancer of the prostate. Epidemiologic evaluation, incidence, and trends, especially in France].

With 7,172 deaths in 1982, prostatic cancer is a frequent cancer in France observed among old men, coming just after the lungs cancers and representing 9.6% of male mortality from malignant disease. Its incidence in the French regional population based on departmental registries is about 25/100.000 (age adjusted to the world standard population). The geographical distribution throughout the world shows a high incidence rate among the black american, the Scandinavian countries and low rates in the south-east of Asia. As well as incidence as for mortality low trends of increase all over the world are observed. In the clinical data from the "Enquete Permanente Cancer" (E.P.C.) the high proportion of metastatic dissemination (48%) at initial time of diagnosis, and also the high proportion of epithelial cancer (92%) emerge from a series of 1,223 prostatic cancer registered between 1975 and 1982. The 9 year-survival relative rate (32%) for the whole group lets appear a level of cure observed after the 8 years of follow-up. Few risk factors have been yet recognized so that it is not easy to identify risk population and propose them any preventions.

Adenocarcinoma↗
PubMed1984

Dynorphin-(1-13) restores the potency of morphine on the tolerant guinea pig ileum.

Since it has been reported that dynorphin (1-13) enhances the analgetic effects of morphine in mice tolerant either to morphine or beta-endorphin and modulates opioid agonist binding in the tolerant state, experiments were initiated to determine whether comparable phenomenon could be obtained in vitro with dynorphin-(1-13) on the isolated longitudinal muscle of the guinea pig ileum. In the guinea pig ileum rendered tolerant to morphine dynorphin-(1-13) was found to cause a dose-dependent restoration in sensitivity to the inhibitory action of morphine. This phenomenon appeared specific for dynorphin-(1-13) since [Leu5]enkephalin, beta-endorphin, and ethylketocyclazocine did not change significantly the IC50 of morphine in the tolerant preparation. Furthermore, dynorphin-(1-13) attenuated the contraction elicited by naloxone in the morphine tolerant-dependent tissue. It is concluded, that dynorphin-(1-13) restores sensitivity to morphine in the tolerant-dependent state by a modulatory effect probably on the mu receptor that is distinct from its kappa action.

Animals↗
PubMed1984

Opioid-like properties of seven dynorphin (1-10) analogs.

In order to disassociate the k action of dynorphin from its other actions, seven analogs were synthesized and evaluated for pharmacologic activity in comparison with dynorphin (1-13) and dynorphin amide (1-10). Dynorphin (1-10) was modified by protecting the terminal carboxy group, incorporating thioproline at position 10 and substituting methionine for leucine at position 5. All analogs exhibited the ability to inhibit electrically-induced twitches of the guinea pig ileum and mouse vas deferens in a manner that was dose dependent and naloxone reversible. The decapeptide terminating with a pyrrolidine group showed the highest potency in the ilea and mouse vas deferens. None of the analogs showed analgetic activity by the mouse tail flick test. Binding studies using mouse brain synaptosomes showed that all seven analogs can displace the binding of tritiated dihydromorphine (DHM), ethylketocyclazocine (EKC) and D-Ala-D-Leucine enkephalin (DADL). The alterations in chemical structure affected affinity of the analogs to the opiate receptor and their pharmacologic properties differently, suggesting that different opiate subtypes may be involved.

Animals↗
PubMed1984

[Comparison of a cohort mortality with the mortality of a reference population. Principle, necessary number of expected deaths and the given power of the test].

This note derives the power of the test comparing the mortality of a cohort to the mortality of a reference population. The principle of the comparison is recalled i.e. computation of the standardised mortality radio (SMR) and test of the null hypothesis: SMR = 1. It is shown how one can compute the power of the test. A numerical example is given.

Adult↗
PubMed1983

K receptor activities of the three opioid peptide families.

A large number of opioid peptides derived from the three established precursors, pro-opiomelanocortin (POMC), pro-enkephalin A (pro-enk A), and pro-enkephalin B (pro-enk B) were tested for their ability to inhibit electrically induced contractions of the isolated rabbit vas deferens, a preparation sensitive to k but not to mu opioid ligands. In the presence of enzyme inhibitors, all peptides exhibit roughly similar potencies, but the shorter peptides display lower potencies in the absence of enzyme inhibitors. This suggests that the loss in activity is due to their enzymatic degradation. It is concluded that the pro-enk B gene codes peptides with high k-receptor activities, whereas peptides produced by the POMC gene are devoid of k-receptor activity and the peptides, coded by the pro-enk A gene exhibit weak to moderate k-receptor activity.

Animals↗
PubMed1983

Hypersensitivity of the opioid-tolerant guinea pig ileum to electrical stimulation after abrupt agonist removal.

Studies were initiated on the myenteric plexus of the guinea pig ileum to ascertain whether a supersensitive response by abrupt withdrawal could be elicited after tolerance development to opioids. After an optimal twitch response to a given electrical stimulus was established and its height measured, the mean concentration of an opioid to inhibit half maximally the response (IC50) was determined. Subsequently, the tissues were rendered tolerant by incubating with 1x to 5x the IC50 of the agonist for two hours. The agonist was then removed by thorough washing with Ringer solution and the twitch height to the same electrical stimulation was remeasured. The increase in twitch height after washing over that before incubation provided an index of the degree of hypersensitivity of the tolerant-dependent tissue. The degree of hypersensitivity was found to increase in relation to the concentration of morphine. Stereo-specificity of agonist action was evinced by a hypersensitive response to levorphanol and not to dextrorphan. The development of hypersensitivity was blocked by naloxone and by chloramphenicol. Ethylketocyclazocine, a k ligand, did not show a hypersensitivity response. It is concluded that physical dependence on u-opioids can be developed in vitro and that it can be quantified by a super-sensitivity response.

Animals↗
PubMed1983

A rapid and simple method for the quantitative determination of tolerance development to opiates in the guinea-pig ileum in vitro.

The rate and degree of tolerance development of morphine, normorphine and methadone were assessed in vitro on the guinea-pig ileum. After the half-maximal concentration to inhibit electrically induced contractions (IC50) for each compound was determined, tolerance to a fixed concentration representing 0.5, 1 or 2 times its IC50 was induced by incubation at 37 degrees C for 1, 2 or 4 hr. The IC50 was then redetermined and the ratio of the IC50 after and before incubation provided a quantitative index of the degree of tolerance development to each agonist. For any given concentration or time, morphine induced the highest, whereas normorphine the intermediate and methadone the lowest degree of tolerance. Tolerance to opiates was associated with some degree of physical dependence as evidenced by the fact that the application of naloxone at the end of each experiment elicited a muscular contraction. Specificity of tolerance development to opiates was demonstrated by several experiments. Coincubation of morphine with naloxone under the same conditions resulted in an inhibition of tolerance development. The stereospecificity of the process was demonstrated by the fact that levorphanol and I-methadone induced a high degree of tolerance, whereas, under the same conditions the less active d-isomers, dextrorphan and d-methadone, did not. Moreover, subsensitivity to acetylcholine, norepinephrine and adenosine monophosphate did not develop in the presence of tolerance to morphine. The validity of this method for investigating mechanisms involved in tolerance and physical dependence was further demonstrated by obtaining data compatible with earlier experiments in vivo that cyclic AMP enhances tolerance development and cycloheximide inhibits this phenomenon. The present method should facilitate studies on the mechanisms involved in opiate tolerance and physical dependence development.

Animals↗
PubMed1982

Effect of 4-aminopyridine and verapamil on the inhibitory action of normorphine on the guinea-pig ileum.

The ability of normorphine to inhibit the muscular twitches elicited by electrical stimulation of the longitudinal muscle of the guinea-pig ileum was antagonized by 4-aminopyridine (4-AP). Incubation with 4-aminopyridine (4-AP) caused a marked increase of the normorphine IC50 and this effect was not modified by naloxone or by the Ca2+ channel blocker, verapamil. Although verapamil caused a significant decrease of the normorphine IC50 it also caused a potent reduction of the contractile effect of acetylcholine. The results suggest that 4-AP and verapamil act on different Ca2+ pools and that verapamil does not primarily affect the presynaptic Ca2+ pool involved in opiate action.

4-Aminopyridine↗
PubMed1982

[Relation between mortality in cancer of the pancreas and food and tobacco consumption in France].

The relationship is given between French pancreatic cancer mortality rates form 1968 to 1976, and some nutritional variables and tobacco. Positive correlations were found between the death rate from pancreatic cancer and sugar, egg and cereal consumption; however, a negative correlation was found with tobacco consumption. A stepwise multiple regression procedure showed an association between the mortality rate from cancer of the pancreas and meat and oil consumption when age had been taken into account.

Adult↗
PubMed1978

Synthesis and local anesthetic activity of benzo[b]furan derivatives.

Several 2-dialkylaminoethyl 3-methyl-2-benzo[b]furancarboxylates, 2-dialkylaminoethyl 3-methyl-2-benzo[b]furancarbamates, and 3-methyl-2-benzo[b]furancarboxamide derivatives were prepared and tested for local anesthetic activity. Piperidinoethyl 3-methyl-2-benzo[b]furancarbamate, 2-diethylaminoethyl 3-methyl-2-benzo[b]-furancarboxylate, and N-(2-diethylaminoethyl)-3-methyl-2-benzo[b]-furancarboxamide were the most potent.

Anesthetics, Local↗
PubMed1978

The effects of unsatisfactory working conditions on the epidemiology of unauthorised absenteeism in an old textile factory in Isfahan, Iran.

Comparison of unauthorised absenteeism rates were made between two large textile factories in Isfahan, Iran. The working conditions in the study factory were rather unsatisfactory, unlike the control factory. Comparison showed significantly higher rates for the study factory: the average annual duration per person was 7 days in the study factory versus 2.5 days in the control factory, and lost time percentage was 2.4% in the former versus 0.84% in the control. Inception rate of persons was 0.73 versus 0.48, and point prevalence rates 0.002 versus 0.001, whilst period prevalence rates were 0.016 versus 0.011 for the study and control factories respectively. Examination of the study factory data was made to determine any possible relationship between unauthorised absenteeism rates and age and length of employment. It was found that higher unauthorised rates were found amongst the younger workers, 100% for those age 19 and under, versus 59.6% for those age 50 and over. 9.16% of workers employed for 1--4 years took such leave against 70.14% of those employed for 10 or more years. Only 18.8% of all workers took certified sickness absenteeism and the rate increased with age. It was suggested that worker dissatisfaction toward unsatisfactory working conditions may be expressed in terms of unauthorised absenteeism. In view of the widespread consequences of such absenteeism, it is recommonded that closer attention be paid to improve the quality of working life.

Absenteeism↗
PubMedDate not supplied

Comparison of the mortality of a cohort with the mortality of a reference population in a prognostic study.

It is standard practice in epidemiological studies to compare the observed mortality of a cohort to the mortality expected in a reference population of the same age and sex distributions computed from national statistics. The same methods can be used in a prognostic study where the effects on survival of potential prognostic factors are studied in a cohort of patients with a given disease. Writing the hazard function in the cohort as the product of the hazard function in the reference population and a function of some characteristics of the patients, one can derive simple estimates and statistical tests of the standardised mortality ratios (Breslow et al.). The study of a cohort of patients with thyroid cancer will provide an example.

Adult↗
PubMedDate not supplied

A method for the rapid development of opiate tolerance in the guinea pig ileum.

The rate and degree of in vitro tolerance development to morphine, normorphine and d,1-methadone were assessed on the excised guinea pig ileum. Agonists in fixed concentrations at 1/4, 1/2, 1 and 2 x IC50 were incubated with the tissue for 1, 2 or 4 hours. The degree of tolerance development was expressed as a ratio of the IC50 after and before incubation. A high degree of tolerance developed to all three agonists and the effect could be prevented by co-incubation with naloxone. Tolerance development was stereo-specific; levorphanol and 1-methadone developed much higher degrees of tolerance than their respective d-isomers. Furthermore, under the same conditions, subsensitivity to acetylcholine, norepinephrine, and adenosine monophosphate did not develop. The in vitro tolerance was accompanied by physical dependence development as evidenced by the fact that naloxone elicited muscular contracture in the tolerant ileum. cAMP enhanced the development of tolerance to normorphine and cycloheximide could reduce this phenomenon. It is concluded that the procedure may facilitate studies on the mechanisms involved in the development of opiate tolerance and physical dependence.

Animals↗