Biomedical subjects
Publications and source records attributed to R Tedesco.
To prepare novel estrogen receptor (ER) ligands, we have developed a facile approach to substituted hexahydrochrysene and tetrahydrobenzo[a]fluorene systems. Substituents, including basic side chains, were added to these systems, and their binding affinity to ERalpha and ERbeta, and in some cases their transcriptional activity were evaluated.
Previously, we reported that certain tetrasubstituted 1,3,5-triaryl-4-alkyl-pyrazoles bind to the estrogen receptor (ER) with high affinity (Fink, B. E.; Mortenson, D. S.; Stauffer, S. R.; Aron, Z. D.; Katzenellenbogen, J. A. Chem. Biol. 1999, 6, 205-219; Stauffer, S. R.; Katzenellenbogen, J. A. J. Comb/. Chem. 2000, 2. 318 329; Stauffer, S. R.: Coletta, C. J.: Sun, J.; Tedesco, R., Katzenellenbogen, B. S.; Katzenellenbogen, J. A. J. Med. Chem. 2000, submitted). To investigate how cyclic permutation of the two nitrogen atoms of a pyrazole might affect ER binding affinity, we prepared a new pyrazole core isomer, namely a 1,3,4-triaryl-5-alkyl-pyrazole (2), to compare it with our original pyrazole (1). We also prepared several peripherally matched core pyrazole isomer sets to investigate whether the two pyrazole series share a common binding orientation. Our efficient, regioselective synthetic route to these pyrazoles relies on the acylation of a hydrazone anion, followed by cyclization, halogenation, and Suzuki coupling. We found that the ER accommodates 1,3,4-triaryl-pyrazoles of the isomeric series only somewhat less well than the original 1,3,5-triaryl series, and it appears that both series share a common binding mode. This preferred orientation for the 1,3,5-triaryl-4-alkyl-pyrazoles is supported by binding affinity measurements of analogues in which the phenolic hydroxyl groups were systematically removed from each of the three aryl groups, and the orientation is consistent, as well, with molecular modeling studies. These studies provide additional insight into the design of heterocyclic core structures for the development of high affinity ER ligands by combinatorial methods.
BACKGROUND: The specificity of hormone action arises from complementary steric and electronic interactions between a hormonal ligand and its cognate receptor. An analysis of such key ligand-receptor contact sites, often delineated by mutational mapping and X-ray crystallographic studies, can suggest ways in which hormone-receptor specificity might be altered. RESULTS: We have altered the hormonal specificity of the estrogen receptor alpha (ER) by making 'coordinated' changes in the A-ring of the ligand estradiol and in the A-ring binding subpocket of ER. These changes were designed to maintain a favorable interaction when both E and ER are changed, but to disfavor interaction when only E or ER is changed. We have evaluated several of these altered ligand and receptor pairs in quantitative ligand binding and reporter gene assays. CONCLUSIONS: In best cases, the new interaction is sufficiently favorable and orthogonal so as to represent the creation of a new hormone specificity, which might be useful in the regulation of transgene activity.
We have found that certain tetrasubstituted pyrazoles are high-affinity ligands for the estrogen receptor (ER) (Fink et al. Chem. Biol. 1999, 6, 205-219) and that one pyrazole is considerably more potent as an agonist on the ERalpha than on the ERbeta subtype (Sun et al. Endocrinology 1999, 140, 800-804). To investigate what substituent pattern provides optimal ER binding affinity and the greatest enhancement of potency as an ERalpha-selective agonist, we prepared a number of tetrasubstituted pyrazole analogues with defined variations at certain substituent positions. Analysis of their binding affinity pattern shows that a C(4)-propyl substituent is optimal and that a p-hydroxyl group on the N(1)-phenyl group also enhances affinity and selectivity for ERalpha. The best compound in this series, a propylpyrazole triol (PPT, compound 4g), binds to ERalpha with high affinity (ca. 50% that of estradiol), and it has a 410-fold binding affinity preference for ERalpha. It also activates gene transcription only through ERalpha. Thus, this compound represents the first ERalpha-specific agonist. We investigated the molecular basis for the exceptional ERalpha binding affinity and potency selectivity of pyrazole 4g by a further study of structure-affinity relationships in this series and by molecular modeling. These investigations suggest that the pyrazole triols prefer to bind to ERalpha with their C(3)-phenol in the estradiol A-ring binding pocket and that binding selectivity results from differences in the interaction of the pyrazole core and C(4)-propyl group with portions of the receptor where ERalpha has a smaller residue than ERbeta. These ER subtype-specific interactions and the ER subtype-selective ligands that can be derived from them should prove useful in defining those biological activities in estrogen target cells that can be selectively activated through ERalpha.
The hemodynamic and platelet effects of the thrombin receptor activating peptide SFLLRN (TRAP) were evaluated in rats. TRAP failed to aggregate rat platelets in vitro (platelet rich plasma) or in vivo in the pulmonary microcirculation. In contrast, TRAP aggregated washed human platelets. Intravenous injection of TRAP (1 mg/kg) in inactin-anesthetized rats produced a biphasic response in blood pressure characterized by an initial depressor response (-25 +/- 3 mmHg for 15-30 s) followed by a pronounced pressor response (50 +/- 7 mmHg for 2-3 min). This increase in blood pressure can be attributed to increases in total peripheral resistance since cardiac output remained unchanged. Further, only the pressor responses were observed in pithed rats suggesting a direct effect of TRAP in causing smooth muscle contraction. Consequently, rat platelets differ from human platelets in that they are resistant to TRAP whereas rat vasculature is highly sensitive to TRAP. These observations suggest that while the thrombin receptors on rat vasculature may be similar to those on human platelets, the receptors and/or the coupling mechanisms in rat platelets appear different from human platelets.
Intracerebroventricular (i.c.v.) administration of glucagon-like peptide-1-(7-37) amide (GLP-1) has been shown to modulate food and water intake. The present studies further characterize the effects of i.c.v. GLP-1 in the regulation of energy balance in lean and obese animals. In both obese and lean Zucker rats, a single i.c.v. infusion of GLP-1 (1-30 microg) resulted in a dose-dependent reduction of food intake and decrease in respiratory quotient relative to the saline control during the first 2 h of the nocturnal cycle. In obese Zucker rats, the food intake was reduced by 73 +/- 11% of the control at the 30 microg dose, whereas a modest 45 +/- 18% reduction was observed in lean rats. Despite the large reduction in food intake seen with GLP-1, there was no compensatory decrease in nocturnal oxygen consumption in the obese Zucker rats. Interestingly, low doses of GLP-1 (1 microg) in lean Zucker rats, which had minimal effects on food intake, caused a 19 +/- 7% increase in O2 consumption during the first 2 h of the nocturnal cycle. These data suggest that central GLP-1 may be an important factor controlling negative energy balance in both the lean and obese Zucker rats.
Patients undergoing abdominal aortic aneurysm repair routinely have a depressed core body temperature during surgery, and hypothermia is known to cause abnormalities in coagulation. This study was designed to determine whether platelet function is altered as a result of hypothermia or heparin during abdominal aortic aneurysm repair. Ten patients scheduled for abdominal aortic aneurysm surgery were prospectively studied. Bleeding times and temperature were measured every hour beginning preoperatively. Each patient was heparinized intraoperatively, and the effects reversed with protamine sulfate prior to closure. Despite efforts to keep the patients warm, all of them developed hypothermia (mean lowest core temperature 34.8 +/- 0.7 degrees C). A significant linear relationship between the change in core temperature and the change in bleeding time was demonstrated. In 7 of 10 cases the greatest change in bleeding time occurred when patients experienced the lowest mean core temperature and not when they were heparinized. These data suggest that hypothermia has a marked effect on platelet function during abdominal aortic aneurysm repair. Although heparin can cause abnormalities in platelet function, hypothermia may be a more important role in inhibiting normal platelet function. By preventing severe hypothermia (< 35 degree C), excessive bleeding associated with abdominal aortic aneurysm repair may be minimized without the concomitant risk of blood product transfusion.
SCH 33844 is a new, potent and long-acting inhibitor of angiotensin converting enzyme (ACE). Antihypertensive, hemodynamic and autonomic actions of SCH 33844 were examined in the present series of experiments. Oral administration of 0.3-30 mg/kg reduced blood pressure of spontaneously hypertensive rats. The magnitude of the response was significantly enhanced by pretreatment of the animals with hydrochlorothiazide. Blood pressure remained significantly depressed 24 hr following doses of 3 and 10 mg/kg. Administration of SCH 33844 (3 mg/kg) twice daily to nonpretreated rats or once daily to diuretic-pretreated animals for 5 days resulted in a progressive decrease in blood pressure. The compound did not reduce blood pressure in nephrectomized rats demonstrating the dependence of its action on renal renin. SCH 33844 (1-10 mg/kg orally) also produced dose-related decreases in pressure in diuretic-pretreated conscious normotensive dogs. However, only a small fall in pressure occurred in non-pretreated dogs. Hemodynamic actions were examined in anesthetized dogs. SCH 33844 (1 mg/kg i.v.) reduced blood pressure, increased cardiac output and caused a large fall in peripheral resistance. Autonomic actions were assessed in pithed rats. The compound (10 mg/kg orally) tended to decrease pressor responses to sympathetic activation and to i.v. norepinephrine. This profile is probably due, at least in part, to vasorelaxation following suppression of angiotensin II generation. In conclusion, SCH 33844 is a potent, long-lasting antihypertensive agent which reduces peripheral vascular resistance and possesses only slight autonomic effects.
SCH 33844 is a new non-sulfhydryl-containing angiotensin converting enzyme (ACE) inhibitor. SCH 33844 diacid inhibited hydrolysis of the synthetic substrate hippuryl-histidyl-leucine by rabbit lung ACE in vitro with an IC50 (concentration inhibiting enzyme by 50%) of 0.81 nM. The ester was 83 times less active. Intravenous administration of SCH 33844 and its diacid inhibited pressor responses to angiotensin I (AI) in anesthetized rats with calculated ID50's of 16 and 8 micrograms/kg, respectively. Oral administration of SCH 33844 (0.03-1 mg/kg) inhibited AI pressor responses in conscious rats with a duration of 24 hr at the highest dose. The diacid was inactive. Intravenous administration of SCH 33844 (100-1000 micrograms/kg) or its diacid (30 micrograms/kg) to anesthetized dogs inhibited AI pressor activity and potentiated the depressor response to bradykinin. SCH 33844 inhibited AI responses in conscious dogs following oral administration of 0.3-3 mg/kg. Oral administration of SCH 33844 (1 mg/kg) to conscious monkeys inhibited AI pressor responses for the 4 hr duration of study. In conclusion, SCH 33844 is a potent, orally effective ACE inhibitor in rats, dogs and monkeys.
In this article the cases of occupational allergic diseases notified to 2 Occupational Health Units in Pavia in the period 1993-1998 are reported. A retrospective study was performed to obtain a descriptive analysis of the diseases. In the studied period 58 cases of occupational allergic diseases were notified. This datum probably underestimates the real occurrence of occupational diseases, because of the low accuracy of the notification system. Allergic skin diseases were more frequent (70.7%) than respiratory diseases.
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We report a comparative study on protein and enzyme content of human periovulatory cervical mucus and endocervical epithelium. The salient results of our investigation are summarized in the following three points: 1) The method of taking of cervical mucus samples may markedly affect the results of protein and enzyme assays. It is warmly advisable to collect mucus samples from the endocervical canal. 2) Cervical mucus from women diagnosed as having cervical-factor infertility is oligoproteic and lacks some enzyme activities always present in normal cases. 3) Human cervical mucus and endocervical epithelium are very similar as for the enzyme distribution, but show quite different LDH-isoenzyme patterns. In the latter tissue, the H subunits constitute about 77 per cent of the whole LDH, suggesting that this enzyme here is functioning to produce pyruvate rather than lactate.