Methodical aspects of text testing in a driving simulator.

A test with 30 test persons was conducted in a driving simulator. The test was a concept exploration and comparison of existing user interaction technologies for text message handling with focus on traffic safety and experience (technology familiarity and learning effects). Focus was put on methodical aspects how to measure and how to analyze the data. Results show difficulties with the eye tracking system (calibration etc.) per se, and also include the subsequent raw data preparation. The physical setup in the car where found important for the test completion.

Circulating chromatin-anti-chromatin antibody complexes bind with high affinity to dermo-epidermal structures in murine and human lupus nephritis.

Murine and human lupus nephritis are characterized by glomerular deposits of electron-dense structures (EDS). Dominant components of EDS are chromatin fragments and IgG antibodies. Whether glomerular EDS predispose for similar deposits in skin is unknown. We analysed (i) whether dermo-epidermal immune complex deposits have similar molecular composition as glomerular deposits, (ii) whether chromatin fragments bind dermo-epidermal structures, and (iii) whether deposits in nephritic glomeruli predispose for accumulation of similar deposits in skin. Paired skin and kidney biopsies from nephritic (NZBxNZW)F1 and MRL-lpr/lpr mice and from five patients with lupus nephritis were analysed by immunofluorescence, immune electron microscopy (IEM) and co-localization TUNEL IEM. Affinity of chromatin fragments for membrane structures was determined by surface plasmon resonance. Results demonstrated (i) presence of EDS containing chromatin fragments and IgG in both organs in nephritic patients, (ii) chromatin fragments possessed high affinity for dermo-epidermal laminins and collagens, (iii) glomerular immune complex deposits did not predict similar interstitial deposits in skin, although such complexes were present in capillary lumina in glomeruli and skin of all nephritic individuals. Thus, chromatin-IgG complexes accounting for lupus nephritis seem to reach skin through circulation, but other undetermined factors are required for these complexes to deposit within skin membranes.

Penetration of fusidic acid and rifampicin into cerebrospinal fluid in low-grade inflammatory meningitis caused by Staphylococcus epidermidis.

Cerebrospinal fluid (CSF) concentration-time curves of rifampicin and fusidic acid were studied in a patient with post-operative meningitis caused by Staphylococcus epidermidis. The patient was treated with this combination of antimicrobial agents because of a severe hypersensitivity reaction to vancomycin. Peak CSF concentrations of rifampicin exceeded the MIC by > 60-fold, while those of fusidic acid just reached the MIC. CSF concentrations of fusidic acid were relatively stable within the range reported for patients with uninflamed meninges, but serum levels were surprisingly low. An increase in the metabolism of fusidic acid induced by rifampicin cannot be excluded.

Does tobacco smoke prevent atopic disorders? A study of two generations of Swedish residents.

BACKGROUND: Earlier studies have given conflicting results regarding the effect of exposure to tobacco smoke on atopic sensibilization. METHODS: A cross-sectional study of present and former smoking habits in relation to atopic disorders from data on 6909 young and middle-aged adults (16-49 years) and their 4472 children (3-15 years) from the Swedish Survey of Living Conditions in 1996-97. RESULTS: The prevalence of allergic asthma and allergic rhino-conjunctivitis decreased, in a dose-response manner (P = 0.03 and P = 0.004, respectively), with increasing exposure to tobacco smoke in the adult study population. This pattern was little changed when potential confounders (sex, age, education, domicile, country of birth) were entered into a multivariate analysis: the adjusted odds ratio (OR) for allergic rhino-conjunctivitis was 0.5 (0.4-0.7) for those who smoked at least 20 cigarettes a day and OR 0.7 (0.6-0.9) for those smoking 10-19 cigarettes, compared with those who reported that they never had smoked Former smokers had a tendency for a slightly lower risk: OR 0.9 (0.8-1.0). In a multivariate analysis, children of mothers who smoked at least 15 cigarettes a day tended to have lower odds for suffering from allergic rhino-conjunctivitis, allergic asthma, atopic eczema and food allergy, compared to children of mothers who had never smoked (ORs 0.6-0.7). Children of fathers who had smoked at least 15 cigarettes a day had a similar tendency (ORs 0.7-0.9). CONCLUSIONS: This study demonstrates an association between current exposure to tobacco smoke and a low risk for atopic disorders in smokers themselves and a similar tendency in their children. There is a need for further studies with a prospective design to certify the causal direction of this association. Smoking habits and atopic disorder in parents should not be considered independent variables in epidemiological studies of the connection between exposure to tobacco smoke and atopy in children.

Body weight characteristics of subjects on asthma medication.

OBJECTIVE: Weight gain is a frequently documented side effect after long-term anti-inflammatory treatment with systemic corticosteroid drugs in patients with asthma. In recent years new types of inhaled corticosteroids have been introduced, which act locally and are more rapidly bio-transformed. Even such corticosteroids may have a detectable, clinically relevant systemic side effect on weight. The aim of this study is to investigate if there is any relationship between body weight and asthma medication. DESIGN: The relationship between asthma medication and body weight was analysed in two combined randomized samples of the adult Swedish population 16-60 y of age (n = 17,912). Multivariate logistic regression analyses were carried out to obtain estimates for (1) body mass index (BMI) indicating 'obesity' (BMI > 29.9 kg/m2) in men and women controlling for self-reported asthma medication, and (2) self-reported asthma medication controlling for BMI. In both cases we furthermore controlled for interview period, age, Swedish region, smoking habits, physical activities and level of education. RESULTS: We found no significantly higher odds for obesity in men (OR = 1.21 (0.55-2.64) or women (OR = 1.97 (0.89-4.38) on asthma medication compared to men and women with pharmacologically untreated asthma even after adjustment for smoking habits, physical activities, level of education and other related co-variables. However, we found significant positive associations between obesity and interview period, age and former smoking and inverse significant relationships with the degree of physical activity. We also found significantly higher adjusted odds for asthma, indicated by self-reported asthma medication, in women (OR = 2.74 (1.91-3.91)) but not in men (OR = 1.57 (0.96-2.56)) with BMI indicating 'obesity'. CONCLUSION: There is no strong evidence to suggest that modern pharmacological asthma treatment may contribute much to the development of obesity in either men or women on asthma medication. Adjustment for smoking habits, physical activities, level of education and other related co-variables have minor effects on these relationships. Obesity may still be an independent risk factor for asthma since we observed significantly higher odds for self-reported asthma medication in women and an almost significant relationship in men even after control for BMI and other related co-variables.

Economic implications of an early postoperative enteral feeding protocol.

OBJECTIVE: To study the cost-effectiveness of an early postoperative feeding protocol for patients undergoing bowel resections. DESIGN: A nonrandomized, prospective, clinical trial. Surgeons elected to participate in the treatment arm before the study's outset. SUBJECTS/SETTING: Treatment (n = 66) and control (n = 159) patients were admitted to a nonprofit general teaching hospital in the Texas Medical Center for similar diagnoses and subsequent bowel resections during an 18-month period. INTERVENTION: Treatment patients who met specific inclusion criteria had a jejunal feeding tube placed during surgery. Tube feedings were initiated within 12 hours after surgery. Control patients who met the same inclusion criteria received usual care. OUTCOMES: A successful outcome was defined as a patient developing no postoperative infection. The average cost of a nosocomial infection is presented. Variable direct and total costs (fixed plus variable) are compared between patient groups. STATISTICAL ANALYSIS: Mean cost was adjusted for rate of success in each patient group according to an analytic model. The mean cost difference between groups was analyzed by independent-samples t tests. Nonparametric Mann-Whitney rank sum tests were used to determine the cost significance of a nosocomial infection. RESULTS: The average variable direct cost savings per successful treatment patient was $1,531, which required an additional variable cost of $108.30 for the dietitian's time. The protocol resulted in a total cost savings of $4,450 per success in the treatment group. CONCLUSION: An early postoperative enteral feeding protocol as part of an outcomes management program for patients undergoing bowel resection is cost-effective.

Perinatal risk factors for atopic disease in conscripts.

BACKGROUND: There is evidence to suggest that atopic disease in adulthood could be manifestations of events in early life. OBJECTIVES: To investigate the relationship between perinatal risk factors and the prevalence of allergic rhinitis and asthma in conscripts. METHODS: A retrospective cohort study, where information from the Military Service Enrolment Register was linked to the national Medical Birth Register. The study included 149 398 male conscripts who were born in Sweden in 1973, 1974 and 1975. Outcome measures were current asthma and allergic rhinitis recognized at the compulsory military conscript examinations. RESULTS: Unifactorial analyses demonstrated that number of older siblings, young maternal age, multiple gestation, prematurity, low birth weight, growth retardation and perinatal asphyxia were all significantly related to a decreased risk of allergic rhinitis among male conscripts. The prevalence rates of allergic rhinitis among conscripts with and without older siblings were 14.1% and 16.2%, respectively (odds ratio 0.85; 95% confidence interval 0.82-0.87). The prevalence rates of allergic rhinitis among those with term birth (>36 weeks), moderately preterm birth (33-36 weeks) and very preterm birth (<33 weeks) were 15.2%, 13.1% and 11.6%, respectively. Older siblings, multiple gestation and young maternal age were highly significant independent determinants of allergic rhinitis. By contrast, the effects of prematurity, low birthweight and asphyxia were weaker and highly correlated. The only independent determinants of asthma were maternal age, birthweight and multiple gestation. Furthermore, maternal age and birthweight had opposite effects on asthma and allergic rhinitis. CONCLUSIONS: In contrast to asthma, allergic rhinitis in young adult men was strongly associated with perinatal events. This may reflect the close relationship between allergic rhinitis and atopic sensitization, whereas asthma has a more multifactorial aetiology.

Complete measurement of the pKa values of the carboxyl and imidazole groups in Bacillus circulans xylanase.

Electrostatic interactions in proteins can be dissected experimentally by determining the pKa values of their constituent ionizable amino acids. To complement previous studies of the glutamic acid and histidine residues in Bacillus circulans xylanase (BCX), we have used NMR methods to measure the pKa s of the seven aspartic acids and the C-terminus of this protein. The pKa s of these carboxyls are all less than the corresponding values observed with random coil polypeptides, indicating that their ionization contributes favorably to the stability of the folded enzyme. In general, the aspartic acids with the most reduced pKa s are those with limited exposure to the solvent and a high degree of conservation among homologous xylanases. Most dramatically, Asp 83 and Asp 101 have pKa s < 2 and thus remain deprotonated in native BCX under all conditions examined. Asp 83 is completely buried, forming a strong salt bridge with Arg 136. In contrast, Asp 101 is located on the surface of the protein, stabilized in the deprotonated form by an extensive network of hydrogen bonds involving an internal water molecule and the neutral side-chain and main-chain atoms of Ser 100 and Thr 145. These data provide a complete experimental database for theoretical studies of the ionization behavior of BCX under acidic conditions.

Transient local presence of nerve fibers at onset of secondary ossification in the rat knee joint.

In view of recent evidence that nerves may be involved in bone formation, the present study examines the local occurrence of axons at the onset of secondary ossification center formation in the knee region of developing rats. Radiographic and histological examination showed that secondary ossification center formation commenced at day 10. At day 15 the epiphyseal ossification had reached a relatively mature state. As seen by light microscopy, cartilage canals first appeared at day 5, reaching the epiphyseal center by day 9. Axons exhibiting a neurofilament-like immunoreactivity emerged from the perichondrial plexa into the cartilage canals. Many calcitonin gene-related peptide (CGRP)-immunoreactive axons were found in the canals, as well as in the perichondrium. Axons with tyrosine hydroxylase-like immunoreactivity were not found in the canals, but such fibers occurred in relation to blood vessels at other sites. The canal-related axons disappeared between days 13 and 15, and the canals themselves did not persist beyond bone formation. As seen in the electron microscope, an individual canal contained 3-10 unmyelinated Schwann cell-enclosed axons with diameters of 0.1-2.0 microM. These observations show that putative sensory unmyelinated axons with CGRP-and SP-like immunoreactivity are transiently present during initiation of bone formation in developing epiphyses. Whether there is a causal relation between transient innervation and osteogenesis remains to be determined.

Calcium entry blockers and activators: conformational and structural determinants of dihydropyrimidine calcium channel modulators.

Dihydropyrimidines 4, 6, and 15, uniquely designed to unambiguously establish structural and conformational determinants for DHP receptor occupation and for modulation of calcium channel function, were prepared and examined for calcium channel modulation. Our results confirm and firmly establish a preference for syn-orientation of an unsymmetrically substituted aryl moiety at the DHP receptor (15d vs 15e). We propose a normal vs capsized DHP boat model to explain structural and conformational requirements for modulation of calcium channel function that requires an obligatory left-hand side alkoxy cis-carbonyl interaction for maximal DHP receptor affinity, the effect of channel function being determined by orientation of the 4-aryl group. Enantiomers having an up-oriented pseudoaxial aryl group (normal DHP boat) will elicit calcium antagonist activity, whereas enantiomers having a down-oriented pseudoaxial aryl group (capsized DHP boat) will elicit calcium agonist activity. Single enantiomers of macrocyclic lactone 15b demonstrate opposite channel activity. Antagonist activity resides in enantiomer 15b-A (S-configuration, left-hand side alkoxy cis-carbonyl with up-oriented pseudoaxial aryl group and normal DHP boat), whereas agonist activity resides in enantiomer 15b-B (R-configuration, left-hand side alkoxy cis-carbonyl with down-oriented pseudoaxial aryl group and capsized DHP boat). Moreover, this model is consistent with and provides a rational explanation of previous literature in this area, most notably the observation of chiral inversion and potency diminution upon replacement of ester by hydrogen in the Bay K 8644 series.

Structure-activity studies of endothelin leading to novel peptide ETA antagonists.

With the goal of producing receptor antagonists, numerous monocyclic and bicyclic endothelin analogs were prepared and tested for vasoconstrictor activity, receptor affinity and functional antagonist activity. Bis-penicillamine endothelin analogs containing Ala or Asn at position 18 were functional antagonists, with Ki values of 20-40 nM but KB values of about 1 microM (e.g., [Pen1,11, Nle7, Ala18]-endothelin-1, Ki = 42 nM, KB = 1.2 microM). While these peptides are antagonists at the ETA receptor, they appear to be at least partial agonists at another receptor subtype.

Binding and function of a potent new thromboxane receptor antagonist, BMS 180,291, in human platelets.

Binding and function of BMS 180,291 ([(+)1S-(1 alpha,2 alpha,3 alpha,4 alpha)]-2-[[3-[4-[(n-pentylamino)carbonyl]-2-oxazolyl]-7- oxabicyclo[2.2.1] hept-2-yl]methyl]benzenepropanoic acid]) in human platelets was examined. Kinetic determination of [3H]BMS 180,291 binding produced ligand-receptor association and dissociation rates of 1.4 x 10(7) +/- 0.2 M-1 x min-1 (n = 5) and 0.04 +/- 0.005 min-1 (n = 5), respectively. The resultant Kd was 3.1 +/- 1.1 nM (n = 5). Saturation binding analysis in platelet membranes was consistent with a single class of [3H]BMS 180,291 binding sites with a Kd of 3.6 +/- 0.19 nM (n = 4) and a binding site maxima (Bmax) of 2099.1 +/- 70.3 fmol/mg of protein (n = 4). Specific [3H]BMS 180,291 binding was inhibited by thromboxane A2/endoperoxide receptor antagonists and agonists with a rank order of potency of: BMS 180,291 > or = SQ 29,548 = I-BOP race 15-(1 alpha,2 beta(5Z), 3 alpha(1E,3S),4 alpha) d7-[3-(3-hydroxy-4-(p-iodophenoxy)-1-butenyl)-7- oxabicyclo[2.2.1]hept-2-yl]5-heptenoic acid) > or = BM 13,505 > or = SQ 30,741 = U 44,609 > U 46,619 >> BM 13,177. Prostaglandin E2 and prostacyclin did not appreciably inhibit the specific binding of [3H]BMS 180,291. BMS 180,291 (10 nM-5 microM) shifted the I-BOP-induced platelet shape change curve to the right in a parallel manner without reduction of the maximal response (KB = 13 +/- 3.5 nM; pA2 = 8 +/- 0.2; slope = -1.0 +/- 0.05), whereas 30 nM drug decreased the maximal I-BOP-induced platelet aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

Dihydropyrimidine angiotensin II receptor antagonists.

The discovery of the nonpeptide angiotensin II (AII) receptor antagonist losartan, previously called DuP 753, has stimulated considerable interest in the synthesis of novel analogs of this compound. Our efforts in this area have resulted in the discovery of dihydropyrimidines as potent AII receptor antagonists. The chemistry leading to this novel class of AII antagonists and their biological properties are reported in this publication. Structure-activity studies showed that a variety of substituents are tolerated on the dihydropyrimidine ring, indicating that the AII receptor is permissive in accepting this region of the nonpeptide antagonists. As reported for imidazole-based AII antagonists, the tetrazolyl dihydropyrimidine analogs were found to be more potent than the corresponding carboxylic acids. Our studies show that dihydropyrimidine analogs 2-butyl-4-chloro-1,6-dihydro-6-methyl-1-[[2'-(1H-tetrazol-5-yl)[1, 1'-biphenyl]-4-yl]methyl]pyrimidine-5-carboxylic acid, ethyl ester (Ki = 8.3 nM), 2-butyl-4-chloro-1,6-dihydro-6-methyl-1- [[2'-(1H-tetrazol-5-yl)[1,1'-biphenyl]-4-yl]methyl]-5- pyrimidinecarboxylic acid (Ki = 1.0 nM), and 2-butyl-6-chloro-1,4-dihydro-4,4-dimethyl-1-[[2'-(1H-tetrazol-5-yl )[1,1'- biphenyl]-4-yl]methyl]-5-pyrimidinecarboxylic acid, ethyl ester (Ki = 1.1 nM), display affinities for the AII receptor which are comparable to or better than losartan (Ki = 9.0 nM). One of these derivatives, 2-butyl-4-chloro-1,6-dihydro-6-methyl-1-[[2'-(1H-tetrazol-5- yl)[1,1'-biphenyl]-4-yl]methyl]pyrimidine-5-carboxylic acid, ethyl ester, showed antihypertensive activity on oral administration to spontaneously hypertensive rats. These results demonstrate that the imidazole of losartan can be successfully replaced with a dihydropyrimidine ring.

Site-specific biotinylation. A novel approach and its application to endothelin-1 analogs and PTH-analog.

We have developed an expeditious method for the incorporation of the biotinylaminocaproyl moiety on the epsilon-amino group of a lysine residue within a peptide chain in a site-specific manner. Using t-Boc chemistry for the solid phase synthesis approach and a base labile, acid stable protecting group (Fmoc-) for the epsilon-amino group of the target lysine, we prepared fully protected resin bound peptides which are site-specifically biotinylated. Following HF cleavage, the uniquely biotinylated peptides were obtained in a high degree of purity. Using this approach, a number of biotinylaminocaproyllysyl derivatives of a monocyclic Endothelin-1 analog were prepared. Synthesis of selected bicyclic analogs of high affinity monocycles led to the preparation of the bicyclic [Nle7]ET-1 analog containing epsilon-biotinylaminocaproyllysine at position-9. This peptide, with Kd = 0.08 nM, has 1000-fold higher affinity for the ETA receptor than the commercially available N alpha-biotinylated Endothelin-1. The general utility of this biotinylation methodology was demonstrated by the synthesis of a site-specifically biotinylated PTH analog which contained several side chain functionalized amino acid residues in its sequence. The synthetic method reported here is convergent in that it allows the facile variation of the length of the spacer and also offers the potential to introduce in a site specific manner other groups such as affinity labels and fluorescent tags.

DuP 753, the selective angiotensin II receptor blocker, is a competitive antagonist to human platelet thromboxane A2/prostaglandin H2 (TP) receptors.

DuP 753 is a potent, selective angiotensin II type 1 (AT1) receptor antagonist. The possibility was investigated that DuP 753 may crossreact with thromboxane A2/prostaglandin H2 (TP) receptors. DuP 753 inhibited the specific binding of the TP receptor antagonist [3H]SQ 29,548 (5 nM) in human platelets with kd/slope factor values of 9.6 +/- 1.4 microM/1.1 +/- 0.02. The AT2-selective angiotensin receptor ligand, PD 123,177 was a very weak inhibitor of specific [3H]SQ 29,548 binding in platelets (Kd/slope factor:200 microM/0.86). [3H]SQ 29,548 saturation binding in the absence and presence of DuP 753 resulted in an increase in equilibrium affinity constant (Kd: 9.3, 22, 33 nM, respectively) without a concentration-dependent reduction in binding site maxima (Bmax: 3597, 4597, 3109 fmol/mg protein, respectively). Platelet aggregation induced by the TP receptor agonist U 46,619 was concentration-dependently inhibited by DuP 753 (IC50 = 46 microM). These data indicate for the first time that DuP 753 is a weak but competitive antagonist at human platelet TP receptors.

Dihydropyrimidine calcium channel blockers. 4. Basic 3-substituted-4-aryl-1,4-dihydropyrimidine-5-carboxylic acid esters. Potent antihypertensive agents.

We have examined a series of novel dihydropyrimidine calcium channel blockers that contain a basic group attached to either C5 or N3 of the heterocyclic ring. Structure-activity studies show that a 1-(phenylmethyl)-4-piperidinyl carbamate moiety at N3 and sulfur at C2 are optimal for vasorelaxant activity in vitro and impart potent and long-acting antihypertensive activity in vivo. One of these compounds (11) was identified as a lead, and the individual enantiomers 12a (R) and 12b (S) were synthesized. Two key steps of the synthesis were (1) the efficient separation of the diastereomeric ureido derivatives 29a/29b and (2) the high-yield transformation of 2-methoxy intermediates 30a/30b to the (p-methoxybenzyl)thio intermediates 31a/31b. Chirality was demonstrated to be a significant determinant of biological activity, with the dihydropyridine receptor recognizing the enamino ester moiety (12a) but not the carbamate moiety (12b). Dihydropyrimidine 12a is equipotent to nifedipine and amlodipine in vitro. In the spontaneously hypertensive rat, dihydropyrimidine 12a is both more potent and longer acting than nifedipine and compares most favorably with the long-acting dihydropyridine derivative amlodipine. Dihydropyrimidine 12a has the potential advantage of being a single enantiomer.

Molecular characterization of angiotensin II type II receptors in rat pheochromocytoma cells.

The binding sites and biochemical effects of angiotensin (A) II were investigated in rat pheochromocytoma (PC12W) cells. Sarcosine1, [125I]-tyrosine4, isoleucine8-AII ([125I]-SI-AII) bound to a saturable population of sites on membranes with an equilibrium dissociation constant (Kd) of 0.4 nM and a binding site maximum of 254 fmol/mg protein. Competitive displacement of [125I]-SI-AII by agonists and antagonists elucidated a rank order of potency of AIII greater than or equal to AII greater than PD 123177 greater than AI greater than [des-Phe]AII [AII(1-7)] much greater than DuP 753. The stable guanine nucleotide analog 5'-guanylyl imidodiphosphate did not alter the binding affinity or slope of the inhibition curves for AI, AII, AIII, or AII(1-7). Treatment of PC12W cells with AII or AIII did not affect the free intracellular calcium concentration, phosphoinositide metabolism, arachidonate release, cyclic GMP, or cyclic AMP concentrations. [125I]-AII binding sites remained on the cell surface and were not internalized after 2 h at 37 degrees C. Angiotensin II did not stimulate tyrosine, serine, or threonine phosphorylation. Northern analysis of PC12W mRNA with an AT1 receptor gene probe failed to produce an RNA:DNA hybrid at low stringency. These data indicate that PC12W cells express a homogeneous population of AT2 binding sites which differ significantly from AT1 receptors in signal transduction and molecular structure. AT2 sites may act via potentially novel, biochemical pathways or, alternatively, be vestigial receptors.

Characterization of binding of a specific antagonist, [3H]-SQ 29,548, to soluble thromboxane A2/prostaglandin H2 (TP) receptors in human platelet membranes.

Binding of [3H]-SQ 29,548 was characterized to soluble thromboxane A2/prostaglandin H2 (TP) receptors from human platelet membranes as a means of examining ligand-receptor interactions outside the lipophilic environment of the cell membrane. Kinetic determination revealed a rate of ligand-receptor association of 1.4 x 10(7) +/- 0.2 M-1 x min-1 and a rate of dissociation of 0.5 +/- 0.07 min-1. The resultant equilibrium affinity constant was 36.3 +/- 5.8 nM. Saturation binding analysis revealed a single class of [3H]-SQ 29,548 binding sites with an affinity constant of 39.7 +/- 4.3 nM and a B(max) of 1735.7 +/- 69.1 fmol/mg protein. Specific [3H]-SQ 29,548 binding was inhibited by specific TP receptor antagonists and agonists in a rank order of potency similar to that seen in platelet membranes: SQ 33,961 much greater than SQ 29,548 greater than BM 13,505 greater than or equal to U 46619 greater than BM 13,177. PGD2, PGE2 and PGI2 did not appreciably inhibit the specific binding of [3H]-SQ 29,548. These data indicate that [3H]-SQ 29,548 binding to soluble human platelet TP receptors was specific, saturable, and reversible.

Interphenylene 7-oxabicyclo[2.2.1]heptane thromboxane A2 antagonists. Semicarbazone omega-chains.

A series of chiral interphenylene 7-oxabicyclo[2.2.1]heptane semicarbazones 19-26 were prepared and evaluated for their in vitro thromboxane (TxA2) antagonistic activity and in vivo duration of action. The potency of 19-26 was found to highly dependent on the substitution pattern of the interphenylene ring and decreased in the order ortho greater than meta much greater than para. SQ 35,091 (25), [1S-(1 alpha,2 alpha,3 alpha,4 alpha)]-2-[[3-[[[(phenylamino) carbonyl]hydrazono]methyl]-7-oxabicyclo[2.2.1]hept-2-yl]methyl] benzenepropanoic acid, was identified as a potent and long-acting TxA2 antagonist. In human platelet rich plasma SQ 35,091 inhibited arachidonic acid (800 microM) and U-46,619 (10 microM) induced aggregation with I50 values of 3 and 12 nM, respectively. In contrast, no inhibition of ADP (20 microM) induced aggregation was observed at greater than 1000 microM. Receptor binding studies with [3H]-SQ 29,548 showed SQ 35,091 was a competitive antagonist with a Kd value of 1.0 +/- 0.1 nM in human platelet membranes. In vivo SQ 35,091 (0.2 mg/kg po) showed extended protection (T50 = 16 h) from U-46,619 (2 mg/kg iv) induced death in mice. These compounds have for the first time demonstrated that a metabolically stable interphenylene alpha-sidechain can be introduced into a prostanoid-like series of TxA2 antagonists with the maintainance of potent antagonistic activity.

Active conformation of 1,4-dihydropyridine calcium entry blockers. Effect of size of 2-aryl substituent on rotameric equilibria and receptor binding.

The conformational requisites at the receptor for unsymmetrically substituted phenyl-1,4-dihydropyridine calcium entry blockers are examined by screening a series of (2'-halophenyl)-1,4-dihydropyridines 1-4, with increasing bulk at the 2'-position of the phenyl ring, for their ability to relax potassium-contracted rabbit aortic smooth muscle and to competitively displace [3H]nitrendipine from its specific binding sites on guinea pig skeletal muscle. The fraction of synperiplanar rotamer in solution for these compounds, as determined by the nuclear Overhauser enhancement method, shows a positive correlation with vasorelaxant activity and receptor binding affinity. These findings are consistent with the synperiplanar rotamer of nonrigid unsymmetrically substituted phenyl 1,4-dihydropyridine calcium channel blockers being the receptor-bound conformation.