High-affinity binding of [125I]RTI-55 to dopamine and serotonin transporters in rat brain

RTI-55 (3 beta-(4-iodophenyl)tropan-2 beta-carboxylic acid methyl ester), one of the most potent inhibitors of dopamine uptake reported to date, was radioiodinated and tested as a probe for the cocaine receptor in Sprague-Dawley rat brain. Saturation and kinetic studies in the striatum revealed that [125I]RTI-55 bound to both a high- and low-affinity site. The Kd for the high-affinity site was 0.2 nM, while the Kd for the low-affinity site was 5.8 nM. The corresponding number of binding sites in the striatum was 37 and 415 pmol/g protein. The pharmacological profile of specific [125I]RTI-55 binding in the striatum was consistent with that of the dopamine transporter. Additionally, [125I]RTI-55 was found to bind with high affinity to the cerebral cortex. Scatchard analysis revealed a single high-affinity component of 0.2 nM with a density of 2.5 pmol/g protein. The pharmacological profile demonstrated by [125I]RTI-55 in the cerebral cortex matched that of the serotonin transporter. Autoradiographic analysis of sagittal brain sections with [125I]RTI-55 binding was consistent with these findings. Specific binding of [125I]RTI-55 was blocked by dopamine uptake inhibitors in areas rich in dopaminergic nerve terminals. Conversely, serotonin uptake inhibitors blocked the binding of [125I]RTI-55 in brain areas rich in serotonergic neurons. These results demonstrate that [125I]RTI-55 may be a very useful ligand for the dopamine and serotonin transporters.

Blood glutathione concentrations in a large-scale human study

Little is known about the variability of blood glutathione (GSH) in human subjects. Thus, we wanted to develop and validate a rapid method for measuring GSH concentrations in whole blood and apply this method to ascertain the variation of GSH in a large-scale study of free-living adults. The assay was highly sensitive (detection limit < 5 pmol) and precise, with an interassay variation of 2.3% and a sampling variation of 3.6%. Applying this method to screen 715 adults, we observed a threefold range of GSH concentrations, with a mean of 1.02 mmol/L and CV of 17%. GSH concentrations were 8-10% greater in smokers than in nonsmokers (P < 0.001). Although we observed no sex differences for GSH, GSH/hemoglobin ratios were 8-18% greater in women < 55 years old than in older subjects (P < 0.05). The results presented here validate the use of this method for large-scale human studies and provide information on the variation and normal values of blood GSH in adults.

Cocaine and 3 beta-(4'-substituted phenyl)tropane-2 beta-carboxylic acid ester and amide analogues. New high-affinity and selective compounds for the dopamine transporter

Several 2 beta-carboxylic acid ester and amide analogues of cocaine and of 3 beta-(4'-substituted phenyl)tropane-2 beta-carboxylic acid were prepared. The binding affinities of these compounds, and of some previously prepared analogues, at the dopamine (DA), norepinephrine (NE), and serotonin (5-HT) transporters were determined. The phenyl esters of 3 beta-(4'-methylphenyl)- and 3 beta-(4'-chlorophenyl)tropane-2 beta-carboxylic acid are highly potent and highly selective for the DA transporter. The isopropyl esters of 3 beta-(4'-chlorophenyl)- and 3 beta-(4'-iodophenyl)tropane-2 beta-carboxylic acid also possess high DA affinity and show significant DA transporter selectivity. Similarly, the phenyl and isopropyl ester analogues of cocaine are much more selective for the DA transporter than cocaine. Tertiary amide analogues of cocaine and of 3 beta-(4'-substituted phenyl)tropane-2 beta-carboxylic acids are more potent inhibitors of radioligand binding at the DA transporter than the primary and secondary amide analogues. In particular, 3 beta-(4'-chlorophenyl)tropane-2 beta-N-morpholinocarboxamide as well as the 3 beta-(4'-chlorophenyl)- and 3 beta-(4'-iodophenyl)tropane-2 beta-N- pyrrolidinocarboxamides possess high affinity and selectivity for the DA transporter. The N,N-dimethylamide cocaine analogue is the most selective cocaine amide derivative for the DA transporter. High correlation between the inhibition of radioligand binding and inhibition of uptake at the DA, NE, and 5-HT transporter was found for a selected group of analogues. Within this group, one compound, the isopropyl ester of 3 beta-(4'-iodophenyl)-tropane-2 beta-carboxylic acid, was found to be more potent in the inhibition of radioligand binding than in the inhibition of DA uptake. Taken together with its high potency and selectivity at the DA transporter, this suggests that this compound may be a lead in the development of a cocaine antagonist.

Comparative pharmacokinetics and pharmacodynamics of epoetin alfa and epoetin beta

Different recombinant human erythropoietin products have been developed. Although they appear to have similar pharmacokinetics and function, these have not been directly compared. This randomized, double-blind, four-period crossover study compared the pharmacokinetics and pharmacodynamics of intravenous and subcutaneous epoetin alfa and epoetin beta in 18 normal male volunteers. As a control, three subjects received placebo treatment. After intravenous administration, the steady-state volume of distribution and beta-phase volume of distribution of epoetin beta were 7.7% and 16.9% larger than for epoetin alfa (p less than 0.05). The terminal elimination half-life after intravenous administration of epoetin beta was 20% longer than the terminal elimination half-life of epoetin alfa. After subcutaneous administration there was a delayed drug absorption with epoetin beta compared with epoetin alfa (p less than 0.05). There was a small but significantly greater absolute reticulocyte response after subcutaneous epoetin beta compared with subcutaneous epoetin alfa. The findings support differences in the pharmacokinetics and function of epoetin alfa and beta that are possibly caused by differences in their glycosylation.

Synthesis, ligand binding, QSAR, and CoMFA study of 3 beta-(p-substituted phenyl)tropane-2 beta-carboxylic acid methyl esters

A series of 3 beta-(p-substituted phenyl)tropane-2 beta-carboxylic acid methyl esters (2) were synthesized and found to possess high affinity for the cocaine binding site in rat striatum. The p-chloro (2c) and p-iodo (2n) compounds, which were the most potent analogues prepared, were found to be 85 and 78 times more potent than (-)-cocaine. The p-bromo (2m) and p-methyl (2d) were also 56 and 60 times more potent than cocaine. QSAR and CoMFA studies were conducted to correlate binding affinity of the cocaine analogues with their structural features. Whereas the QSAR study gave relatively low correlations, the CoMFA study gave a correlation with high predictive value.

Lactobacillus acidophilus inhibits growth of Campylobacter pylori in vitro

Campylobacter pylori has been implicated as a causative factor in acid-peptic disease. Lactobacillus acidophilus is known to inhibit the growth of pathogens in the human gastrointestinal tract. We recovered C. pylori from gastric antral biopsies of seven patients with acid-peptic disease; the isolates were then cultured in brucella broth. The effect of L. acidophilus (cultured in DeMan-Rogosa-Sharpe broth) on the growth of C. pylori was tested by a mixed culture technique. L. acidophilus inhibited the growth of all seven isolates of C. pylori in vitro. All these isolates were also inhibited by the L. acidophilus culture supernatant (brucella blood agar cup technique) obtained at or after 48 h of incubation. Inhibition of C. pylori growth was also observed with 1 and 3% lactic acid but not with 0.5 and 1% hydrogen peroxide, the L. acidophilus sonic extract, or a citrate-phosphate buffer (pH 4.0). We conclude that the inhibitory action of L. acidophilus on C. pylori is dependent on an extracellular secretory product, probably lactic acid. This inhibitory effect may be of therapeutic relevance in patients with C. pylori-positive acid-peptic disease.

3-Aryl-2-(3'-substituted-1',2',4'-oxadiazol-5'-yl)tropane analogues of cocaine: affinities at the cocaine binding site at the dopamine, serotonin, and norepinephrine transporters

Previous studies have shown that 3 beta-(substituted phenyl)tropan-2 beta-carboxylic acid esters possess high affinity for the cocaine binding site on the dopamine transporter both in vitro and in vivo and inhibit dopamine uptake in vitro. Since 1,2,4-oxadiazoles are excellent bioisosteres of ester groups, we have prepared several 3 beta-(substituted phenyl)-2 beta-(3-substituted 1',2',4'-oxadiazol-5'-yl)tropanes (5b-h) and all four stereoisomers of (1R,5S)-3 phenyl-2-(3-methyl-1',2',4'-oxadiazol-5'-yl)tropane (5a and 6-8). The 3 alpha-phenyl-2-alpha-(3'-methyl-1',2',4'-oxadiazole) isomer 7 was prepared from a stereoselective addition of phenyllithium to (1R,5S)-2-(3'-methyl-1',2',4'-oxadiazol-5-yl)-8-methyl-8- azabicyclo[3.2.1]oct-2-ene (11). The binding affinities for 5a-h and 6-8 at the dopamine, serotonin, and norepinephrine transporters were obtained. In general these bioisosteres showed potencies for the dopamine transporter similar to those of their parent esters. 3 beta-(4'-Chlorophenyl)-2 beta-(3'-phenyl-1',2',4'-oxadiazol-5'-yl)tropane (5d) was the most potent analogue with an IC50 of 1.62nM. However, 3 beta-(4'-chlorophenyl)-2 beta-(3'-methoxyphenyl-1',2'4'- oxadiazol-5'-yl)tropane (5e) with an IC50 of 1.81 nM was the most selective analogue for the dopamine transporter showing NE/DA and 5-HT/DA ratios of 461 and 186, respectively. The cis- and trans-3 alpha-phenyl-2-(3'-methyl-1',2',4'-oxadiazol-5'-yl)tropanes (7 and 8), which exist in a boat conformation, have IC50 values only slightly greater than that of the 3 beta,2 beta-isomer (5a) which possesses the cocaine stereochemistry.

Hereditary thrombophilia as a cause of Budd-Chiari syndrome: a study from Western India

The inherited deficiencies of protein C, protein S, antithrombin III, factor V Leiden mutation, prothrombin gene polymorphism, and antiphospholipids were studied in 53 Budd-Chiari syndrome (BCS) and 33 portal vein thrombosis (PVT) cases and compared with 223 age- and sex-matched controls. Protein C deficiency was detected in 7 (13.2%), protein S in 3 (5.7%), and antithrombin III in 2 (3.8%) of the BCS cases. Factor V Leiden was the most common risk factor, i.e., 14 of 53 (26.4%) in BCS cases followed by protein C, as compared with PVT cases, i.e., 2 of 33 (6.06%) and controls, i.e., 5 of 223 (2.3%). In PVT cases, protein C deficiency was present in 3 (9.09%), protein S deficiency in 1 (3.03%), and factor V Leiden mutation in 2 (6.06%) of the cases. The prothrombin gene polymorphism was not found in either the controls or the patients. The antiphospholipids were seen in 11 (20.75%) of the BCS cases and 6 (18.18%) of the PVT cases. Other acquired risk factors like pregnancy, surgery, and oral contraceptives were present in 8 (15.09%) of BCS and 3 (9.09%) of PVT cases. Thus overall, 59% of the BCS and 30% of the PVT cases could be explained by at least one of the etiologic factors studied.

Synthesis, ligand binding, and QSAR (CoMFA and classical) study of 3 beta-(3'-substituted phenyl)-, 3 beta-(4'-substituted phenyl)-, and 3 beta-(3',4'-disubstituted phenyl)tropane-2 beta-carboxylic acid methyl esters

Several new 3 beta-(4'-substituted phenyl)-, 3-beta-(3'-substituted phenyl)-, and 3 beta-(3',4'-disubstituted phenyl)tropane-2 beta-carboxylic acid methyl esters were prepared and assayed for inhibition of [3H]WIN 35,428 binding to the dopamine transporter. The 3 beta-(3',4'-dichloro) and 3 beta-(4'-chloro-3'-methyl) analogues (2w and 2y; RTI-111 and RTI-112, respectively) with IC50 values of 0.79 and 0.81 nM showed the highest affinity. The contributions of quantitative structure-activity relationship (QSAR) models derived from the classical and comparative molecular field analysis (CoMFA) approaches to rational drug design were examined. CoMFA models were derived using steric and electrostatic potentials with SYBYL default values while the classical models were derived from pi and MR parameters. Using a 12-compound training set, both models were used for predicting the binding affinity of compounds both inside and outside the training set. The CoMFA study provided new insight into the steric and electrostatic factors influencing binding to the DA transporter and provided additional support for our original finding that CoMFA is useful in predicting and designing new compounds for study. The classical QSAR models, which were easier to obtain, suggest that the distribution property (pi) of the compounds is an important factor. Overall, the SAR, CoMFA, and conventional QSAR studies elaborated some features of the cocaine binding site pharmacophore and provided useful predictive information.

Non-nociceptive capsaicin-sensitive nerve terminal stimulation allows for an original vasodilatory reflex in the human skin

A significant increase of cutaneous laser Doppler flowmetry was found before blood flow decreases with increasing pressure during a 5 mmHg min-1 increase of pressure strain on the finger. Pre-treatment with a local anaesthetic or chronically applied capsaicin, resulted in the disappearance of the vasodilatory response. These results suggest an original vasodilatory axon reflex response to non-noxious pressure strain which is initiated by capsaicin-sensitive nerve terminals in the human skin.

Marfan syndrome. Demonstration of abnormal elastin in aorta

Aortae from three patients with classic presentation of Marfan syndrome, who died of vascular complications, were subjected to biochemical analyses of the connective tissue; for comparison, aortae from eight age-matched controls, without evidence of connective tissue abnormalities, were examined. Elastin was prepared from the aortae by two techniques. First, the tissues were extracted with 5 M guanidine-HCl, bacterial collagenase digestion and reduction with dithiothreitol (elastin I preparation). Secondly, this material was further purified by extraction with 0.1 M NaOH at 99 degrees C (elastin II preparation). Amino acid analyses of both elastin preparations indicated that the values for desmosine and isodesmosine were reduced in Marfan cases to approximately one-half of the control values. A corresponding increase in lysyl residues was noted in elastin II preparations. Also, the concentration of elastin per milligram dry weight of tissue was reduced in Marfan cases. The hydroxyproline content of elastin was increased in two cases with the Marfan syndrome. Recoveries indicated that the alkali treatment solubilized 46.2% of the elastin I preparations in Marfan aortae compared with 23.7% in controls. In contrast to elastin, the concentration and solubility of collagen were unchanged; the amino acid composition and the genetic types of insoluble collagen isolated by limited pepsin proteolysis were the same in both Marfan and control aortae. The results of our study demonstrate that the cross-linking of aortic elastin is reduced in the three patients with Marfan syndrome. Thus, a defect in elastin could explain the vascular fragility observed clinically in these patients.

Vasodilatation in response to repeated anodal current application in the human skin relies on aspirin-sensitive mechanisms

The vasodilatation resulting from prolonged square-wave monopolar current application as used in iontophoresis is assumed to rely on an axon reflex. Involvement of prostaglandins in the anodal current-induced vasodilatation remains unclear. We tested the hypothesis that prostaglandins participate in a sensitisation mechanism to current application rather than as direct vasodilators. In healthy volunteers, laser Doppler flowmetry (LDF) was recorded in the forearm during and following isolated or repeated 0.1 mA transcutaneous anodal current applications, using deionised water as a vehicle. Segmented current applications of 6 or 12 mC resulted in an LDF increase twice that observed following current applications of comparable total charge delivered all at once (P < 0.05). Following a 1 min anodal application, a slow and prolonged LDF drift occurred (slope: 0.3 +/- 0.5 arbitrary units min(-1)). When the same current application was repeated after intervals of 5 and 20 min, an abrupt vasodilatation occurred, with maximal LDF amplitude of 53.5 +/- 34.0 and 48.2 +/- 19.1 arbitrary units, respectively. Pretreatment with 1 g oral aspirin abolished the abrupt vasodilatation to repeated current application but not the initial slow drift. We suggest that vasodilatation occurs through two parallel pathways: (1) a slow progressive drift of LDF of limited amplitude insensitive to aspirin pretreatment, and (2) an abrupt vasodilatation probably resulting from afferent fibre activation, appearing if a preliminary sensitisation by current application is performed. Sensitisation lasts for at least 20 min, and is blocked by aspirin, suggesting participation of prostanoids.

Pharmacokinetics and pharmacodynamics of codeine in end-stage renal disease

The pharmacokinetics and pharmacodynamics of codeine and its metabolites codeine glucuronide, morphine, and morphine glucuronide were assessed after the administration of a single 60 mg oral dose of codeine sulfate and a single 60 mg intravenous dose of codeine phosphate in six healthy volunteers and six patients on chronic hemodialysis. Plasma and urine drug and metabolite concentrations were determined by sensitive and specific RIA procedures. Pharmacodynamics were assessed by pupillometry and vital sign determinations. Codeine elimination half-life and mean residence time were increased significantly in the hemodialysis group (18.69 +/- 9.03 hours and 12.77 +/- 7.09 hours, mean +/- SD, respectively) compared with the healthy volunteer group (4.04 +/- 0.60 hours and 3.90 +/- 0.52 hours, respectively). The total body clearance and volume of distribution of codeine were not significantly different between groups. Peak concentrations, times to peak concentrations, and AUCs for the three metabolites were also not significantly different between the groups, in part as a result of significant interpatient variability in the hemodialysis group. Examination of pupillometry and vital sign data did not reveal clinically significant differences in pharmacodynamics between the groups. Adjustment of dosage regimen may be required in some patients with uremia receiving multiple-dose codeine therapy.

Secondary amine analogues of 3 beta-(4'-substituted phenyl)tropane-2 beta-carboxylic acid esters and N-norcocaine exhibit enhanced affinity for serotonin and norepinephrine transporters

N-Norcocaine (2) and six N-nor-3 beta-(4'-substituted phenyl)tropane-2 beta-carboxylic acid esters (4a-f) were synthesized by N-demethylation of cocaine (1) and the appropriate 3 beta-(substituted phenyl)-tropane analogues (3a-f) with alpha-chloroethyl chloroformate. Radioligand binding affinities of 2 and 4a-f at the DA, 5-HT, and NE transporter were measured and compared to those of 1 and 3a-f. N-Demethylation produced relatively small effects at the DA transporter. In contrast, 4-19-fold and 2-44-fold enhanced affinity at the serotonin and norepinephrine transporter resulted from demethylation. N-Nor-3 beta-(4'-iodophenyl)tropane-2 beta-carboxylic acid methyl ester (4d) with an IC50 = 0.36 nM showed the greatest affinity for the serotonin transporter. However, N-nor-3 beta-(4'-ethylphenyl)tropane-2 beta-carboxylic acid methyl ester (4e) showed the greatest selectivity for the serotonin transporter.

Cholangiopathy associated with portal hypertension: diagnostic evaluation and clinical implications

BACKGROUND

There are few studies of biliary changes due to portal hypertension. We ascertained the incidence of such changes on endoscopic retrograde cholangiography and determined the reliability of biochemistry, ultrasonography (US) and hepatobiliary radionuclide scan in detecting this type of cholangiopathy.

METHODS

Forty-two patients with portal hypertension were studied.

RESULTS

Cholangiopathy was detected by cholangiography in 17 of 20 patients with extrahepatic portal venous obstruction. Abnormalities (mainly strictures and caliber irregularity) were seen in the common bile duct (5) and common hepatic duct (7) and in the right (8) and left (11) hepatic ducts (mainly dilatation). One of 11 patients with noncirrhotic portal fibrosis had a dilated right hepatic duct. Three of 11 patients with cirrhosis had pruned intrahepatic ducts. Eight patients with portal venous obstruction had elevated alkaline phosphatase levels; two had elevated bilirubin levels. US detected gallbladder varices (11) and choledochal varices (9) in patients with extrahepatic portal venous obstruction. Biliary abnormalities were detected on hepatobiliary scintigraphy in 16 of 17 patients.

CONCLUSIONS

Cholangiopathy associated with portal hypertension occurs exclusively in patients with extrahepatic portal venous obstruction. It rarely leads to functional obstruction; jaundice does not occur in the absence of functional blockage. Elevated alkaline phosphatase level (after excluding bile duct calculi), presence of gallbladder varices on US, and abnormal radionuclide scans are reliable in detecting these lesions.

Acute oxalate nephropathy after massive ascorbic acid administration

A single 45-g dose of intravenous ascorbic acid, a metabolic precursor of oxalate, was administered to a patient as adjuvant therapy for primary amyloidosis and the nephrotic syndrome. Acute oliguric renal failure occurred. Postmortem histopathologic examination of renal tissue revealed extensive intratubular deposition of crystalline material, which was confirmed as calcium oxalate by a microincineration technique. There were no extrarenal deposits of calcium oxalate. Plasma oxalate and ascorbic acid concentrations were increased. We conclude that therapy with high-dose ascorbic acid is a potential cause of oxalate nephropathy.

Effects of murine-derived anti-methamphetamine monoclonal antibodies on (+)-methamphetamine self-administration in the rat

Two murine-derived anti-methamphetamine monoclonal antibodies were studied as potential pharmacokinetic antagonists of (+)-methamphetamine self-administration by rats. Intravenous administration of a 1 g/kg dose of the lower affinity [antibody equilibrium dissociation constant (K(d)) = 250 nM] monoclonal antibody (mAb) designated mAb6H8, 1 day before the start of several daily 2-h self-administration sessions produced effects that depended on the dose of (+)-methamphetamine. mAb6H8 increased the rate of self-administration of a unit dose of 0.06 mg/kg (+)-methamphetamine, had little effect on the rate of self-administration of a unit dose of 0.03 mg/kg (+)methamphetamine, and lowered the rate of self-administration of a unit dose of 0.01 mg/kg (+)-methamphetamine to a level similar to that after saline substitution. mAb-induced changes in rates of self-administration occurred very early in self-administration sessions and lasted for 3 to 7 days. Intravenous administration of a 1 or a 0.6 g/kg dose of a higher affinity (K(d) = 11 nM) mAb designated mAb6H4, 24 h before the first of several self-administration sessions, produced very similar effects to the lower affinity mAb, despite the more than 20-fold greater affinity for (+)-methamphetamine. It is proposed that these anti-methamphetamine antibodies bind some of the self-administered (+)-methamphetamine before it can penetrate into brain, thereby reducing the amount of free drug available to function as a reinforcer. Although neither of these mAb medications are optimal antibodies for treating (+)-methamphetamine abuse, the experiments demonstrate that anti-(+)-methamphetamine monoclonal antibodies can attenuate the self-administration of the drug and suggest the potential of using monoclonal antibodies as pharmacokinetic antagonists of (+)-methamphetamine.

[123/125I]RTI-55, an in vivo label for the serotonin transporter

[123I]RTI-55, an iodinated derivative of the cocaine analog 3 beta-phenyltropane-2 beta-carboxylic acid methyl ester, was evaluated as an agent for in vivo labeling of the serotonin transporter. Labeling of the precursor of RTI-55 with I-123 was efficient and yielded a high specific activity product. After intravenous injection of [123I]RTI-55 into rats, the tracer accumulated in regions with high densities of serotonin and dopamine uptake sites. The distribution of [123I]RTI-55 binding in areas rich in serotonin uptake sites correlated with [3H]serotonin uptake measured in vitro in the same regions. Specific [123I]RTI-55 binding to serotonin uptake sites was inhibited by paroxetine but not by GBR 12,909. Treatment of rats with neurotoxic doses of fenfluramine caused decreases of 66% (in the hypothalamus) to 83% (in the superior colliculi) of specific [125I]RTI-55 binding in all areas except in the striatum and the olfactory tubercles (regions rich in dopamine transporters). These results indicate that [123/125I]RTI-55 binds, although not selectively, to the serotonin transporter in vivo. Furthermore, they suggest that [123I]RTI-55 holds promise as a SPECT imaging agent for the study of the serotonin transporter in humans in health and disease.

Synthesis, ligand binding, and quantitative structure-activity relationship study of 3 beta-(4'-substituted phenyl)-2 beta-heterocyclic tropanes: evidence for an electrostatic interaction at the 2 beta-position

A set of 3 beta-(4'-substituted phenyl)-2 beta-heterocyclic tropanes was designed, synthesized, and characterized. We discovered that these compounds can function as bioisosteric replacements for the corresponding WIN 35,065-2 analogs which possess a 2 beta-carbomethoxy group. Several of the compounds showed high affinity and selectivity for the dopamine transporter (DAT) relative to the serotonin and norepinephrine transporters. From the structure-activity relationship study, the 3 beta-(4'-chlorophenyl)-2 beta-(3'-phenylisoxazol-5-yl)tropane (5d) emerged as the most potent and selective compound. The binding data for 2 beta-heterocyclic tropanes were found to show a high correlation with molecular electrostatic potential (MEP) minima near one of the heteroatoms in the 2 beta-substituents. In contrast, low correlations were found for other MEP minima near the 2 beta-substituent as well as for calculated log P or substituent volume. These quantitative structure-activity relationship studies are consistent with an electrostatic contribution to the binding potency of these WIN 35,065-2 analogs at the DAT.

2 beta-substituted analogues of cocaine. Synthesis and inhibition of binding to the cocaine receptor

The potencies of a series of 2 beta-substituted cocaine analogues to displace [3H]-3 beta-(p-fluorophenyl)tropane-2 beta-carboxylic acid methyl ester binding in rat striatal membranes demonstrate the requirement for a 2 beta-substituent with two hydrogen-bond acceptors. The insensitivity of the ester moiety to steric and electronic factors suggests its modification to provide site-specific irreversible ligands.

Correlation of office and ambulatory blood pressure measurements with urinary albumin and N-acetyl-beta-D-glucosaminidase excretions in essential hypertension

Ambulatory blood pressure (ABP) correlates better than office blood pressure with hypertensive changes in the heart and vasculature. Using the 24-hour urinary excretions of albumin and N-acetyl-beta-D-glucosaminidase (NAG) as markers, we examined the relationship between office and ABP and target-organ changes in the kidney in 42 untreated patients with essential hypertension. Mean urinary albumin excretion was 23.2 +/- 34.3 mg/day and mean urinary NAG excretion was 45.1 +/- 22.9 nmol/hr/mg creatinine. Urinary albumin excretion was positively correlated with both office and mean 24-hour systolic blood pressure (r = 0.31, P less than 0.05; and r = 0.44, P less than 0.01, respectively). Urinary NAG excretion was positively correlated with 24-hour ambulatory systolic, diastolic, and mean blood pressure (r = 0.32, P less than 0.05; r = 0.32, P less than 0.05; and r = 0.39, P less than 0.05, respectively), but not with office blood pressure. Thus, urinary albumin and NAG excretions are positively correlated with blood pressure and may be useful markers of renal involvement in patients with essential hypertension. Additionally, ABP may be more reliable than office blood pressure in identifying those patients at risk for hypertensive target-organ changes in the kidney.

Synthesis, nicotinic acetylcholine receptor binding, and antinociceptive properties of 2-exo-2-(2'-substituted 5'-pyridinyl)-7-azabicyclo[2.2.1]heptanes. Epibatidine analogues

A convenient, high-yield synthesis of 7-tert-butoxycarbonyl-7-azabicyclo[2.2.1]hept-2-ene (5), which involved the addition of tributyltin hydride to 7-tert-butoxycarbonyl-2-p-toluenesulfonyl-7-azabicyclo[2.2.1]hept-2-ene (4) followed by elimination of the tributyltin and p-tolylsulfonyl groups using tetrabutylammonium fluoride was developed. The addition of 2-amino-5-iodopyridine to 5 under reductive Heck conditions provided 7-tert-butoxycarbonyl-2-exo-(2'-amino-5'-pyridinyl)-7-azabicyclo[2.2.1]heptane (6). Compound 6 was the key intermediate used to prepare epibatidine analogues where the 2'-chloro group on the pyridine ring was replaced with a fluorine (1b), bromine (1c), iodine (1d), hydroxy (1e), amino (1f), dimethylamino (1g), trifluoromethanesulfonate (1h), and hydrogen (1i) group. (+)- and (-)-Epibatidine and compounds 1b-d and 1i all possess similar binding affinities at the alpha(4)beta(2) nAChR receptors labeled by [(3)H]epibatidine. Compound 1f has affinity similar to nicotine, whereas compounds 1e, 1g, and 1h have much lower affinity. The binding affinity appears to be dependent upon the electronic nature of the substituent. However, other factors are also involved. None of the compounds possesses appreciable affinity for the alpha(7) nAChR labeled by [(125)I]iodo-MLA. With the exception of 1f and 1g, all the epibatidine analogues are full agonists (tail flick test) in producing antinociception after intrathecal injection in mice.