Status and perspectives of biomarker validation for diagnosis, stratification, and treatment.

OBJECTIVES: The aim of this study was to discuss the status of and perspective for biomarker validation in view of the challenges imposed on national healthcare systems due to an increasing number of citizens with chronic diseases and new expensive drugs with effects that are sometimes poorly documented. The demand for a paradigm shift toward stratification of patients or even 'personalized medicine' (PM) is rising, and the implementation of such novel strategies has the potential to increase patient outcomes and cost efficiency of treatments. The implementation of PM depends on relevant and reliable biomarkers correlated to disease states, prognosis, or effect of treatment. Beyond biomarkers of disease, personalized prevention strategies (such as individualized nutrition guidance) are likely to depend on novel biomarkers. STUDY DESIGN: We discuss the current status of the use of biomarkers and the need for standardization and integration of biomarkers based on multi-omics approaches. METHODS: We present representative cases from laboratory medicine, oncology, and nutrition, where present and emerging biomarkers have or may present opportunities for PM or prevention. RESULTS: Biomarkers vary greatly in complexity, from single genomic mutations to metagenomic analyses of the composition of the gut microbiota and comprehensive analyses of metabolites, metabolomics. Using biomarkers for decision-making has previously often relied on measurements of single biomolecules. The current development now moves toward the use of multiple biomarkers requiring the use of machine learning or artificial intelligence. Still, the usefulness of biomarkers is often challenged by suboptimal validation, and the discovery of new biomarkers moves much faster than standardization efforts. To reap the potential benefits of personalization of treatment and prevention, healthcare systems and regulatory authorities need to focus on validation and standardization of biomarkers. CONCLUSION: There is a great public health need for better understanding of the usefulness, but also limitations, of biomarkers among policy makers, clinicians, and scientists, and efforts securing effective validation are key to the future use of novel sets of complex biomarkers.

White matter lesions and temporal lobe atrophy related to incidence of both dementia and major depression in 70-year-olds followed over 10 years.

BACKGROUND AND PURPOSE: A number of studies have suggested associations between dementia and depression in older adults. One reason could be that these disorders share structural correlates, such as white matter lesions (WMLs) and cortical atrophy. No study has examined whether these lesions precede both dementia and depression independently of each other in the general population. METHODS: Whether WMLs and cortical atrophy on computed tomography predict dementia and depression was investigated in a population-based sample of 70-year-olds (n = 380) followed over 10 years. Exclusion criteria were dementia, major depression, history of stroke and a Mini-Mental State Examination score below 26 at baseline in 2000-2001. Dementia was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, third edition, revised, and depression according to the Diagnostic and Statistical Manual of Mental Disorders, fifth edition. Primary outcomes included dementia and major depression at 10-year follow-up. RESULTS: Adjusted logistic regression models, including both WMLs and temporal lobe atrophy, showed that moderate to severe WMLs [odds ratio (OR) 3.96, 95% confidence interval (CI) 1.23-12.76] and temporal lobe atrophy (OR 2.93, 95% CI 1.13-7.60) predicted dementia during a 10-year follow-up independently of major depression. Similarly, both moderate to severe WMLs (OR 3.84, 95% CI 1.25-11.76) and temporal lobe atrophy (OR 2.52, 95% CI 1.06-5.96) predicted depression even after controlling for incident dementia. CONCLUSION: White matter lesions and temporal lobe atrophy preceded 10-year incidence of both dementia and depression in 70-year-olds. Shared structural correlates could explain the reported associations between dementia and depression. These brain changes may represent independent and complementary pathways to dementia and depression. Strategies to slow progression of vascular pathology and neurodegeneration could indirectly prevent both dementia and depression in older adults.

Ascorbic acid-induced crosslinking of lens proteins: evidence supporting a Maillard reaction.

The incubation of calf lens extracts with 20 mM ascorbic acid under sterile conditions for 8 weeks caused extensive protein crosslinking, which was not observed with either 20 mM sorbitol or 20 mM glucose. While no precipitation was observed, ascorbic acid did induce the formation of high-molecular-weight protein aggregates as determined by Agarose A-5m chromatography. Proteins modified by ascorbic acid bound strongly to a boronate affinity column, however, crosslinked proteins were present mainly in the unbound fraction. These observations suggest that the cis-diol groups of ascorbic acid were present in the primary adduct, but were either lost during the crosslinking reaction or sterically hindered from binding to the column matrix. The amino acid composition of the ascorbic acid-modified proteins was identical to controls except for a 15% decrease in lysine. Amino acid analysis after borohydride reduction, however, showed a 25% decrease in lysine, a 7% decrease in arginine and an additional peak which eluted between phenylalanine and histidine. Extensive browning occurred during the ascorbic acid-modification reaction. This resulted in protein-bound chromophores with a broad absorption spectrum from 300 to 400 nm, and protein-bound fluorophores with excitation/emission maxima of 350/450 nm. A 4 week incubation of dialyzed crude lens extract with [1-14C]ascorbic acid showed increased incorporation for 2 weeks, followed by a decrease over the next 2 weeks as crosslinking was initiated. The addition of cyanoborohydride to the reaction mixture completely inhibited crosslinking and increased [1-14C]ascorbic acid incorporation to a plateau value of 180 nmol per mg protein. Amino acid analysis showed a 50% loss of lysine, and 8% decrease in arginine and the presence of a new peak which eluted slightly earlier than methionine. These data are consistent with the non-enzymatic glycation of lens proteins by either ascorbic acid or an oxidation product of ascorbic acid via a Maillard-type reaction.

The binding and inhibition of trypsin by alpha-crystallin.

One of the major lens-structural proteins, alpha-crystallin, is a multimeric protein containing 40 subunits of approx. 20 kDa each. There are two subunit types with distinct but similar structures. This protein was capable of inhibiting trypsin, chymotrypsin and elastase, but had no effect on thrombin or kallikrein. Complete inhibition was not observed, but rather plateau levels of inhibition were obtained in each case. Maximum inhibition was observed at a ratio of 1 mol of alpha-crystallin for every 9-10 mol of trypsin. alpha-Crystallin also inhibited the labeling of the active site of trypsin by [3H]diisopropyl fluorophosphate (DFP). Greater than 90% inhibition of DFP labeling was observed at a ratio of 1 mol of alpha-crystallin for every 7-8 mol of trypsin. Both trypsin and [3H]DFP-labeled trypsin formed a complex with alpha-crystallin, as demonstrated by gel-filtration chromatography. The active site of trypsin when bound to alpha-crystallin was still capable of reacting with p-nitrophenyl p-guanidobenzoate and soybean trypsin inhibitor, but was inaccessible to alpha 1-antitrypsin. These data suggest that alpha-crystallin acts as a multivalent modified inhibitor which is consistent with the proposed quaternary structure of alpha-crystallin.

Dietary exposure to volatile and non-volatile N-nitrosamines from processed meat products in Denmark.

Recent epidemiological studies show a positive association between cancer incidence and high intake of processed meat. N-nitrosamines (NAs) in these products have been suggested as one potential causative factor. Most volatile NAs (VNAs) are classified as probable human carcinogens, whereas the carcinogenicity for the majority of the non-volatile NA (NVNA) remains to be elucidated. Danish adults (15-75 years) and children (4-6 years) consume 20 g and 16 g of processed meat per day (95th percentile), respectively. The consumption is primarily accounted for by sausages, salami, pork flank (spiced and boiled) and ham. This consumption results in an exposure to NVNA of 33 and 90 ng kg bw(-1) day(-1) for adults and children, respectively. The exposure to VNA is significantly lower amounting to 0.34 and 1.1 ng kg bw(-1) day(-1) for adults and children, respectively. Based on a BMDL10 of 29 µg kg bw(-1) day(-1) a MOE value ≥17,000 was derived for the exposure to NA known to be carcinogenic (VNA including NSAR), indicating an exposure of low concern. The exposure to the NVNA is substantially higher and if found to be of toxicological significance the exposure may be of concern.

Agonists at the alpha4beta2 nicotinic acetylcholine receptors: structure-activity relationships and molecular modelling.

Agonists of the alpha4beta2 nicotinic acetylcholine receptors have been synthesised as potential drugs for treatment of a variety of diseases. In this review, the published nicotinic agonists are presented and, on the basis of the molecular structure, the compounds are divided into three compound classes, nicotinoids (structurally close to nicotine), bicyclic compounds (structurally close to epibatidine and anatoxin-a), and analogues of imidacloprid (structurally close to the insecticide imidacloprid). The structure-activity relationships are discussed within and in between the classes. On the basis of computational studies of ligands for the nicotinic acetylcholine receptors the structure-activity relationships are discussed and a possible binding mode suggested. The binding mode encompasses: (A) an interaction between an anionic site in the receptor and the protonated nitrogen atom in the ligand, (B) a hydrogen bond between a hydrogen bond donor in the receptor and a hydrogen bond acceptor in the ligand, (C) an interaction between a pi-system (heteroaromatic ring, carbonyl bond) in the ligand and another pi-system or a positively charged amino acid residue in the binding site, (D) a pi-cation interaction between aromatic residues in the receptor binding site and the protonated nitrogen atom in the ligand, and (E) steric interactions of positive and negative character around the aliphatic and the heteroaromatic part of the ligand.

The use of bioisosteric groups in lead optimization.

It is now half a century since Friedman introduced the term bioisosterism for the similar biological activity of structurally related compounds. Since then, the concept has been used extensively and successfully in the optimization of lead compounds in drug discovery. The number of chemical lead compounds has expanded enormously in recent years due to the expression of an increasing number of recombinant proteins, and the screening of these new protein targets against a large number of compounds in high-throughput screens. For the fine-tuning of lead compounds to obtain candidates suitable for clinical trials, which is in most circumstances still a tedious process, the use of bioisosteric replacement can be of significant value. This is especially the case in optimizing for selectivity for a specific target and in improving the pharmacokinetic properties of lead compounds. The use of bioisosteres in lead optimization is illustrated by some recent examples from the literature.

Improving the nicotinic pharmacophore with a series of (Isoxazole)methylene-1-azacyclic compounds: synthesis, structure-activity relationship, and molecular modeling.

A series of (isoxazole)methylene-1-azacyclic compounds was prepared. The compounds were tested for affinity to central nicotinic acetylcholine receptors (nAChRs) and central muscarinic receptors. The compounds covered a broad range of affinities for the nAChRs (IC(50) = 0.32 to >1000 nM), with selectivities for the nAChRs over the muscarinic receptors in the range of 3-183. The high-affinity compound (Z)-26 (3-(4-methyl-5-isoxazolyl)methylene-1-azabicyclo[2.2. 2]octane, IC(50) = 3.2 nM) having only one energy minimum was used as the reference structure in a computational study. This ligand has enabled definition of an important distance parameter, and the existence of this parameter was supported by showing that other potent nicotinic ligands (for example, nicotine and epibatidine) fit the model.

Novel functional M1 selective muscarinic agonists. 2. Synthesis and structure-activity relationships of 3-pyrazinyl-1,2,5,6-tetrahydro-1-methylpyridines. Construction of a molecular model for the M1 pharmacophore.

A series of 3-(3-substituted-pyrazinyl)-1,2,5,6-tetrahydro-1-methylpyridines were synthesized and found to have high affinity for central muscarinic receptors. The ability of some of these compounds to inhibit the electrically stimulated twitch of the guinea pig vas deferens indicated that the compounds were M1 agonists. M1 agonist activity was related to the length of the side chain attached to the pyrazine ring, with maximal activity being obtained with the hexyloxy side chain. The (hexyloxy)pyrazine 3f lacked M2 agonist activity as it failed to affect the guinea pig atria and was also relatively devoid of M3 agonist activity as determined by its lack of tremorogenic and sialogogic effects in mice. A comparison of the M1 agonist efficacy of these pyrazines and related 1,2,5-thiadiazoles and 1,2,5-oxadiazoles suggested that M1 efficacy was related to the magnitude of electrostatic potential located over the nitrogens of the respective heterocycles. The heteroatom directly attached to the 3 position of the pyrazine or 1,2,5-thiadiazole heterocycle markedly influenced the M1 efficacy of the compounds by determining the energetically favorably conformers for rotation about the bond connecting the tetrahydropyridyl ring and the heterocycle. A three-dimensional model for the M1-activating pharmacophore was proposed based on computational studies and the model of the muscarinic pharmacophore proposed by Schulman.

Novel functional M1 selective muscarinic agonists. Synthesis and structure-activity relationships of 3-(1,2,5-thiadiazolyl)-1,2,5,6-tetrahydro-1-methylpyridines .

A series of novel 3-(3-substituted-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro- 1-methylpyridines (substituted-TZTP; 5a-l, 7a-h, 8, 9c-n, 11, 13j) were synthesized and tested for central muscarinic cholinergic receptor affinity by using [3H]-oxotremorine-M (Oxo-M) and [3H]-pirenzepine (Pz) as ligands. The potency and efficacy of the compounds for the pharmacological defined M1 and M2 muscarinic receptors were determined on isolated electrically stimulated rabbit vas deferens and on spontaneously beating isolated guinea pig atria, respectively. Selected compounds were also tested for M3 activity in the isolated guinea pig ileum. The C1-8 alkoxy-TZTP 5a-l analogues all displaced [3H]-Oxo-M and [3H]-Pz with low nanomolar affinity. Depicting chain length against Oxo-M binding and against Pz binding the unbranched C1-8 alkoxy-TZTP (5a-h) derivatives produced U-shaped curves with butoxy- (5d) and (pentyloxy)-TZTP (5e) as the optimum chain length, respectively. This U-shaped curve was also seen in the ability of the compounds 5a-h to inhibit the twitch height in the vas deferens preparation. The (pentyloxy)- (5e) and the (hexyloxy)-TZTP (5f) analogues produced an over 90% inhibition of the twitch height with IC50 values in the low picomolar range. In both the atria and in the ileum preparations 5f had low efficacy and potency. With the (alkylthio)-TZTP (7a-h) analogues the structure-activity relationship was similar to the one observed with the alkoxy (5a-h) analogues, but generally 7a-h had higher receptor affinity and was more potent than the corresponding 5a-h. However, the C3-8 alkyl-TZTP (9c,e,g,h) analogues had 10-100 times lower affinity for the central muscarinic receptors than the corresponding alkoxy and alkylthio derivatives, and their efficacy in the vas deferens preparation was too low to obtain IC50 values. The unsubstituted TZTP (11) compound was a potent but nonselective muscarinic agonist. The two 3-(3-butoxy/(hexyloxy)-1,2,5-oxadiazol-4-yl)-1,2,5,6-tetrahy dro-1- methylpyridines (butoxy/hexyloxy)-OZTP; 19a/b) were also synthesized and tested. Both 19a and 19b had much lower affinity for the central muscarinic receptors than 5d and 5f, and the efficacy of 19a,b was too low to give IC50 values in the vas deferens preparation. Therefore, the C5-6 (alkyloxy)/(alkylthio)-TZTP's represent a unique series of potent functional M1 selective muscarinic agonists.

Conformationally constrained analogues of the muscarinic agonist 3-(4-(methylthio)-1,2,5-thiadiazol-3-yl)-1,2,5,6-tetrahydro-1-methylpyr idine. Synthesis, receptor affinity, and antinociceptive activity.

Conformationally constrained analogues of the potent muscarinic agonist 3-(4-methylthio)-1,2,5-thiadiazol-3-yl)-1,2,5,6-tetrahydro-1-methy lpyridine (methylthio-TZTP, 17) were designed and synthesized with the aim of (a) improving the antinociceptive selectivity over salivation and tremor and (b) predicting the active conformation of 17 with respect to the dihedral angle C4-C3-C3'-N2'. Using MOPAC 6.0 tricyclic analogues (7, 15, 16) with C4-C3-C3'-N2' dihedral angles close to 180 degrees and a rotation hindered analogue (9) with a C4-C3-C3'-N2' dihedral angle close to 274 degrees were designed, as these conformations had previously been suggested as being the active conformations. The analogues were tested for central muscarinic receptor binding affinity, for their antinociceptive activity in the mouse grid shock test, and, in the same assay, for their ability to induce tremor and salivation. The data showed that the tricyclic analogues (7, 15, 16) were equipotent with 17 as analgesics, but with no improved side effect profiles. The rotation-hindered analogue 9 had neither muscarinic receptor binding affinity nor antinociceptive activity. These results suggest that the active conformation of 17 has a C3-C4-C3'-N2' dihedral angle close to 180 degrees.

Functionally selective M1 muscarinic agonists. 3. Side chains and azacycles contributing to functional muscarinic selectivity among pyrazinylazacycles.

In an attempt to improve upon the M1 agonist activity of the selective M1 agonist xanomeline and related compounds, the M1 muscarinic efficacies and potencies of 3- and 6-substituted pyrazinylazacycles were varied by changing both the 3- and 6-substituents as well as the azacycle. Significant improvements in efficacy and potency over the previously prepared [3-(hexyloxy)pyrazinyl]tetrahydropyridine 19 were obtained with the [3-(hexyloxy)pyrazinyl]-quinuclidine 5i. The M1 activity of 5i showed some enantioselectivity with (S)-5i being ca. 4-fold more potent than (R)-5i. Like 19 and xanomeline, 5i was a functionally selective M1 agonist that showed greater functional selectivity than widely studied pyrazinylquinuclidine 5n (L-689,660). The improved functional selectivity of 5i over 5n could be attributed to the additional binding interactions between the hexyloxy side chain of 5i and the M1 receptor that are not available to 5n. Although 5i may show M1 functional selectivity comparable to xanomeliine, 5i is a less efficacious and potent M1 agonist than xanomeline.

1,2,5-Thiadiazole analogues of aceclidine as potent m1 muscarinic agonists.

The acetyl group of the muscarinic agonist aceclidine 4 was replaced by various 1,2,5-thiadiazoles to provide a new series of potent m1 muscarinic agonists 17 and 18. Optimal m1 muscarinic agonist potency was achieved when the 1,2,5-thiadiazole substituent was either a butyloxy, 17d, or butylthio, 18d, group. Although 1,2,5-oxadiazole 37 and pyrazine 39 are iso-pi-electronic with 1,2,5-thiadiazole 17d, both analogues were substantially less active than 17d. Compounds with high muscarinic affinity and/or m1 muscarinic agonist efficacy were also obtained when the 3-oxyquinuclidine moiety of 17d or 18c was replaced by ethanolamines, hydroxypyrrolidines, hydroxyazetidine, hydroxyisotropanes, or hydroxyazanorbornanes. The structure-activity data support the participation of the oxygen or sulfur atom in the substituent on the 1,2,5-thiadiazole in the activation of the m1 receptor. Several of these new 1,2,5-thiadiazoles have m1 agonist efficacy, potency, and selectivity comparable to those of xanomeline 2 in the muscarinic tests investigated.

Muscarinic agonists with antipsychotic-like activity: structure-activity relationships of 1,2,5-thiadiazole analogues with functional dopamine antagonist activity.

Muscarinic agonists were tested in two models indicative of clinical antipsychotic activity: conditioned avoidance responding (CAR) in rats and inhibition of apomorphine-induced climbing in mice. The standard muscarinic agonists oxotremorine and pilocarpine were both active in these tests but showed little separation between efficacy and cholinergic side effects. Structure-activity relationships of the alkylthio-1,2,5-thiadiazole azacyclic type muscarinic partial agonists are shown, revealing the exo-6-(3-propyl/butylthio-1,2, 5-thiadiazol-4-yl)-1-azabicyclo[3.2.1]octane analogues (4a,b and 9a, b) to be the most potent antipsychotic agents with large separation between efficacy and cholinergic side effects. The lack of enantiomeric selectivity suggests the pharmacophoric elements are in the mirror plane of the compounds. A model explaining the potency differences of closely related compounds is offered. The data suggest that muscarinic agonists act as functional dopamine antagonists and that they could become a novel treatment of psychotic patients.

1-(1,2,5-Thiadiazol-4-yl)-4-azatricyclo[2.2.1.0(2,6)]heptanes as new potent muscarinic M1 agonists: structure-activity relationship for 3-aryl-2-propyn-1-yloxy and 3-aryl-2-propyn-1-ylthio derivatives.

Two new series of 1-(1,2,5-thiadiazol-4-yl)-4-azatricyclo[2.2.1.0(2, 6)]heptanes were synthesized and evaluated for their in vitro activity in cell lines transfected with either the human M1 or M2 receptor. 3-Phenyl-2-propyn-1-yloxy and -1-ylthio analogues substituted with halogen in the meta position showed high functional potency, efficacy, and selectivity toward the M1 receptor subtype. A quite unique functional M1 receptor selectivity was observed for compounds 8b, 8d, 8f, 9b, 9d, and 9f. Bioavailability studies in rats indicated an oral bioavailability of about 20-30%, with the N-oxide as the only detected metabolite.

Muscarinic analgesics with potent and selective effects on the gastrointestinal tract: potential application for the treatment of irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a pathopysiolocal condition characterized by abnormal bowel habits that are frequently accompanied by abdominal pain. Current therapy based on reducing high-amplitude GI contractions with nonselective muscarinic antagonists is limited in efficacy due to typical muscarinic side effects and provides no pain relief. We have previously found potent antinociceptive agents acting through muscarinic receptors. In the present work, new 1,2,5-thiadiazole-based structures with muscarinic activity have been evaluated both for activity as analgesics in the mouse withing assay and for activity in normalizing spontaneous cluster contractions in ferret jejunum as a model of IBS in humans. (5R,6R)-exo-6-[4-[(4,4,4-Trifluorobutyl)thio]-1,2,5-thiadiazol+ ++-3-yl] -1-azabicyclo[3.2.1]octane (35, LY316108/NNC11-2192) was found to offer an exceptional profile combining analgesic potency in mouse writhing (ED50 = 0.1 mg/kg) along with potency for normalization of GI motility (ED50 = 0.17 mg/kg). This combination of GI and analgesic potency suggests 35 as an excellent candidate for evaluation as a potential treatment of IBS.

Ascorbic acid and glucose oxidation by ultraviolet A-generated oxygen free radicals.

PURPOSE: To determine the relative rate of oxidation of ascorbic acid (ASA) and glucose under conditions used for glycation reactions in vitro and by ultraviolet A (UVA)-generated oxygen free radicals using human lens sensitizers. METHODS: ASA and [14C]glucose were incubated in 0.1 M phosphate buffer, and the rate of oxidation was determined by absorbance at 265 nm and by thin-layer chromatography, respectively. Oxidation also was measured during the UVA irradiation of 2 mg/ml solutions of human lens water-insoluble proteins. The role of individual reactive oxygen species was determined by the protective effects of superoxide dismutase, catalase, and sodium azide. RESULTS: ASA was oxidized rapidly in 0.1 M phosphate buffer. This loss was prevented by the addition of a metal chelator, by previous chelex resin treatment of the buffer, or by the addition of lens proteins. Glucose was not oxidized under any of the above conditions. UVA irradiation with 2 mg/ml human lens protein as sensitizer oxidized 1 mM ASA after several hours but oxidized, at most, only 2 microM glucose even after 8 hours of irradiation. Superoxide anion was responsible for 24%, and singlet oxygen for 40%, of the ASA oxidized. UVA-generated H2O2 caused little or no oxidation of ASA. H2O2 did accelerate the oxidation of ASA in phosphate buffer, but this was almost completely prevented by the addition of either a chelating agent or lens proteins. CONCLUSIONS: The conditions used for glycation reactions in vitro rapidly oxidized ASA, but not glucose. The UVA-dependent generation of oxygen free radicals also oxidized ASA at a 10(3) faster rate than glucose. Superoxide anion and singlet oxygen were identified as the principal oxidants of ASA in this process. These data argue that ASA may be the primary glycating agent in aging normal lenses.

Direct bronchial artery revascularization and en bloc double lung transplantation--surgical techniques and early outcome.

BACKGROUND: Lung transplantation including direct bronchial artery revascularization (BAR) has produced promising early results in small clinical series. METHODS: In Copenhagen primary en bloc double lung transplantation with BAR, with the left mammary artery used as conduit, has been performed in 47 patients from 1992 to the end of 1995. After introduction of the bloc into the recipient, the mammary-to-bronchial artery anastomosis is performed as the first anastomosis, allowing perfect exposure and early reperfusion. Internal mammary-bronchial artery arteriography has been performed routinely after operation. RESULTS: Bronchoscopic examination performed in all patients documented normal airway healing in 42, disturbed in two, and complicated in three. Arteriography performed in 42 patients demonstrated complete BAR in 25, incomplete in 15, and failed BAR in 2. Failed BAR was associated with complicated airway healing. The 1- and 2-year survival rate (Kaplan-Meyer) is 83%. Eleven patients have died, only one within 30 days. The total incidence of bronchiolitis obliterans syndrome at 3 years (with Kaplan-Meier technique) is 33%. Successful BAR has also been performed with an adjusted technique in a limited number of heart-lung and single lung transplantations. Our total experience of BAR in any type of lung transplantation includes 65 patients with an arteriographic BAR success rate of 94% (50 of 53 examined patients). CONCLUSIONS: Experience has improved the surgical technique and has made BAR reliable and safe, be it double lung, single lung, or heart-lung transplantation. Early results are good, but only follow-up will show if long-term results after lung transplantation will be improved by BAR. Already today, en bloc double lung transplantation with BAR is a viable alternative to sequential bilateral lung transplantation.

Thrombus organization plays no major role in late neointimal formation after angioplasty in porcine coronary arteries.

Thrombus organization has been suggested to play a major role in late neointimal formation after coronary angioplasty. We sought to describe the time sequence of lesion formation after angioplasty in porcine coronary arteries and to quantify the relation between early thrombosis and late neointimal formation. Deep vessel wall injury was induced by conventional balloon angioplasty in the circumflex (CX) and right coronary (RCA) arteries and by retraction of a chain-encircled balloon in the left anterior descendent artery (LAD). Lesions were assessed by histomorphometry at days 0, 1, 4, 7, 14, 28, and 56 after angioplasty. A response-to-injury index (lesion area/injury length) was determined for each artery. Angioplasty led to rupture/removal of media. Thrombus was present at the exposed adventitia at days 0, 1, and 4. From day 7, neointima was observed on the luminal side of the arterial wall. All thrombus had disappeared at day 28, at which only neointima was observed. Histomorphometry revealed that lesion formation after angioplasty was a gradually increasing process from day 0 to day 28 with no further growth from day 28 to day 56. Maximal thrombus size (day 4, RCA: 0.07+/-0.04 mm, CX: 0.23+/-0.16 mm, LAD: 0.15+/-0.11 mm) was significantly smaller than late neointimal formation (day 28, RCA: 0.68+/-0.18 mm, CX: 0.63+/-0.23 mm, LAD: 0.71+/-0.18 mm) in all three arteries (p < .03). Lesion formation after angioplasty is a gradually increasing process for 4 weeks. Maximal thrombus size is about four times smaller than late neointimal formation. Thus, thrombus organization plays no major role in late neointimal formation.

Unexpected antipsychotic-like activity with the muscarinic receptor ligand (5R,6R)6-(3-propylthio-1,2,5-thiadiazol-4-yl)-1-azabicyclo[3.2.1]octane .

(5R,6R)6-(3-propylthio-1,2,5-thiadiazol-4-yl)-1-azabicyclo[3 .2.1]octane (PTAC) is a potent muscarinic receptor ligand with high affinity for central muscarinic receptors and no or substantially less affinity for a large number of other receptors or binding sites including dopamine receptors. The ligand exhibits partial agonist effects at muscarinic M2 and M4 receptors and antagonist effects at muscarinic M1, M3 and M5 receptors. PTAC inhibited conditioned avoidance responding, dopamine receptor agonist-induced behavior and D-amphetamine-induced FOS protein M5 expression in the nucleus accumbens without inducing catalepsy, tremor or salivation at pharmacologically relevant doses. The effect of PTAC on conditioned avoidance responding and dopamine receptor agonist-induced behavior was antagonized by the acetylcholine receptor antagonist scopolamine. The compound selectively inhibited dopamine cell firing (acute administration) as well as the number of spontaneously active dopamine cells (chronic administration) in the limbic ventral tegmental area (A10) relative to the non-limbic substantia nigra, pars compacta (A9). The results demonstrate that PTAC exhibits functional dopamine receptor antagonism despite its lack of affinity for the dopamine receptors and indicate that muscarinic receptor partial agonists may be an important new approach in the medical treatment of schizophrenia.