A 16-element phased-array head coil

beta2-Integrin adhesion molecules play crucial roles in monocyte transmigration and adherence to the inflamed extracellular matrix. While integrin engagement contributes to inflammatory cell activation, little is known about the precise signaling pathways that are important to integrin-dependent monocyte activation. We examined the role of tyrosine phosphorylation and extracellular-signal regulated kinase (ERK) activity in beta2-integrin signaling in monocytes. Cross-linking of the LFA-1 (CD11a/CD18) and MAC-1 (CD11b/CD18) integrins on the surface of THP-1 monocytic cells induced the accumulation of tyrosine phosphoproteins. As part of this signal both ERK-1 and ERK-2 are tyrosine phosphorylated. In vitro kinase assays documented an increase in ERK-2 activity following both LFA-1 and MAC-1 cross-linking. beta2-Integrin cross-linking also led to a marked increase in 4-h procoagulant activity (PCA) in THP-1 cells and purified human monocytes. Inhibition of tyrosine phosphorylation by genistein (10 microg/ml), or selective ERK inhibition with PD98059 (10 microM), was able to block the integrin-dependent induction of PCA in both THP-1 cells and human monocytes. Thus, beta2 integrin signaling in monocytic cells can flow through the tyrosine phosphorylation and activation of the ERK mitogen activated protein kinases, which is essential for the subsequent expression of tissue factor. These results suggest that the ERK proteins likely function to integrate various adhesion-dependent signals during the process of monocyte transmigration.     

ST/b and DBA/2 mice differ in brain alpha-bungarotoxin binding and alpha 7 nicotinic receptor subunit mRNA levels: a quantitative autoradiographic analysis

Inbred mouse strains vary in sensitivity to a number of behavioral and physiological effects produced by nicotine. Differences in sensitivity to nicotine are correlated with variance in the number of brain nicotinic receptors as measured in regionally dissected brain tissue. The studies reported here used quantitative autoradiography and in-situ hybridization methods to measure regional levels of alpha-bungarotoxin (alpha BTX) binding and alpha 7 mRNA levels. Two inbred mouse strains, ST/b and DBA/2, were compared because these strains differ maximally in sensitivity to nicotine-induced seizures and in alpha BTX binding measured in regional brain homogenates. The binding of alpha BTX was significantly greater in the St/b strain in 42 of 127 brain regions that were analyzed, and a trend towards increased binding was seen in many additional brain regions. The most consistent strain differences were found in hippocampal, thalamic and pontine nuclei. Strain differences in alpha 7 mRNA levels were also detected, but these were not as widespread as were the alpha BTX binding differences. The alpha 7 mRNA levels were significantly correlated with alpha BTX binding in both mouse strains which suggests that the strain differences in binding are related, in part, to the levels of alpha 7 mRNA.     

Molecular recognition of diketide substrates by a beta-ketoacyl-acyl carrier protein synthase domain within a bimodular polyketide synthase

BACKGROUND: Modular polyketide synthases (PKSs) are large multifunctional proteins that catalyze the biosynthesis of structurally complex bioactive products. The modular organization of PKSs has allowed the application of a combinatorial approach to the synthesis of novel polyketides via the manipulation of these biocatalysts at the genetic level. The inherent specificity of PKSs for their natural substrates, however, may place limits on the spectrum of molecular diversity that can be achieved in polyketide products. With the aim of further understanding PKS specificity, as a route to exploiting PKSs in combinatorial synthesis, we chose to examine the substrate specificity of a single intact domain within a bimodular PKS to investigate its capacity to utilize unnatural substrates. RESULTS: We used a blocked mutant of a bimodular PKS in which formation of the triketide product could occur only via uptake and processing of a synthetic diketide intermediate. By introducing systematic changes in the native diketide structure, by means of the synthesis of unnatural diketide analogs, we have shown that the ketosynthase domain of module 2 (KS2 domain) in 6-deoxyerythronolide B synthase (DEBS) tolerates a broad range of variations in substrate structure, but it strongly discriminates against some others. CONCLUSIONS: Defining the boundaries of substrate recognition within PKS domains is crucial to the rationally engineered biosynthesis of novel polyketide products, many of which could be prepared only with great difficulty, if at all, by direct chemical synthesis or semi-synthesis. Our results suggest that the KS2 domain of DEBS1 has a relatively relaxed specificity that can be exploited for the design and synthesis of medicinally important polyketide products.     

The metabolic anatomy of tremor in Parkinson's disease

OBJECTIVE: To identify regional metabolic brain networks related specifically to the presence of tremor in PD. BACKGROUND: The pathophysiology of parkinsonian tremor is unknown. Because tremor in PD occurs mainly in repose, we used resting state PET with 18F-fluorodeoxyglucose (FDG) to identify specific metabolic brain networks associated with this clinical manifestation. METHODS: We studied two discrete groups of eight PD patients with and without tremor using FDG/PET. Both patient groups were matched for gender, age, and Unified Parkinson Disease Rating Scale ratings for akinesia and rigidity. Ten normal volunteer subjects served as controls. RESULTS: Network analysis with the Scaled Subprofile Model was performed in two steps. 1) We computed the expression of the PD-related pattern (PDRP) identified by us previously in each of the PD patients and control subjects. Although PDRP subject scores were abnormally elevated in the combined PD cohort (p < 0.005), these values did not differ in the PD patient groups with and without tremor (p = 0.36). 2) We used SSM to analyze the data from the combined PD cohort comprising both patient groups. We found that PD patients with tremor were characterized by increased expression of a metabolic network comprising the thalamus, pons, and premotor cortical regions. Subject scores for this pattern were elevated in the tremor group compared with the atremulous patient group and the normal control group (p < 0.005). CONCLUSIONS: The findings suggest that PD patients with tremor are characterized by distinct increases in the functional activity of thalamo-motor cortical projections. Modulation of this functional anatomic pathway is likely to be the mechanism for successful interventions for the relief of parkinsonian tremor.     

Potent and selective bicyclic lactam inhibitors of thrombin: Part 2: P1 modifications

The synthesis and antithrombotic activity of a series of nonpeptide bicyclic thrombin inhibitors is described. We have explored the SAR with modifications to the P1 site. The introduction of arginine mimetics at the P1 site led to potent and selective thrombin inhibitors.     

Effects of antipsychotic treatment on polysomnographic measures in schizophrenia: a replication and extension

OBJECTIVE: The authors sought to replicate and extend previous observations of improvement in some EEG sleep measures during the course of antipsychotic treatment in schizophrenia patients. METHOD: Fourteen medication-free patients with schizophrenia underwent 2 nights of sleep EEG monitoring before and after 3-4 weeks of treatment with clinically determined doses of haloperidol or thiothixene. RESULTS: Measures of sleep continuity improved consistently. REM latency increased, although five of 14 patients continued to exhibit short REM latencies (less than 60 minutes). Stage 3 sleep increased during neuroleptic treatment, while stage 4 sleep did not change. CONCLUSIONS: These data demonstrate partial improvement of some but not all EEG sleep measures in schizophrenic patients through the course of neuroleptic treatment. They suggest that shortened REM latency and disturbed sleep continuity might represent reversible state abnormalities, while reduced slow-wave sleep may represent a more persistent trait abnormality in schizophrenia.