Finite element modeling of three-dimensional pulsatile flow in the abdominal aorta: relevance to atherosclerosis

The infrarenal abdominal aorta is particularly prone to atherosclerotic plaque formation while the thoracic aorta is relatively resistant. Localized differences in hemodynamic conditions, including differences in velocity profiles, wall shear stress, and recirculation zones have been implicated in the differential localization of disease in the infrarenal aorta. A comprehensive computational framework was developed, utilizing a stabilized, time accurate, finite element method, to solve the equations governing blood flow in a model of a normal human abdominal aorta under simulated rest, pulsatile, flow conditions. Flow patterns and wall shear stress were computed. A recirculation zone was observed to form along the posterior wall of the infrarenal aorta. Low time-averaged wall shear stress and high shear stress temporal oscillations, as measured by an oscillatory shear index, were present in this location, along the posterior wall opposite the superior mesenteric artery and along the anterior wall between the superior and inferior mesenteric arteries. These regions were noted to coincide with a high probability-of-occurrence of sudanophilic lesions as reported by Cornhill et al. (Monogr. Atheroscler. 15:13-19, 1990). This numerical investigation provides detailed quantitative data on hemodynamic conditions in the abdominal aorta heretofore lacking in the study of the localization of atherosclerotic disease.     

Antiasthmatic activity of the second-generation phosphodiesterase 4 (PDE4) inhibitor SB 207499 (Ariflo) in the guinea pig

We evaluated the airway activity of the novel phosphodiesterase type 4 inhibitor SB 207499 [Ariflo; c-4-cyano-4-(3-cyclopentyloxy-4-methoxyp henyl-r-1-cyclohexane carboxylic acid)], in the guinea pig. Ovalbumin (OA)-induced contractions of guinea pig isolated tracheal strips were inhibited by SB 207499 with an EC50 of 1 microM but had little or no effect on exogenous agonist-induced contraction, which suggests that its effect on OA-induced contraction in vitro is primarily due to inhibition of mediator release from mast cells. In anesthetized guinea pigs, SB 207499 inhibited OA-induced bronchoconstriction with i.v. and p.o. ID50 values of 1.7 and 17 mg/kg, respectively. At 1, 3 and 6 hr after SB 207499 (30 mg/kg p.o.), OA-induced bronchospasm was inhibited by 92%, 70% and 58%, respectively, corresponding to elevated plasma concentrations of 1.62 +/- 0.19, 1.65 +/- 0.29 and 0. 93 +/- 0.24 microg/ml, respectively, of SB 207499. SB 207499 also inhibited house dust mite-induced bronchoconstriction (ID50 = 0.9 mg/kg i.v. and 8.9 mg/kg p.o.). In contrast to its lack of bronchorelaxant activity in vitro, SB 207499 inhibited bronchospasm induced by i.v. leukotriene D4 (LTD4) [ID50 = 3 mg/kg i.v.]. The bronchorelaxant effect of i.v.-administered SB 207499 was at least additive with that of salbutamol in reversing infused histamine-enhanced airway tone, but it did not alter base line or enhance salbutamol-induced cardiovascular effects. In conscious guinea pigs, SB 207499 (10 or 30 mg/kg p.o.), 1 hr before antigen or LTD4 challenge, markedly reduced bronchospasm and subsequent eosinophil influx as measured by bronchoalveolar lavage 24 hr after provocation. SB 207499 administered after OA or LTD4 challenge also reduced airway eosinophilia measured at 24 hr after OA challenge or 96 hr after LTD4 challenge. These results, coupled with the broad anti-inflammatory activity of SB 207499 previously described (Barnett et al., 1998), suggest that SB 207499 will be useful in the treatment of asthma and other inflammatory disorders.     

Concordance analysis of microbial genomes

The set of proteins which are conserved across families of microbes contain important targets of new anti-microbial agents. We have developed a simple and efficient computational tool which determines concordances of putative gene products that show sets of proteins conserved across one set of user specified genomes and not present in another set of user specified genomes. The thresholds and the homology scoring criterion are selectable to allow the user to decide the stringency of the homologies. The system uses a relational database to store protein coding regions from different genomes, and to store the results of a complete comparison of all sequences against all sequences using the FASTA program. Using Web technology, the display of all the related proteins for a given sequence and calculation of multiple sequence alignments (using CLUSTALW) can be performed with the click of a button. The current database holds 97 365 sequences from 19 complete or partial genomes and 8798905 FASTA comparison results. A example concordance is presented which demonstrates that the target of the quinolone antibiotics could have been identified using this tool.     

The involvement of innervation in the regulation of fetal adrenal steroidogenesis

Over the last decade, great interest has been generated in evaluation of the extent of neural control of the adrenal cortex and in adrenal cortical/medullary paracrine interactions. The purpose of this review is to summarize current knowledge of fetal adrenal cortical innervation and to present an overview of those studies of fetal adrenal function indicating that adrenal innervation plays a functional role in the control of glucocorticoid secretion under basal conditions and in response to a variety of homeostatic challenges. It will be helpful in understanding both the innervation of the adrenal cortex and the role of adrenal innervation in steroidogenesis during fetal development to briefly review experimental studies that have shed light on adrenal steroidogenesis during postnatal life. This is helpful for two reasons: 1) the vast majority of studies of adrenal innervation and its effect on steroidogenesis have utilized postnatal animals and 2) since the fetus is preparing for postnatal life, evaluating the level of function achieved postnatally provides crucial insights into the developmental stages of adrenal innervation and its role in steroidogenesis in preparing the fetus for an independent postnatal existence.     

Leprosy patients with lepromatous disease recognize cross-reactive T cell epitopes in the Mycobacterium leprae 10-kD antigen

BACKGROUND: Cough associated with gastroesophageal reflux (GER) may originate in extrathoracic airway receptors made hypersensitive by acid-induced mucosal injury. OBJECTIVE: We investigated the role of laryngeal disease and dysfunction in the pathogenesis of GER-associated cough in nonasthmatic patients. METHODS: Seven patients with GER-associated cough were compared with 7 patients with GER but no cough. The patients underwent fiberoptic endoscopy for assessment of laryngitis and esophagitis (expressed by scores); esophageal manometry; 24-hour pH monitoring; lung function tests; and histamine inhalation challenge with assessment of bronchial threshold (concentration provoking 10% fall in FEV1 [PC10]), extrathoracic airway threshold (concentration provoking 25% fall in the maximal midinspiratory flow [PC25MIF50]), and cough threshold (concentration provoking 5 or more coughs PCcough). The patients were reevaluated after 3 months of medical treatment for GER. RESULTS: Patients with cough, compared with those without cough, had significantly higher laryngitis scores (P = .002), lower esophageal sphincter pressures, longer time with pH below 4 (P = .003), greater number of episodes of reflux longer than 5 minutes (P = .016), longer esophageal clearance time (P = .048), and significantly lower PC25MIF50 (P = .005) and PCcough (P = .008) values. Laryngitis score was significantly inversely related to either PCcough (P < .001) or PC25MIF50 (P <.01) but not to PC10. Laryngitis score, PC25MIF50, and PCcough were all closely related to GER severity. After GER treatment, laryngitis, PC25MIF50, and PCcough were all significantly improved. CONCLUSIONS: These findings suggest that GER-associated cough is strongly associated with laryngeal disease and dysfunction consequent to acid reflux injury in nonasthmatic patients.     

Drug-induced reinstatement of heroin- and cocaine-seeking behaviour following long-term extinction is associated with expression of behavioural sensitization

The present study was designed to evaluate the relationship between reinstatement of drug-seeking behaviour following long-term extinction of intravenous (i.v.) drug self-administration (an animal model for craving) and long-term behavioural sensitization. Rats were allowed to self-administer heroin (50 microg/kg per inj., 14 daily sessions), cocaine (500 microg/kg per inj., 10 daily sessions) or saline. Following a 3-week extinction period, reinstatement tests were performed to evaluate priming effects of amphetamine, cocaine and heroin on nonreinforced drug-seeking behaviour. In addition, the occurrence of long-term behavioural sensitization in rats with a history of heroin or cocaine self-administration was determined. Heroin-seeking behaviour was reinstated by heroin (0.25 mg/kg), amphetamine (1.0 mg/kg) and cocaine (10 mg/kg). In addition, animals with a history of heroin self-administration displayed locomotor sensitization to both heroin and amphetamine. Cocaine-seeking behaviour was reinstated by cocaine and amphetamine, but not by heroin. Interestingly, locomotor sensitization to amphetamine, but not heroin, was observed in animals with a history of cocaine self-administration. In other words, the induction of drug-seeking behaviour following a prolonged drug-free period was found to be associated with the expression of long-term behavioural sensitization. These data provide experimental evidence for a role of behavioural sensitization in the incentive motivation underlying drug-seeking behaviour. If drug hyperresponsiveness would indeed be a crucial factor in drug-induced craving in human addicts, pharmacological readjustment of the neuroadaptations underlying drug sensitization may prevent relapse to drug use long after detoxification.     

Selection and characterization of Toxoplasma gondii mutants resistant to artemisinin

Toxoplasma gondii infection, like malaria, is sensitive to inhibition by artemisinin (ART). Mechanisms of action for ART in malaria treatment have been proposed, but little is known about its effects in T. gondii infection. To better understand its inhibitory effects on T. gondii, mutants resistant to ART were selected by progressive culture in permissive levels of the drug. Five clonal isolates were established and characterized. The isolates were approximately 65-fold less sensitive to ART than is the parental RH and showed cross-resistance to the ART derivatives dihydroartemisinin and artemether. In addition to ART resistance, 1 clone (C9) formed morphologically unusual parasitophorous vacuoles and another (A2) was avirulent for mice and protected mice from challenge with the wild type. These clonal T. gondii mutant isolates will be useful for the study of not only the mechanism of action of ART but also parasite vacuole biology and virulence factors.     

S-fluoxetine in the prophylaxis of migraine: a phase II double-blind randomized placebo-controlled study

A tubular bioassay was used to measure analytically the local production and concentration of the antifungal Trichoderma secondary metabolite 6-n-pentyl-2H-pyran-2-one (6PAP) at the Trichoderma antagonist/pathogen interface. 6PAP levels significantly increased in the presence of the pathogen Botrytis cinerea, typically 300-700%, and were highest near the pathogen source. The level of response for a particular Trichoderma isolate was found to vary with the test organism used. Two products produced by biotransformation of 6PAP by B. cinerea in response to the interaction were also detected.     

Protein thermostability above 100 degreesC: a key role for ionic interactions

The discovery of hyperthermophilic microorganisms and the analysis of hyperthermostable enzymes has established the fact that multisubunit enzymes can survive for prolonged periods at temperatures above 100 degreesC. We have carried out homology-based modeling and direct structure comparison on the hexameric glutamate dehydrogenases from the hyperthermophiles Pyrococcus furiosus and Thermococcus litoralis whose optimal growth temperatures are 100 degreesC and 88 degreesC, respectively, to determine key stabilizing features. These enzymes, which are 87% homologous, differ 16-fold in thermal stability at 104 degreesC. We observed that an intersubunit ion-pair network was substantially reduced in the less stable enzyme from T. litoralis, and two residues were then altered to restore these interactions. The single mutations both had adverse effects on the thermostability of the protein. However, with both mutations in place, we observed a fourfold improvement of stability at 104 degreesC over the wild-type enzyme. The catalytic properties of the enzymes were unaffected by the mutations. These results suggest that extensive ion-pair networks may provide a general strategy for manipulating enzyme thermostability of multisubunit enzymes. However, this study emphasizes the importance of the exact local environment of a residue in determining its effects on stability.