Unexpected return of spontaneous circulation after cessation of resuscitation (Lazarus phenomenon)

The heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-beta]pyridine NPhIP) is a major dietary component in individuals eating cooked meats or fish. This heterocyclic amine requires biochemical activation, mainly through cytochrome P4501A2, and can be detoxified chiefly by 4'hydroxylation through other cytochromes, and be in turn converted through phase 2 enzymes to readily excreted conjugates. The active form of PhIP is mutagenic in Salmonella typhimurium TA98 and is a useful substrate to study the possible chemoprotective action of phytochemicals. We found that black and green tea depressed the mutagenicity of PhIP in dose-related fashion, and decaffeinated tea was less powerful an inhibitor. This led to the study of caffeine, that displayed effective dose-related inhibition of the mutagenicity of PhIP. Other antioxidants such as lycopene, the active antioxidant from tomatoes, and daidzein and genistein from soy products, also had a dose-related inhibition of the mutagenicity of PhIP. We conclude that PhIP is a good substrate found in several human foods to determine the protective effect of phytochemicals from vegetables, and beverages.     

Isolation of acidophilic methane-oxidizing bacteria from northern peat wetlands

Acidic northern wetlands are an important source of methane, one of the gases that contributes to global warming. Methane oxidation in the surface of these acidic wetlands can reduce the methane flux to the atmosphere up to 90 percent. Here the isolation of three methanotrophic microorganisms from three boreal forest sites is reported. They are moderately acidophilic organisms and have a soluble methane monooxygenase. In contrast to the known groups of methanotrophs, 16S ribosomal DNA sequence analysis shows that they are affiliated with the acidophilic heterotrophic bacterium Beijerinckia indica subsp. indica.     

Effects of anaphylaxis mediators on partitioned pulmonary vascular resistance during ragweed shock in dogs

We examined the effect of anaphylactic shock on the longitudinal distribution of pulmonary vascular resistance (PVR) in ragweed-sensitized dogs in which PVR was partitioned into an upstream arterial component (Rus) and a downstream venous and capillary component (Rds). We also assessed whether Rus and Rds would be reduced by pretreatment with histamine H1- and H2-receptor blocking agents and with cyclooxygenase and lipoxygenase pathway inhibitors. Anesthetized animals were examined on separate occasions 3 wk apart in which one of the treatments was randomly given. The pulmonary arterial occlusion technique was used to determine segmental pressure drops. During ragweed challenge, PVR increased approximately 4 times compared with the preshock value (3.04 vs. 12. 07 mmHg . l-1 . min; P < 0.05). Although both Rus and Rds increased postshock, the greatest relative increase occurred in Rds. None of the treatments reduced partitioned resistances compared with no treatment. Our results show that, under conditions of anaphylactic shock, increases in Rus and Rds could not be ascribed to release of histamine or products of the cyclooxygenase and lipoxygenase pathways.     

Tumour seeding following percutaneous endoscopic gastrostomy placement in head and neck cancer

We report the case of a patient with advanced squamous carcinoma of the supraglottic larynx and hypopharynx who developed metastatic gastric deposits occurring at the site of a percutaneous endoscopic gastrostomy tube, inserted 10 months previously by the pull technique. We review seven previous reports of tumour deposits occurring at the site of placement of a percutaneous endoscopic gastrostomy in patients with head and neck cancer, and consider alternative methods of enteral feeding in such patients.     

Aggressiveness, hypoalgesia and high blood pressure in mice lacking the adenosine A2a receptor

Adenosine is released from metabolically active cells by facilitated diffusion, and is generated extracellularly by degradation of released ATP. It is a potent biological mediator that modulates the activity of numerous cell types, including various neuronal populations, platelets, neutrophils and mast cells, and smooth muscle cells in bronchi and vasculature. Most of these effects help to protect cells and tissues during stress conditions such as ischaemia. Adenosine mediates its effects through four receptor subtypes: the A1, A2a, A2b and A3 receptors. The A2a receptor (A2aR) is abundant in basal ganglia, vasculature and platelets, and stimulates adenylyl cyclase. It is a major target of caffeine, the most widely used psychoactive drug. Here we investigate the role of the A2a receptor by disrupting the gene in mice. We found that A2aR-knockout (A2aR-/-) mice were viable and bred normally. Their exploratory activity was reduced, whereas caffeine, which normally stimulates exploratory behaviour, became a depressant of exploratory activity. Knockout animals scored higher in anxiety tests, and male mice were much more aggressive towards intruders. The response of A2aR-/- mice to acute pain stimuli was slower. Blood pressure and heart rate were increased, as well as platelet aggregation. The specific A2a agonist CGS 21680 lost its biological activity in all systems tested.     

Physical activity patterns associated with cardiorespiratory fitness and reduced mortality: the Aerobics Center Longitudinal Study

OBJECTIVES: This study examined cross sectionally the physical activity patterns associated with low, moderate, and high levels of cardiorespiratory fitness. METHODS: Physical activity was assessed by questionnaire in a clinic population of 13,444 men and 3972 women 20 to 87 years of age. Estimated energy expenditure (kcal.wk-1) and volume (min.wk-1) of reported activities were calculated among individuals at low, moderate, and high fitness levels (assessed by maximal exercise tests). RESULTS: Average leisure time energy expenditures of 525 to 1650 kcal.wk-1 for men and 420 to 1260 kcal.wk-1 for women were associated with moderate to high levels of fitness. These levels of energy expenditure can be achieved with a brisk walk of approximately 30 minutes on most days of the week. In fact, men in the moderate and high fitness categories walked between 130 and 138 min.wk-1, and women in these categories walked between 148 and 167 min.wk-1. CONCLUSIONS: Most individuals should be able to achieve these physical activity goals and thus attain a cardiorespiratory fitness level sufficient to result in substantial health benefits.