Antioxidant defence during cardiopulmonary bypass surgery.

OBJECTIVE: Cardiac surgery may lead to severe oxidative stress due to formation of oxidation products generated during ischemia and reperfusion. We investigated to which extent oxidative stress influences a number of endogenous antioxidants and markers of cellular activation. METHODS: At six time points blood was withdrawn from patients undergoing coronary artery bypass grafting, using the on-pump procedure. RESULTS: Both glutathione peroxidase and superoxide dismutase show a gradual and strong increase in activity during surgery (40 and 30%, respectively), returning to baseline values 24 h after surgery. The total antioxidant capacity has a maximum increase of 60%. Markers of cellular activation, such as eosinophil cationic protein and tryptase also increase during the procedure. CONCLUSION: Cardiac surgery results in systemic inflammation accompanied or caused by severe oxidative stress. The human body has a strong innate oxidative defence screen, which is probably not sufficient to fully compensate for the total amount of oxidative damage.     

The shufflon of Salmonella enterica serovar Typhi regulates type IVB pilus-mediated bacterial self-association

Previously, it was shown that type IVB pili encoded by the Salmonella enterica serovar Typhi pil operon are used to facilitate bacterial entry into human intestinal epithelial cells in vitro and that such entry is inhibited by purified prepilin (pre-PilS) protein (X.-L. Zhang, I. S. M. Tsui, C. M. C. Yip, A. W. Y. Fung, D. K.-H. Wong, X. Dai, Y. Yang, J. Hackett, and C. Morris, Infect. Immun. 68:3067-3073, 2000). The pil operon concludes with a simple shufflon, and a recombinase gene product (Rci) inverts DNA in the C-terminal region of the pilV gene to allow synthesis of two distinct PilV proteins, PilV1 and PilV2, which are presumptive minor pilus proteins. We show here that the type IVB pili mediate bacterial self-association, but only when the PilV1 and PilV2 proteins are not expressed. This may be achieved in wild-type serovar Typhi by rapid DNA inversion activity of the shufflon. We show that the inversion activity inhibits the expression of genes inserted between the 19-bp inverted repeats used for Rci-mediated recombination and that the activity of Rci increases when DNA is supercoiled. The data suggest that serovar Typhi self-associates under conditions (such as low oxygen tension in the gut) that favor DNA supercoiling. These results explain (i) the function of the serovar Typhi shufflon and (ii) why there are only two possible shufflon states, in contrast to the many possible states of other shufflon systems. The data further indicate that a very early step in serovar Typhi pathogenesis may be type IVB pilus-mediated self-association of bacteria in the anaerobic human small intestine prior to invasion of the human gut epithelium. The suggested type IVB pilus-dependent step in typhoid fever pathogenesis may partially explain the enhanced invasiveness of serovar Typhi for humans.     

Factors in the inactivation of Encephalomyocarditis virus in aerosols.

Encephalomyocarditis virus in aerosols is inactivated rapidly at relative humidities below 50%. In glycerol-water mixtures a similar decrease of infectivity occurs when the glycerol concentration exceeds 78% (wt/wt), corresponding to a relative humidity of 50%. The decay in aerosols does not involve oxygen or surface-dependent factors. Variation of temperature shows the inactivation to be a low-energy process with an activation enthalpy of 15 kcal per mol. The damage could be ascribed to dehydration of the virion, presumably proceeding to removal of structurally essential water molecules. This might trigger irreversible changes in the protein coat, resulting in disintegration of the virion.     

GETTING NO RESPECT: BARRIERS TO MAMMOGRAPHY FOR A GROUP OF SWEDISH WOMEN

Mammography screening is a highly sensitive and specific method to detect breast cancer at an early stage. If screening campaigns are to be cost effective, compliance is valuable. However, many women do not attend when called for mammography screening. Our aim in this study is to understand and explain why women become nonattenders. A sample of 16 nonattending women, aged between 43 and 73 years, participated in this qualitative study, by interviews or written comments. The core category discovered in the data was ``getting no respect.'' The informants did not feel respected from either the society or the health care system. Below this core category, two categories were identified: the mammography examination and affecting circumstances. The performance and its effects comprised the content of the category of mammography examination. The category affecting circumstances included knowledge about risk factors, prevention, and practical or emotional arguments.     

Carbon dioxide inhalation as a human experimental model of panic: The relationship between emotions and cardiovascular physiology

Inhaling carbon dioxide (CO₂)-enriched air induces fear and panic symptoms resembling real-life panic attacks, the hallmark of panic disorder. The present study aimed to describe the emotional and cardiovascular effects evoked by inhaling CO₂, taking shortcomings of previous studies into account. Healthy volunteers underwent a double inhalation of 0, 9, 17.5, and 35% CO₂, according to a randomized, cross-over design. In addition to fear, discomfort, and panic symptom ratings, blood pressure and heart rate were continuously monitored. Results showed a dose-dependent increase in all self-reports. Systolic and diastolic blood pressure rose with increasing CO₂ concentration, whereas heart rate results were less consistent. Diastolic blood pressure and heart rate variation correlated with fear and discomfort. Based on this relationship and the observation that the diastolic blood pressure most accurately mimicked the degree of self-reported emotions, it might serve as a putative biomarker to assess the CO₂-reactivity in the future.