Blood-respiratory and acid-base changes during extended diving in the bimodally respiring freshwater turtle Rheodytes leukops

Changes in blood-gas, acid-base, and plasma-ion status were investigated in the bimodally respiring turtle, Rheodytes leukops, during prolonged dives of up to 12 h. Given that R. leukops routinely submerges for several hours, the objective of this study was to determine whether voluntarily diving turtles remain aerobic and simultaneously avoid hypercapnic conditions over increasing dive lengths. Blood PO2, PCO2, and pH, as well as plasma concentrations of lactate, glucose, Na+, K+, Cl-, total Ca, and total Mg were determined in venous blood collected from the occipital sinus. Blood PO2 declined significantly with dive length; however, oxy-haemoglobin saturation remained greater than 30% for all R. leukops sampled. No changes were observed in blood PCO2, pH, [HCO3-], or plasma glucose, with increasing dive length. Despite repeated dives lasting more than 2 h, plasma lactate remained less than 3 mmol l(-1) for all R. leukops sampled, indicating the absence of anaerobiosis. Compensatory acid-base adjustments associated with anaerobiosis (e.g. declining [Cl-], increasing total [Ca] and [Mg]) were likewise absent, with plasma-ion concentrations remaining stable with increasing dive length. Results indicate that R. leukops utilises aquatic respiration to remain aerobic during prolonged dives, thus effectively avoiding the development of a metabolic and respiratory acidosis.

Endoscopic intratracheal carbon dioxide measurements during pediatric flexible bronchoscopy

Background: CO2 monitoring is recommended for thoracic telescopic procedures and for spontaneous breathing general anesthesia in children. During flexible bronchoscopy (FB) in children, the various currently available methods of CO2 measurements are limited. The CO2 falls and increases have been reported in FB but it is unknown whether airway lesions predispose to CO2 change. The aim of this study was to describe and validate endoscopic intratracheal CO2 measurements in children undergoing FB under spontaneously breathing GA. Methods: Endtidal CO2 (PECO2) measurements at the start (Start-CO2) and end (End-CO2) of FB on 100 consecutive children were performed using a newly designed endoscopic intratracheal method. To validate the method blood gas sampling was simultaneously performed in 28 children and results analyzed using the Bland and Altman method, intraclass correlation and 95% range for repeatability. Results: End-CO2 and CO2-change (End-CO2 minus Start-CO2) were significantly different in children with airway lesions (CO2 change: no lesion = 3 mmHg, extrathoracic airway lesion = 4.5, intrathoracic airway lesion = 8, P = 0.038). There was no significant difference in Start-CO2 values among the groups. CO2-change in those aged > 12 months was similar to those >12 months. Intratracheal CO2 measurements were comparable with arterial blood values in the Bland and Altman plots. The intraclass correlation was 0.69 and 95% range for repeatability was 3.7-4.17 mmHg. Conclusions: Midtracheal PECO2 provides a useful estimate of PaCO2 for monitoring the respiratory status of children undergoing FB. The presence of airway lesions rather than age is associated with significant increased PCO2 rise.

Population effects on individual systolic blood pressure: A multilevel analysis of the World Health Organization MONICA project

Individuals from the same population share a number of contextual circumstances that may condition a common level of blood pressure over and above individual characteristics. Understanding this population effect is relevant for both etiologic research and prevention strategies. Using multilevel regression analyses, the authors quantified the extent to which individual differences in systolic blood pressure (SBP) could be attributed to the population level. They also investigated possible cross-level interactions between the population in which a person lived and pharmacological (antihypertensive medication) and nonpharmacological (body mass index) effects on individual SBP. They analyzed data on 23,796 men and 24,986 women aged 35-64 years from 39 worldwide Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) study populations participating in the final survey of this World Health Organization project (1989-1997). SBP was positively associated with low educational achievement, high body mass index, and use of antihypertensive medication and, for women, was negatively associated with smoking. About 7-8% of all SBP differences between subjects were attributed to the population level. However, this population effect was particularly strong (i.e., 20%) in antihypertensive medication users and overweight women. This empirical evidence of a population effect on individual SBP emphasizes the importance of developing population-wide strategies to reduce individual risk of hypertension.

A population of HLA-DR+ immature cells accumulates in the blood dendritic cell compartment of patients with different types of cancer

Dendritic cell (DC) defects are an important component of immunosuppression in cancer. Here, we assessed whether cancer could affect circulating DC populations and its correlation with tumor progression. The blood DC compartment was evaluated in 136 patients with breast cancer, prostate cancer, and malignant glioma. Phenotypic, quantitative, and functional analyses were performed at various stages of disease. Patients had significantly fewer circulating myeloid (CD11c(+)) and plasmacytoid (CD123(+)) DC, and a concurrent accumulation of CD11c(-)CD123(-) immature cells that expressed high levels of HLA-DR+ immature cells (DR+IC). Although DR+IC exhibited a limited expression of markers ascribed to mature hematopoietic lineages, expression of HLA-DR, CD40, and CD86 suggested a role as antigen-presenting cells. Nevertheless, DR+IC had reduced capacity to capture antigens and elicited poor proliferation and interferon-gamma secretion by T-lymphocytes. Importantly, increased numbers of DR+IC correlated with disease status. Patients with metastatic breast cancer showed a larger number of DR+IC in the circulation than patients with local/nodal disease. Similarly, in patients with fully resected glioma, the proportion of DR+IC in the blood increased when evaluation indicated tumor recurrence. Reduction of blood DC correlating with accumulation of a population of immature cells with poor immunologic function may be associated with increased immunodeficiency observed in cancer.

An archaeology of the instant? Action and narrative in microscopic archaeological residue analyses

The discovery and interpretation of microscopic residues on stone artefacts is an expanding front within archaeological science, allowing reconstructions of the past use of specific tools. With notable exceptions, however, the field has seen little theoretical development, relying largely on a rationale in which either individual findings are widely generalized or the age of the site determines the importance of the results. Here an approach to residue interpretation is proposed that draws on notions of narrative, scale, action and agency as one means of expanding the theoretical scope and application of residue studies. It is suggested that the individual resonance of the findings of residue analyses with people in the present day can be used to provide a more nuanced understanding of past actions, which in turn allows both better integration and communication of those findings within and outside the archaeological comm unity, and begins to overcome the problems associated with the typically small sample sizes analysed in stone-tool residue studies.

Heritability and Stability of Resting Blood Pressure in Australian Twins

In Australian twins participating in three different studies (1979-1996), the contribution of genetic and environmental influences to variation in resting systolic (SBP) and diastolic blood pressure (DBP) was studied. The sample consisted of 368 monozygotic and 335 dizygotic twin pairs with measurements for both individuals. Blood pressure measurements in two studies were available for 115 complete twin pairs, and 49 twin pairs had measurements in three studies. This allowed assessment of blood pressure tracking over an average period of 12 years in the age range of 23 to 45 years. Multivariate analyses showed significant heritability (h(2)) of blood pressure in all studies (SBP h(2) = 19%-56%, DBP h(2) = 37%-52%). In addition, the analyses showed that the blood pressure tracking was explained by the same set of genetic factors. These results replicate an earlier finding in Dutch twins that also showed stability of the contribution of genetic factors to blood pressure tracking.

Numerical analysis of gas and micro-particle interactions in a hand-held shock-tube device

A unique hand-held gene gun is employed for ballistically delivering biomolecules to key cells in the skin and mucosa in the treatment of the major diseases. One of these types of devices, called the Contoured Shock Tube (CST), delivers powdered micro-particles to the skin with a narrow and highly controllable velocity distribution and a nominally uniform spatial distribution. In this paper, we apply a numerical approach to gain new insights in to the behavior of the CST prototype device. The drag correlations proposed by Henderson (1976), Igra and Takayama (1993) and Kurian and Das (1997) were applied to predict the micro-particle transport in a numerically simulated gas flow. Simulated pressure histories agree well with the corresponding static and Pitot pressure measurements, validating the CFD approach. The calculated velocity distributions show a good agreement, with the best prediction from Igra & Takayama correlation (maximum discrepancy of 5%). Key features of the gas dynamics and gas-particle interaction are discussed. Statistic analyses show a tight free-jet particle velocity distribution is achieved (570 +/- 14.7 m/s) for polystyrene particles (39 +/- 1 mu m), representative of a drug payload.