A numerical simulation of intranasal air temperature during inspiration

OBJECTIVES/HYPOTHESIS: In vivo measurements of the intranasal air temperature are feasible. The present study was designed to reproduce temperature distributions within the human nasal cavity by means of numerical simulation. STUDY DESIGN: Numerical simulation. METHODS: Based on computed tomography (CT), a steady-state computational fluid dynamics (CFD) simulation was performed displaying the temperature distribution throughout the human nasal cavity during inspiration. The results of the numerical simulation were compared with in vivo temperature measurements. RESULTS: The numerical simulation demonstrated that the major increase of the inspiratory air temperature can be found in the anterior nasal segment, especially within the nasal valve area, which is comparable to in vivo measurements. Intranasal areas of high temperature were characterized by turbulent airflow with vortices of low velocity. The results of numerical simulation showed an excellent comparability to the results of previous in vivo measurements in the entire nasal cavity. CONCLUSION: The anterior nasal segment is the most effective part of the nose in heating of the ambient air. The findings demonstrated the complexity of the relationship between airflow patterns and heating of inspired air. A numerical simulation of the temperature distribution using CFD is practicable.     

Effect of oral bacteria on peripheral blood leukocyte interleukin-6 and soluble interleukin-6 receptor production

To determine the effect of pathogenic oral bacteria on interleukin 6 (IL-6) and soluble IL-6 receptor production, we measured their release by human peripheral blood mononuclear cells in vitro. Unseparated peripheral blood mononuclear cells, peripheral blood lymphocytes (monocyte depleted), pure T cells, or monocytes were cultured with Actinobacillus actinomycetemcomitans, Capnocytophaga gingivalis, Capnocytophaga ochracea, Fusobacterium nucleatum or Porphyromonas gingivalis for 24 h. Supernatants were tested for IL-6 and soluble IL-6 receptor by enzyme-linked immunosorbent assay. Only monocytes and peripheral blood mononuclear cells responded with significant IL-6 release in the presence of all bacteria tested. However, peripheral blood lymphocytes were capable of producing IL-6 when activated by phytohemagglutinin or IL-2 followed by bacteria, though substantially less than cultures containing monocytes. No bacteria tested increased soluble IL-6 receptor release over spontaneous soluble IL-6 receptor release. We conclude that monocytes release IL-6 after contact with oral pathogens; however, soluble IL-6 receptor from T cells and monocytes is constitutively produced and may modulate EL-6 actions.     

Effect of low and moderate doses of recombinant human erythropoietin on the haematological response in premature infants on a high protein and iron intake

There is no consensus regarding protein intake and the doses of recombinant human erythropoietin (r-HuEpo) and iron in the treatment of anaemia of prematurity (AOP). This open, randomized study has compared the effectiveness of 50 IU r-HuEpo/kg with that of 100 IU/kg, both given subcutaneously thrice weekly. In addition, two different protein supplements have been compared; lyophilized human milk protein and a commercial cow’s milk product. Total protein intake was 3 g/kg per day. Daily iron dose was 18–36 mg. “Healthy” preterm infants (n = 32, birth weight: 800–1400 g, gestational age ≤ 31 weeks) were studied from age 3 to 8 weeks. The two protein regimens yielded no differences in body growth, reticulocyte count or Hb concentration. In both r-HuEpo dose groups increased number of reticulocytes followed start of treatment; higher levels were, however, found in the group receiving 100 IU/kg. Mean Hb concentration plateaued at 12 g/dl for infants receiving 100 IU/kg, at 11 g/dl in the 50 IU/kg group. Even though serum levels of ferritin and transferrin saturation indicated no iron deficiency, soluble transferrin receptor increased in both groups, more rapidly and to higher levels in the 100 IU/kg group. In addition, the number of infants having more than 8% hypochromic red cells increased in both groups. Conclusions Commercial cow’s milk protein added to human milk was as good as human milk protein supplementation in supporting growth and erythropoiesis. Fifty IU/kg r-HuEpo thrice weekly during AOP stimulated erythropoiesis significantly, but less so than 100 IU/kg. Even when using high oral doses of iron to preterms receiving r-HuEpo, our data suggested a certain degree of iron deficient erythropoiesis. Received: 20 January 1996 / Accepted: 2 February 1996     

Die Endoskopie als Diagnostik und Therapie bei der kinderlosen Frau

Ohne Zusammenfassung     

The relationship between water vapour saturation of inhaled air and nasal patency.

The nasal cavity volume and the temperature of the nasal mucosa are considered to be the most important predictors of nasal conditioning. The aim of this study was to assess the relationship between the intranasal degree of water vapour saturation of inhaled air and nasal patency. Intranasal humidity values at different locations within the nasal cavity of 15 healthy subjects were compared to nasal airway resistance detected by active anterior rhinomanometry (AAR). Repeated measurements were carried out during one day to obtain varying nasal cavity volumes due to the nasal cycle. The end-inspiratory humidity data were obtained with a miniaturised capacitive humidity sensor at defined detection sites within the anterior nasal segment without interruption of nasal breathing. Measurements were carried out at four different times during one day. The degree of water vapour saturation did not correlate with the values of the AAR at any intranasal detection site and time of detection during one day. The study supports the view that there is no correlation between the degree of water vapour saturation within the anterior nasal segment and the nasal resistance during the nasal cycle over the day. Although nasal patency varies because of the nasal cycle, the changes of nasal cavity volume due to the nasal cycle do not seem to influence the degree of water vapour saturation of the inspiratory air.     

Taking Nature's Pulse

Book reviewed in this article: Ecosystem Health: New Goals for Environmental Management . Ed. Robert Costanza, Bryan G. Norton, and Benjamin D. Haskell     

Mechanism of resistance to tumor necrosis factor

To find clues as to the possible mechanisms of resistance against the cytotoxic activity of tumor necrosis factor (TNF), we developed TNF-resistant and TNF-sensitive subclones of the human cervic carcinoma cell line ME 180 and the mammary carcinoma cell line BT-20. Resistant subclones were selected by gradually increasing the TNF concentration in the culture medium over 4 months or 20 passages. Resistance to TNF was conserved in the absence of TNF after nearly 3 years and less than 100 passages. There were no differences in the number and affinity of TNF receptors between the sensitive and resistant clones. Similarly, SDS-PAGE of cell lysates showed identical bands. Sensitivity to actinomycin D, mitomycin C, and interferon-gamma was the same. No TNF message could be demonstrated in either subclone. As tumors grown in nude mice derived from the sensitive and resistant clones responded equally well to an intratumoral injection of TNF, we conclude that different mechanisms are responsible for sensitivity and resistance to the cytotoxic effect of TNF in vitro and in vivo.