Effect of a single breath of 100% oxygen on respiration in neonates during sleep

To determine the effect of a single breath of 100% O2 on ventilation, 10 full-term [body wt 3,360 +/- 110 (SE) g, gestational age 39 +/- 0.4 wk, postnatal age 3 +/- 0.6 days] and 10 preterm neonates (body wt 2,020 +/- 60 g, gestational age 34 +/- 2 wk, postnatal age 9 +/- 2 days) were studied during active and quiet sleep states. The single-breath method was used to measure peripheral chemoreceptor response. To enhance response and standardize the control period for all infants, fractional inspired O2 concentration was adjusted to 16 +/- 0.6% for a control O2 saturation of 83 +/- 1%. After 1 min of control in each sleep state, each infant was given a single breath of O2 followed by 21% O2. Minute ventilation (VE), tidal volume (VT), breathing frequency (f), alveolar O2 and CO2 tension, O2 saturation (ear oximeter), and transcutaneous O2 tension were measured. VE always decreased with inhalation of O2 (P less than 0.01). In quiet sleep, the decrease in VE was less in full-term (14%) than in preterm (40%) infants (P less than 0.001). Decrease in VE was due primarily to a drop in VT in full-term infants as opposed to a fall in f and VT in preterm infants (P less than 0.05). Apnea, as part of the response, was more prevalent in preterm than in full-term infants. In active sleep the decrease in VE was similar both among full-term (19%) and preterm (21%) infants (P greater than 0.5). These results suggest greater peripheral chemoreceptor response in preterm than in full-term infants, reflected by a more pronounced decrease in VE with O2. The results are compatible with a more powerful peripheral chemoreceptor contribution to breathing in preterm than in full-term infants.     

gamma-Tocopherol nebulization by a lipid aerosolization device improves pulmonary function in sheep with burn and smoke inhalation injury

Fire accident victims who sustain both thermal injury to skin and smoke inhalation have gross evidence of systemic and pulmonary oxidant damage and acute lung injury. We hypothesized that gamma-tocopherol (gT), a reactive O(2) and N(2) scavenger, when delivered into the airway, would attenuate lung injury induced by burn and smoke inhalation. Acute lung injury was induced in chronically prepared, anesthetized sheep by 40% total burn surface area, third-degree skin burn and smoke insufflation (48 breaths of cotton smoke, <40 degrees C). The study groups were: (1) Sham (not injured, flaxseed oil (FO)-nebulized, n=6); (2) SA-neb (injured, saline-nebulized, n=6); (3) FO-neb (injured, FO-nebulized, n=6); and (4) gT+FO-neb (injured, gT and FO-nebulized, n=6). Nebulization was started 1 h postinjury, and 24 ml of FO with or without gT (51 mg/ml) was delivered into airways over 47 h using our newly developed lipid aerosolization device (droplet size: 2.5-5 microm). The burn- and smoke inhalation-induced pathological changes seen in the saline group were attenuated by FO nebulization; gT addition further improved pulmonary function. Pulmonary gT delivery along with a FO source may be a novel effective treatment strategy in management of patients with acute lung injury.     

Effects of myeloid sirtuin 1 deficiency on hypothalamic neurogranin in mice fed a high-fat diet

Hypothalamic inflammation has been known as a contributor to high-fat diet (HFD)-induced insulin resistance and obesity. Myeloid-specific sirtuin 1 (SIRT1) deletion aggravates insulin resistance and hypothalamic inflammation in HFD-fed mice. Neurogranin, a calmodulin-binding protein, is expressed in the hypothalamus. However, the effects of myeloid SIRT1 deletion on hypothalamic neurogranin has not been fully clarified. To investigate the effect of myeloid SIRT1 deletion on food intake and hypothalamic neurogranin expression, mice were fed a HFD for 20 weeks. Myeloid SIRT1 knockout (KO) mice exhibited higher food intake, weight gain, and lower expression of anorexigenic proopiomelanocortin in the arcuate nucleus than WT mice. In particular, KO mice had lower ventromedial hypothalamus (VMH)-specific neurogranin expression. However, SIRT1 deletion reduced HFD-induced hypothalamic neurogranin. Furthermore, hypothalamic phosphorylated AMPK and parvalbumin protein levels were also lower in HFD-fed KO mice than in HFD-fed WT mice. Thus, these findings suggest that myeloid SIRT1 deletion affects food intake through VMH-specific neurogranin-mediated AMPK signaling and hypothalamic inflammation in mice fed a HFD.     

Production, recovery and immunogenicity of the protective antigen from a recombinant strain of Bacillus anthracis

The protective antigen (PA) is one of the three components of the anthrax toxin. It is a secreted nontoxic protein with a molecular weight of 83 kDa and is the major component of the currently licensed human vaccine for anthrax. Due to limitations found in the existing vaccine formulation, it has been proposed that genetically modified PA may be more effective as a vaccine. The expression and the stability of two recombinant PA (rPA) variants, PA-SNKE-ΔFF-E308D and PA-N657A, were studied. These proteins were expressed in the nonsporogenic avirulent strain BH445. Initial results indicated that PA-SNKE-ΔFF-E308D, which lacks two proteolysis-sensitive sites, is more stable than PA-N657A. Process development was conducted to establish an efficient production and purification process for PA-SNKE-ΔFF-E308D. pH, media composition, growth strategy and protease inhibitors composition were analyzed. The production process chosen was based on batch growth of B. anthracis using tryptone and yeast extract as the only source of carbon, pH control at 7.5, and antifoam 289. Optimal harvest time was 14–18 h after inoculation, and EDTA (5 mM) was added upon harvest for proteolysis control. Recovery of the rPA was performed by expanded-bed adsorption (EBA) on a hydrophobic interaction chromatography (HIC) resin, eliminating the need for centrifugation, microfiltration and diafiltration. The EBA step was followed by ion exchange and gel filtration. rPA yields before and after purification were 130 and 90 mg/l, respectively. The purified rPA, without further treatment, treated with small amounts of formalin or adsorbed on alum, induced, high levels of IgG anti-PA with neutralization activities. Journal of Industrial Microbiology & Biotechnology (2002) 28, 232–238 DOI: 10.1038/sj/jim/7000239 Received 28 August 2001/ Accepted in revised form 20 December 2001     

Interleukin-10 regulates arterial pressure in early primate pregnancy

OBJECTIVES: In pregnancy, the placental contribution of cytokines to maternal immunosuppression has been established, however their role in normal maternal blood pressure regulation has not been identified. We investigate the contribution of interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-alpha) to the vasodilation of early pregnancy in non-human primates. We also sequenced the IL-10 baboon gene and compared it with humans. METHODS: The effect of four different treatments, administered sequentially (semi-random-design) on resting 18h, night time, or hourly mean arterial pressure (MAP) and heart rate (HR) were measured using telemetry. An anti-human IL-10 monoclonal antibody (MAb, 1mg, n=7), anti-TNF-alpha antibody (n=3), a combination of anti-IL-10 and anti-TNF-alpha antibodies (n=5) or saline (n=3) control were administered intravenously to baboons in early pregnancy. Plasma and placental IL-10 concentration was measured before and after injection in all animals. RESULTS: Anti-human IL-10 MAb caused a significant increase in MAP of 2.6+/-0.5mmHg over the 18-h period (p<0.05). Administration of TNF-alpha alone or in combination with IL-10 did not alter MAP. There was 97% sequence homology of IL-10 cDNA between humans and baboons. CONCLUSIONS: IL-10 was shown to regulate the vasodilation of early pregnancy in Papio hamadryas. This partial role of IL-10 in the early BP response of primate pregnancy may be relevant to pathophysiological states of human pregnancy such as preeclampsia.     

Measurement of pO2 by luminescence lifetime spectroscopy: A comparative study of the phototoxicity and sensitivity of [Ru(Phen)3]2+ and PdTCPP in vivo

Dysfunctions in tissue metabolism can be detected at early stages by oxygen partial pressure (pO₂) measurement. The measurement of emission lifetimes offers very promising and non‐invasive approach to estimate pO₂ in vivo. This study compares two extensively used oxygen sensors and assesses their in vivo oxygen sensitivity and phototoxic effect. Luminescence lifetime of Ru‐polypyridyl complex and of Pd‐porphyrin is measured in the Chick's Chorioallantoic Membrane (CAM) model with a dedicated optical fiber‐based, time‐resolved spectrometer. The Pd‐porphyrin luminescence lifetimes measured in the CAM model exposed to different pO₂ levels are longer and have a broader dynamic range (10–100 μs) than those of Ru‐polypyridyl complex (0.6–1 μs). The combined statistical analysis based on an estimate of the kurtosis and skewness, bootstrapping method and routine normality tests is performed. The indicators of the averages and signal to noise ratio stability are also calculated. The combination of several data processing allows selection of the better sensor for a given application. In particular, it is found that the advantage of Ru‐polypyridyl complex over Pd‐porphyrin is two‐fold: i) Ru‐polypyridyl complex datasets have consistently better statistical characteristics, ii) Ru‐polypyridyl exhibits lower cytotoxicity.

     

Host-specific regulation of nodulation genes in Rhizobium is mediated by a plant-signal, interacting with the nodD gene product

We have identified a nodD gene from the wide host-range Rhizobium strain MPIK3030 (termed nodD1) which is essential for nodulation on Macroptilium atropurpureum (siratro). Experiments with nodA–lacZ gene fusions demonstrate that the MPIK3030 nodD1 regulates expression of the nodABC genes. Additionally, we used nodC–lacZ fusions of Rhizobium meliloti to show that the MPIK3030 nodD1 gene induces expression of these fusions by interacting with plant factors from siratro and from the non-host Medicago sativa (alfalfa). The R. meliloti nodD genes, however, only interact with alfalfa exudate. In line with these results, no complementation of MPIK3030 nodD1 mutants could be obtained on siratro with the R. meliloti nodD genes, while the MPIK3030 nodD1 can complement nodD mutants of R. meliloti on alfalfa. Furthermore, R. meliloti transconjugants harbouring the MPIK3030 nodD1 efficiently nodulate the illegitimate host siratro. When compared with other nodD sequences, the amino acid sequence of the MPIK3030 nodD1 shows a conserved aminoterminus, whereas the carboxy-terminus of the putative gene product diverges considerably. Studies on a chimeric MPIK3030/R. meliloti nodD gene indicates that the carboxy-terminal region is responsible for the interaction with plant factor(s) and may have evolved in different rhizobia specifically to interact with plant–host factors.     

Lipid phenotyping of lung epithelial lining fluid in healthy human volunteers

Background

Lung epithelial lining fluid (ELF)—sampled through sputum induction—is a medium rich in cells, proteins and lipids. However, despite its key role in maintaining lung function, homeostasis and defences, the composition and biology of ELF, especially in respect of lipids, remain incompletely understood.

Objectives

To characterise the induced sputum lipidome of healthy adult individuals, and to examine associations between different ELF lipid phenotypes and the demographic characteristics within the study cohort.

Methods

Induced sputum samples were obtained from 41 healthy non-smoking adults, and their lipid compositions analysed using a combination of untargeted shotgun and liquid chromatography mass spectrometry methods. Topological data analysis (TDA) was used to group subjects with comparable sputum lipidomes in order to identify distinct ELF phenotypes.

Results

The induced sputum lipidome was diverse, comprising a range of different molecular classes, including at least 75 glycerophospholipids, 13 sphingolipids, 5 sterol lipids and 12 neutral glycerolipids. TDA identified two distinct phenotypes differentiated by a higher total lipid content and specific enrichments of diacyl-glycerophosphocholines, -inositols and -glycerols in one group, with enrichments of sterols, glycolipids and sphingolipids in the other. Subjects presenting the lipid-rich ELF phenotype also had significantly higher BMI, but did not differ in respect of other demographic characteristics such as age or gender.

Conclusions

We provide the first evidence that the ELF lipidome varies significantly between healthy individuals and propose that such differences are related to weight status, highlighting the potential impact of (over)nutrition on lung lipid metabolism.