Action of sorbic acid on Staphylococcus metabolism: a microcalorimetric investigation.

Effect of sorbic acid, an antimicrobial food preservative, on the cellular metabolism of Staphylococcus aureus was observed microcalorimetrically. The highly reproducible and characteristic thermograms of the microorganism were affected significantly by the preservative in a concentration dependent manner. Both the peak heat and total heat dissipation profiles were affected by 50% at the maximum permitted concentration (0.2%) for use in foods.     

Differences in the altered energy metabolism of hemorrhagic shock and hypoxemia.

The effect of hemorrhagic shock, hypoxemia, and anoxia on the levels of adenine and pyridine nucleotides of liver and kidney was assessed. ATP levels in liver and kidney of animals in shock or animals subjected to 7 min of anoxia decreased by 85 and 73%, respectively. Under hypoxic conditions (arterial PO2 AT 18 MMHg), the decrease was only 62 and 48% in liver and kidney, respectively. Tissue NAD levels decreased and NADH levels increased during shock but were found to be essentially unaltered during experimental hypoxemia. Thus, shock produced greater alterations in adenine and pyridine nucleotides than did hypoxemia alone, indicating that stagnant hypoxemia due to shock is more deleterious to energy metabolism than is severe hypoxemia with an otherwise normal circulation. The results also suggest that if an anterial PO2 OF 18 MMHg represents the initial stages of tissue hypoxia, then tissue ATP levels are a more sensitive indicator of this than NAD levels.     

Transorbital Sonographic Evaluation of Normal Optic Nerve Sheath Diameter in Healthy Volunteers in Bangladesh

Introduction

Measurement of optic nerve sheath diameter (ONSD) by ultrasound is increasingly used as a marker to detect raised intracranial pressure (ICP). ONSD varies with age and there is no clear consensus between studies for an upper limit of normal. Knowledge of normal ONSD in a healthy population is essential to interpret this measurement.

Methods

In a prospective observational study, ONSD was measured using a 15 MHz ultrasound probe in healthy volunteers in Chittagong, Bangladesh. The aims were to determine the normal range of ONSD in healthy Bangladeshi adults and children, compare measurements in males and females, horizontal and vertical beam orientations and left and right eyes in the same individual and to determine whether ONSD varies with head circumference independent of age.

Results

136 subjects were enrolled, 12.5% of whom were age 16 or under. Median ONSD was 4.41 mm with 95% of subjects in the range 4.25–4.75 mm. ONSD was bimodally distributed. There was no relationship between ONSD and age (≥4 years), gender, head circumference, and no difference in left vs right eye or horizontal vs vertical beam.

Conclusions

Ultrasonographic ONSD in Bangladeshi healthy volunteers has a narrow bimodal distribution independent of age (≥4 years), gender and head circumference. ONSD >4.75 mm in this population should be considered abnormal.     

Dietary patterns,abdominal visceral adipose tissue,and cardiometabolic risk factors in African Americans: The Jackson heart study

Objective:

To examine the relative association of abdominal visceral adipose tissue (VAT) with cardiometabolic risk factors between African and European Americans.

Design and Methods:

We conducted a cross‐sectional study of 2035 African Americans from Jackson Heart Study (JHS) and 3170 European Americans from Framingham Heart Study (FHS) who underwent computed tomography assessment of VAT and subcutaneous adipose tissue (SAT). The FHS participants were weighted to match the age distribution of the JHS participants and the metabolic risk factors were examined by study groups in relation to VAT.

Results:

JHS participants had higher rates of obesity, hypertension, diabetes and metabolic syndrome than FHS participants (all p = 0.001). The associations were weaker in JHS women for VAT with blood pressure, triglycerides, HDL‐C, and total cholesterol (p_interaction = 0.03 to 0.001) than FHS women. In contrast, JHS men had stronger associations for VAT with high triglycerides, low HDL, and metabolic syndrome (all p_interaction = 0.001) compared to FHS men. Similar associations and gender patterns existed for SAT with most metabolic risk factors.

Conclusions:

The relative association between VAT and cardiometabolic risk factors is weaker in JHS women compared to FHS women, whereas stronger association with triglycerides and HDL were observed in JHS men.     

Influence of mycorrhizal fungi on seed germination and growth in terrestrial and epiphytic orchids

Epiphytes constitute over 70% of orchid diversity, but little is known about the functioning of their mycorrhizal associations. Terrestrial orchid seeds germinate symbiotically in soil and leaf litter, whereas epiphytic orchids may be exposed to relatively high light levels from an early stage of development and often produce green seeds. This suggests that seedlings of the two groups of orchids may differ in their responses to light and requirements for mycorrhiza-supplied carbon. The interactive effects of light, exogenous carbon and mycorrhizal status on germination and growth were investigated in vitro using axenic agar microcosms for one tropical epiphyte and three geophytic orchid species. The geophytic species strongly depended on their mycorrhiza for growth and this could not be substituted by exogenous sucrose, whereas the epiphytic species achieved 95% of the mycorrhizal seedling volume when supplied with exogenous sucrose in the dark. Mycorrhiza status strongly interacted with light exposure, enabling germination. Light inhibited or severely reduced growth, especially for the terrestrial orchids in the absence of mycorrhiza. For the first time, this study showed the parallel ecological importance of mycorrhizal fungi in overcoming light inhibition of seed germination and growth in both terrestrial and epiphytic orchids.     

Fatty Acids Induce Chloride Permeation in Rat Liver Mitochondria by Activation of the Inner Membrane Anion Channel (IMAC)

The inner membrane of freshly isolated mammalian mitochondria is poorly permeable to Cl(-). Low, nonlytic concentrations (< or =30 microM) of long-chain fatty acids or their branched-chain derivatives increase permeation of Cl(-) as indicated from rapid large-scale swelling of mitochondria suspended in slightly alkaline KCl medium (supplemented with valinomycin). Myristic, palmitic, or 5-doxylstearic acid are powerful inducers of Cl(-) permeation, whereas lauric, phytanic, stearic, or 16-doxylstearic acid stimulate Cl(-) permeation in a lesser extent. Fatty acid-induced Cl(-) permeation across the inner membrane correlates well with the property of nonesterified fatty acids to release endogenous Mg(2+) from mitochondria. Myristic acid stimulates anion permeation in a selective manner, similar as was described for A23187, an activator of the inner membrane anion channel (IMAC). Myristic acid-induced Cl(-) permeation is blocked by low concentrations of tributyltin chloride (IC(50) approximately 1.5 nmol/mg protein). Moreover, myristic acid activates a transmembrane ion current in patch-clamped mitoplasts (mitochondria with the outer membrane removed) exposed to alkaline KCl medium. This current is best ascribed to the opening of an ion channel with a single-channel conductance of 108 pS. We propose that long-chain fatty acids can activate IMAC by withdrawal of Mg(2+) from intrinsic binding sites.     

Lyn- and ERK-mediated vs. Ca2+-mediated neutrophil O2- responses with thermal injury

We evaluated thedependency of neutrophil O production on PTK-Lyn andMAPK-ERK1/2 in rats after thermal injury. Activation of PTK-Lyn wasassessed by immunoprecipitation. Phosphorylation of ERK1/2 was assessedby Western blot analysis. O production was measuredby isoluminol-enhanced luminometry. Imaging technique was employed tomeasure neutrophil [Ca²⁺]_i in individualcells. Thermal injury caused marked upregulation of Lyn and ERK1/2accompanying enhanced neutrophil O production.Treatment of rats with PTK blocker (AG556) or MAPK blocker (AG1478)before burn injury caused complete inhibition of the respective kinaseactivation. Both AG556 and AG1478 produced an ~66% inhibition inO production. Treatment with diltiazem (DZ) producedan ~37% inhibition of O production withoutaffecting Lyn or ERK1/2 activation with burn injury. Ca²⁺mobilization was upregulated with burn injury but not affected bytreatment of burn rats with AG556. Unlike the partial inhibition ofburn-induced O production by AG556, AG1478, or DZ,platelet-activating factor antagonist (PAFa) treatment of burn ratsproduced near complete inhibition of O production.PAFa treatment also blocked activation of Lyn. The findings suggestthat the near complete inhibition of O production byPAFa was a result of blockade of PTK as well as Ca²⁺signaling. Overall, our studies show that enhanced neutrophil O production after thermal injury is a result ofpotentiation of Ca²⁺-linked and -independent signalingtriggered by inflammatory agents such as PAF.

     

Gut-associated lymphoid T cell suppression enhances bacterial translocation in alcohol and burn injury

The mechanism of alcohol-mediated increased infection in burn patients remains unknown. With the use of a rat model of acute alcohol and burn injury, the present study ascertained whether acute alcohol exposure before thermal injury enhances gut bacterial translocation. On day 2 postinjury, we found a severalfold increase in gut bacterial translocation in rats receiving both alcohol and burn injury compared with the animals receiving either injury alone. Whereas there were no demonstrable changes in intestinal morphology in any group of animals, a significant increase in intestinal permeability was observed in ethanol- and burn-injured rats compared with the rats receiving either injury alone. We further examined the role of intestinal immune defense by determining the gut-associated lymphoid (Peyer's patches and mesenteric lymph nodes) T cell effector responses 2 days after alcohol and burn injury. Although there was a decrease in the proliferation and interferon-gamma by gut lymphoid T cells after burn injury alone; the suppression was maximum in the group of rats receiving both alcohol and burn injuries. Furthermore, the depletion of CD3(+) cells in healthy rats resulted in bacterial accumulation in mesenteric lymph nodes; such CD3(+) cell depletion in alcohol- and burn-injured rats furthered the spread of bacteria to spleen and circulation. In conclusion, our data suggest that the increased intestinal permeability and a suppression of intestinal immune defense in rats receiving alcohol and burn injury may cause an increase in bacterial translocation and their spread to extraintestinal sites.     

A Phase I Double Blind,Placebo-Controlled,Randomized Study of the Safety and Immunogenicity of an Adjuvanted HIV-1 Gag-Pol-Nef Fusion Protein and Adenovirus 35 Gag-RT-Int-Nef Vaccine in Healthy HIV-Uninfected African Adults

Background

Sequential prime-boost or co-administration of HIV vaccine candidates based on an adjuvanted clade B p24, RT, Nef, p17 fusion protein (F4/AS01) plus a non-replicating adenovirus 35 expressing clade A Gag, RT, Int and Nef (Ad35-GRIN) may lead to a unique immune profile, inducing both strong T-cell and antibody responses.

Methods

In a phase 1, double-blind, placebo-controlled trial, 146 healthy adult volunteers were randomized to one of four regimens: heterologous prime-boost with two doses of F4/AS01_E or F4/AS01_B followed by Ad35-GRIN; Ad35-GRIN followed by two doses of F4/AS01_B; or three co-administrations of Ad35-GRIN and F4/AS01_B. T cell and antibody responses were measured.

Results

The vaccines were generally well-tolerated, and did not cause serious adverse events. The response rate, by IFN-γ ELISPOT, was greater when Ad35-GRIN was the priming vaccine and in the co-administration groups. F4/AS01 induced CD4+ T-cells expressing primarily CD40L and IL2 +/- TNF-α, while Ad35-GRIN induced predominantly CD8+ T-cells expressing IFN-γ +/- IL2 or TNF-α. Viral inhibition was induced after Ad35-GRIN vaccination, regardless of the regimen. Strong F4-specific antibody responses were induced. Immune responses persisted at least a year after the last vaccination. The complementary response profiles, characteristic of each vaccine, were both expressed after co-administration.

Conclusion

Co-administration of an adjuvanted protein and an adenovirus vector showed an acceptable safety and reactogenicity profile and resulted in strong, multifunctional and complementary HIV-specific immune responses.

Trial Registration

ClinicalTrials.gov NCT01264445     

Vitamin D Prevents Hypoxia/Reoxygenation-Induced Blood-Brain Barrier Disruption via Vitamin D Receptor-Mediated NF-kB Signaling Pathways

Maintaining blood-brain barrier integrity and minimizing neuronal injury are critical components of any therapeutic intervention following ischemic stroke. However, a low level of vitamin D hormone is a risk factor for many vascular diseases including stroke. The neuroprotective effects of 1,25(OH)2D3 (vitamin D) after ischemic stroke have been studied, but it is not known whether it prevents ischemic injury to brain endothelial cells, a key component of the neurovascular unit. We analyzed the effect of 1,25(OH)₂D₃ on brain endothelial cell barrier integrity and tight junction proteins after hypoxia/reoxygenation in a mouse brain endothelial cell culture model that closely mimics many of the features of the blood-brain barrier in vitro. Following hypoxic injury in bEnd.3 cells, 1,25(OH)₂D₃ treatment prevented the decrease in barrier function as measured by transendothelial electrical resistance and permeability of FITC-dextran (40 kDa), the decrease in the expression of the tight junction proteins zonula occludin-1, claudin-5, and occludin, the activation of NF—kB, and the increase in matrix metalloproteinase-9 expression. These responses were blocked when the interaction of 1,25(OH) )₂D₃ with the vitamin D receptor (VDR) was inhibited by pyridoxal 5’-phosphate treatment. Our findings show a direct, VDR-mediated, protective effect of 1,25(OH) )₂D₃ against ischemic injury-induced blood-brain barrier dysfunction in cerebral endothelial cells.