A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

Characteristics of 2-oxoglutarate and glutamate transport in spinach chloroplasts

The transport of glutamate, 2-oxoglutarate and malate in intact spinach chloroplasts was determined using a double-silicone-layer centrifugation technique in which the silicone layers stayed separated at the end of centrifugation. Glutamate was found to be transported via the dicarboxylate but not the 2-oxoglutarate translocator. Hence the kinetic parameters (i.e.K _m,K _i andV _max) determined in glutamate-preloaded chloroplasts represent the kinetic constants of the dicarboxylate translocator. Measurements from malate- or succinate-preloaded chloroplasts represent the aggregate values of both the dicarboxylate and the 2-oxoglutarate translocators. Calculations showed that the 2-oxoglutarate and glutamate transport required to support the high fluxes of photorespiratory NH₃ recycling could be achieved if the transport of these two dicarboxylates occurred on separate translocators. It is proposed that during photorespiration the transport of 2-oxoglutarate into and glutamate out of the chloroplast occurred via the 2-oxoglutarate and the dicarboxylate translocators, respectively. These transports are coupled to malate counter-exchange in a cascade-like manner resulting in a net 2-oxoglutarate/glutamate exchange with no net malate uptake.Abbreviation 2-OG 2-oxoglutarate     

Pulmonary mechanics during rapid mechanical ventilation in rabbits with saline-lavaged lungs

Infants with respiratory failure are frequently mechanically ventilated at rates exceeding 60 breaths/min. We analyzed the effect of ventilatory rates of 30, 60, and 90 breaths/min (inspiratory times of 0.6, 0.3, and 0.2 s, respectively) on the pressure-flow relationships of the lungs of anesthetized paralyzed rabbits after saline lavage. Tidal volume and functional residual capacity were maintained constant. We computed effective inspiratory and expiratory resistance and compliance of the lungs by dividing changes in transpulmonary pressure into resistive and elastic components with a multiple linear regression. We found that mean pulmonary resistance was lower at higher ventilatory rates, while pulmonary compliance was independent of ventilatory rate. The transpulmonary pressure developed by the ventilator during inspiration approximated a linear ramp. Gas flow became constant and the pressure-volume relationship linear during the last portion of inspiration. Even at a ventilatory rate of 90 breaths/min, 28-56% of the tidal volume was delivered with a constant inspiratory flow. Our findings are consistent with the model of Bates et al. (J. Appl. Physiol. 58: 1840-1848, 1985), wherein the distribution of gas flow within the lungs depends predominantly on resistive factors while inspiratory flow is increasing, and on elastic factors while inspiratory flow is constant. This dynamic behavior of the surfactant-depleted lungs suggests that, even with very short inspiratory times, distribution of gas flow within the lungs is in large part determined by elastic factors. Unless the inspiratory time is further shortened, gas flow may be directed to areas of increased resistance, resulting in hyperinflation and barotrauma.     

Distortion of chest wall and work of diaphragm in preterm infants

Chest wall distortion is common in infants and is especially visible in preterm infants. It has been suggested that this distortion increases the volume displacement of the diaphragm during inspiration, which may be associated with muscular fatigue and apnea. We studied 10 preterm infants who had no evidence of lung disease, investigating the effect of chest wall distortion on the volume displacement and work of the diaphragm. The volume changes of the respiratory system were partitioned using an inductance plethysmograph. The minute volume displacement and the work of the diaphragm were calculated using the partitioned abdominal volume change and the gastric and esophageal pressures. The paradoxical movement of the chest wall lasted an average of 36% of inspiration. The minute volume displacement of the diaphragm ranged from 72 to 176% of the minute pulmonary ventilation, and diaphragmatic work ranged from 94 to 793% of that performed on the lungs. The amount of chest wall distortion, as reflected by the duration of the paradoxical chest wall movement, the minute volume excursion, or work of the diaphragm, was not related to the mechanical properties of the lungs. This estimated work load may represent a significant expenditure of calories in these infants and may contribute to the development of diaphragmatic fatigue, apnea, and a prolonged need for mechanical ventilation.     

Identification of two general diffusion channels in the outer membrane of pea mitochondria.

Reconstitution experiments were performed on lipid bilayer membranes in the presence of detergent solubilized mitochondrial membranes of pea seedlings (Pisum sativum). The addition of the detergent-solubilized material to the membranes resulted in a strong increase of the membrane conductance. To identify the proteins responsible for membrane activity the detergent extracts were applied to a hydroxyapatite (HTP) column and the fractions were tested for channel formation. The eluate of the column contained a protein which migrated as a single band with an apparent molecular mass of 30 kDa on SDS-PAGE. This channel was identified as the porin of pea mitochondria since it formed voltage-dependent channels with single-channel conductances of 1.5 and 3.7 nS in 1 M KCl and an estimated effective diameter of about 1.7 nm. Further elution of the column with KCl containing solutions yielded fractions which resulted in the formation of transient channels in lipid bilayer membranes. These channels had a single-channel conductance of 2.2 nS in 1 M KCl and had also the characteristics of general diffusion pores with an estimated effective diameter of 1.2 nm. Zero-current membrane potential measurements suggested that pea porin was anion-selective in the open state. The selectivity of the second channel was investigated by the measurement of the reversal potential. It was also slightly anion-selective. Its possible role in the metabolism of mitochondria is discussed.     

Production of DON-related trichothecenes byFusarium graminearum Schw from Krasnodarski krai of the USSR

34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals.