Physiology of aging related to outcome in the adult respiratory distress syndrome

Thirty-nine patients with adult respiratory distress syndrome (ARDS) were enrolled in a study to identify potential age-related changes in organ system function that may help explain the apparent association between age and poor outcome in these patients. Criteria for enrollment included an arterial PO2-to-inspired O2 concentration ratio less than or equal to 200 in a clinical setting consistent with ARDS. Patients were excluded if they were less than 18 yr old, had clinical manifestations of congestive heart failure, were seropositive for the human immunodeficiency virus, or had stage II metastatic lung cancer. Patients were divided into two groups: those less than 60 yr old (mean 42 +/- 3 yr, n = 17) and those greater than or equal to 60 yr old (73 +/- 2 yr, n = 16). A group of six patients was analyzed as a separate subset based on a body temperature less than or equal to 97.5 degrees F at enrollment (hypothermic patients, 73 +/- 4 yr old). Sepsis was present in 67% of the nonhypothermic patients and in all the hypothermic patients. Mortality rates were 12% in the patients less than 60 yr and 69% in the nonhypothermic patients greater than or equal to 60 yr. All the hypothermic patients died. Sequential data obtained over 6 days were compared within and between groups. The following results were obtained. 1) The ratio of arterial PO2 to inspired O2 fraction was greater and the positive end-expiratory pressure used was significantly less in the patients greater than or equal to 60 yr old compared with the younger group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Feeding and growth of juvenile sea bass: the effect of ration and temperature on growth rate and efficiency

The effect of ration on the growth of pairs of juvenile sea bass Dicentrarchus labrax fed squid mantle was recorded at four temperatures: 6, 10, 14 and 18) C, covering the range typical of Welsh coastal waters. Initial weight of the fish ranged from 2.8 to 15.9 g. A predictive model for the maximum meal size (M_max) at temperatures between 10 and 18) C, accounted for 95% of the variance in lnM_max. Even when offered excess food, bass at 6) C had a low rate of food consumption [0.19% body weight (BW) day^?1] and lost weight (G=?0.04% day^?1). Predictive regression models for specific growth rate (G) accounted for 86% of the variance at reduced rations and 70% at maximum meals. The relationship between G (calculated for total biomass per tank) and ration was a decelerating curve. G at maximum meals increased with temperature, at lower rations G decreased with temperature. For a pair of bass with a combined weight of 15 g, predicted maintenance ration ranged between 0.7 and 2.3% BW day^?1 and increased with temperature. Maximum meal size was more sensitive to temperature than maintenance ration. At 18) C optimum ration was 7.4% BW day^?1. At lower temperatures, the optimum ration was the maximum meal. The maximum gross growth efficiency was 17.4% at 18) C. Mean absorption efficiency was 94.8%. Ration level had no significant effect on absorption efficiency, which was lowest at 6) C. Condition indices (Fulton condition factor, wet and dry liver—somatic indices and body depth index) increased with meal size at all temperatures except 6) C. An increase in temperature between 10 and 18) C generally resulted in a decrease in condition indices at a given ration. When comparisons were made at a given standard length, gut and carcass weight increased with ration. Visceral fat and gut weight decreased with increased temperature.     

Abnormal deletions in the T-cell receptor delta locus of mouse thymocytes.

Separate genetic elements (V, D, and J) encode the variable regions of lymphocyte antigen receptors. During early lymphocyte differentiation, these elements rearrange to form contiguous coding segments (VJ and VDJ) for a diverse array of variable regions. Rearrangement is mediated by a recombinase that recognizes short DNA sequences (signals) flanking V, D, and J elements. Signals flank both the 5' and 3' sides of each D element, thereby allowing assembly of a functional VDJ gene. However, in rearrangements involving the D delta 2 and J delta 1 elements of the mouse T-cell receptor delta (TCR delta) locus, we unexpectedly found that the D delta 2 element and a portion of its 5' signal are often deleted. Approximately 50% of recovered D delta 2 to J delta 1 rearrangements from thymocytes of adult wild-type mice showed such deletions. An additional 20% of the rearrangements contained standard D delta 2-J delta 1 coding junctions but showed some loss of nucleotides from the 5' D delta 2 signal. This loss was clearly associated with another event involving a site-specific cleavage at the 5' signal/coding border of D delta 2 and rejoining of the modified signal and coding ends. The abnormal loss of D delta 2 and a portion of the 5' D delta 2 signal was infrequently observed in D delta 2-to-J delta 1 rearrangements recovered from neonatal mice. The possible basis and significance of this age-dependent phenomenon are discussed.     

Biotransformations of Aroclor 1242 in Hudson River test tube microcosms.

A microcosm system to physically model the fate of Aroclor 1242 in Hudson River sediment was developed. In the dark at 22 to 25 degrees C with no amendments (nutrients, organisms, or mixing) and with overlying water being the only source of oxygen, the microcosms developed visibly distinct aerobic and anaerobic compartments in 2 to 4 weeks. Extensive polychlorinated biphenyl (PCB) biodegradation was observed in 140 days. Autoclaved controls were unchanged throughout the experiments. In the surface sediments of these microcosms, the PCBs were biologically altered by both aerobic biodegrading and reductive dechlorinating microorganisms, decreasing the total concentration from 64.8 to 18.0 micromol/kg of sediment in 1140 days. This is the first laboratory demonstration of meta dechlorination plus aerobic biodegradation in stationary sediments. In contrast, the primary mechanism of microbiological attack on PCBs in aerobic subsurface sediments was reductive dechlorination. The concentration of PCBs remained constant at 64.8 micromol/kg of sediment, but the average number of chlorines per biphenyl decreased from 3.11 to 1.84 in 140 days. The selectivities of microorganisms in these sediments were characterized by meta and para dechlorination. Our results provide persuasive evidence that naturally occurring microorganisms in the Hudson River have the potential to attack the PCBs from Aroclor 1242 releases both aerobically and anaerobically at rapid rates. These unamended microcosms represent a unique method for determining the fate of released PCBs in river sediments.     

STABILIZATION MECHANISM IN SWIMMING ODONTOCETE CETACEANS BY PHASED MOVEMENTS

Propulsive movements of the caudal oscillating flukes produce large forces that could induce equally large recoil forces at the cranial end of the animal, and, thus, affect stability. To examine these vertical oscillations, video analysis was used to measure the motions of the rostrum, pectoral flipper, caudal peduncle, and fluke tip for seven odontocete cetaceans: Delphinapterus leucas, Globicephala melaena, Lagenorhynchus obliquidens, Orcinus orca, Pseudorca crassidens, Stenella plagiodon , and Tursiops truncatus. Animals swam over a range of speeds of 1.4–7.30 m/sec. For each species, oscillatory frequency of the fluke tip increased linearly with swimming speed. Peak-to-peak amplitude at each body position remained constant with respect to swimming speed for all species. Mean peak-to-peak amplitude ranged from 0.02 to 0.06 body length at the rostrum and from 0.17 to 0.25 body length at the fluke tip. The phase relationships between the various body components remain constant with respect to swimming speed. Oscillations of the rostrum were nearly in phase with the fluke tip with phase differences out of—9.4°-33.0° of a cycle period of 360°. Pectoral flipper oscillations trailed fluke oscillations by 60.9°-123.4°. The lower range in amplitude at the rostrum compared to the fluke tip reflects increased resistance to vertical oscillation at the cranial end, which enhances the animal's stability. This resistance is likely due to both active and passive increased body stiffness, resistance on the flippers, phased movements of body components, and use of a lift-based propulsion. Collectively, these mechanisms stabilize the body of cetaceans during active swimming, which can reduce locomotor energy expenditure and reduce excessive motions of the head affecting sensory capabilities.     

Permeability of chloroplast envelopes to mg: effects on protein synthesis

When suspended in media lacking free Mg²⁺, chloroplasts from young pea plants (Pisum sativum CV Progress No. 9) lose 25 to 75% of their stromal Mg²⁺ content to the medium, without breakage. This effect amounts for the inhibition of protein synthesis in the dark by ATP in excess of the Mg²⁺ provided, since free ATP chelates Mg²⁺. The rate of loss is from 1 to 4.5 microgram-atoms Mg²⁺/milligram Chl/hour; and depleted chloroplasts take up Mg²⁺ from the medium at even faster rates, to a total amount not much more than that present originally (0.8 to 1.8 microgram-atoms/milligram Chl with an average of 1.33 ± 0.32 μg-atoms/mg Chl). Leakage is completely prevented by 0.25 to 0.40 millimolar external Mg²⁺. Addition of Mg²⁺ at a level sufficient to prevent leakage from intact chloroplasts results in approximately 20% stimulation in light-driven protein synthesis.     

The subunit characterization of Callinectes sapidus hemocyanin.

Hemocyanin from the blue crab, Callinectes sapidus, sediments at 25.7 S and has a native molecular weight of 940 000 +/- 20 000. Under solution conditions of increased pH (approximately 10) or ionic strength, the native molecule dissociates to a 17 S species. Reversal of this dissociation was unsuccessful. At pH 10 and with the removal of Mg2+, the 17 S species reversibly dissociates to form a subunit species which sediments at 6 S. A comparison of the circular dichroic spectra of the 25.7 S and 6 S hemocyanins suggests that little happens to the structural integrity of the polypeptide backbone upon the two dissociations. Molecular weight estimations under reducing and denaturing conditions indicate that the 6 S hemocyanin species represents the constituent polypeptide chain of the protein molecule. Chemical analysis suggests the presence of a small amount, less than 3%, of carbohydrate bound to the polypeptide chain. Electrophoresis of the hemocyanin in the presence of sodium dodecyl sulfate or urea reveals two major electrophoretic species of either slightly different chemical composition or slightly different polypeptide chain length.     

INVESTIGATION OF SECONDARY STRUCTURES AND MACROMOLECULAR INTERACTIONS IN BACTERIOPHAGE P22 BY LASER RAMAN SPECTROSCOPY

Laser Raman spectra of the DNA bacteriophage P22 and of its precursor particles and related structures have been obtained using 514.5-nm excitation. The spectra show that P22 DNA exists in the B form both inside of the phage head and after extraction from the phage. The major coat protein (gp5) contains a secondary structure composed of 18% α-helix, 20% β-sheet and 62% irregular conformations. The scaffolding protein (gp8) in the phage prohead is substantially richer than gp5 in α-helical content. Among the amino acid residues which give prominent Raman lines, the spectra show that tryptophans are exposed to solvent and most tyrosines are hydrogen bonded to positive donor groups. The above features of phage DNA and protein structures are nearly invariant to changes in temperature up to 80°C, indicating a remarkable thermal stability of the phage head and its encapsulated DNA.