Diffusing capacity of the lung for carbon monoxide

A phage-display technology was used to produce a single-chain Fv antibody fragment (scFv) from the 30AA5 hybridoma secreting anti-glycoprotein monoclonal antibody (MAb) that neutralizes rabies virus. ScFv was constructed and then cloned for expression as a protein fusion with the g3p minor coat protein of filamentous phage. The display of antibody fragment on the phage surface allows its selection by affinity using an enzyme-linked immunosorbent assay (ELISA); the selected scFv fragment was produced in a soluble form secreted by E. coli. The DNA fragment was sequenced to define the germline gene family and the amino-acid subgroups of the heavy (VH) and light (VL) chain variable regions. The specificity characteristics and neutralization capacity of phage-displayed and soluble scFv fragments were found to be identical to those of the parental 30AA5 MAb directed against antigenic site II of rabies glycoprotein. Phage-display technology allows the production of new antibody molecule forms able to neutralize the rabies virus specifically. The next step could be to engineer and produce multivalent and multispecific neutralizing antibody fragments. A cocktail of multispecific neutralizing antibodies could contain monovalent, bivalent or tetravalent scFv fragments, for passive immunoglobulin therapy.     

Pathogenesis of non-traumatic atlanto-axial subluxation (Grisel''s syndrome)

Ten years ago' endothelium derived relaxing factor' was identified as nitric oxide (NO.). This highly significant discovery revealed the importance of NO. in normal physiology and pathophysiology. Research over the past decade into the potential therapeutic use of inhaled NO. in the management of ARDS is reviewed. In critical care, inhaled NO. seems to produce selective pulmonary vasodilation and this is already beginning to have an impact on the management of lung injuries including ARDS. The effect of NO. in multi-system failure is not yet established. Formal evaluation in the form of clinical trials has yet to be undertaken, and further study of all the potential side effects and toxicity are required for conclusive evidence of the value of inhaled NO. in the treatment of ARDS.     

Postmortem serum and tissue redistribution of fluoxetine and norfluoxetine in dogs following oral administration of fluoxetine hydrochloride (Prozac)

Antemortem serum and postmortem serum and tissues were evaluated to determine if postmortem redistribution of the antidepressant, fluoxetine (Prozac) and its major active metabolite, norfluoxetine, occurred in dogs following oral administration of fluoxetine hydrochloride. Beagle dogs (four males) received daily oral doses of 10 mg fluoxetine/kg for five days. Antemortem serum concentrations of fluoxetine and norfluoxetine were determined 3 and 24 h following administration of the first four daily doses of fluoxetine and 3 h after the fifth dose in order to monitor for steady-state serum concentrations of parent and metabolite prior to postmortem serum concentration determinations. Antemortem serum concentrations of fluoxetine and norfluoxetine 3 h postdose on Day 5 ranged from 530 to 1210 ng/mL and 1460 to 1980 ng/ mL, respectively. Immediately following the 3 h blood sample on Day 5, each dog was euthanized. Serum concentrations of fluoxetine and norfluoxetine were determined from blood samples collected from the vena cava, heart, and clotted blood within the heart at 2 h after death in two dogs and 12 h after death in the remaining two dogs. Similarly, tissue concentrations of fluoxetine and norfluoxetine in heart, liver, and lung were determined 2 and 12 h postmortem. Serum concentrations of fluoxetine and norfluoxetine from the vena cava and heart 2 h postmortem were 2.2- to 6.0-fold and 2.3- to 3.6-fold higher, respectively, than antemortem serum concentrations. Similarly, serum concentrations of fluoxetine and norfluoxetine from vena cava and heart 12 h postmortem were 1.3- to 3.5-fold and 1.7- to 3.3-fold higher, respectively, than antemortem serum concentrations. However, 2-h and 12-h postmortem serum concentrations of fluoxetine and norfluoxetine from clotted blood within the heart were equal to or less than levels determined in antemortem serum. Results from 2-h and 12-h postmortem average tissue concentrations of fluoxetine and norfluoxetine in heart, liver, and lung demonstrated that fluoxetine and norfluoxetine concentrations in myocardium were similar 2 h and 12 h postmortem. However, in liver, fluoxetine concentrations decreased 39% and norfluoxetine concentrations decreased 23% from 2 h to 12 h postmortem. Even greater postmortem decreases in fluoxetine and norfluoxetine concentrations were observed in lung. Fluoxetine and norfluoxetine concentrations in lung decreased 49% and 39%, respectively, from 2 h to 12 h postmortem. In conclusion, this study demonstrated that fluoxetine and norfluoxetine undergo postmortem redistribution in the dog. Furthermore, postmortem serum concentrations appear to be dependent on the sample site and the degree of coagulation of the blood. Finally, postmortem decreases in concentrations of fluoxetine and norfluoxetine in liver and lung may, in part, explain the observed increase in serum concentrations at 2 and 12 h postmortem.     

Parameters determining the strength and toughness of particulate filled epoxide resins

The effects of such parameters as the filler volume fraction, particle size, aspect ratio, modulus and strength of filler, resin-filler adhesion and toughness of the matrix on the stiffness, strength and toughness of particulate filled epoxide resins have been evaluated. The mechanisms of deformation and rupture in these multiphase materials are discussed, illustrated byin situ mechanical tests in the scanning electron microscope.     

High nitrification rate at low pH in a fluidized bed reactor with chalk as the biofilm carrier.

A typical steady state bulk pH of about 5 was established in a nitrifying fluidized bed with chalk as the only buffer agent. In spite of the low pH, high rate nitrification was observed with the nitrification kinetic parameters in the chalk reactor similar to those of biological reactors operating at pH>7. Various methods were used to determine the reasons for high rate nitrification at such low pH including (i) determination of bacterial species, (ii) microsensor measurements in the biofilm, and (iii) comparison of nitrification performance at low pH with a non-chalk fluidized bed reactor. Fluorescence in situ hybridization (FISH) using existing 16S rRNA-targeted oligonucleotide probes showed common nitrifying bacteria in the low pH chalk reactor. The prevalent nitrifying bacteria were identified in the Nitrosomonas oligotropha, Nitrosomonas europeae/eutropha, Nitrosospira and Nitrospira related groups, all well known nitrifiers. Microelectrode measurements showed that the pH in the biofilm was low and similar to that of the bulk pH. Finally, reactor performance using a non-chalk biofilm carrier (sintered glass) with the same bacterial inoculum also showed high rate nitrification below pH 5. The results suggest that inhibition of nitrification at low pH is highly overestimated.     

Analysis of the catalyic mechanism of a fungal lipase using computer-aided design and structural mutants

Both an active enzyme conformation and stabilization of tetrahedraltransition states are essential for the catalysis of ester bondhydrolysis by lipases. X-ray structural data and results fromsite-directed mutagenesis experiments with proteases have beenused as a basis for predictions of amino acid residues likelyto have key functions in lipases. The gene encoding a lipasefrom Rhizopus oryzae was cloned and expressed in Escherichiacoli. Site-directed mutagenesis of this gene was used to testthe validity of computer-aided predictions of the functionalroles of specific amino acids in this enzyme. Examination ofthe kinetic constants of the Rhizopus oryzae lipase variantsallowed us to identify amino acid residues which are directlyinvolved in the catalytic reaction or which stabilize the activegeometry of the enzyme. The combination of these results withmolecular mechanics simulations, based on a homology-derivedstructural model, provided new information about structure-functionrelationships. The interpretation of the data is consistentwith results obtained with other hydrolases, such as proteases.     

Forward telescoping: the question matters

This study examines the effect of pulse repetition rate (PRR), pulse intensity, and bicuculline on the minimum threshold (MT) and latency of inferior collicular neurons of the big brown bat, Eptesicus fuscus, under free-field stimulation conditions. It tests the hypothesis that changes in MT and latency of collicular neurons are co-dependent on PRR. The number of impulses in inferior collicular neurons (n = 245) increased either monotonically (25%) or non-monotonically (75%) with pulse intensity. Latencies either decreased to a plateau (72%), fluctuated unpredictably within 3 ms (21%) or changed very little (7%) with increasing pulse intensity. Latencies and MTs of most collicular neurons increased by 1.5-24 ms (mean +/- SD = 4.8 +/- 3.3 ms) and 4-75 dB (mean +/- SD = 22.1 +/- 16.2 dB) with increasing PRR. In most neurons (94%), the latency increase was completely (42%) or partially (52%) eliminated when pulse intensity was compensated for the MT increase with PRR. Complete elimination of latency was achieved by bicuculline application. In a few neurons (6%), the latency increase with PRR was not affected by compensated pulse intensity or bicuculline application.