An improved system for the control of dissolved oxygen in freshwater aquaria

A system for the removal and control of dissolved oxygen (DO) from freshwater was designed and constructed with aquarium-type fish studies in mind. Degassed water was obtained using a partial vacuum of -14 psi, and DO regulated at an aquarium scale using electronically controlled aeration with timed partial water renewal. The degassing system was capable of producing water with approximately 1.7 mg L(-1) DO within 10 min of operation, and 0.55 mg L(-1) after 2h. The control system was capable of maintaining DO levels of ca 0.8 mg L(-1) over 48 h in the absence of aeration and further capable of precisely controlling DO levels as low as 1.16+/-0.002 mg L(-1) (mean+/-SEM) with aeration over a 48 h period.     

Antidepressant treatment of pathologic laughing or crying in elderly stroke patients

Pathologic laughing or crying (PLC), a complication of many neurologic disorders, involves behavior that is either inappropriate to the context or to the patient's subjective feeling state. It is due to a dysregulation of the motoric components of emotional experience. PLC is distinct from, but often associated with, major depression. The relatively few reports on treatment of PLC are primarily with tricyclic antidepressants. We report the effective treatment of PLC due to stroke in three patients with nortriptyline or fluoxetine. The cases also illustrate the broad spectrum of depressive symptoms (from none to a major depression) seen in patients with PLC. We discuss treatment implications and directions for future research.     

Development of a novel, rapid processing protocol for polymerase chain reaction-based detection of bacterial infections in synovial fluids

We describe the development of a molecular detection system designed for use with synovial fluid (SF)-based infections. The methodology employs a lysis/extraction procedure that effectively disrupts microorganisms allowing for release of the microbial DNA and its amplification by polymerase chain reaction (PCR). We tested the effectiveness of adding a mixed-bed, ion-exchange resin to the extract to remove PCR inhibitory components present in the SF. After centrifugation to separate the resin, DNA contained in the supernatant is subjected to PCR using oligonucleotide primers designed for broad-spectrum microorganism detection. Amplification products are analyzed by agarose gel electrophoresis and/or DNA hybridization methodology. We report here the detection sensitivity and specificity of the protocol using SF inoculated with Escherichia coli and Staphyloccocus aureus. We have applied this new methodology to clinical SF specimens with results superior to standard laboratory culturing assays.     

An outline theory of surface morphology development during radiation enhanced reactant gas erosion

A phenomenological model of erosion of solids by reactive gases enhanced by simultaneous surface irradiation (e.g. by ions) is developed. The model is based upon the assumption that the radiation generates activated atomic states which can be preferentially removed, with accompanying atomic erosion, at a rate proportional to the product of the surface activated state density and reactant gas flux. This model allows deduction of erosion velocity as a function of surface orientation and it is shown how knowledge of this function can be used to predict the evolution of surface morphology.     

Photoaffinity labeling of the human erythrocyte nucleoside transporter by N6-(p-Azidobenzyl)adenosine and nitrobenzylthioinosine. Evidence that the transporter is a band 4.5 polypeptide

N6-(p-Azidobenzyl)adenosine (ABA) and nitrobenzylthioinosine (NBMPR) were employed as covalent probes of the nucleoside transport mechanism in human erythrocytes. NBMPR, a potent inhibitor of nucleoside transport, binds tightly (KD 0.3-1 nM) to specific sites on nucleoside transporter elements. ABA, a less potent inhibitor of uridine influx, competitively inhibited NBMPR binding (Ki 15 nM). [3H]ABA was bound tightly (KD 13.4 nM) but reversibly to sites on erythrocytes which appeared to be those which bind NBMPR. ABA binding was inhibited by uridine and adenosine. Irradiation with UV light caused site-bound [3H]ABA on erythrocyte membranes to become covalently bound and, similarly, photoactivation resulted in covalent attachment of membrane-bound [3H]NBMPR. In the presence of dithiothreitol, a free radical scavenger, photoactivation of the site-bound 3H-ligand on membranes depleted of extrinsic membrane proteins resulted in selective incorporation of 3H into band 4.5 of the membrane polypeptides which were resolved on sodium dodecyl sulfate-polyacrylamide gel electropherograms. This result, when considered with previous findings, indicates that the NBMPR-binding component of the nucleoside transport mechanism (or the entire mechanism, if the NBMPR site is an integral part) is a band 4.5 polypeptide.     

Lung mechanics in sitting and horizontal body positions

We measured lung compliance, pulmonary flow-resistance, and expiratory reserve volume (ERV) in ten healthy young adults in sitting, supine, and lateral positions. Average lung compliance was 0.21 in sitting, 0.19 in lateral and 0.16 L.cm H2O-1 in supine positions. The change was significant (p less than 0.01) between sitting and supine position. Flow-resistance increased from 1.78 in sitting to 2.5 cm H2O.L-1.s (p less than 0.001) in lateral positions, and did not increase further in the supine posture in spite of a 35 percent decrease in ERV (p less than 0.001). Since it is known that lower airways resistance increases with decreasing lung volume, the lack of change in flow-resistance when shifting from lateral to supine posture suggests that upper airways flow-resistance (larynx and oropharynx) is greater in the lateral decubitus than in the supine positions. The decrease of lung compliance in horizontal postures probably reflects increased pulmonary blood volume and small airways closure.