Choosing highly specific primers for the polymerase chain reaction using the octomer frequency disparity method: application to Chlamydia trachomatis.

The eight-nucleotide sequence (octomer) at the 3' end of PCR primers is important to PCR specificity. We describe a correlation between the specificity of PCR primers used with human DNA and the frequency of the 3' octomer in a human database. We therefore applied a methodology (OFD) based on octomer frequency disparity to identify 16 PCR targets in the chromosome of the intracellular bacterium, Chlamydia trachomatis (Ct). In addition, the 16 sets of primers were tested with a standard procedure. All the primer pairs were highly specific for Ct and did not lead to non-specific amplification when used with human DNA. This work shows that the choice of specific PCR primers is possible using a method based on the statistical representativeness of octomers in genomes.

Comparison of bifocal and progressive addition lenses on aviator target detection performance.

The objective of this project was to determine if the type of presbyopic correction worn by aviators, conventional bifocal versus progressive addition lenses (PAL's), differentially affects aviator visual search performance. Experienced aviators, most with tactical fighter aircraft experience, searched for high-contrast targets under simulated dawn/dust (mesopic) lighting conditions (approximately 3.0 cd/m2) while wearing either a standard bifocal (ST-25) or PAL spectacle correction. Latency of locating high-contrast targets under these viewing conditions was differentially affected by the type of presbyopic correction used. Specifically, compared to a standard bifocal (ST-25), a PAL correction (Varilux Infinity) significantly lowered the time needed to locate static targets at a cockpit instrument viewing distance (83 cm). Accuracy of target location responses was not affected by the type of correction used. In addition, 7 months post-experiment, 7 of the 12 participants (58%) indicated that they used their PAL correction exclusively when flying the T-39 Sabre Liner. Three subjects (25%) used their PAL correction intermittently (primarily at night) when flying and two subjects preferred not to use the PAL's. These results suggest that relative to bifocals, speed of responding to static targets at intermediate viewing distances may be improved by wearing PAL's, and that subjects were able to adapt to PAL lenses quickly in a laboratory setting, using them later in a functional aviation environment.

The fate of eyewear in aircraft ejections.

Ejection from jet aircraft has been exhaustively studied from many perspectives; e.g., causes of ejection, types and causes of ejection injuries, etc. Curiously, no reports exist describing the fate of eyewear in ejections. Many pilots wear required corrective lenses during flight operations, and many wear tinted lenses. What happens to these during ejection? What injuries are a result of the eyewear? What factors can be identified that influence retention of the eyewear and severity of related injury? Do contact lenses provide significant advantages? There were 48 ejections occurring between 1977 and 1990 that involved corrective or tinted lens use that were retrospectively examined using Naval Safety Center records and personal questionnaires. There were five contact lens wearers included. Retention rates were calculated as functions of several variables. Although 37 of 46 lost all lenses, each instance of retention occurred with visor down, oxygen mask on, helmet properly secured, and at lower ejection speeds. Related injuries were minor and occurred in only 20%. The utility and need for enforcement of standard operating procedures (i.e., mask on, helmet secured, and visor down) was clearly demonstrated. Only 19 of 46 clearly met all 3 criteria. Contact lens users were too few to allow meaningful conclusions.

Ethanol-induced signal transducing mechanism associated with a transient antiviral state in human amniotic cells.

Short-term effects of ethanol on human amnion cells were investigated by studying the cellular signaling processes and the replication of vesicular stomatitis virus. Treatment of human amniotic cells with ethanol transiently triggers the breakdown of inositol phospholipids, stimulates intracellular [Ca2+]i mobilization and activates the translocation of protein kinase C. Activation of this signal transduction mechanism is associated with the development of an antiviral state, as proven by studying 3H-uridine incorporation into the RNA of vesicular stomatitis virus. Induction of the antiviral state in human amniotic cells correlates with the solubility of the alcohols in the lipid membrane of the cells.

Photo-refractive keratectomy (PRK): threat or millennium for military pilots?

The development of the excimer laser, which is capable of correcting myopia without leaving obvious scars as does radial keratotomy, makes it certain that this promising but very new modality is something the military aviation community will be facing in the immediate future. Methods of detection are available, but are expensive and time-consuming. Should military aviation permit or even sponsor a group of PRK student pilots in order to observe them closely, and then perhaps use this new modality in place of contact lenses or even spectacles?

Signal transducing mechanisms in interferon action (a brief review).

Experimental results suggest that protein kinase C (PK-C) may play a substantial role in the action of IFNs, but the precise biochemical pathway remains unknown. Recent evidences reveal the complexity of the mechanism of IFN-action and show that the IFN-alpha, -beta and -gamma induced pathways are overlapping. We briefly discuss what is known in this field and suggest a way in which the contrasting views might be reconciled.

Strain selection for ß-carotene production by Dunaliella.

Four strains of Dunaliella were grown at 25°C and pH 8±0.5, with continous illumination at 200 W/m(2). Their maximum specific growth rates ranged from 0.093 day(-1) to 0.234 day(-1), nitrate yields from 3.0 to 7.8 g cells/g NaNO3 and lipid contents from 3% to 6% of the dry wt, with carotenes 50 to 80% of the lipids. Of the carotenes, ß-carotene made up 7 to 19%; all-trans-ß-carotene 32 to 52% and 9-cis-ß-carotene 29 to 55%. There are, therefore, considerable intra-specific differences between strains of Dunaliella.

Oxytocin stimulates translocation of protein kinase C and induces antiviral state in human amnion cells.

Association of protein kinase C (PKC) activity to the membrane fraction was observed in oxytocin treated human amnion cells (UAC). In addition, oxytocin was shown to induce an antiviral state and to inhibit multiplication of vesicular stomatitis virus (VSV) in UAC. These observations together with earlier findings indicate that activation of inositol phospholipid breakdown with a consecutive activation of PKC is a common signal transduction pathway in interferon action and hormonal stimulation.

Ultrastructural changes of human amniotic cells induced by natural human interferon-alpha.

Human interferon-alpha (Hu-IFN alpha) and phorbol myristate acetate (PMA), a direct activator of protein kinase C (PK-C), induce the translocation of protein kinase C from the cytosol to the membrane fraction. By the use of transmission (TEM) and scanning (SEM) electron microscopy we have shown that treatment of human amniotic cells (UAC) with Hu-IFN alpha resulted in profound changes in the shape, volume and ultrastructure of the cells. Most treated cells had enlarged nuclei with marginal condensation of chromatin. Nucleolar segregation, disintegration and clumping of nucleolar components were also observed. The number of interdigitating cell processes decreased and the cell surface microvilli became shortened. Similar ultrastructural alterations were induced by PMA also. All these functional and morphological data strongly support the hypothesis that protein kinase C is a key factor in IFN-mediated cell reactions.

Phospholipase C and phospholipase A2 are involved in the antiviral activity of human interferon-alpha.

Treatment of human amniotic cells (UAC) with human interferon-alpha (Hu-IFN alpha) or phorbol myristate acetate (PMA) resulted in translocation of protein kinase C (PK-C) activity from the cytosol fraction to that of the membranes. Analysis of 32P incorporation into phospholipid fractions and studies of alterations in fatty acid content for the major phospholipids of IFN-treated cells suggest that phospholipases C and A2 are activated by Hu-IFN alpha. Addition of neomycin (an inhibitor of phospholipase C), as well as mepacrine (an inhibitor of phospholipase A2) to IFN-treated cells inhibited the antiviral activity of Hu-IFN alpha in the vesicular stomatitis virus (VSV)-UAC system used. These observations indicate that (i) activation of PK-C and (ii) diacylglycerol formation, arachidonic acid and/or lysophosphatidylcholine release are important steps in the mechanism of action of IFN.

Interferon (IFN)-like antiviral effect is induced by unspecific cross-linking of cell surface receptors.

Treatment of human amniotic cells (UAC) with Cytodex 1 (DEAE-dextran) results in the development of an antiviral state of the cells, as proven by studying (i) the cytopathic effect and (ii) [3H]uridine incorporation into the RNA of vesicular stomatitis virus (VSV) after VSV infection. The same treatment transiently triggers the breakdown of inositol phospholipids and activates the translocation of protein kinase C (PKC). On the basis of these data it can be suggested that cross-linking of cell surface receptors by a solid carrier bearing covalently bound positive charges may result in IFN-like effects.

Inositol phospholipid turnover and protein kinase C translocation are stimulated by poly(I).poly(C) in human amnion cells (UAC).

Polyinosinic-polycytidylic acid, a potent inducer of inducer of interferon (IFN) production and activator of some IFN-induced enzymes, inhibits [3H]uridine incorporation into the RNA of vesicular stomatitis virus even in the absence of IFN synthesis, transiently triggers the breakdown of inositol phospholipids and activates the translocation of protein kinase C. Since IFNs also have similar activities these results suggest that IFN induction and IFN function are realised through common biochemical pathways.

Mixing and power characteristics of drag board device in shallow pool.

Mixing and stirring of a 20-m(2) shallow pool by means of a drag board device has been investigated. The board closes the pool cross section except for a slit of a few centimeters above the bottom, and it is slowly moved back and forth, forcing the water to run through the slit and thereby creating a turbulent backwhirl. Power drawn and the drag on the board has been measured together with the velocities of the water at different locations in the wake of the board. Power number N(p) has been correlated with the Reynolds N(Re) and the bottom clearance numbers N(c) by the expressions \documentclass{article}\pagestyle{empty}\begin{document}$$ N_p = 13,465N_{\rm Re};{-0.774} N_c;{0.1016} N_{\rm Re} < 80.000\\N_p = 5.4N_{\rm Re};{-0.0863} N_c;{0.104} N_{\rm Re} > 80.000 $$\end{document} Power and Reynolds numbers are defined as usual with the square root of the board-immersed-area as the characteristic length. The bottom clearance number is defined as the ratio of the water depth in the pool to the difference between water depth and the board width immersed in water. Flow pattern behind the board consists of large vortex loops causing the fluid to circulate from bottom to top and producing a thorough mixing effect. The drag board seems to have several advantages over conventional paddle wheels for the mixing and stirring of algal cultures in shallow ponds.

A novel approach for understanding the effects of interferons--a working hypothesis.

Experimental results accumulated during the last two decades prove that there are no mechanisms specific for interferon (IFN) action. Thus, IFN effects must be realized through the relatively limited number of metabolic pathways available for cell functions. Triggering the receptor system in association with membrane phospholipid breakdown, which plays an important role in signal transduction for a variety of biologically active substances, is suitable to explain generation of the pleiotropic IFN effects, too. Prevalence of one or the other of the "positive" and "negative" pathways of this signal transducing system depending on various known and up-to-now unknown factors may be responsible for the sometimes contradictory effects of IFNs.

Antiviral activity of phorbol myristate acetate and possible relationships with interferon action.

Signal-induced turnover of membrane phospholipids represents a fundamental transducing mechanism that induces a signal cascade resulting in mobilization of calcium, activation of protein kinase C by diacylglycerol, release of arachidonic acid and stimulation of cyclic GMP production. In this pathway tumor-promoting phorbol esters such as phorbol myristate acetate (PMA) may substitute for diacylglycerol. The interferon-like antiviral effect of PMA described here suggests that the inositol phospholipid-diacylglycerol-protein kinase C signal-transducing mechanism may be involved in interferon action.

Variations on the theme of involutional entropion and the Quickert repair.

The late Marvin Quickert originated a lower lid entropion repair successful especially in recurrent cases. Probable reasons for its success is correction of all three main conditions predisposing to entropion, namely increased horizontal length, excessive vertically mobile preseptal orbicularis, and lax retractors, whereas other entropion procedures correct only one or two factors. A bridge flap of lid is created by an incision at the base of the tarsus, and this is then transected vertically in its outer third. The amount of horizontal redundance determined, a rectangle of full thickness lid is excised, and the ends reapproximated. Wies type sutures are placed approximating superior anterior lamella to inferior posterior lamella. Redundant skin is excised laterally and the entire skin incision closed. A Wies procedure resulting in immediate ectropion can easily be converted to this procedure.