bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Validity of Scaling Transient Conjugate Heat Transfer Characteristics
Authors: Maffulli R. , Marinescu G. , He L.
Published: January 2020

Accurate prediction of unsteady thermal loads is of paramount importance in several engineering disciplines and applications. Performing time-accurate unsteady conjugate heat transfer (CHT) simulations presents considerable challenges due to the markedly different time scales between the solid and fluid domains. Two methods have been recently proposed, aimed at addressing this issue: multiscale modeling (MSM) and equalized time-scales (ET). The former is based on the separation of the disparate short and long temporal scales of the solution and subsequent averaging of the flow/energy equations. In the latter, the equalization of the time scales is achieved through manipulation of the solid's thermal properties. Both methods are very appealing due to the possibility of being easily implemented on an existing solver. It becomes, thus, relevant to assess their performance and/or limitations. This paper work presents a comparative study of the two methods for the prediction of transient thermal load, first using a simplified case of a solid body with uniform temperature, then through the investigation of the prewarming phase of a steam turbine. Both methods are then compared against a reference baseline fully coupled (FC) CHT solution. The results show how the MSM allows greater accuracy and robustness with considerable saving in computational cost with respect to the baseline solution.
A Starting Control Strategy of Single-Cylinder Two-Stroke Free-Piston Engine Generator
Authors: Lu Jinkang , Xu Zhaoping , Liu Dong , Liu Liang
Published: January 2020

Free-piston engine generator is a novel energy conversion system, which is known to have advantages of variable compression ratio and variable fuel. The free-piston must be controlled to overcome challenges like misfire, after-combustion, and other abnormal combustion in the starting process, as well as to prevent the piston from colliding with the cylinder head. This article proposes a control strategy based on the combustion state for the cold start-up process of single-cylinder two-stroke free-piston engine generator. The combustion state is judged based on in-cylinder pressure at the early beginning of expansion stroke, and the duration and direction of coil current are adjusted to ensure the aimed bottom turning center of the stroke. A control-oriented model including the cold start-up combustion model of the prototype is presented, and the control strategy is verified by the experiment of the prototype. The results show that the free-piston engine generator can start successfully and overcome abnormal combustion during the cold start-up process.
Help-Seeking Beliefs Among Anabolic Androgenic Steroid Users Experiencing Side Effects: An Interpretive Phenomenological Analysis
Authors: Gilmore Hugh , Shannon Stephen , Leavey Gerard , Dempster Martin , Gallagher Shane , Breslin Gavin
Published: January 2020

Recreational athletes comprise the most prevalent population using illegal Anabolic Androgenic Steroids (AAS). Despite regulatory efforts, substances are widely accessible, and most users report the experience of harmful side effects. It remains unclear why few users seek professional medical help. The aim of this study was to determine AAS users’ experience of side effects and help-seeking beliefs using an Interpretative Phenomenological Analysis of six interviews. Participants were from the United Kingdom (n = 5) and United States (n = 1), had all experienced side effects, with some reporting prolonged use of AAS (>10 years) and self-manufacturing the drugs from raw ingredients. Results showed that AAS users discredit medical professionals’ competencies, and practice cognitive dissonance by avoiding challenging situations. A microculture for information-sharing has developed among AAS users who initially self-treat to counteract side effects, leaving them vulnerable to further harm. To conclude, there is an urgent need for educational interventions that outline the risky practice of unregulated AAS use and self-treatments, and the need to seek professional help. Such interventions could be developed through a co-production basis, and be implemented by current/former AAS users alongside the medical community.
Step Counts From Satellites: Methods for Integrating Accelerometer and GPS Data for More Accurate Measures of Pedestrian Travel
Authors: Wood Brian M. , Pontzer Herman , Harris Jacob A. , Mabulla Audax Z.P. , Hamilton Marc T. , Zderic Theodore W. , Beheim Bret A. , Raichlen David A.
Published: January 2020

The rapid adoption of lightweight activity tracking sensors demonstrates that precise measures of physical activity hold great value for a wide variety of applications. The corresponding growth of physical activity data creates an urgent need for methods to integrate such data. In this paper, we demonstrate methods for 1) synchronizing accelerometer and Global Positioning System (GPS) data with optimal corrections for device-related time drift, and 2) producing principled estimates of step counts from GPS data. These methods improve the accuracy of time-resolved physical activity measures and permit pedestrian travel from either sensor to be expressed in terms of a common currency, step counts. We show that sensor-based estimates of step length correspond well with expectations based on independent measures, and functional relationships between step length, height, and movement speed expected from biomechanical models. Using 123 person-days of data in which Hadza hunter-gatherers wore both GPS devices and accelerometers, we find that GPS-based estimates of daily step counts have a good correspondence with accelerometer-recorded values. A multivariate linear model predicting daily step counts from distance walked, mean movement speed, and height has an R2 value of 0.96 and a mean absolute percent error of 16.8% (mean absolute error = 1,354 steps; mean steps per day = 15,800; n = 123). To best represent step count estimation error, we fit a Bayesian model and plot the distributions of step count estimates it generates. Our methods more accurately situate accelerometer-based measures of physical activity in space and time, and provide new avenues for comparative research in biomechanics and human movement ecology.
The Effect of Combined Aerobic Exercise and Calorie Restriction on Mood, Cognition, and Motor Behavior in Overweight and Obese Women
Authors: Žlibinaitė Laura , Solianik Rima , Vizbaraitė Daiva , Mickevičienė Dalia , Skurvydas Albertas
Published: January 2020

Background: The benefits of weight loss programs on mood, cognitive, and motor behavior are largely limited to those of calorie restriction or exercise alone. Our aim was to investigate the effect of combined calorie restriction and aerobic exercise intervention on mood, brain activity, and cognitive and motor behavior in overweight and obese women. Methods: Participants aged 36–56 years were randomized to either a control or an experimental group (aerobic exercise + 12.5% energy intake reduction) for a 6-month period. Changes in brain-derived neurotrophic factor levels, mood, prefrontal cortex activity, cognitive and motor performance were assessed. Results: Confusion and depression increased in the control group (P < .05), whereas tension decreased in the experimental group (P < .05). Brain-derived neurotrophic factor level and learning of a speed–accuracy task remained unchanged. Although prefrontal cortex activity and executive functions were not affected, the reaction time of visual scanning and associative learning were improved in the experimental group (P < .05). An improvement in reaction time during the speed–accuracy task was observed (P < .05). Conclusion: Combined calorie restriction and aerobic exercise intervention improved the psychosocial state, had little impact on cognition, and no effect on brain activity and learning of the speed–accuracy task.
The Influence of Socialization Factors on Physical Educators’ Conceptions of Assessment and Perceived Quality of Assessment
Authors: Starck Jenna R. , Richards K. Andrew R. , Lawson Michael A. , Sinelnikov Oleg A.
Published: January 2020

Purpose: Framed by occupational socialization theory, this study examined relationships among teachers’ perceived quality of assessment practices, workplace factors, and their conceptions of assessment. Methods: Ninety in-service physical education teachers from Alabama completed an online survey that attended to perceptions of organizational support, marginalization, valuation toward assessment, assessment quality, and class size. Associations were estimated using ordinary least squares regression. Results: In contrast to our initial hypothesis, no significant relationships were found between perceived assessment quality and perceived organizational support, marginalization, and class size. However, our regression analysis yielded significant results when assessment’s importance for education was the outcome variable. Discussion/Conclusions: The results indicated that teachers’ valuation of assessment included holding students and schools accountable, but was irrelevant to improving education. In addition, marginalization and perceived organizational support impacted teachers’ valuation toward using assessments to improve education. Research on assessment quality may depend first on widespread adoption of physical education teacher education assessment practices.
Memory engrams: Recalling the past and imagining the future
Authors: Josselyn Sheena A. , Tonegawa Susumu
Published: January 2020

The neural substrate of memory

The ability to form memory is an essential trait that allows learning and the accumulation of knowledge. But what is a memory? There has been a long history of searching for the neuronal substrate that forms memory in the brain, and the emerging view is that ensembles of engram cells explain how memories are formed and retrieved. In a Review, Josselyn and Tonegawa discuss the evidence for engram cells as a substrate of memory, particularly in rodents; what we have learned so far about the features of memory, including memory formation, retrieval over time, and loss; and future directions to understand how memory becomes knowledge.

Science
, this issue p.
eaaw4325
Electrostatic control of photoisomerization pathways in proteins
Authors: Romei Matthew G. , Lin Chi-Yun , Mathews Irimpan I. , Boxer Steven G.
Published: January 2020

Electrostatics guide chromophore twist

Photoisomerization—the twisting of bonds in a molecule in response to absorption of light—is exploited in biology to sense light and can influence the photophysical properties of fluorescent proteins used in imaging applications. Romei
et al.
studied this behavior by introducing unnatural amino acids into the photoswitchable green fluorescent protein Dronpa2, thus systematically altering the electronic properties of the chromophore (see the Perspective by Hu
et al.
). Crystal structures and spectroscopic analyses of a series of these variants support a model in which the electrostatic interactions between the chromophore and its environment influence the barrier heights for twisting around different bonds during photoisomerization. These insights may guide future design of photoswitchable proteins with desired properties.

Science
, this issue p.
76
; see also p.
26
A Kelch13-defined endocytosis pathway mediates artemisinin resistance in malaria parasites
Authors: Birnbaum Jakob , Scharf Sarah , Schmidt Sabine , Jonscher Ernst , Hoeijmakers Wieteke Anna Maria , Flemming Sven , Toenhake Christa Geeke , Schmitt Marius , Sabitzki Ricarda , Bergmann Bärbel , Fröhlke Ulrike , Mesén-Ramírez Paolo , Blancke Soares Alexandra , Herrmann Hendrik , Bártfai Richárd , Spielmann Tobias
Published: January 2020

An artemisinin resistance mechanism

Species of the malaria parasite
Plasmodium
live in red blood cells and possess a highly conserved gene called
kelch13
. Single point mutations in this gene are associated with resistance to the frontline artemisinin drugs. Birnbaum
et al.
found that Kelch13 and associated proteins comprise an endocytic compartment associated with feeding on host erythrocytes (see the Perspective by Marapana and Cowman). Hot targets for artemisinin research also occur in this compartment, including the proteins UBP1, AP-2µ, and the parasite homolog of the endocytosis protein Eps15. Inactivation of Kelch13 compartment proteins revealed that these are required for endocytosis of host hemoglobin. Artemisinins are activated by hemoglobin degradation products, so these mutations render the parasite resistant to these drugs to different extents.

Science
, this issue p.
51
; see also p.
22
Total synthesis reveals atypical atropisomerism in a small-molecule natural product, tryptorubin A
Authors: Reisberg Solomon H. , Gao Yang , Walker Allison S. , Helfrich Eric J. N. , Clardy Jon , Baran Phil S.
Published: January 2020

A twisted small-molecule synthesis

Some molecules are easy to draw on paper, whereas others contain rings and contortions that require one to think in three dimensions. Reisberg
et al.
set out to synthesize the bicyclic small molecule tryptorubin A but found that their initial attempt produced a molecule with the right bonds but the wrong molecular shape, a form of noncanonical atropisomerism. The authors then devised a synthesis where they locked in the correct isomer before forming the second ring, which produced a product indistinguishable from the authentic natural product. Such structural isomers may be lurking when working with complex small molecules with constrained rotation.

Science
, this issue p.
458
Cooked starchy rhizomes in Africa 170 thousand years ago
Authors: Wadley Lyn , Backwell Lucinda , d’Errico Francesco , Sievers Christine
Published: January 2020

Middle Stone Age cooking

Early evidence of cooked starchy plant food is sparse, yet the consumption of starchy roots is likely to have been a key innovation in the human diet. Wadley
et al.
report the identification of whole, charred rhizomes of plants of the genus
Hypoxis
from Border Cave, South Africa, dated up to 170,000 years ago. These archaeobotanical remains represent the earliest direct evidence for the cooking of underground storage organs. The edible
Hypoxis
rhizomes appear to have been cooked and consumed in the cave by the Middle Stone Age humans at the site.
Hypoxis
has a wide geographical distribution, suggesting that the rhizomes could have been a ready and reliable carbohydrate source for
Homo sapiens
in Africa, perhaps facilitating the mobility of human populations.

Science
, this issue p.
87
Clarity in 2020
Authors: Thorp H. Holden
Published: January 2020

We begin 2020 (or should I say 20/20) awash in references to ophthalmology. In that vein, we hope to make science clearer and brighter in the months ahead—which brings me to the issue of transparency.
Increased Resistance of
Pseudomonas aeruginosa
to Carbenicillin After Reversion from Spheroplast to Rod Form
Authors: Watanakunakorn Chatrchai , Phair John P. , Hamburger Morton
Published: January 2020

Five of six strains of
Pseudomonas aeruginosa
had at least fourfold increase in resistance to carbenicillian after they reverted from carbenicillin-induced spheroplasts to rod forms. The most susceptible laboratory strain showed the greatest increase in resistance. There was a marked inoculum effect on the minimal inhibitory concentration of carbenicillin when high inocula (10
7
colony-forming units) or very low inocula (10
2
or 10
3
colony-forming units) were used. Population analysis of this reverted strain revealed increase in resistance of the entire population of cells to carbenicillin. However, the degree of resistance was not homogenous. Only a few cells were highly resistant. Comparison of the effect of carbenicillin on the growth of the parent and reverted strains confirmed the increase in resistance of the reverted strain. The resistance remained stable after 42 passages.
New Classification of
Neisseria meningitidis
by Means of Bactericidal Reactions
Authors: Gold Ronald , Wyle Frederic A.
Published: January 2020

A bactericidal assay is described which allows identification of distinct serotypes within a serogroup of
Neisseria meningitidis
. Antisera produced in rabbits against seven group C strains by two intravenous inoculations of live organisms were found to contain two types of bactericidal antibodies. One, directed against the group-specific polysaccharide, caused various degrees of killing of all strains. Absorption of this antibody by purified group C polysaccharide revealed the presence of the second bactericidal antibody. This antibody was directed against antigenically distinct factors associated with serotype specificity. Extensive cross-absorption yielded antisera with activity directed against four separate factors. The presence of a factor in a strain was indicated by its susceptibility to killing by antisera containing antibody to that factor. A serotype was defined by the particular combination of factors. Six different serotypes, containing one or two factors, were identified among 16 group C strains examined.
Polymorphonuclear Leukocyte Chemotactic Activity in Rabbit Serum and Guinea Pig Serum Treated with Immune Complexes: Evidence for C5a as the Major Chemotactic Factor
Authors: Snyderman Ralph , Phillips Jean , Mergenhagen Stephan E.
Published: January 2020

A number of polymorphonuclear leukocyte (PMN) chemotactic factors derived from complement components have been described. We sought to determine which of these factors accounted for the majority of PMN chemotactic activity in rabbit serum and guinea pig serum treated with preformed immune complexes. Normal rabbit sera, guinea pig sera, or rabbit sera deficient in C6 were treated with homologous antibovine serum-albumin-bovine serum-albumin complexes. Sera so treated contained one major PMN chemotactic factor which was heat-stable (56 C for 30 min), had a molecular weight of approximately 15,000, and did not require the presence of C6 for its generation. This factor appears to be analogous to C5a.
Nature of "memory" in T-cell-mediated antibacterial immunity: anamnestic production of mediator T cells
Authors: North R J
Published: January 2020

Mice that survived an immunizing infection with Listeria monocytogenes remained specifically resistant to lethal secondary infection for several months. This acquired, long-lived state of resistance was not dependent on activated macrophages that remained after the primary response. It depended, instead, on an acquired long-lived capacity on the part of immunized mice for generating mediator T cells faster and in larger numbers than normal mice. The number of mediator T cells generated in response to secondary infection was proportional to the level of infection. The results suggest that the accelerated production of mediator T cells that occurs in response to secondary infection represents the expression of a state of immunological T-cell memory.
Nonspecific resistance to Escherichia coli in mice
Authors: Shayegani M , Parsons L M
Published: January 2020

Nonspecific cell-mediated immunity to a relatively virulent strain of Escherichia coli was studied in mice infected with Staphylococcus aureus and elicited with specific antigens. The infected and elicited mice were protected against as intraperitoneal challenge by E. coli for an observation period of 7 days, whereas normal mice, given the same number of bacteria, died within 18 to 24 h. However, the amount of time elapsing between elicitation and challenge greatly affected the rate of protection. Little or no protection was observed in mice injected with S. aureus but not elicited or in mice injected with staphylococcal antigens but not infected with staphylococci.
Effect of pneumococci on blood clotting, platelets, and polymorphonuclear leukocytes
Authors: Guckian J C
Published: January 2020

Infections due to Streptococcus pneumoniae and products from the organism have been associated with alterations in blood clotting and function of platelets. Pneumococci and pneumococcal polysaccharide shortened the clotting times of whole blood, platelet-rich plasma (PRP), and platelet-poor plasma (PPP) in vitro. Clotting times of PPP and PRP from C6-deficient animals were likewise decreased. The bacteria had no effect on the one-stage prothrombin time or the partial thromboplastin time when the organisms were used as activating agents. Platelets aggregated in the presence of pneumococci, but aggregation was prevented by the addition of cyclic adenosine 3', 5'-monophosphate (cAMP). Furthermore, cAMP corrected the shortened clotting time of PRP in the presence of pneumococci. The clumping and release of polymorphonuclear coagulant that was induced by pneumococci was not prevented by cAMP. Thus, pneumococci exert several dose-dependent thromboplastic effects: (i) release of platelet thromboplastic substances; (ii) a direct thromboplastic effect; and (iii) release of polymorphonuclear coagulant.
In vivo and in vitro stimulation of mouse spleen leukocytes by BL-20803, a low-molecular-weight interferon inducer
Authors: Siminoff P
Published: January 2020

BL-20803, a low-molecular-weight compound, although able to elicit circulating interferon in the mouse, failed to protect cultured cell lines in vitro from infection by interferon-sensitive viruses. Of the tissues analyzed for interferon content after oral administration of the drug to mice, spleen and lung contained the largest amounts of the virus inhibitor. Spleen cells from such dosed animals when isolated into in vitro cultures elaborated small amounts of interferon into the culture medium. The time sequence of acquisition by spleen cells of the ability to produce interferon closely correlated with the kinetics of development of the circulating interferon response in the intact mouse. When spleen cells were separated on the basis of adherence or nonadherence to a plastic surface, the bulk of the interferon activity was found to be associated with the adherent cells. Upon exposure to BL-20803 in cell culture, adherent cells and, to a lesser extent, nonadherent cells from untreated mice were stimulated to produce interferon-like activity. The biological behavior of BL-20803 is shown to have striking similarities with that of the structurally different low-molecular-weight inducer tilorone hydrochloride.
Selective adhesion of microorganisms to the ductular epithelium of the bovine mammary gland
Authors: Frost A J
Published: January 2020

Streptococcus agalactiae, Streptococcus faecalis, Staphylococcus aureus, Escherichia coli, and Corynebacterium bovis were examined for their ability to adhere to the ductular epithelial cells of the bovine udder. S. agalactiae and S. aureus adhered readily and in large numbers, whereas the other organisms adhered poorly or not at all. The organisms showing the ability to adhere are those which frequently cause mastitis. These data suggest that selective adherence to the ductular epithelium may be the first stage in the pathogenesis of streptococcal and staphylococcal mastitis.
Siderochrome production by Yersinia pestis and its relation to virulence
Authors: Wake A , Misawa M , Matsui A
Published: January 2020

P+ plague strains contained more siderochrome-producing organisms than P-. Siderochrome enhanced the mouse virulence of an F1+Vw+P1+P-Pu+ strains, inhibited P1 activity, and could be assayed by a paper disk titration method.
Localized immunity in experimental bovine mastitis caused by Mycoplasma dispar
Authors: Gourlay R N , Howard C J , Brownlie J
Published: January 2020

Development of immunity to reinfection with Mycoplasma dispar occurred in the bovine mammary gland and appeared to be confined to the quarter or quarters previously infected with this mycoplasma; it was not generalized throughout the gland. Immunity followed the inoculation of virulent strains of M. dispar but not of an avirulent strain. The immunity engendered protected against both homologous and heterologous strains of M. dispar. Challenge of immune quarters with virulent M. dispar resulted in a transient polymorphonuclear cell response greater than that observed in previously uninoculated quarters.
Chitin assay used to demonstrate renal localization and cortisone-enhanced growth of Aspergillus fumigatus mycelium in mice
Authors: Lehmann P F , White L O
Published: January 2020

Aspergillus fumigatus mycelium in untreated mice (N-mice) and cortisone acetate-treated mice (C-mice) has been quantified by chemical assay of fungal chitin. Cortisone pretreatment rendered mice more susceptible to infection by A. fumigatus (mean lethal dose at 20 days, congruent to 10(6) for N-mice; less than 10(4) for C-mice). In both N- and C-mice there was renal localization of mycelial infection at conidial doses less than the mean lethal dose. At a conidial dose greater than the mean lethal dose, mycelial infection was found in the kidneys and brain of N-mice and in the kidneys, liver, and heart of C-mice. Chitin assay results showed that A. fumigatus mycelium grew more rapidly in C-mice. It is suggested that the resistance of N-mice to mycelial development may be an important mechanism whereby natural resistance to A. fumigatus is conferred.
Increased susceptibility to bacterial infection as a sequela of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin
Authors: Thigpen J E , Faith R E , McConnell E E , Moore J A
Published: January 2020

The effects of subclinical levels of 2,3,7,8-tetrachloridibenzo-p-dioxin (TCDD) on the response of mice to infection with either Salmonella bern or Herpesvirus suis, also known as pseudorabies virus, are reported. TCDD is a contaminant of certain commercially useful chemicals, such as chlorinated phenols or herbicides. It has been shown to cause thymic atrophy and to suppress cell-mediated immunity in laboratory animals. Sublethal levels of TCDD were used: 0.5, 1,5, 10, or 20 mug/kg, given through a gastric tube once weekly for 4 weeks. A significant decrease in weight gain compared with control mice occurred at the 20-mug dosage. Dose schedules of 1 mug or more, followed by salmonella infection, resulted in significant increases in mortality and decreases in the time from infection to dealth. However, TCDD had no significant effect on mortality in the pseudorabies-infected mice. The most important finding in this study is that extremely low levels of TCDD, which do not produce clinical or pathological change, still have the capacity to affect host defense.
Identification of cholesterol in the receptor site for rickettsiae on sheep erythrocyte membranes
Authors: Ramm L E , Winkler H H
Published: January 2020

Cholesterol was identified as an essential component of the receptor on the sheep erythrocyte to which Rickettsia prowazeki adsorbs before lysing the cell. Erythrocytes or ghosts, derived by hypotonic lysis, were treated with proteolytic enzymes, sialidase, sulfhydryl reagents, and periodate without affecting their ability to adsorb rickettsiae. Lipid extracts of ghosts and erythrocytes, on the other hand, contained receptor activity. Fractionation of the lipid extracts by silicic acid column chromatogrphy resulted in the isolation of receptor activity in a neutral lipid fraction. The lipid fractions demonstrated receptor acitity at 34 C but not at 0 C. These properties are also characteristic of the receptor activity with erythrocytes and ghosts. Cholesterol, co-lyophilized with palmitic acid, was found to possess receptor activity. Palmitic acid alone, cholesterol-lecithin, cholestane-palmitic acid, and various phospholipids and glycolipids had no receptor activity. Ghosts treated with amphotericin B or digitonin, compounds that bind to cholesterol in the membrane, lost their ability to adsorb rickettsiae.
Adaptation of an osmotically fragile L-form of Streptococcus pyogenes to physiological osmotic conditions and its ability to destroy human heart cells in tissue culture
Authors: Leon O , Panos C
Published: January 2020

An osmotically fragile L-form of Streptococcus pyogenes, type 12, was quickly rendered osmotically stable by decreasing the sodium chloride content of the growth medium and with the temporary use of oleic acid. The change from osmotic fragility to stability was accompanied by changes in cell yield, generation time, saturated/unsaturated fatty acid ratio of the membrane, and cytoplasmic protein composition. Finally, this resulting osmotically stable L-form survived and was capable of rapidly destroying Girardi human heart cells in tissue culture.
Aleutian disease of mink: production of 14C-labeled antiviral antibodies by mink lymphoid cells in vitro
Authors: Bloom M E
Published: January 2020

Lymphoid cells from mink infected with Aleutian disease virus produced labeled, specific antiviral antibody when incubated in medium containing [14C]tyrosine.
Quantitative reduction of 2,3,4-triphenyl tetrazolium chloride by hamster trachea organ cultures: effects of Mycoplasma pneumoniae cells and membranes
Authors: Gabridge M G , Polisky R B
Published: January 2020

The ability of Mycoplasma pneumoniae cells and membranes to affect tetrazolium reduction by hamster trachea organ cultures was evaluated. Uninfected trachea explants reduced 2,3,5-triphenyl tetrazolium chloride (TTC) and nitro-blue tetrazolium when incubated at 37 C in the absence of air. Reduced tetrazolium salts (formazans) were extractable with acetone or ethylene glycol and could be quantitated spectrophotometrically. The optimal assay system involved the use of three or more tracheal rings incubated for 2 h in 0.12% TTC in Tyrode balanced salts supplemented with 1.2% sodium succinate. Formazan was extracted for 5 min with acetone, and the optical density (490 nm) was determined. Trachea explants with metabolic activity reduced or obliterated by freeze-thaw lysis, heat (56 C X 30 min), or cyanide (0.1 M NaCN X 30 min) had negligible ciliary activity and tetrazolium reduction activity (optical density at 490 nm [dry weight]). Tracheas exposed to mycoplasma cells or membranes also showed significantly decreased ciliary activity and tetrazolium reduction; e.g., only 5pc of the ciliary activity and reduction capacity remained after 5 days in culture when infected with M. pneumonia PI 1428 cells. The data indicate that the exposure of ciliated respiratory epithelium to mycoplasma cells or membranes results in diminished oxidative metabolism, and that the ability to reduce TTC to its formazan is correlated with relative ciliary activity.
Role of the rfa locus in the immunogenicity of common enterobacterial antigen
Authors: Marx A , Petcovici M
Published: January 2020

Escherichia coli O14 is one of the few strains of Enterobacteriaceae which in the rabbit engender antibodies in high titers against the common enterobacterial antigen (CA). It is a rough strain that does not possess a specific side chain in its lipopolysaccharide structure (rfa+rfb-). An rfa mutant (rfa-rfb-) was isolated from this parental strain. Chemical analysis revealed the absence of one glucose and of one galactose molecule in the core polysaccharide of the mutant. The incomplete synthesis of the core was accompanied by loss of immunogenicity of CA. In the mutant, in contrast to the wild type, CA was not bound to the core; hence, the core lipopolysaccharide might exert immunosuppressive activity on CA. A protein fraction of normal rabbit serum was shown to destroy the erythrocyte-coating capacity of CA. This fraction also displayed immunosuppressive activity on free CA but not on CA bound to the core polysaccharide.
Use of cryopreserved virus-infected target cells in a lymphocytotoxicity 51Cr release microassay for cell-mediated immunity to cytomegalovirus
Authors: Thong Y H , Hensen S A , Vincent M M , Fuccillo D A , Stiles W A , Bellanti J A
Published: January 2020

A new 51Cr-release microassay is described for the measurement of cell-mediated immunity to cytomegalovirus, using cryopreserved target cells acutely infected with cytomegalovirus.
Aerosol vaccination of mice with a live, temperature- sensitive recombinant influenza virus
Authors: Jemski J V , Walker J S
Published: January 2020

Mice were vaccinated intranasally (i.n.) or with small-particle aerosols (SPA; 2 mum) or large-particle aerosols (LPA; 8 mum) of an attenuated, temperature-sensitive, recombinant A influenza (H3N2) virus, ts-1 (E). Serum virus-neutralizing and hemagglutination inhibition antibodies were detected for all vaccinated mice by 28 days. Bronchoalveolar wash fluids had increased levels of immunoglobulin (IgG, IgA) only in the i.n. -vaccinated mice. Hemagglutination and virus-neutralizing antibodies were detected in the SPA- and i.n. -vaccinated groups but not in the LPA vaccinates. Upon challenge with SPA of a mouse virulent H3N2 influenza vitus, total protection was obtained for the SPA- and I.N. -vaccinated mice, whereas only 89% of the LPA group survived. Replication of the challenge virus was signifcantly repressed in both the lower and upper respiratory tracts of the three groups of vaccinated mice compared to the nonvaccinated controls. The protection afforded the SPA- and i.n. -vaccinated mice was the same as measured for mice after recovery from earlier subelthal active infection with virulent virus.
Interactions of antisera, sera, and oral fluid with glucosyltransferases
Authors: Burckhardt J J , Guggenheim B
Published: January 2020

Partially purified glucosyltransferases (GTF) isolated from Streptococcus mutans OMZ 176 and respective rabbit antisera were used to study enzyme-antibody interactions. A comparison between sensitive serological techniques and a functional inhibition test based on a radioenzyme assay demonstrated that the latter test system was the only one that discriminated between different antisera. Positive reactions in high dilutions in the former test systems were explained by the involvement of non-GTF contaminants and/or antibodies against enzyme regions distant to the catalytic site. The minute cross-reactions between two enzyme fractions and the respective antisera in the functional inhibition test indicated that the two immunogens contained mainly GTF that differed in the structure of their catalytic region. Control rabbit sera, rat oral fluid, and insoluble and soluble glucans considerably activated the GTF eluted with a 0.5 M phosphate buffer from hydroxapatite. It is suggested that these enzymes had additional binding sites for macromolecules inherent to rabbit sera and rat oral fluid, respectively, and that the observed increase in enzyme activity was due to a more stable enzyme conformation. Possibly the stimulation of GTF by the soluble glucan fraction was caused by a primer and/or acceptor function; however, this was not the case of the insoluble glucan. A stable complex was formed in the absence of the enzyme substrate, sucrose, the activity of which was not readily enhanced. It is concluded that the GTF of strain OMZ 176 are composed of multiple, multi-reactive molecules that enable these enzymes to act as cross-linking agents.
Interaction of purified leukocidin from Pseudomonas aeruginosa with Bovine polymorphonuclear leukocytes
Authors: Scharmann W
Published: January 2020

The interaction of purified leukocidin from Pseudomonas aeruginosa, strain 158, with polymorphonuclear leukocytes of cattle (PMLC) was studied by using 125I-labeled toxin. According to the Scatchard plot, PMLC offered two binding sites for leukocidin: one at the surface of the plasma membrane, and a second one that presumably became accessible to the toxin in the course of the cytotoxic action. Toxin once fixed to PMLC at 37 C could not be detached from the cells by either chemical or mechanical treatment. However, active leukocidin was liberated if it was bound to PMLC at 4 C and the temperature of the cell suspension was subsequently increased to 37 C. In the presence of Ca2+, the velocity of toxin fixation was accelerated and the rate of fixation was increased. Preliminary investigations on the identification of the leukocidin-binding material indicated the leukocidin receptor to be an integral protein of the plasma membrane.
Interaction of Chlamydia trachomatis organisms and HeLa 229 cells
Authors: Kuo C C , Grayston T
Published: January 2020

The infection of HeLa 229 cells in monolayer culture with trachoma (B/TW-5/OT) and lymphogranuloma venereum (LGV) (L2/434/Bu) organism was studied in terms of two parameters: radioactivity counts of cell-associated tritium labeled organisms at the initial stage of inoculation for measurement of attachment, and inclusion counts of infection cells after incubation for measurement of growth. Factors affecting attachment and inclusion formation and correlation of the two are presented. It was shown that attachment is an important initial step in infection by Chlamydia trachomatis. The rate of attachment was temperature dependent. The attachment of LGV organisms was affected more profoundly by temperature than was that of trachoma organisms. Attachment and inclusion formation of trachoma and LGV organisms were inhibited by heparin. Diethylaminoethyl-dextran was again shown to enhance attachment and inclusion formation of trachoma but not LGV organisms. NaF had no effect on attachment, but inhibited inclusion formation of both trachoma and LGV organisms. Both attachment and inclusion formation of trachoma organisms were strongly enhanced by centrifugation of the inoculum onto the cell monolayer. Although inclusion formation of trachoma organism was much greater in susceptible cells (HeLa 229) than relatively insusceptible cells (fetal tonsil), attachment was only slightly greater. The results based on the test of two cell lines suggested that attachment prpbably is not a critical factor in determing a cell line's susceptibility to infection with trachoma organisms.
Influence of the indigenous gastrointestinal microbial flora on duodenal Mg2+ -dependent and (Na+ + K+) -stimulated adenosine triphosphatase activities in mice
Authors: Yolton D P , Savage D C
Published: January 2020

Mg-dependent and (Na+ + K+)-stimulated adenosine triphosphatase (ATP-ase) activities were assayed in butanol extracts of duodenal tissue from germ-free, specific-pathogen-free, and ex-germfree mice associated with an indigenous microflora from specific-pathogen-free mice. In the germfree mice the levels of both ATPase activities were significantly higher than the levels in specific-pathogen-free mice. By contrast, the ex-germfree animals colonized by an entire indigenous microflora, the values fell to levels close to those for specific-pathogen-free animals. (Na+ + K+)-stimulated ATPase was not inhibited by ouabain in extracts from any of the three kinds of mice. These findings show that the indigenous microbial flora influences the intestinal ATPase activity of mice and, because of the connection between (Na+ + K+-stimulate ATPase and active transpoort, undoubtedly affects the process of absorption in the intestinal tract.
Immunoglobulins A, G, and M in serum and in some secretions of monkeys (Macaca fascicularis syn. irus)
Authors: Cole M F , Bowen W H
Published: January 2020

The purpose of this investigation was to study the distribution and levels of the following immunoglobulins, IgA, IgG, and IgM ,in sera and in some secretions of monkeys (M. fascicularis). IgG, IgA, and IgM were isolated from monkey serum and secretory IgA was separated from monkey milk by combined gel filtration and ion-exchange chromatography. These pure preparations served as standards to quantitate immunoglobulins in sera and secretions by single radial immunodiffusion. Antisera were raised in the rabbit against the pure immunoglobulins and also against the whole secretions to identify the immunoglobulins in immunoelectrophoresis. In common with humans, the major immunoglobulin in serum and amniotic fluid is IgG and the IgG/IgA ratio is greater than unity. In secretions IgA is the dominant immunoglobulin and the IgG/IgA ratio is less than 1. In general, the levels of immunoglobulins in the sera and secretions of monkeys paralleled the levels found in humans. No age-related increase in immunoglobulin levels was detected in the sera of monkeys.
Correlation between pseudomonas burn wound infection and granulocyte antibacterial activity
Authors: McEuen D D , Blair P , Delbene V E , Eurenius K
Published: January 2020

The relationship of granulocyte bactericidal activity with three strains of pseudomonas and the virulence of these same organisms in a scald-burned rat model was investigated. Resistance to bactericidal activity was measured for each strain, using an in vitro assay and normal rat peritoneal granulocytes. Mortality was recorded for rats receiving a 30% third-degree scald burn with simultaneous pseudomonas burn wound infection. A positive correlation between mortality and resistance to bactericidal activity of granulocytes was obtained. These studies stress the importance of pseydomonas strain specificity in burn wound infection and indicate that mortality from these strains may be specifically related to their resistance to the bactericidal activity of leukocytes.
Pili as a mediator of the attachment of gonococci to human erythrocytes
Authors: Buchanan T M , Pearce W A
Published: January 2020

Isolated pure gonococcal pili were found capable of producing direct agglutination of human erythrocytes. Four different strains of gonococci were compared, and hemagglutination was produced by isolated pili or piliated gonococci but not by nonpiliated gonococci of each strain. Pili from each of the four strains were antigenically distinguishable using antisera specific for pili to agglutinate piliated gonococci, form precipitin lines in Ouchterlony immunodiffusion, or inhibit hemagglutination caused by purified pili or piliated gonococci. However, these tests also demonstrate some shared antigenicity among pili. Shared antigens among the four pili types were quantitated at less than or equal to 2.5% by radioimmunoassay. Inhibition of hemagglutination was most marked with antiserum to the homologous pili type. Inhibition of hemagglutination by antiserum to heterologous pili suggested that shared antigens on pili from B and 2686 strains of gonococci are located near the erythrocyte attachment moiety of B strain pili and removed from the attachment moiety of 2686 strain pili. These results suggest that antigenic heterogeneity of pili will prove an important factor in any efforts to use pili as a vaccine for gonorrhea.
Characteristics of atypical Neisseria gonorrhoeae from disseminated and localized infections
Authors: Morello J A , Lerner S A , Bohnhoff M
Published: January 2020

Approximately 6% of 1,200 clinical isolates of Neisseria gonorrhoeae were atypical because they produced smaller than normal colonies on conventioal chocolate agar and fermented glucose weakly. Auxotyping studies indicated that these atypical strains required for growth arginine, uracil, and, in most instances, hypoxanthine. In addition, all of them were susceptible to 0.02 U of penicillin/ml. None of the normal colony isolates, including those susceptible to the same low concentration of penicillin, had the same nutritional characteristics. Atypical strains comprised almost half of the isolates from disseminated infections, but only 5% of those from localized infections. Auxotyping was used to identify the contact of a patient who became reinfected nine times with an atypical gonoccal strain. In addition to its usefulness in such epidemiological studies, this technique has enabled us to distinguish a subgroup of gonococci with apparent increased pathogenicity.
Treponema pallidum infection in subcutaneous polyethylene chambers in rabbits
Authors: Tight R R , Perkins R L
Published: January 2020

Male New Zealand white rabbits with subcutaneous polyethylene chambers in place for at least 3 months were inoculated by one of the following three methods: (i) "intra-chamber" (IC) inoculation with "normal" chamber fluid: (ii) intratesticular inoculation with Treponema pallidum; or (iii) IC inoculation with T. pallidum. Rabbits given dexamethasone only, oxisuran only, both drugs, or no drug were observed serially after inoculation. T. pallidum survived and temporarily multiplied to significant numbers within subucutaneous chambers after IC inoculation in rabbits given dexamethasone. In rabbits not treated with dexamethasone, T. pallidum counts in chamber fluid decreased rapidly and remained at low levels for 30 days after IC inoculation. Oxisuran appeared to have little or no effect on T. pallidum multiplication. All rabbits studied had a nonreactive serum and chamber fluid serological test for syphilis before inoculation. All rabbits inoculated with T. pallidum eventually developed reactive serum and chamber fluid serological tests. The IC route of inoculation was associated with a delay in the development of serum serological reactivity and with earlier chamber fluid reactivity as compared with the intratesticular route of inoculation. An immediate but transent influx of polymorphonuclear leukocytes was associated with IC inoculation of T. pallidum. Chamber fluid total protein content declined very slightly in all groups of rabbits during the month after inoculations. Successful cultivation of T. pallidum in an in vivo setting suggests that this animal model may be useful in further studies of the biology of the organism of the pathogenesis, immunology, and treatment of syphilis.
Identification of the stumptailed macaque virus as a new papovavirus
Authors: Reissig M , Kelly T J , Daniel R W , Rangan S R , Shah K V
Published: January 2020

A new viral agent, stumptailed macaque virus (STMV), isolated from uninoculated stumptailed macaque kidney cultures was identified. The virions had the size and morphology of papovaviruses of the simian virus 40 (SV40)-polyoma subgroup, but many of them appeared to have an additional outer envelope. The deoxyribonucleic acid of STMV was a superhelical circular molecule, with a mean length 91% of that of SV40. The antigenic relationship of this virus with other members of the group was examined by immune electron microscopy of isolated virions and by immunofluorescent staining of virus-infected cells. STMV was immunologically distinct from SV40, BK virus (BKV), polyoma virus, and JC virus. Its tumor antigen may be related to those of SV40 and BKV.
Adhesive properties of Vibrio cholerae: adhesion to isolated rabbit brush border membranes and hemagglutinating activity
Authors: Jones G W , Abrams G D , Freter R
Published: January 2020

Adhesion of vibrios to the small intestine may occur (i) by association of the bacteria with secreted mucus gel or (ii) by adherence of the bacteria to the surface of epithelial cells. In the present study, vibrios readily adhered to isolated brush border membranes obtained from rabbit intestinal epithelial cells. Adhesion was temperature dependent and required the presence of divalent cations such as calcium. The agglutination of human O erythrocytes by Vibrio cholerae was observed also, and the hemagglutination test appeared to detect the same mechanism that was involved in the adhesion of vibrios to brush borders. When the bacteria were grown in broth they were adhesive and hemagglutinating, but vibrios grown on agar plates or suspended in buffer for 15 min at 37 C lacked these abilities, even though they retained undiminished motility. These two model systems differed, however, in that strontium promoted only adhesion to brush borders. The significance of this difference remains to be determined. Vibrios were observed to penetrate intestinal mucus gel and occasionally to become entrapped in it. However, there was no evidence that vibrios attached to mucus gel.
Stimulation of lymphocyte proliferation by killed mycobacteria and other bacterial species
Authors: Bekierkunst A
Published: January 2020

Killed mycobacteria and some mycobacterial fractions induced spleen cells from normal C3H mice to incorporate tritiated thymidine to a relatively high degree. Thymocytes under the same conditions were not activated. However, incorporation of thymidine was significantly increased when mixtures of thymus and spleen cells were cultured in the presence of the inducers. A similar activation of spleen cells was displayed in the presence of gram-positive and gram-negative non-mycobacterial species.