bluuebunny/crossref_metadata_2025 huggingface dataset:
Inertia Forces in Lubricating Films
Authors: Brand R. S.
Published: June 2021

The usual theory of hydrodynamic lubrication is based on the assumption that the inertia forces in the equations of motion are negligible compared to the viscous forces. This paper shows that if the Reynolds number ρRω/μ is of the same order as R/h, then the inertia forces will be of the same order as the viscous forces.
The Analysis of Dynamic Stresses in Aircraft Structures During Landing as Nonstationary Random Processes
Authors: Fung Y. C.
Published: June 2021

The basic fact is recognized that throughout the service life of an airplane there occurs a variety of landing conditions and, consequently, it is subjected to transient dynamic loads of varied time histories. Accordingly, a statistical analysis is proposed. The landing-gear impact load is regarded as a nonstationary random process. In this paper the ensemble means and the correlation functions of landing impacts are defined and their experimental determination from flight or drop tests is illustrated. From these the mean response (displacement, bending moment, shear, or stress), the root mean square deviation from the mean, and higher statistical moments are computed. The results are used to find the most probable maximum stress (at any point in the structure) attained in a given number of landings, or the most probable total number of landings a given aircraft can withstand. A stress envelope can be derived which represents the distribution of the severest stress in the structure for a large number of landings. A design based on such an envelope, statistically, will have a uniform factor of safety over the entire aircraft with respect to landings.
Steady-State Behavior of Systems Provided With Nonlinear Dynamic Vibration Absorbers
Authors: Arnold F. R.
Published: June 2021

The response of vibrating systems subjected to sinusoidal excitations and to the action of nonlinear dynamic vibration absorbers is determined by means of a simple procedure. Extensive information including that from more complicated methods of analysis is obtainable. System behavior is described by means of “response diagrams,” and certain peculiarities are discussed.
A Study of the Stability of Plane Fluid Sheets
Authors: Hagerty W. W. , Shea J. F.
Published: June 2021

In studying the performance of a system for producing sprays of any kind it would be desirable to arrive at an expression which would relate the drop-size distribution and the spatial distribution of the drops in terms of the variables of the system including pressure, density, surface tension, and geometry. In an earlier study of the performance of hollow-cone swirl-type nozzles, photographs were taken of the region where the fluid sheet breaks up into drops. These photographs showed that before the break-up occurred, waves or ripples appeared on the surface of the liquid sheet. It was believed that the waves were responsible for the break-up and that frequency and wave length of the ripples might be related to the size range of drops produced. Difficulties were encountered in an analytical treatment of the stability of the surface produced by a swirl-type nozzle, the surface being a hyperboloid of revolution. Therefore a system was selected for study in which a flat sheet of fluid is produced by a slender orifice, and which may be subjected to waves of any desired frequency. This plane sheet, exposed on both sides, appears to have the essential characteristics of the sheet produced by a conventional nozzle.
Nonlinear Dynamic Coupling in a Beam Vibration
Authors: McDonald P. H.
Published: June 2021

This investigation treats the vibration of a uniform beam with hinged ends which are restrained, and which has arbitrary initial conditions of motion. A representative example is discussed in which the beam is subjected to a concentrated lateral force at the mid-point of its span and released from rest at the deflected position. The equations of motion are found to be inherently nonlinear, even for small vibrations, and there is dynamic coupling of the modes. It is found that the frequencies of the various modes are functionally related to the initial conditions, particularly the amplitudes of all the modes.
A Matrix Solution for the Vibration Modes of Nonuniform Disks
Authors: Ehrich F. F.
Published: June 2021

An arbitrary disk is represented by a simulated disk composed of circumferential strips. Alternate strips are considered to be massless, constant-thickness elements with the average local elastic properties of the actual disk. Intermediate strips are considered to have the properties of local mass and polar moment of inertia, but to have no physical dimensions or elasticity. A matrix vector, formed of the local antinodal value of deflection, slope, moment, and transverse force, may be operated on by matrices representative of the elastic strips and by matrices representative of the vibratory inertia loading, centrifugal inertia loading, internal stress, and external supports at the mass strips. Thus the influence of boundary conditions at the outer edge on conditions at the inner edge may be calculated in a simple efficient manner. Successive guesses of vibration frequency lead to final satisfaction of all boundary conditions. Concise treatment of all types of boundary conditions and numerical values of required matrices are given in tables. The results of a sample calculation are compared with exact analytic results.
Studies in Dynamic Photoelasticity
Authors: Frocht M. M. , Flynn P. D.
Published: June 2021

Equipment and techniques are described for obtaining dynamic photoelastic stress patterns from arbitrary lines in plane-stress systems by means of streak photography. Streak-type stress patterns of such lines were obtained which provide continuous records throughout the entire period of impact (of the order of milliseconds) at times of exposure of 2/3 microsec. This is thirty times faster than the time of exposure (20 microseconds) obtained by Tuzi and Nisida in 1935. Dynamic photoelastic stress patterns showing stress-wave propagation are given for a bar struck axially by a rigid mass, and these patterns show that a uniform state of stress was obtained. Theoretical stress patterns based on the Boussinesq solution are in essential agreement with the experimental results.
Pretwisted Beams and Columns
Authors: Zickel John
Published: June 2021

A theory is developed for the behavior of pretwisted structural members of thin-walled section with slight initial bending. The stresses are at first determined along and perpendicular to the fibers and are then transformed to stresses in the cross section and along the axis. Although the development is perfectly general the integrations are only indicated for doubly symmetric sections. The buckling of doubly symmetric columns which are initially straight but are pretwisted at a constant rate is treated in detail. The results show that columns of decidedly unequal principal moments of inertia can be strengthened up to 90 per cent, but columns of equal moments of inertia are weakened by initial twist. In analogy to the Euler load of the buckling theory for straight, untwisted columns, a reduced Euler load is defined. The buckling load is the product of this reduced Euler load and a stiffening factor.
Tensor-Flexibility Analysis of Pipe-Supporting Systems
Authors: Soule J. W.
Published: June 2021

A general tensor method of analysis is used to derive the equations of performance of a complete piping system, including effect of pipe weight, supports, and thermal expansion.
A Study of Axisymmetric Vibrations of Cylindrical Shells as Affected by Rotatory Inertia and Transverse Shear
Authors: Lin T. C. , Morgan G. W.
Published: June 2021

An analysis is presented of the problem of the propagation of axisymmetric waves in an elastic circular tube. The theory includes the effects of rotatory inertia and transverse shear in the same manner as does Timoshenko’s theory of the vibrations of bars. These effects are of importance for waves at high frequencies; they tend to decrease the velocity of propagation and introduce an additional mode due to shear.
A Suction Device Using Air Under Pressure
Authors: Welanetz L. F.
Published: June 2021

An analysis is made of the suction holding power of a device in which a fluid flows radially outward from a central hole between two parallel circular plates. The holding power and the fluid flow rate are determined as functions of the plate separation. The effect of changing the proportions of the device is investigated. Experiments were made to check the analysis.
Some Dynamic Properties of Oil-Film Journal Bearings With Reference to the Unbalance Vibration of Rotors
Authors: Hagg A. C. , Sankey G. O.
Published: June 2021

Some dynamic properties of oil films have been determined experimentally and their significance in the problem of unbalance vibration and critical speeds of rotor systems is illustrated by an example. It is shown that oil films have an important role in the imbalance-vibration behavior of rotor systems, particularly the vibration magnification at resonance.
Note on Torsion With Variable Twist
Authors: Reissner Eric
Published: June 2021

In a recent paper (1) the author considered anew the problem of determining corrections to the Saint Venant theory of torsion, induced by restraint against warping at the end section of the beam. The present note is intended to furnish some further discussion of these earlier results.
A Study of Orthogonally Stiffened Plates
Authors: Hoppmann W. H. , Huffington N. J. , Magness L. S.
Published: June 2021

A previous theory and method for the analysis of orthogonally stiffened plates (1) has been extended to include additional study of theoretical and experimentally determined frequencies of vibration and strain distributions. Some details of calculations based on the theory as well as experimental results are provided in curves and tables. Sufficient verification of the theory is obtained to warrant serious consideration of possible use of the method for design purposes.
Effects of Boundary Conditions and Initial Out-of-Roundness on the Strength of Thin-Walled Cylinders Subject to External Hydrostatic Pressure
Authors: Galletly G. D. , Bart R.
Published: June 2021

Using classical small-deflection theory, an investigation was made of the effects of boundary conditions and initial out-of-roundness on the strength of cylinders subject to external hydrostatic pressure. The equations developed in this paper for initially out-of-round cylinders with clamped ends, and a slightly modified form of the equations previously derived by Bodner and Berks for simply supported ends, were applied to some actual test results obtained from nine steel cylinders which had been subjected to external hydrostatic pressure. Three semiempirical methods for determining the initial out-of-roundness of the cylinders also were investigated and these are described in the paper. The investigation indicates that if the initial out-of-roundness is determined in a manner similar to that suggested by Holt then the correlation between the experimental and theoretical results is quite good. The investigation also indicates that while the difference in collapse pressures for clamped-end and simply supported perfect cylinders may be quite considerable, this does not appear to be the case when initial out-of-roundnesses of a practical magnitude are considered.
On the Determination of a Viscoelastic Model for Stress Analysis of Plastics
Authors: Bland D. R. , Lee E. H.
Published: June 2021

A method of assessing whether or not the measured variation of complex compliance with frequency for a viscoelastic material is consistent with a four-element model is presented. The four-element model was chosen since it is relatively simple to analyze, and exhibits the three main types of viscoelastic response; namely, instantaneous elasticity, viscous flow, and delayed elasticity. If the compliance measurements are found to conform with the behavior of a four-element model over the whole or part of the frequency range studied, a graphical method of determining the model constants is presented. The significance of the application of such a model to stress analysis under transient loading is discussed.
Deflection of a Beam Referred to Any Set of Rectangular Centroidal Axes
Authors: Levy J. C.
Published: June 2021

An expression is developed for the deflection of a straight beam subjected to unsymmetrical bending which eliminates the necessity of first finding the principal axes and principal moments of inertia of the section. Since it is already possible to calculate the position of the neutral axis and also the stress distribution without referring to principal axes, the present work offers one method of completing such a solution for the class of problems where deflections besides stresses are required.
Effect of Imperfections on Buckling of Thin Cylinders Under External Pressure
Authors: Donnell L. H.
Published: June 2021

The buckling of thin cylinders under external pressure is studied by finite-deflection theory, assuming the same type of imperfections as had been assumed in a previous study of buckling under axial compression (3). Unlike the axial compression case only a small elastic postbuckling reduction in resistance is found, and this only for long cylinders. However, if reasonable imperfections are assumed, failure loads initiated by yielding are found to be of the same order as those indicated by experiments.
A Calculation Method of Surface Wear of Plastic Line Gear Pair Under Dry Friction Conditions
Authors: Lin Yifan , Chen Yangzhi , Ye Changkun , Lyu Yueling
Published: June 2021

Parallel line gear pair (PLGP) can achieve pure rolling meshing along its theoretical contact curves under the ideal condition. However, the actual meshing positions may deviate from the theoretical ones under the actual operating conditions, which may result in the alternation of contact pressure distribution and cause relative sliding of the meshing surfaces. Contact pressure and relative sliding are two main factors causing surface wear. A calculation method of surface wear of plastic line gear (LG) pair under dry friction conditions was studied theoretically and experimentally, taking a polyoxymethylene (POM) PLGP as an example. Based on the geometric model of PLGP considering the misalignments under the actual operating conditions, this method employs the three-element model and influence coefficient method to compute the contact pressure with the consideration of the viscoelasticity of the gear material. Archard’s wear equation is applied to calculate the surface wear depth. Results of the wear experiment of the POM PLGP specimens validated the feasibility of the calculation method. This study provides a necessary basis for the engineering application of plastic LG pairs.
Charging and Discharging Characteristics of Sensible Energy Storage System With Multiple Cylindrical Passages
Authors: Kumar Ravi , Patil Anil Kumar , Kumar Manoj
Published: June 2021

Sensible energy storage systems can be integrated with domestic and industrial systems to fulfill energy needs in the absence of an energy source. The present study experimentally investigates the thermal characteristics of a sensible energy storage system with multiple cylindrical passages during the charging and discharging cycles. Transient temperature distribution, energy storage, energy release, and charging/discharging energy efficiency are evaluated by varying the mass flowrate of air from 0.022 to 0.031 kg/s and inlet air temperature from 45 to 75 °C. The maximum charging energy efficiency of 81.3% was found at 55 °C inlet temperature and 0.031 kg/s of the mass flowrate of air. The maximum discharging energy efficiency is found to be 74.3% corresponding to 45 °C inlet temperature and 0.031 kg/s of the mass flowrate of air.
Perception of the acoustic environment during COVID-19 lockdown in Argentina
Authors: Maggi Ana L. , Muratore Jimena , Gaetán Sara , Zalazar-Jaime Mauricio F. , Evin Diego , Pérez Villalobo Jorge , Hinalaf María
Published: June 2021

The COVID-19 pandemic has significantly modified the behavior of societies. The application of isolation measures during the crisis resulted in changes in the acoustic environment. The aim of this work was to characterize the perception of the acoustic environment during the COVID-19 lockdown of people residing in Argentina in 2020. A descriptive cross-sectional correlational study was carried out. A virtual survey was conducted from April 14 to 26, 2020, and was answered mainly by social network users. During this period, Argentina was in a strict lockdown. The sample was finally composed of 1371 people between 18 and 79 years old. It was observed that most of the participants preferred the new acoustic environment. Mainly in the larger cities, before the isolation, mechanical sounds predominated, accompanied by the perception of irritation. Confinement brought a decrease in mechanical sounds and an increase in biological sounds, associated with feelings of tranquility and happiness. The time window opened by the lockdown offered an interesting scenario to assess the effect of anthropogenic noise pollution on the urban environment. This result offers a subjective approach, which contributes to understanding the link between individuals and communities with the environment.
The CHD8/CHD7/Kismet family links blood-brain barrier glia and serotonin to ASD-associated sleep defects
Authors: Coll-Tané Mireia , Gong Naihua N. , Belfer Samuel J. , van Renssen Lara V. , Kurtz-Nelson Evangeline C. , Szuperak Milan , Eidhof Ilse , van Reijmersdal Boyd , Terwindt Isabel , Durkin Jaclyn , Verheij Michel M. M. , Kim Chang N. , Hudac Caitlin M. , Nowakowski Tomasz J. , Bernier Raphael A. , Pillen Sigrid , Earl Rachel K. , Eichler Evan E. , Kleefstra Tjitske , Kayser Matthew S. , Schenck Annette
Published: June 2021

Autism-associated CHD8/CHD7/kismet deficiency in blood-brain barrier glia causes developmental hyperserotonemia and sleep defects.
Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: A test for future predictions
Authors: Clemens Steven C. , Yamamoto Masanobu , Thirumalai Kaustubh , Giosan Liviu , Richey Julie N. , Nilsson-Kerr Katrina , Rosenthal Yair , Anand Pallavi , McGrath Sarah M.
Published: June 2021

Pleistocene and future South Asian monsoon rainfall are linked to greenhouse gases, ice volume, and southern hemisphere moisture.
RNase L limits host and viral protein synthesis via inhibition of mRNA export
Authors: Burke James M. , Gilchrist Alison R. , Sawyer Sara L. , Parker Roy
Published: June 2021

RNase L–mediated shutoff of nuclear mRNA export limits viral protein synthesis and regulates antiviral cytokine production.
Decoding the dynamic tumor microenvironment
Authors: Clauset Aaron , Behbakht Kian , Bitler Benjamin G.
Published: June 2021

An opportunity to improve cancer outcomes with machine learning.
Abcc1 and Ggt5 support lymphocyte guidance through export and catabolism of
S
-geranylgeranyl-
l
-glutathione
Authors: Gallman Antonia E. , Wolfreys Finn D. , Nguyen David N. , Sandy Moriah , Xu Ying , An Jinping , Li Zhongmei , Marson Alexander , Lu Erick , Cyster Jason G.
Published: June 2021

This work establishes how P2RY8 ligand is exported and degraded to regulate lymphocyte behavior in lymphoid follicles and bone marrow.
Getting toGether in Germinal centers
Authors: Stoler-Barak Liat , Shulman Ziv
Published: June 2021

Ggt5 cleaves the ligand of P2RY8 in lymph node follicles and generates a gradient that supports B cell confinement to germinal centers.
It’s good to have Gremlins in the zone
Authors: Gustafson Claire E. , Maltzman Jonathan S.
Published: June 2021

A unique subset of Gremlin1-expressing fibroblastic reticular cells mediate cDC homeostasis and functionality within lymph nodes.
Concomitant but Not Causal Association Between Surface Charge and Inhibition of Phagocytosis by Cryptococcal Polysaccharide
Authors: Kozel Thomas R. , Reiss Errol , Cherniak Robert
Published: June 2021

The mechanism by which capsular polysaccharides inhibit phagocytosis is not clearly understood. We investigated the association between a negative surface charge and inhibition of phagocytosis by the capsular polysaccharide of
Cryptococcus neoformans
. A two-polymer aqueous-phase system containing phosphate ions was used to assess surface charge. Opsonins such as normal bovine serum and normal human immunoglobulin G reduced the surface charge on non-encapsulated cryptococci and simultaneously enhanced phagocytosis. These same opsonins had no effect on phagocytosis or surface charge of encapsulated cryptococci. F (ab′)
2
fragments of normal human immunoglobulin G neither enhanced phagocytosis nor altered the surface charge of non-encapsulated cryptococci. Addition of purified cryptococcal polysaccharide to non-encapsulated cells inhibited phagocytosis of the yeast and induced a strong negative charge at the yeast surface. Chemical modification to reduce the surface charge of either purified cryptococcal polysaccharide or intact encapsulated cryptococci produced a small loss of phagocytosis-inhibiting activity; however, all treated polysaccharide preparations retained a significant ability to inhibit phagocytosis of the yeast. These results indicated that the association between surface charge and inhibition of phagocytosis was largely circumstantial, and presence of a negative surface charge could not account for the powerful antiphagocytic action of cryptococcal polysaccharide.
Evaluation of Influenza A/Hong Kong/123/77 (H1N1)
ts
-1A2 and Cold-Adapted Recombinant Viruses in Seronegative Adult Volunteers
Authors: Murphy Brian R. , Rennels Margret B. , Douglas R. Gordon , Betts Robert F. , Couch Robert B. , Cate Thomas R. , Chanock Robert M. , Kendal Alan P. , Maassab Hunien F. , Suwanagool Surapol , Sotman Steven B. , Cisneros Luis A. , Anthony William C. , Nalin David R. , Levine Myron M.
Published: June 2021

Two attenuated influenza A donor viruses, the A/Udorn/72
ts
-1A2 and the A/Ann Arbor/6/60 cold-adapted (
ca
) viruses, are being evaluated for their ability to reproducibly attenuate each new variant of influenza A virus to a specific and desired level by the transfer of one or more attenuating genes. Each of these donor viruses has been able to attenuate influenza A viruses belonging to the H3N2 subtype by the transfer of one or more attenuating genes. To determine whether these two donor viruses could attenuate a wild-type virus that belonged to a different influenza A subtype,
ts
-1A2 and
ca
recombinants of a wild-type virus representative of the A/USSR/77 (H1N1) Russian influenza strain were prepared and evaluated in adult doubly seronegative volunteers at several doses. The recombinants derived from both donor viruses were attenuated for the doubly seronegative adults. Less than 5% of infected vaccinees developed a febrile or systemic reaction, whereas five of six recipients of wild-type virus developed such a response. The 50% human infectious dose (HID
50
) for each recombinant was approximately 10
5.0
50% tissue culture infective doses. The virus shed by the
ts
-1A2 and
ca
vaccinees retained the
ts
or
ca
phenotype, or both. This occurred despite replication of the recombinant viruses for up to 9 days. No evidence for transmission of the
ca
or
ts
-1A2 recombinant virus to controls was observed. A serum hemagglutination inhibition response was detected in less than 50% of the infected vaccinees. However, with the more sensitive enzyme-linked immunosorbent assay, a serological response was detected in 100% of the
ca
vaccinees given 300 HID
50
and approximately 70% of
ca
or
ts
vaccinees who received 10 to 32 HID
50
of virus. These results indicate that the recombinants derived from both donor viruses were satisfactorily attenuated and were stable genetically after replication in doubly seronegative adults although they induced a lower serum hemagglutination inhibition response than that found previously for H3N2
ts
and
ca
recombinants.
Immunity to pathogenic free-living amoebae: role of humoral antibody
Authors: Cursons R T , Brown T J , Keys E A , Moriarty K M , Till D
Published: June 2021

Pathogenic free-living amoebae are common in nature, but few clinical infections by these amoebae have been reported. This has prompted studies of host susceptibility factors in humans. A survey of normal human sera from three New Zealand Health Districts was made; antibodies to pathogenic free-living amoebae were found in all sera, with titers ranging from 1:5 to 1:20 for Naegleria spp. and from 1:20 to 1:80 for Acanthamoeba spp. The antibodies belonged mainly to immunoglobulin G and immunoglobulin M classes. The presence of a specific neutralizing factor against Acanthamoeba spp. but not Naegleria spp. was demonstrated. Possible protective mechanisms are discussed.
Candidacidal activity of mouse macrophages in vitro
Authors: Maiti P K , Kumar R , Mohapatra L N
Published: June 2021

Mouse peritoneal macrophages were infected in vitro with Candida albicans, and the phagocytic and candidacidal activities were estimated by microscopic examination of Giemsa-stained cells. Activated macrophages obtained from either BCG-vaccinated animals or by in vitro exposure of normal macrophages to phytohemagglutinin-induced lymphokines exhibited higher phagocytic and candidacidal activities than did normal macrophages. However, activated macrophages obtained by in vitro exposure of macrophages to candida-induced lymphokines exhibited the highest phagocytic and candidacidal activities. The incorporation of immune mouse serum into the culture medium also enhanced the phagocytic and candidacidal activities of the normal macrophages but failed to improve the function of the activated macrophages. These results suggest that both activated macrophages and antibodies may be required for controlling candida infections in mice.
Reactivation of temperature-sensitive and non-temperature-sensitive infectious bovine rhinotracheitis vaccine virus with dexamethasone
Authors: Pastoret P P , Babiuk L A , Misra V , Griebel P
Published: June 2021

Latent infections by a temperature-sensitive (ts) infectious bovine rhinotracheitis virus vaccines was produced as frequently as by non-ts vaccine virus. Thus virus could be reactivated in seven of eight ts vaccinates and six of eight non-ts vaccinates after dexamethasone treatment. Virus excretion could be detectable for 1 to 8 days at a level of 2 x 10(6) to 3 x 10(8) plaque-forming units per ml of nasal secretions. The reactivated virus was shown to be the same as the original virus used for vaccination by its inability to grow at the restrictive temperature (39 degrees C) as well as by its restriction endonuclease cleavage pattern.
Mitogen-induced amplification of blastogenesis in lipopolysaccharide-precultured lymphocytes
Authors: Lopatin D E , Mangan D F , Horner I S , Peebles F L
Published: June 2021

Human peripheral blood lymphocytes were cultured in vitro with lipopolysaccharide (LPS) for 48 h. After washing, stimulation with a concanavalin A (ConA) or pokeweed mitogen (PWM) resulted in a synergistic blastogenic response that was greater than the sum of the independently stimulated control cultures. Addition of fresh autologous lymphocytes after LPS preculture produced an additional increment of synergy. The nature of the responding and helping effects was determined by coculturing irradiated or nonirradiated lymphocyte suspensions that had been precultured with either LPS or ConA/PWM. Such studies indicated that amplification was the result of a mitogen-activated helper activity, which facilitated the blastogenic response to LPS. Experiments with lymphocytes resolved into T- and B-cell-enriched fractions indicated that the LPS-responsive cells were of the B type and that the help was provided by a mitogen-activated T-cell population. These studies indicated that LPS can induce human B-cell blastogenesis; however, a helper function must be provided by a T-cell subpopulation. This helper activity is inducible by pretreatment of the T cells with plant lectins.
A discrete population of mononuclear phagocytes detected by monoclonal antibody
Authors: LeBlanc P A , Katz H R , Russell S W
Published: June 2021

Rat monoclonal antibody raised against cultured mouse bone marrow was used to detect an antigenic determinant on a discrete population of mouse mononuclear phagocytes by indirect immunofluorescence. The antigen was expressed on adherent, late-cultured bone marrow macrophages and chronic inflammatory peritoneal macrophages elicited by the injection of thioglycolate broth. Binding of the antibody to resident peritoneal or alveolar macrophages, blood monocytes, or freshly explanted bone marrow cells was not detected. Less than 10% of acute inflammatory mononuclear phagocytes expressed the antigen. The antibody did not bind detectably to lymphocytes, granulocytes, erythrocytes, fibroblasts, or the cells of several murine tumor lines. Results suggesting binding to mast cells were equivocal. The antigen was species, but not strain, specific. It was concluded that maturation, at least, was required for expression of the antigen. Results suggested that additional influences were also involved.
Muramic acid detection in mammalian tissues by gas-liquid chromatography-mass spectrometry
Authors: Fox A , Schwab J H , Cochran T
Published: June 2021

Muramic acid is a component of the peptidoglycan moiety of cell walls of all bacteria and blue-green algae and is not found elsewhere in nature. A gas-liquid chromatography-mass spectrometry assay for muramic acid in tissue is described. The application of the method to the detection of muramic acid in tissues of rats with streptococcal cell wall-induced polyarthritis is demonstrated. Because the method has the potential to measure total bacterial biomass in tissue, it should prove to be an important assay in elucidating the etiological role of bacterial debris in chronic inflammatory diseases in humans.
Relationship of Antibody to Outcome in Neonatal Herpes Simplex Virus Infections
Authors: Yeager Anne S. , Arvin Ann M. , Urbani Lenore J. , Kemp John A.
Published: June 2021

Neutralizing antibody titers to herpes simplex virus type 1 (HSV-1) and HSV-2 were measured at birth in normal infants and uninfected infants of mothers with genital HSV infections during pregnancy and at the onset of infection in 5 infants with mild infections and 11 infants with severe infections. Thirty-eight percent of premature and 29% of term infants had neutralization titers of <1:5. High titers ([unk]1:40) were found in 55% of infants of mothers with primary infections during pregnancy and in 76% of infants of mothers with recurrent infections. The mean titers to HSV-1 and -2 in 5 infected infants with mild infections were 1:56 and 1:65 at the time of onset of infection, whereas the mean titers in 11 infants with severe infections were 1:11 and 1:12. Six natally exposed infants who remained asymptomatic were also studied and had a mean titer to HSV-1 of 1:85 and to HSV-2 of 1:69. Therefore, infants with high titers of transplacentally derived antibody had a more favorable outcome than infants with lower titers. Ninety-five percent of the infants of mothers with recurrent infections had a Rawls index of more than 85, suggesting that the antibody response was to HSV-2. However, low levels of antibody with this type specificity failed to protect four infants from infection with HSV-2. Augmentation of the neutralization titer to HSV-2 by the amount of complement present in cord serum was less than twofold. The study suggests that the quantity of antibody derived transplacentally affects the outcome of infection after natal exposure to herpes simplex virus. Complete neutralization of virus by antibody may occur in some infants, and prolongation of the incubation period and modification of the infection may occur in others.
Immunochemical properties of Vi antigen from Salmonella typhi Ty2: presence of two antigenic determinants
Authors: Szewczyk B , Taylor A
Published: June 2021

Antigen Vi of Salmonella typhi was found to have at least two antigenic determinants. In one of them, O-acetyl moiety played a dominant role. The second antigenic determinant did not involve O-acetyl residues, but both carboxyl and N-acetyl groups were necessary for the antigen-antibody reaction. These results were obtained by performing serological tests with antigen Vi, with its structural analog, polygalacturonic acid, and with the derivatives of both polysaccharides.
Host-Etiological Agent Interactions in Intranasally and Intraperitoneally Induced Cryptococcosis in Mice
Authors: Lim Thuang S. , Murphy Juneann W. , Cauley Larry K.
Published: June 2021

Inbred CBA/J mice were used in developing a defined in vivo model for studying host-parasite relationships in cryptococcosis. Mice were infected either intranasally or intraperitoneally with 10
3
viable
Cryptococcus neoformans
cells. At weekly intervals over a 92-day period,
C. neoformans
growth profiles in the lungs, spleens, livers, and brains of the infected animals were determined. In addition, humoral and delayed-type hypersensitivity responses and cryptococcal antigen levels were assayed in these mice. Intranasally infected mice developed strong delayed-type hypersensitivity reactions in response to cryptococcal culture filtrate (CneF) antigen, and there was good correlation between acquisition of delayed-type hypersensitivity and the reduction of
C. neoformans
cell numbers in infected tissues. In contrast, intraperitoneally infected mice displayed greater numbers of
C. neoformans
cells in tissues and had somewhat suppressed delayed-type hypersensitivity responses to CneF antigen. Anticryptococcal antibodies were not detected in intranasally or intraperitoneally infected mice, but cryptococcal polysaccharide antigen titers were relatively high in both groups. The transfer of sensitized spleen cells from intranasally infected mice to syngeneic naive recipient mice resulted in the transfer of delayed-type hypersensitivity responsiveness to cryptococcal antigen in the recipients. The intranasally induced infection in mice was similar to the naturally acquired infection in humans; therefore we are proposing that this murine-cryptococcosis model would be useful in gaining a greater understanding of host-etiological agent relationships in this disease.
Analysis and Characterization of Herpes Simplex Virus After Its Persistance in a Lymphoblastoid Cell Line for 15 Months
Authors: Roumillat L. F. , Feorino P. M. , Caplan D. D. , Lukert P. D.
Published: June 2021

Infection of a human lymphoblastoid cell line (F-365 line containing Epstein-Barr viral capsid antigen, derived from an individual without overt signs of lymphoma, infectious mononucleosis, or leukemia) with herpes simplex virus (HSV), maintained and observed for 15 months, was characterized by the continuous production of infectious extracellular virus. By the 5th day postinfection 75% of the cells produced HSV antigen as detected by fluorescent antibody, and by the 10th day 90% did so; production continued through the 15th month. Only 11% of single isolated cells produced detectable infectious virus. HSV produced after the 3rd month formed smaller plaque in monolayer cell culture than did the parental virus. No antigenic or polypeptide change in the HSV was detected by crossed immunoelectrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis over the 15-month cultivation in F-365 cells. Cell susceptibility and HSV virulence did not appear to change. The HSV-lymphoblastoid cell culture provided a useful model in which to study long-term virus-cell interactions.
Fixation and Inactivation of Staphylococcal Leukocidin by Phosphatidylcholine and Ganglioside G
M1
in Rabbit Polymorphonuclear Leukocytes
Authors: Noda Masatoshi , Kato Iwao , Hirayama Toshiya , Matsuda Futami
Published: June 2021

Staphylococcal leukocidin is resolved by chromatography on carboxymethyl cellulose columns into two components, which are designated F (fast) and S (slow). Fixation and inactivation of both components were studied as follows. (i) Leukocidin activity was confined to the first 10 min of intoxication, and the maximal effect resulted from treating 10
6
rabbit peripheral polymorphonuclear leukocytes per 20 μl with 0.5 ng of each component of leukocidin. The S component was more responsible for the interaction with the leukocytes than the F component. (ii) The F component was inactivated by phosphatidylcholine at concentrations which corresponded to molar proportions of 1:1 and bound to [
14
C]phosphatidylcholine at equimolar proportions. (iii) The S component was inactivated by ganglioside G
M1
at 1:1 molar proportions, but not by any of the related glycolipids. Ganglioside G
M1
also was precipitated with the S component by a gel diffusion technique. Subunit B of cholera toxin competitively inhibited the binding of the S component to rabbit leukocyte membranes. This indicates that ganglioside G
M1
may resemble or be part of the receptor site for the S component.
Attachment of Oral
Cytophaga
Species to Hydroxyapatite-Containing Surfaces
Authors: Celesk Roger A. , London Jack
Published: June 2021

Model systems simulating the cementum portion of teeth were used to characterize the attachment process by which certain species of oral
Cytophaga
initiate the colonization of the tooth root surface in vitro. The adsorption of these bacteria to spheroidal hydroxyapatite beads and mechanically powdered root material followed Langmuir isotherm kinetics. From such data, the number of binding sites per 20 mg of substrate and the affinity constants were evaluated for two strains of
Cytophaga
sp. Resting cells of the two strains tested adhered relatively tenaciously to hydroxyapatite beads in numbers similar to those observed with cells of
Streptococcus sanguis
. Attachment of bacteria to the substrates was partially inhibited by (i) coating the substrates with human serum or saliva, (ii) pretreating cell suspensions with proteinase K or phospholipase C or D, or (iii) exposing the cells to temperatures greater than 60°C for 15 min. Treating resting cell suspensions with pronase, neuraminidase, phospholipase A2, or 0.1 M ethylenediaminetetraacetic acid had no effect on the attachment process.
Phospholipase B in the Brains and Meninges of Nonsensitized and Sensitized Rats After Challenge with
Angiostrongylus cantonensis
Authors: Ottolenghi Athos , Weatherly Norman F. , Larsh John E.
Published: June 2021

After a primary infection with 100
Angiostrongylus cantonensis
larvae, infected rats showed elevated phospholipase B activity in meningeal and brain homogenates beginning with the first week and continuing through the first month of infection. The rise in phospholipase B values through the first 4 weeks, with a prolonged peak spanning days 30 to 31, coincided with the invasion and maturation of the parasites in the brain, and the ensuing sharp decline in phospholipase B levels, shown by the readings on day 45, coincided in turn with the known migration of the worms from the brain to the lungs, which begins about 5 weeks after infection. In the meninges, the pattern of enzyme elevation was generally similar to that in the brain samples except that the highest activity was seen earlier at days 8 to 9, followed by a gradual decline by days 30 to 31 and a sharper drop by day 45. Rats challenged with 100 larvae 53 days after the primary infection exhibited an almost immediate rise of phospholipase B activity in both the brain and meninges; the peaks of activity occurred at day 1 for the meninges and day 25 for the brain, and levels above control values were still present at day 50. Comparison of the total enzymatic content of the cerebral tissue and meninges revealed that a remarkably high proportion of the phospholipase B activity was contained in the meninges. The inference that elevated levels of this enzyme in the cerebral tissue of
A. cantonensis
-infected rats are due to inflammatory reactions within the meningeal envelopes was confirmed by histochemical demonstration of specific sites of enzymatic activity limited to the meninges. It is of interest that 80% of the cells positive for the enzyme were clearly identifiable as eosinophils since an association of bone marrow eosinophilia and high phospholipase B levels in rats infected with
A. cantonensis
was shown in our earlier study of rats infected with this parasite.
Pathogenicity of Candida tropicalis and Candida albicans after gastrointestinal inoculation in mice
Authors: Wingard J R , Dick J D , Merz W G , Sandford G R , Saral R , Burns W H
Published: June 2021

The ability of clinical isolates of Candida albicans and candida tropicalis to invade through normal and damaged gastrointestinal mucosa was determined. Adult mice were treated with either gentamicin or gentamicin and cytarabine. Suspensions of yeast cells (10(7)) were administered through a catheter intraesophageally. Invasion was determined by culturing liver, kidney, and lung tissue from mice sacrificed after 48 h. C. albicans and C. tropicalis were incapable of invading through normal gastrointestinal mucosa in mice treated only with gentamicin. Two isolates of C. tropicalis penetrated the damaged gastrointestinal mucosa in 69% (49 of 71) of mice treated with gentamicin and cytarabine. In contrast, three isolates of C. albicans penetrated he damaged gastrointestinal mucosa in only 23% (14 of 62) of mice. These results suggest that C. tropicalis is more capable of invading through damaged gastrointestinal mucosa than C. albicans. The observations in this mouse model parallel those seen in patients on cytotoxic drugs. Therefore, this model offers a tool for investigation of the pathogenicity of these organisms in a model analogous to the compromised host.
Radioiodination of an outer membrane protein in intact Rickettsia prowazekii
Authors: Smith D K , Winkler H H
Published: June 2021

Intact Rickettsia prowazekii was radiolabeled with the glucose oxidase-lactoperoxidase method of iodination. Separation of the rickettsial extract into cytoplasmic, outer and inner membrane fractions demonstrated that the outer membrane was preferentially labeled. Analysis of the polypeptides of these fractions on high-resolution slab polyacrylamide gels showed that most of the 125I was in polypeptide T49, an outer membrane constituent. Additional outer membrane polypeptides were iodinated in broken envelope preparations, demonstrating that T49 is uniquely accessible to the external environment and the asymmetric polypeptide organization of the outer membrane.
Production and properties of heat-stable extracellular hemolysin from Pseudomonas aeruginosa
Authors: Johnson M K , Boese-Marrazzo D
Published: June 2021

Of 12 strains of Pseudomonas aeruginosa, 10 were found to produce heat-stable extracellular hemolysin in highly aerated peptone broth supplemented with glycerol, fructose, or mannitol. Glucose supported good hemolysin production only in medium that was highly buffered. The yield of both cells and hemolysin was lower with organic acids as supplement. Growth-limiting phosphate concentrations produced maximum hemolysin levels. Purified hemolysin preparations contained two hemolytic glycolipids. The kinetics of hemolysis at various levels of purified lysin and the effects of variation in lysin and erythrocyte concentration are described.
Alterations in serum opsonic activity and complement levels in pneumococcal disease
Authors: Giebink G S , Dee T H , Kim Y , Quie P G
Published: June 2021

Pneumococcal opsonic activity and concentrations of pneumococcal capsular polysaccharide antigen, C3, C4 factor B, C3 and factor B breakdown products were measured in the serum obtained acutely from 12 patients with serious pneumococcal disease. One patient showed markedly reduced pneumococcal opsonic activity, borderline-low C3, and the presence of C3 and factor B breakdown products and died. Although eight additional patients showed depressed levels of C3 or C4 or the presence of C3 or factor B breakdown products, none had reduced pneumococcal opsonic activity. All of the three remaining patients had normal opsonic activity and C3 and C4 levels. Covalescent serum was obtained from eight patients; six had normal C3 and C4 levels, and two had persistent C4 depression. These data show that complement is activated during pneumococcal disease and suggest that extensive complement activation may impair pneumococcal opsonic activity in certain patients and thereby compromise an important host defense mechanism.
A plasmid in Legionella pneumophila
Authors: Knudson G B , Mikesell P
Published: June 2021

Sixteen strains from the six serogroups of Legionella pneumophila were examined for the presence of extrachromosomal genetic elements by a modified cleared lysate procedure, dye-buoyant centrifugation, and agarose gel electrophoresis. Two strains, Atlanta-1 and Atlanta-2 from serogroup II, each contained a plasmid of cryptic function with a molecular weight of ca. 30 megadaltons.
Inhibition of Escherichia coli heat-stable enterotoxin by indomethacin and chlorpromazine
Authors: Greenberg R N , Murad F , Chang B , Robertson D C , Guerrant R L
Published: June 2021

Purified heat-stable enterotoxin (ST) from a procine strain of enterotoxigenic Escherichia coli activates quanylate cyclase in particulate fractions of rat intestinal tissue and induces fluid accumulation in suckling mice. These effects of ST were examined in the presence of either indomethacin or chlorpromazine. We also examined the effects of these two drugs on fluid accumulation in suckling mice induced by the 8-bromo analog of cyclic guanosine monophosphate. Either indomethacin or chlorpromazine reduced ST activation of guanylate cyclase. Both drugs also reduced intestinal fluid accumulation in suckling mice that resulted from submaximal doses of ST (both P < 0.001). However, there was no reduction in fluid secretion by either drug when a maximally effective dose of ST was used, suggesting that inhibition of fluid secretion by both drugs can be overcome by increasing the ST dose and that a threshold level of guanylate cyclase activity results in maximal secretory response. Both drugs also reduced basal guanylate cylase activity in rat intestinal tissue and fluid secreton in suckling mice. Chlorpromazine also reduced intestinal secretion mediated by 8-bromo cyclic guanosine monophosphate (P < 0.001). These findings indicate that chlorpromazine interferes with the effects of ST both before and after its activation of guanylate cyclase, whereas indomethacin interfers with ST only before its activation of guanylate cyclase.
Relationship of in vitro immune responses to Epstein-Barr herpesvirus and severity of infectious mononucleosis
Authors: Goldstein K , Lai P K , Lightfoote M , Andrese A P , Fuccillo D , Connor R J , Levine P H
Published: June 2021

Immune responses to Epstein-Barr herpesvirus (EBV) and EBV-related antigens were studied serially in 18 patients with heterophil antibody-positive infectious mononucleosis and in 18 control subjects. Enhanced cellular immune responses to EBV particles and to EBV intracellular soluble antigens were found in the patients at convalescence, suggesting that the development of specific cellular immune responses was associated with apparent control of the virus infection. In addition, a correlation between severity of disease and specific cellular immune response was found. Patients with severe clinical signs were found to have a more active cellular immune response to EBV intracellular soluble antigens early in the infection compared with patients with mild disease. This suggests that an increased immune reactivity to intracellular antigens during the early part of the illness is related to the severity of clinical manifestations in infectious mononucleosis. Serum antibody to viral capsid antigen and early antigen was not related to the severity of clinical disease.