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Biomedical subjects

R E Lincoln

Publications and source records attributed to R E Lincoln.

At least 19 recordsLinked to original sources
PubMed1994

Nonhealing extraction sites: two case reports and a differential diagnosis.

Two cases of squamous cell carcinoma associated with third molars are presented. The diagnosis for both cases was made after the teeth were removed. The presenting signs and symptoms are discussed, along with the differential diagnosis of slow healing, painful third molar extraction sites. This article stresses the importance of close postoperative followup and the need for timely intervention to minimize patient morbidity.

Adult↗
PubMed1988

Cognitive disturbance in hospitalized and institutionalized elders.

The purpose of this study was to examine the relationship between empirical findings and a theoretical model of cognitive disturbance among 94 hospitalized and 78 institutionalized elders. Path analysis was used to determine the magnitude of relationships between variables described in the model. Neural function was the only variable in both groups that was significantly associated with greater cognitive disturbance. In the hospitalized group, neural structural changes and physiologic alterations contributed indirectly to cognitive disturbance by their effects on neural function. Further, neural function indirectly affected cognitive disturbance through its effects on sensory deficits. In the institutionalized group, environmental deficits and neural functions were significantly related to greater cognitive disturbance. Except for the direct effects of neural function on activity limitations and physiologic alterations on mental health, all the relationships between the variables described by the model were significantly different between hospitalized and institutionalized elders. The results suggest that different interventions to reduce cognitive disturbances may be required for institutionalized and hospitalized elders.

Activities of Daily Living↗
PubMed1971

Growth of pathogenic virus in a large-scale tissue culture system.

A model system is described for the mass propagation of Rift Valley fever (RVF) virus, utilizing large-volume fermentor units for suspension culture of tissue cells and the subsequent production of virus. Comparisons between laboratory- and fermentor-scale operations of tissue cell growth gave equivalent results. Cell viability dropped 24 to 30 hr postinfection with a subsequent virus yield between 10(8.0) and 10(9.0) mouse intracerebral median lethal doses per milliliter. Infecting volumes of tissue cell culture (20- or 40-liter working volumes) had no apparent effect on virus yields. Tissue cells grown under either oxidation-reduction potential- and pH-controlled or uncontrolled conditions showed little or no difference in their ability to produce RVF virus. We believe this tissue cell virus process to have potential application for large-scale production of vaccines for human or veterinary use or for the mass propagation of certain carcinogenic viruses for cancer research, once use of established lines for this purpose is accepted.

Animals↗
PubMed1971

Ultrafiltration as a method for concentrating Rift Valley fever virus grown in tissue culture.

Filtration by means of a Diaflo ultrafilter was used to concentrate three 1,000-ml lots and one 3,000-ml lot of tissue culture-grown Rift Valley fever virus. Quantitation of both infectivity and total protein was achieved. Water treatment with continued ultrafiltration of the virus concentrate provided a final virus product approximately 99.25% free of low-molecular-weight materials originally present in the growth medium.

Animals↗
PubMed1971

Growth of human lymphoid cells (Raji strain) in a five-liter fermentor.

Procedures used to produce an established line of mammalian cells (L cell) in a New Brunswick fermentor were adapted to propagate human lymphoid cells in suspended culture. Control of pH within defined limits was more effective for regulation of cell metabolism than control of oxidation-reduction potential. An unusually high rate of agitation was required.

Burkitt Lymphoma↗
PubMed1970

Evaluation of methods for reestablishment of L-cell suspension cultures directly from liquid nitrogen stored stocks.

Methods were developed and evaluated for the preservation of tissue cells grown in suspension culture and the reestablishment of suspension cultures directly from inoculum stored at -175 C. The factors investigated were processing pH, temperature of processing, freezing medium, and method of inoculation of the starter suspension cultures from the frozen stock (-175 C). Three parameters, cell viability, cell size, and growth potential in suspension culture after freezing, were used to evaluate the various factors. The results indicate that cells processed at 4 C, frozen at 1 C per min to -50 C in a medium containing 5% dimethyl sulfoxide plus 10% bovine serum at concentrations of 2 x 10(7) to 4 x 10(7) cells/ml, and stored at -175 C will reestablish suspension cultures directly from frozen seed. A 1-ml amount of frozen stock inoculated into 99 ml of medium routinely produced 2 x 10(6) to 3 x 10(6) viable cells/ml (2 x 10(8) to 3 x 10(8) total cells) in suspension culture in 4 to 5 days. Inoculum preserved by this procedure grew equally well in either serum-free or serum-containing growth medium.

Animals↗
PubMed1970

Concentration of Rift Valley fever and Chikungunya viruses by precipitation.

Simple and efficient methods for concentrating Rift Valley fever (RVF) virus and chikungunya (CHIK) virus are described. Ammonium sulfate, potassium sulfate, or alcohol was used as a precipitating agent and the precipitate was resuspended to volumes suitable for further processing and purification. The methods permitted concentration of live RVF virus and CHIK virus about 100-fold with negligible losses of virus. RVF virus retained a high level of infectivity with potassium aluminum sulfate and alcohol, but CHIK virus retained a higher infectivity level with ammonium sulfate than with potassium aluminum sulfate. The data indicate that serum plays an important role in the concentration of both viruses, at least when the sulfate methods are used.

Animals↗
PubMed1969

Interacting factors that influence long-term storage of live Pasteurella tularensis vaccine and Rift Valley fever virus.

Studies were conducted on the interaction of various parameters which affect the storage stability and growth potential of liquid cultures of Pasteurella tularensis live vaccine strain (LVS) and Rift Valley fever virus Van Wyk strain (RVFV). Storage variables studied with LVS included four storage temperatures (4, -20, -65, -175 C), single and multiple freeze-thaw cycles, two freezing and two thawing rates (slow and fast), various inoculum levels (1, 3, 5, and 10%) for the determination of growth potential, and the retention of immunizing potential (mice and guinea pig) after storage. Neither the freezing rate nor the number of freeze-thaw cycles seriously affected the growth of LVS after storage at -175C; however, the slow rate of thaw proved deleterious as were all temperatures of storage except -175 C after 1 year of storage, as shown by both criteria of evaluation. RVFV produced in two combinations of cell lines and media (LM cell line-199 peptone medium and LDR cell line-Eagle's minimum essential medium) was stored at three serum levels (10, 20, 40%), three pH values (6.2., 7.0, 7.8), and three temperatures (-20, -65, -175 C). These studies indicated: (i) virus produced in the LDR cell line and Eagle's medium was more stable than that produced in the LM cell line and 199 peptone medium for either short- or long-term storage; (ii) serum levels did not affect stability; and (iii) low pH resulted in losses during long-term storage under all conditions tested. Thus, cryogenic storage is advantageous for stock culture maintenance of bacteria and viruses and for other similar applications.

Animals↗
PubMed1969

Evaluation of factors related to growth of Rift Valley fever virus in suspended cell cultures.

The effect of several controlled variables on the peak titer and fold increase of Rift Valley fever virus grown in suspension culture on two variants of Earle's L cell, L-DR and L-MA clone 1-1, was studied. No significant amount of cell-associated virus was found at 24 hr, indicating a release of virus soon after its formation. Mild sonic treatment of the virus produced in serum-free medium increased the infective titer about 10x. This difference was not observed with virus produced in medium supplemented with serum. Peak titer was not affected by medium used during the infection period, by multiplicity of inoculum (MOI), or by initial cell concentration within the test range of 10(4) to 2 x 10(6) cell/ml. Cell strain employed influenced titer, because the L-DR cell did not produce virus efficiently at low MOI and low initial cell concentration. The time of peak titer and fold replication was dependent on MOI and initial cell concentration. Differences in virus propagation in monolayer and suspension systems are discussed.

Animals↗
PubMed1968

A precise method for replicating suspension cultures of mammalian cells.

A simple, readily assembled shaker-culture system for the cultivation of mammalian cells is described. No specialized glassware and equipment were used in this system, which consists of an Erlenmeyer flask fitted with a breather-sampling assembly. This unit was employed to quantitate the effects of several variables, including medium ingredients, serial transfers, and freezing and storage on two variants of the L-cell line. This system is reproducible and precise and allows for growth of cells in suspension for extended periods of time. Large numbers of cells can be mass-produced. Many replicates can be run simultaneously to yield data for statistical analysis.

Culture Media↗
PubMed1968

Growth and metabolism of live vaccine strain of Pasteurella tularensis.

The growth and metabolism of the live vaccine strain of Pasteurella tularensis in different media were investigated. Maximal growth was observed in a medium containing a sulfuric acid digest of casein as amino acid source. Amino acid metabolism produced considerable ammonia, and the rate of ammonia evolution was directly proportional to the growth rate. The most likely route for amino acid breakdown is nonspecific oxidative deamination.

Amino Acids↗
PubMed1968

Purification and properties of in vitro-produced anthrax toxin components.

The three components of the toxin of Bacillus anthracis, edema factor (EF), protective antigen (PA), and lethal factor (LF), were purified 197-, 156-, and 1,025- fold, with 38, 78, and 11% recovery, respectively. Each purified component was serologically active, distinct, and free from the other components. The purified EF produced edema when mixed with PA, and the purified PA was an active immunogen. The components did not appear to be simple proteins by spectrophotometric analysis. As they were purified, the pH range in which they were most stable narrowed, centering between pH 7.4 and 7.8. Heat readily destroyed the biological activity of the components but not their serological activity. The rat lethality test showed that, with a constant amount of LF and an increasing amount of PA, the time to death reached a minimum and then was extended. When an increasing amount of LF was added to a constant amount of PA, the time to death became shorter as more LF was added. The biological, immunological, and serological properties of the components were shown to vary independently with storage and extent of purification so that serological activity was not always directly correlated with biological activity. Evidence is presented that the components can exist in different molecular configurations or as aggregates, and that this property is influenced by the state of component purity and by the environment.

Animals↗