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Parasitic arthropods of sympatric meadow voles and white-footed mice at Fort Detrick, Maryland.

Twelve species of parasitic arthropods (one sucking louse, two fleas, one tick, and eight mites) were recovered from 51 meadow voles, Microtus pennsylvanicus (Ord); whereas nine species (one sucking louse, one bot, three fleas, one tick, and three mites) were collected from 48 white-footed mice, Peromyscus leucopus (Rafinesque), live-trapped on the grounds of Fort Detrick, Frederick County, MD., during 1990 and 1991. The most commonly collected arthropods from M. pennsylvanicus were the fur mite, Listrophorus mexicanus Fain (approximately 2,720 specimens); the tropical rat mite, Ornithonyssus bacoti (Hirst) (987); the laelapid mites, Laelaps kochi Oudemans (733) and Androlaelaps fahrenholzi (Berlese (322); the sucking louse, Hoplopleura acanthopus (Burmeister) (121); the tick, Dermacentor variabilis (Say) (47); and the chigger mite, Neotrombicula whartoni (Ewing) (45). Arthropod densities were lower on P. leucopus, from which the most frequently recorded species were the sucking louse, Hoplopleura hesperomydis (Osborn) (98 specimens); the fleas, Epitedia wenmanni (Rothschild) (85) and Orchopeas leucopus (Baker) (61); and the mite, A. fahrenholzi (83). Although six species of arthropods parasitized both species of rodents, only two of these, A. fahrenholzi and D. variabilis, were relatively common on both hosts. Therefore, although the habitats of both host species partially overlap, their associated parasitic arthropods remain principally host specific. The potential significance of these findings with respect to vector-borne disease transmission is discussed.

Animals↗

An assessment of health status among medical research volunteers who served in the Project Whitecoat program at Fort Detrick, Maryland.

Between 1954 and 1973, more than 2000 men entering military service as conscientious objectors participated in Project Whitecoat as medical research volunteers for the Army's biological warfare defense program. An assessment of self-reported, current health status among 358 "exposed" individuals and 164 unexposed control subjects found no conclusive evidence that receipt of investigational agents was related to adverse health outcomes. No differences in current overall health, current exercise levels, self-reported symptoms, and self-reported medical conditions were seen between the study groups. Possible associations were seen between exposure to antibiotics or other biological agents and self-reported asthma (13.0% vs. 2.4%, relative risk [RR] = 6.00, 95% confidence interval [CI] = 1.03-34.90, p = 0.050), as well as between receipt of tularemia vaccine(s) and self-reported asthma (13.3% vs. 2.4%, RR = 6.15, 95% CI = 1.03-36.70, p = 0.049) and increased frequency/severity of headaches (35.6% vs. 18.3%, RR = 2.46, 95% CI = 0.99-6.15, p = 0.074). However, the size of the population under study was insufficient to assert with confidence that these statistical associations are real.

Aged↗

Immunization against tularemia: analysis of the effectiveness of live Francisella tularensis vaccine in prevention of laboratory-acquired tularemia.

A retrospective analysis was made of cases of laboratory-acquired infections with Francisella tularensis among civilian employees at Fort Detrick, Maryland. The incidence and clinical presentation of tularemia during the decade 1950-1959, when the phenol-killed Foshay vaccine was used routinely for immunization of employees, were compared with similar data from the first decade (1960-1969) after the live tularemia vaccine had come into use. The incidence of typhoidal tularemia fell (from 5.70 to 0.27 cases per 1,000 at-risk employee-years; P less than 0.001), whereas the incidence of ulceroglandular tularemia remained unchanged (from 0.76 to 0.54 cases per 1,000 at-risk employee-years). Ulceroglandular tularemia in employees immunized with live vaccine was characterized by clinical signs and symptoms that were milder than those in employees vaccinated with the Foshay vaccine.

Bacterial Vaccines↗

Sequential immunization of laboratory personnel with influenza A/New Jersey/76 split- and whole-virus vaccines.

One hundred thirty-three healthy, at-risk Fort Detrick laboratory workers were inoculated with 400 chick cell-agglutinating (CCA) units of influenza A/New Jersey/76 split-virus vaccine (Wyeth Laboratories, Philadelphia, Pa.). Systemic and local reactions were infrequent, mild, and comparable to those of a sham-vaccinated group of volunteers. Only 28% of subjects 19-24 years old developed titers of hemagglutination-inhibiting (HAI) antibody of greater than or equal to 1:20, whereas titers of 91%-100% of subjects 25-62 years old reached this level. Thirty-one vaccinated subjects with no or low titers of antibody were given a booster dose (400 CCA units) of Wyeth vaccine six weeks after the first inoculation. Only 58%-67% of these vaccinees achieved HAI titers of greater than or equal to 1:20 after the booster. Fourteen persons required a second booster dose for protection; after vaccination with 400 CCA units of whole-virus vaccine from Merck Sharp and Dohme (West Point, Pa.), 89%-100% of the 14 vaccinees finally achieved HAI titers of greater than or equal to 1:20. The split-virus vaccine was safe, but it was poorly antigenic as a primary vaccine in persons 19-24 years old and as a booster in persons of all ages who have poor antibody responses in general.

Adult↗

Historical concepts of interactions, synergism and antagonism between nutrition and infection.

In the 1950s textbooks of nutrition made little or no mention of a relation to infection. The same was true for treatises on infectious disease. Relevant studies in experimental animals and a number of classical clinical observations were available pointing out the role of infection in precipitating nutritional disorders. However, clinicians and nutritionists did not recognize the importance of the relationship. The field and metabolic studies of the Institute of Nutrition of Central America and Panama (INCAP) in the 1950s demonstrated that malnutrition and infection in humans are generally synergistic. These studies stimulated the review of available evidence that resulted in the 1968 WHO monograph on "Interactions of Nutrition and Infection." It provided extensive evidence for the role of infections in precipitating clinical malnutrition and for the impact of malnutrition on morbidity and mortality from infection. The high frequency of diarrhea in underprivileged young children led to intensive studies in many countries of its effect on nutritional status and to recognition of the high prevalence of "weanling diarrhea." The effects of infection on nutritional status were then extensively and elegantly investigated at Fort Detrick, MD, and hormonal and cytokine mechanisms identified. The subsequent explosion in knowledge of cell-mediated immune mechanisms has led to an understanding of how malnutrition lowers this resistance. Today, recognition of the synergistic relationship between nutrition and infection influences most public health interventions to prevent malnutrition.

Adolescent↗

Spontaneous tumors in the Dunkin-Hartley guinea pig.

Seventy-nine spontaneous neoplasms in Dunkin-Hartley guinea pigs were observed over a 9-year period in the Fort Detrick guinea pig colony. Sixty-three of the neoplasms were found during approximately 8,500 necropsies performed on animals under 27 months of age. The remaining 16 tumors were in 34 breeders maintained after 27 months of age on a natural life-span study. Of this group, 10 (29.4%) developed neoplasms by the termination of the study, when the animals were 80 months of age. The skin tumor, trichofolliculoma, of which there were 29, comprised the largest tumor classification.

Age Factors↗

Studies on immunity to toxins of Clostridium botulinum. VII. Purification and detoxification of trypsin-activated type E toxin.

Fiock, Mary A. (Fort Detrick, Frederick, Md.), Allen Yarinsky, and James T. Duff. Studies on immunity to toxins of Clostridium botulinum. VII. Purification and detoxification of trypsin-activated type E toxin. J. Bacteriol. 82:66-71. 1961.-A procedure was described for production, purification, and conversion to toxoid of the Clostridium botulinum type E trypsin-treated toxin. A medium containing 1.5% trypticase, 0.5% yeast extract, 0.075% cysteine hydrochloride, and 1.0% glucose consistently yielded activated culture toxicities of 300,000 mouse intraperitoneal ld(50)/ml. Purification of the toxin was accomplished by precipitation with ammonium sulfate, extraction with calcium chloride, and reprecipitation with ethanol in the cold. The resulting partially purified toxin had a specific activity of 45,000,000 ld(50)/mg nitrogen. Purified toxins were converted to toxoid by incubation with formalin and adsorbed on aluminum phosphate. Good immune responses were obtained to the toxoids in mice, guinea pigs, and rabbits.

Animals↗

Growth of Venezuelan equine encephalomyelitis virus in L cells. II. Growth in submerged culture.

Hardy, Frank M. (U. S. Army Chemical Corps, Fort Detrick, Frederick, Maryland), and Arthur Brown. Growth of Venezuelan equine encephalomyelitis virus in L cells. II. Growth in submerged culture. J. Bacteriol. 82:449-457. 1961.-The detailed kinetics of Venezuelan equine encephalomyelitis virus multiplication and release and the progressive cell death due to the virus infection were studied in a uniformly susceptible L cell population. The adsorption phase was complete in approximately 15 min with multiplicities of 1, 10, and 100 MICLD(50). An eclipse phase showing the disappearance of some of the infectious virus activity lasted between 3 and 4 hr. An exponential increase of cell-associated and free virus then occurred until peak titer was reached (16 to 18 hr). Relatively constant titers of cell-associated or free virus were obtained from the time peak titer was attained until the 52nd hour of incubation. At that time the cell-associated titer declined more rapidly than the free virus titer. These constant titers, however, masked a continued production and release of new infectious virus. By viable and nonviable cell counts, it was determined that cell death occurred relatively late in the phase of constant growth and release.

Animals↗

Growth of Listeria monocytogenes in defined media.

Friedman, Mischa E. (U. S. Army Chemical Corps, Fort Detrick, Frederick, Md.), and William G. Roessler. Growth of Listeria monocytogenes in defined media. J. Bacteriol. 82:528-533. 1961-Listeria monocytogenes, strains A4413, JHH, and 9037-7, require organic sulfur, valine, and isoleucine for growth. In addition, A4413 requires leucine, whereas 9037-7 requires leucine, histidine, and arginine. Glutamine is stimulatory for all three strains. Further, A4413 is stimulated also by histidine, arginine, and methionine, and JHH by histidine, arginine, and leucine. With A4413, glutamine can be replaced by inorganic ammonium salts, urea, or asparagine but not by glutamic acid. Growth inhibition by d-serine is reversed by glycine or alanine. Growth with agitation in defined media is very poor and subculture is not possible unless unidentified products of enzymatic hydrolysis of proteins are present.A requirement for lipoic acid was not observed with five strains of L. monocytogenes.

Alanine↗

New solid medium for enhanced growth of Pasteurella tularensis.

Gaspar, Andrew J. (Fort Detrick, Frederick, Md.), Hugh B. Tresselt, and Martha K. Ward. New solid medium for enhanced growth of Pasteurella tularensis. J. Bacteriol. 82:564-569. 1961.-The purpose of this work was to develop a solid medium for more rapid growth of Pasteurella tularensis, especially from small inocula comparable to those generally encountered in clinical materials. AFTER TITRATION OF VARIOUS INGREDIENTS, SEPARATELY AND IN COMBINATION, THE OPTIMAL BASE WAS FOUND TO BE: 2.6% tryptose broth (Difco) with thiamine, 0.5% cysteine-HCl, 0.2% sodium thioglycolate, 1.0% glucose, dissolved by mixing without heat, and adjusted to pH 7.2 +/- 0.03. To this base 1.0% agar (Difco) is added and dissolved by heating in flowing steam for about 5 min prior to autoclaving at 121 C for 20 min. After sterilization and cooling, 5.0% defibrinated rabbit blood is added aseptically. Plates of the completed medium are incubated at 37 C for 24 hr prior to use. Colonies of P. tularensis approximately 1.0 mm in diameter are obtained on this medium after 26 to 29 hr incubation if conditions of high relative humidity (90 to 100% saturation) are maintained.The mechanisms involved in the growth enhancement obtained on this medium are under study. The role of thioglycolate appears to be that of keeping in solution the relatively high concentration of cysteine-HCl required. The specific methods of preparation described, the incubation of plates prior to use, and final incubation under conditions of high humidity all are important for optimal results. This developmental work has employed only pure cultures. Attempts are being made to develop a selective medium, using this new preparation as base, for the direct isolation of P. tularensis from a variety of clinical materials.

Animals↗

Pesticins. I. Pesticinbacterium interrelationships, and environmental factors influencing activity.

Brubaker, Robert R. (U. S. Army Biological Laboratories, Fort Detrick, Frederick, Md.) and Michael J. Surgalla. Pesticins. I. Pesticin-bacterium interrelationships, and environmental factors influencing activity. J. Bacteriol. 82: 940-949. 1961-A second bacteriocin-like substance produced by all tested strains of Pasteurella pestis and P. pseudotuberculosis is described. This activity, termed pesticin II, is active against the two avirulent P. pestis strains, A12 and Java. These strains do not produce pesticin I, which inhibits the growth of type I strains of P. pseudotuberculosis. Pesticin I was also found to be active against certain strains of Escherichia coli, strain A12, but not strain Java, and some P. pestis isolates which also produce pesticin I. A number of E. coli strains produce a substance which also inhibits the growth of strains A12 and Java; the activity of this substance is dependent upon the presence of high concentrations of Ca(++). The activity of both pesticins is inhibited under anaerobic conditions or in the presence of antiserum. The activity of pesticin I, but not pesticin II, is suppressed by Fe(+++), hemin, certain hemin-containing proteins, Mg(++), and inorganic phosphate. Suppression of pesticin I activity by Fe(+++) can be reversed by the addition of either Ca(++) or Sr(++) or by metal chelating agents. All tested strains of P. pestis and P. pseudotuberculosis produce a metabolite which suppresses the activity of pesticin I. The activity of this substance, termed pesticin I inhibitor, is enhanced by Fe(+++), and to a lesser extent by Mg(++) or by inorganic phosphate; its activity is suppressed by Mn(++) and by protamine sulfate.

Bacteriocins↗

Transduction in Bacillus subtilis.

Thorne, Curtis B. (Fort Detrick, Frederick, Md.). Transduction in Bacillus subtilis. J. Bacteriol. 83:106-111. 1962.-A bacteriophage, SP-10, isolated from soil carries out general transduction in Bacillus subtilis. Phage propagated on a streptomycin-resistant mutant of the wild-type strain W-23 was capable of transducing to prototrophy strain 168 (indole(-)), as well as all of the auxotrophic mutants of W-23-S(r) tested, which included mutants requiring arginine, histidine, adenine, guanine, thiamine, leucine, or methionine. Although strain 168 was transduced by phage SP-10, lytic activity on this strain could not be detected and attempts to propagate the phage on it failed. Transductions occurred at frequencies in the range of 10(-6) to 10(-5) per plaque-forming unit. Homologous phage was ineffective, deoxyribonuclease had no effect on the frequency of transduction, and transduction was prevented by the addition of phage antiserum. Phage SP-10 was capable of lysogenizing strain W-23-S(r), and this condition was maintained through repeated growth and sporulation cycles in potato-extract medium. Although heating at 65 C for 60 min inactivated free phage particles, spores retained their lysogenic condition after such heat treatment. When heat-treated spores of the lysogenic cultures were used as inocula for growth in a nutrient broth-yeast extract-glucose medium, filtrates contained 10(9), or more, phage particles per ml.

Adenine↗