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Biomedical subjects

F C Pearson

Publications and source records attributed to F C Pearson.

At least 19 recordsLinked to original sources
PubMed1993

Murine cytomegalovirus-inhibitory effects of ImuVert.

ImuVert, a sterile preparation composed primarily of Serratia marcescens membrane vesicles and ribosomes, was significantly inhibitory to murine cytomegalovirus (MCMV) infections in BALB/c mice. Antiviral activity was manifested as increased survivor number and decreased recoverable virus titers in spleens, lungs and salivary glands. Treatments were intraperitoneal (i.p.) beginning 24 h pre, 4 h post- or 24 h post-virus inoculation and then repeated 4 days later. Doses of 5, 16 or 50 micrograms/mouse were effective; 160 micrograms/mouse, which caused host weight loss in toxicity controls, was not inhibitory to the infection. A single i.p. treatment of mice substantially augmented natural killer (NK) cell activity and increased total B-cells, while reducing total T- and T-helper cells. A late (48 h) decline in T-cell function and transient increases in B-cell function were observed in the treated animals. Serum interferon was not induced. Mice pretreated with anti-asialo GM1 antibody to reduce their NK cell populations, then infected with MCMV and treated with ImuVert were protected to the same degree as normal animals. Severe combined immunodeficient mice infected with MCMV and treated with ImuVert were not protected from the infection. These data suggest ImuVert to act by a mechanism other than NK cell activation in preventing MCMV infections.

Animals↗
PubMed1992

Protection from chemotherapy-induced neutropenia by ImuVert.

Neutropenia is a major cause of chemotherapy-induced morbidity. This study examines the effect of ImuVert on the course of neutropenia from Cytoxan and Adriamycin. In adult rats treated with either Cytoxan or Adriamycin and ImuVert, the absolute neutrophil count remained above 7,000 and 2,000, respectively, for the duration of ImuVert therapy. In contrast, in the control Cytoxan group the absolute neutrophil count reached 300/mm3 on day 5 and remained below 1,000 from day 4 through day 7. In the Adriamycin control group, the nadir absolute neutrophil count reached 600/mm3 on day 7 and remained below 100 from day 6 through day 8. C3H/EJ mice (endotoxin-hyporesponsive) treated with Cytoxan developed an absolute neutrophil count below 1,000 from day 4 through day 7. In contrast, in the group concomitantly treated with ImuVert, the nadir absolute neutrophil count remained below 1,000 only on days 4 and 5. The authors conclude that stimulation of endogenous cytokine production by ImuVert may provide a potentially useful approach to bone marrow rescue from chemotherapy.

Animals↗
PubMed1992

Use of a biological extract of Serratia marcescens to decrease doxorubicin-induced myelosuppression in dogs.

Fifteen dogs were given doxorubicin, IV, at a dosage of 30 mg/m2 of body surface. A commercially available biological extract of Serratia marcescens (BESM) was administered SC to 9 of these dogs (0.04 mg/kg of body weight every third day, n = 2; 0.08 mg/kg every other day, n = 2; and 0.08 mg/kg daily, n = 5), beginning the day after administration of doxorubicin, in an attempt to find an optimal dosage and schedule of administration of BESM to reduce the duration and severity of chemotherapy-induced myelosuppression. Nine additional dogs were randomized into 3 groups of 3 dogs to receive 1 of the following dosages of BESM SC: 0.08, 0.16, and 0.32 mg/kg. Serum was harvested immediately prior to treatment and at 2, 4, 6, 8, 12, 24, 48, and 72 hours from this latter group of dogs for subsequent analysis of canine granulocyte colony-stimulating factor (G-CSF) by enzyme immunoassay. Increasing the dosage and schedule of administration of BESM reduced the duration and severity of doxorubicin-induced myelosuppression. Neutrophil counts of the group of dogs given BESM daily at a dosage of 0.08 mg/kg and the controls were evaluated statistically. The neutrophil count increased significantly (P < 0.05) above pretreatment values in BESM-treated dogs after day 7. Median neutrophil counts of the BESM-treated dogs were never significantly lower than pretreatment values, whereas the median counts of the dogs treated with doxorubicin alone were significantly below normal for 6 days (days 7-12).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of prior cancer chemotherapy on human tumor-specific cytotoxicity in vitro in response to immunopotentiating biologic response modifiers.

Tumor-specific cytotoxicity was measured in fresh human biopsy specimens by a modification of the differential staining cytotoxicity assay. ImuVert, a cytokine inducer derived from Serratia marcescens, which produces broad-spectrum activation of both macrophages and lymphocytes, was dramatically more effective when it was tested in tumors obtained from patients with previously treated, chemotherapy-responsive adenocarcinomas (breast and ovary) than when it was tested in tumors obtained from either previously untreated patients or previously treated patients with chemotherapy-refractory adenocarcinomas (colon, lung, pancreas, stomach, kidney, gallbladder, uterus, and prostate). Similar findings, relating to prior chemotherapy treatment status, were obtained for tumor necrosis factor and interferon gamma, but not for interleukin-2 or interferon alpha. On the basis of these findings and on other evidence in the literature, we speculate that response to chemotherapy produces massive release and processing of tumor antigens. We further speculate that this response leads to a state in which the human immune system is primed (via in situ vaccination) to respond to exogenous macrophage-activation signals with potent, specific antitumor effects.

Adenocarcinoma↗
PubMed1991

Evaluation of a biologic response modifier derived from Serratia marcescens: effects on feline macrophages and usefulness for the prevention and treatment of viremia in feline leukemia virus-infected cats.

Normal feline bone marrow-derived macrophages released maximum concentrations of interleukin-6, tumor necrosis factor, and interleukin-1 when stimulated with ImuVert (Cell Technology Inc, Boulder, CO, USA) at dosages of 1.0 microgram/ml, 5.0 micrograms/ml, and 10.0 micrograms/ml, respectively. When ImuVert was administered to healthy adult cats, significant elevations in rectal temperature and neutrophil counts were observed 10 and 24 hours after each treatment. Weekly treatment with ImuVert failed to prevent or reverse viremia in cats when initiated prior to or 6 weeks after inoculation with feline leukemia virus.

Animals↗
PubMed1990

ImuVert activation of natural killer cytotoxicity and interferon gamma production via CD16 triggering.

The effect and mechanism of action of ImuVert, a new biological response modifier consisting of ribosomes and natural membrane vesicles of Serratia marcescens, on endogenous natural killer (NK) cells and activated NK activity has been analyzed. The studies showed that endogenous NK activity of peripheral blood mononuclear cells (PBMC) from normal cell donors was significantly increased (P less than 0.03) against K562, U937, and Molt-4 target cells. PBMC from cord blood of newborn infants lacking NK activity were upregulated (1.5-4 fold over endogenous NK activity) by ImuVert. Other studies showed that the abnormal NK activity of PBMC from patients with the human immunodeficiency virus (HIV) infection was significantly augmented in vitro (P less than 0.01) by ImuVert. ImuVert strongly stimulated interferon gamma production and in combination with interleukin 2 produced synergistically enhanced interferon gamma production and greater cytotoxicity than that induced by either alone. Studies on lymphocyte differentiation antigen expression following treatment with ImuVert indicated that ImuVert triggers interferon gamma production through binding the low affinity IgG Fc receptor, type III, CD16. The studies suggest that ImuVert may trigger interferon gamma production by binding to the Fc receptor and that the amplitude of the ensuing reaction and the ability of ImuVert to induce cytotoxicity in a setting where this activity has been down regulated is based on the absence of suppressor activation or direct contra suppressor activity.

Antigens, Differentiation↗
PubMed1990

Selective potentiation of host resistance in mice following treatment with Pyrexol.

The purpose of this study was to examine the effect of treatment with the biologic response modifier Pyrexol on murine host resistance to various infectious organisms. Adult female CD1 mice were treated with a single subcutaneous 100-micrograms injection of Pyrexol at 14, 7, 5, 2, or 1 day prior to infection with various infectious organisms. These organisms included the Herpes simplex type 2 and influenza viruses, as well as the bacteria Listeria monocytogenes and Streptococcus zooepidemicus. Pyrexol treatment was found to significantly potentiate resistance to Listeria organisms, but had no appreciable effect on resistance to any of the other organisms tested. Previous reports have demonstrated that treatment with Pyrexol augments a number of cell-mediated immune parameters, several of which have been shown to be responsible for the elimination of Listeria organisms. These results suggest that Pyrexol is capable of selectively potentiating host resistance to infection.

Animals↗
PubMed1988

Determination of endotoxin levels and their impact on interleukin-1 generation in continuous ambulatory peritoneal dialysis and hemodialysis.

Endotoxins represent a family of ubiquitous bacterial lipopolysaccharides found in water and raw materials. These substances have the ability to generate interleukin-1 (IL-1) and induce fever, as well as other acute phase phenomena. A study was undertaken to determine levels of background endotoxin in (1) continuous ambulatory peritoneal dialysis solution, (2) spent dialysate subsequent to overnight dwell, (3) hemodialysis solution, and (4) Limulus amebocyte lysate-reactive material (LAL-RM) in hemodialyzers and patient plasma. Levels of endotoxin in all of the above cases were less than thought to be required to induce biological activity, such as pyrogenicity, through IL-1 generation. Although nanogram amounts of LAL-RM are associated with some hollow-fiber membranes as well as the plasma of patients on those membranes, this material per se does not appear to produce IL-1 in vitro.

Endotoxins↗
PubMed1987

The possible role of Limulus-amebocyte-lysate-reactive material in hemodialysis. First-use syndrome.

Hypersensitivity-like reactions are an infrequent but persistent clinical manifestation of hemodialysis. Although a Limulus-amebocyte-lysate-reactive material (LAL-RM) has been demonstrated in some hemodialyzers, its potential role in causing anaphylactoid reactions has not been addressed heretofore. In this chapter, current knowledge about LAL-RM will be presented and integrated with the major mechanisms generally recognized to induce hypersensitivity-type reactions. These mechanisms include: classical induction of allergy by IgE and classical complement activation by IgG and IgM. Alternative complement activation will be not discussed as it has been extensively reported in the literature of hemodialysis and because LAL-RM has not been shown to activate C3a extensively.

Anaphylaxis↗
PubMed1986

Allergic reactions in healthy plateletpheresis donors caused by sensitization to ethylene oxide gas.

We observed immediate-type hypersensitivity reactions in 6 of 600 donors who underwent automated plateletpheresis procedures. Ethylene oxide gas, which was used to sterilize plastic components in the disposable apheresis kits, represented a possible source of sensitization. In skin-prick testing, 4 of the 6 donors who had had a hypersensitivity reaction and none of 40 controls who had not had such a reaction had positive tests when an ethylene oxide-human serum albumin reagent was used (P less than 0.001). Radioallergosorbent testing revealed that serum from 4 of the 6 donors who had reactions, but from only 1 of 145 controls, contained IgE antibodies to ethylene oxide-albumin (P less than 0.001). All six of the donors who had reactions had specific ethylene oxide-induced basophil histamine release (mean release [+/- SE], 34.2 +/- 5.6 percent), whereas none of four controls had specific histamine release in response to ethylene oxide (mean release, 5.7 +/- 1.2 percent; P less than 0.005). Repeat plateletpheresis in five of the donors who reacted was accompanied by a recurrence of mild allergic symptoms. These studies demonstrate that sensitization to ethylene oxide gas can occur in healthy plateletpheresis donors and that it may result in immediate hypersensitivity reactions during the donation. The prevalence of such reactions was 1.0 percent in our apheresis donor population.

Blood Component Removal↗
PubMed1986

Establishment of beta-hydroxy fatty acids as chemical marker molecules for bacterial endotoxin by gas chromatography-mass spectrometry.

Selected ion-monitoring gas chromatography-mass spectrometry was used for detection of beta-hydroxy fatty acids as an independent assay for the presence or absence of endotoxin in materials claimed to induce nonspecific activation of Limulus amoebocyte lysate. To this end, suspensions of gram-negative and -positive bacteria, one fungal species, cerebrospinal fluid, and hollow-fiber hemodialyzer rinses were assayed for endotoxin by gas chromatography-mass spectrometry and the Limulus amoebocyte lysate assay. Good qualitative agreement was shown for both methods when suspensions of test organisms were assayed. Two false-negative results were obtained by gas chromatography-mass spectrometry assays of cerebrospinal fluid and were shown to be a result of insufficient endotoxin in the cerebrospinal fluid specimens for detection by gas chromatography-mass spectrometry. Hemodialyzer rinses were Limulus assay positive; however, no beta-hydroxy fatty acids were detected by gas chromatography-mass spectrometry. These data were compared with data obtained from USP rabbit pyrogen tests of the rinse materials (nonpyrogenic) and chemical characterization of the Limulus assay-reactive rinses, which showed the rinses to be cellulosic in nature. It is suggested that beta-hydroxy fatty acids, as assayed by selected ion-monitoring gas chromatography-mass spectrometry, be used as chemical marker molecules for the presence or absence of endotoxin in materials reported to cause nonspecific activation of Limulus amoebocyte lysate.

Candida albicans↗
PubMed1986

Effect of monophosphoryl lipid A on host resistance to bacterial infection.

The ability of monophosphoryl lipid A (MPLA) to enhance nonspecific host resistance to bacterial infections was studied. Mice were treated with MPLA prior to intraperitoneal challenge with Escherichia coli or Staphylococcus epidermidis. Animals received additional MPLA for 2 days postinfection, and survival rates were determined. Ten micrograms of MPLA per mouse significantly improved the survival of animals infected with either bacterial species. Dose-response studies showed significant MPLA-induced protection at doses of 6 micrograms/kg against E. coli challenge and 60 micrograms/kg against S. epidermidis challenge.

Adjuvants, Immunologic↗
PubMed1985

Reactions during hemodialysis caused by allergy to ethylene oxide gas sterilization.

In patients receiving long-term hemodialysis (HD), we have examined the presence of IgE-dependent sensitization to ethylene oxide (EO) gas, which is used for sterilization of disposable medical products including dialyzers. Serum was obtained from 25 patients who experienced acute allergic reactions during HD, five patients receiving HD with isolated eosinophilia, and 37 unselected patients receiving HD. Sera from 22 of 25 of the allergic reaction group and from five of 35 of the unselected group were demonstrated to contain IgE antibodies with specificity for EO. Corresponding IgG antibodies were also present. No such antibodies were detected in serum from normal controls or ragweed-allergic patients. The serum from one patient with isolated eosinophilia had a borderline elevated IgE antibody level. These results demonstrate a close relationship between the presence of IgE antibodies to EO and HD-related allergic reactions in this patient population.

Ethylene Oxide↗
PubMed1985

Evaluation of papain/chymopapain cross allergenicity.

Recent clinical evidence suggests that papain and chymopapain may share common allergenicity. Patients that become sensitized to papain may subsequently experience an allergic reaction when they are exposed to chymopapain. This study demonstrates a cross antigenicity between the proteolytic enzyme preparations papain and chymopapain. Serum samples from six patients who demonstrated 4+ skin reactions to papain also revealed positive RAST ratios to both papain and chymopapain. In addition, serum samples from 12 clinically nonreactive patients who had discolysis with chymopapain demonstrated positive RAST results to papain as well as to chymopapain.

Allergens↗
PubMed1985

Comparison of several control standard endotoxins to the National Reference Standard Endotoxin--an HIMA collaborative study.

A collaborative study, initiated under the auspices of the Health Industry Manufacturers Association (HIMA), was designed to establish the relationship of Escherichia coli O55:B5 endotoxin (the control standard endotoxin of HIMA and the Food and Drug Administration's Office of Medical Devices) to the U.S. National Reference Standard Endotoxin and to two internationally used control standard endotoxins. By using two Limulus amoebocyte lysate test systems, it was established that the E. coli O55:B5 endotoxin lot originally used by HIMA and the Office of Medical Devices to establish Limulus amoebocyte lysate release test criteria for pyrogen testing of medical devices contains approximately 4.5 endotoxin units (EU) per ng. Thus, the 1.0-ng/kg endotoxin dose limit currently established for medical devices is approximately the same as the 5.0-EU/kg endotoxin limit (on an activity basis) established by several other Food and Drug Administration agencies for human and animal parenteral drugs and biological products.

Endotoxins↗