Biomedical subjects

P Bugelski

Publications and source records attributed to P Bugelski.

9 recordsLinked to original sources

PubMed2001

Principal component analysis of mass spectra of peptides generated from the tryptic digestion of protein mixtures.

Principal component analysis (PCA) has been used to analyse mass spectral peptide profiles obtained from the enzymatic digestion of standard protein mixtures. Scores and loadings plots clearly revealed peptide fragments that differentiated one protein mixture from another. Peptide map search results identified with a high degree of certainty any additional proteins in these mixtures. As a proof-of-concept this methodology was applied to hepatic protein mixtures obtained from rats treated with two hepatotoxic compounds: methapyriline and SB-219994. Liver proteins were extracted, pre-separated by one-dimensional polyacrylamide gel electrophoresis, subjected to tryptic digestion and analysed by mass spectrometry. Two up-regulated proteins, glutathione S-transferase with methapyrilene and peroxisomal bifunctional enzyme with SB-219994, were identified in this manner.

Amino Acid Sequence↗

PubMed1999

Antithrombotic efficacy of a novel murine antihuman factor IX antibody in rats.

A murine antihuman factor IX monoclonal antibody (BC2) has been generated and evaluated for its capacity to prolong the activated partial thromboplastin time (aPTT) in vitro and ex vivo and to prevent arterial thrombosis in a rat model in vivo. BC2 extended aPTT to a maximum of 60 to 80 seconds at 100 to 1000 nmol/L in vitro (rat and human plasma, respectively) and ex vivo (rat) after dosing of rats up to 6 mg/kg in vivo. BC2, administered as bolus (1 to 6 mg/kg) followed by infusion (0.3 to 2 mg x kg(-1) x h(-1)), dose-dependently prevented thrombosis of an injured rat carotid artery (FeCl(3)-patch model), increased time to artery occlusion, and reduced incidence of vessel occlusion. BC2 efficacy in preventing arterial thrombosis exceeded that of heparin (bolus 15 to 120 U/kg followed by infusion 0.5 to 4.0 U x kg(-1) x min(-1)), whereas the latter rendered the blood incoagulable (aPTT>1000 seconds). BC2 demonstrated complete antithrombotic efficacy also as a single bolus given either as prevessel or postvessel injury as evidenced by reduction of thrombus mass (from 4.18+/-0.49 to 1.80 +/-0.3 mg, P<0.001), increasing vessel patency time (from 14.9+/-0.9 minutes to 58.3+/-1.7 minutes, P<0.001) and decreasing incidence of vessel occlusion from 100% to 0% in vehicle- versus BC2-treated rats, respectively. BC2 (3 mg/kg, IV) administered in a single bolus resulted in 50% reduction in thrombus mass (P<0.01), extended vessel patency time (P<0.001), extended aPTT only 4-fold, and had no effect on blood loss via a tail surgical wound; heparin, at doses that reduced thrombus mass to a similar extent, extended aPTT beyond 1000 seconds (over 500-fold) and increased blood loss from 1.8+/-0.7 to 3.3 +/-0.6 mL (P<0.001). These data suggest that BC2 may provide enhanced therapeutic efficacy in humans at lesser interference with blood hemostasis than heparin.

Anesthesia↗

PubMed1994

Soluble human complement receptor type 1 inhibits complement-mediated host defense.

Soluble complement receptor type 1 (sCR1) is a powerful inhibitor of complement activation. Because of this ability, sCR1 may prove to be an important therapeutic agent that can be used to block the immunopathologic effects of uncontrolled complement activation in a variety of clinically significant disorders. Although several previous studies have examined the ability of sCR1 to inhibit complemented-mediated immunopathologic damage, there is no information on its ability to interfere with the host's defense against infection. In the current experiments sCR1 exerted a concentration-dependent inhibitory effect on the phagocytosis of Streptococcus pneumoniae by human polymorphonuclear leukocytes in vitro. Not only di sCR1 inhibit complement-dependent opsonization of the pneumococcus but at higher concentrations it also inhibited the ingestion of bacteria which had been previously opsonized. Furthermore, when rats were injected with sCR1, it inhibited both their serum hemolytic activity and serum opsonic activity in a dose-dependent fashion. Finally, for rats treated with sCR1, the 50% lethal dose was S. pneumoniae and Pseudomonas aeruginosa. These data demonstrate that sCR1 significantly inhibits complement-mediated host against bacterial infection.

Animals↗

PubMed1988

An emulsion formulation of amphotericin B improves the therapeutic index when treating systemic murine candidiasis.

Incorporating amphotericin B into liposomes was reported to decrease amphotericin B toxicity without a concomitant loss of antifungal efficacy. We formulated an alternative emulsion-based delivery system for amphotericin B and compared it with Fungizone. The maximal tolerated dose (MTD) in mice was 1 mg of Fungizone/kg; however, the MTD was greater than 9 mg of the Intralipid emulsion formulation/kg. The emulsion formulation and Fungizone were equipotent for treating systemic candidiasis in mice. Amphotericin B nephrotoxicity, as manifested by polyuria that was resistant to antidiuretic hormone, was markedly diminished when amphotericin B was administered as an emulsion to rats. Loss of potassium from human red blood cells was also reduced by formulating this agent within emulsions. The emulsion formulation extended the survival time of mice that had established Candida albicans infections, when compared with the Fungizone treatment. The efficacy and reduced toxicity of the amphotericin B emulsion are findings suggesting that the emulsion formulation is preferable to Fungizone.

Amphotericin B↗

PubMed1985

Organic hydroperoxide-induced lipid peroxidation and cell death in isolated hepatocytes.

Organic hydroperoxides such as tert-butyl hydroperoxide (TBHP) are cytotoxic to suspensions of isolated hepatocytes. The exact mechanism of toxicity is unknown but may involve peroxidation of cellular lipids, alkylation of cellular macromolecules, or alterations in cellular calcium homeostasis. These studies were designed to examine lipid peroxidation as a mechanism of organic hydroperoxide-induced cell death. Hepatocytes isolated from mice were more susceptible to the cytotoxic effects of TBHP than were rat hepatocytes. TBHP-induced cell death was preceded by malondialdehyde formation which was also greater in mouse than rat hepatocytes. Species differences in lipid peroxidation were due to intrinsic properties of hepatocyte membranes as lipids isolated from mouse liver and peroxidized with iron/ascorbate formed approximately eightfold more malondialdehyde than lipids isolated from rat liver. Initiation of lipid peroxidation in mouse and rat hepatocytes with iron/ascorbate caused the formation of malondialdehyde equal to that seen with TBHP and a slight depletion of cellular GSH. As with TBHP, malondialdehyde formation induced by iron/ascorbate was greater in mouse than in rat hepatocytes. However, iron/ascorbate had no effect on hepatocyte viability or morphology from either species. Furthermore, TBHP-induced malondialdehyde and ethane formation in isolated rat hepatocytes were completely blocked by promethazine whereas cell toxicity was altered only slightly. Therefore, these data do not support a role for lipid peroxidation in the acute cytotoxicity of TBHP to suspensions of isolated rat hepatocytes.

Animals↗

PubMed1982

Involvement of macrophages in the eradication of established metastases following intravenous injection of liposomes containing macrophage activators.

Liposomes containing encapsulated lymphokines or muramyl dipeptide (MDP), when injected i.v. into C57BL/6 mice, produced significant destruction of established lung and lymph node metastases from a s.c. highly metastatic B16-BL6 melanoma. We present evidence that eradication of the metastases is mediated by the activation of host macrophages to the tumoricidal state. Results from three separate types of experiments support this conclusion. (a) When macrophage-activating agents such as lymphokines of MDP were delivered in liposomes that were not efficiently retained in the lung, little or no activation of lung macrophages was observed, and growth of metastases was unaltered. (b) Eradication of metastases was not observed when tumor-bearing animals were treated with agents that impaired macrophage function (e.g., silica, carrageenan, hyperchlorinated drinking water) prior to systemic therapy with liposome-encapsulated lymphokines or liposome-encapsulated MDP. (c) Macrophages activated in vitro by liposome-encapsulated MDP and then injected i.v. into mice bearing experimental lung metastases also significantly inhibited lung metastases. These results suggest that the augmented host response against pulmonary and lymph node metastases generated by the systemic administration of liposome-encapsulated lymphokines or MDP is mediated via activated cytotoxic macrophages.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1982

Analysis of the fate of systemically administered liposomes and implications for their use in drug delivery.

Functional and ultrastructural studies of liposomes injected i.v. into inbred C57BL/6N mice were performed to determine whether free liposomes can traverse capillaries. In the liver and spleen, organs with discontinuous (sinusoidal) capillaries, ultrastructural and cell fractionation studies revealed that small (300- to 800-A diameter), sonicated, unilamellar liposomes were more efficient in penetrating liver sinusoids to interact with hepatocytes than were large (0.5- to 10-micrometers) multilamellar liposomes. Ultrastructural studies of the behavior of liposomes in the continuous capillaries of the lungs revealed that circulating phagocytic cells engulf the liposomes in the capillaries. Transcapillary migration of free liposomes was not observed. We conclude that free liposomes are unable to extravasate to reach the alveoli for subsequent engulfment by alveolar macrophages. Instead, liposomes in the lung capillaries are engulfed by circulating blood phagocytes which subsequently migrate to the alveoli to become alveolar macrophages. Experiments on the recruitment of blood monocytes into the lungs subjected to whole- or partial-body X-radiation confirmed that transfer of i.v.-injected liposomes to the alveolar compartment was mediated by blood monocytes. The inability of liposomes to escape from continuous capillaries and their rapid uptake by circulating and fixed phagocytic cells calls into question the feasibility of using liposomes to "target" drugs to cells in extravascular tissues.

Animals↗

PubMed1980

Design of liposomes to improve delivery of macrophage-augmenting agents to alveolar macrophages.

Factors affecting the localization of liposomes injected i.v. in the lung have been studied to identify the optimal type of liposome for delivery of macrophage-activating agents to the lung to augment the tumoricidal activity of alveolar macrophages (AM). Comparison of pulmonary retention of liposomes of differing size, surface charge, and composition following i.v. injection into inbred mice revealed that large multilamellar (MLV) and reversed-phase-evaporation (REV) liposomes are arrested in the lung more efficiently than are small unilamellar liposomes of identical lipid composition. MLV and REV containing negatively charged amphiphiles arrest in the lung more efficiently than do neutral MLV's or REV's or MULV's and REV's containing positively charged amphiphiles. Comparison of the ability of liposomes containing a variety of negatively charged amphiphiles to localize in the lung established that optimal localization was achieved using MLV and REV prepared from phosphatidylserine (PS) and phosphatidylcholine (PC) (3:7 mol ratio) or PS:PC:lysolecithin (4.95:4.95:0.1 mol ratio). The proportion of these liposomes retained in the lung after i.v. injection was constant over a wide dose range (0.02 to 20 mumol phospholipid per mouse), but hemodilution due to i.v. inoculation of liposomes in volumes exceeding 0.2 ml reduced retention in the lung. Uptake of liposomes by AM was demonstrated by showing that i.v. injection of PS:PC MLV liposomes containing fluorescein-labeled bovine serum albumin resulted in localization of fluorescence within AM recovered by pulmonary lavage. Similarly, AM recovered after i.v. injection of PS:PC MLV liposomes containing lymphokine preparations rich in macrophage-activating factor (MAF) activity exhibited tumoricidal activity. In contrast, macrophages recovered from control animals given injections of unencapsulated MAF or liposomes containing lymphocyte supernatants without MAF activity were devoid of cytotoxic activity. Neutral (PC) MLV liposomes containing MAF, which show only very limited retention in the lung, were ineffective in activating AM in situ. We conclude that negatively charged MLV liposomes (PS:PC, 3:7 mol ratio) localize efficiently in the lung and that macrophage-activating agents encapsulated within such liposomes can successfully activate lung macrophages in situ.

Animals↗

PubMedDate not supplied

Leukotriene D4 (LTD4) induces mucus secretion from goblet cells in the guinea pig respiratory epithelium.

To study the potential role of leukotriene (LTD4) as a mucus secretagogue, anesthetized and spontaneously breathing guinea pigs were intubated and challenged with various concentrations of an LTD4 aerosol. The resulting changes in airway resistance and compliance were then observed for 20 min, after which the animals were euthanized and the lower respiratory tract airways fixed for morphometric evaluation. Sections for these airways were stained with alcian blue-periodic acid Schiff (AB-PAS), photographed, and the content of AB-PAS positive granules in the epithelium of the extrapulmonary bronchi quantified. The fractional volume of mucus granules in the respiratory epithelial volume. Aerosol LTD4 produced a dose-dependent decrease in the granule fractional volume (GFV) over the range of 0.1 to 1 microgram/ml when compared with epithelia challenged with saline aerosols. Increasing the concentration of administered LTD4 from 1 microgram to 3 micrograms/ml produced further bronchoconstriction but had no further effect on the GFV. Decreases in GFV did not appear to be secondary to smooth muscle contraction since aerosols of other agonists (0.05% histamine and 1% acetylcholine), which yielded resistance changes similar to those of LTD4, did not effect the GFV. Pretreatment with an aerosol of the specific LTD4 receptor antagonist SK&F 104353-Z2 produced a dose-dependent inhibition of the changes in both the airway resistance and GFV. The data suggest that LTD4 mediates epithelial mucus secretion as well as bronchoconstriction in the guinea pig airway and may provide an additional therapeutic use for specific LTD4 receptor antagonists in the treatment of obstructive pulmonary disease.

Animals↗