WS1279, a novel lipopeptide isolated from Streptomyces willmorei. Biological activities

WS1279, a new lipopeptide isolated from the fermentation broth of Streptomyces willmorei No. 1279, stimulated the proliferation of mouse bone marrow cells in vitro and accelerated the recovery of granulocyte counts in bone marrow from leukopenia induced by mitomycin C (MMC) in mice. The glycerylcysteine moiety of WS1279 is necessary and the lipid peptide structure is required for manifestation of full stimulating activity in vitro. WS1279 was the most effective on the proliferation of bone marrow cells among the tested immunostimulants in vitro. However, the effect of WS1279 on restoration of reduced granulocyte counts in MMC-induced leukopenia in mice was less than that of FK-565, lipopolysaccharide, picibanil or forphenicinol. WS1279 augmented host resistance to infection with Staphylococcus aureus 47 in normal and immunosuppressed mice.

The effect of two-domain tissue factor pathway inhibitor on endotoxin-induced disseminated intravascular coagulation in rabbits

Disseminated intravascular coagulation (DIC) is a common complication in sepsis, and may result from endotoxin-induced exposure of tissue factor on the surface of monocytes and endothelial cells. Tissue factor pathway inhibitor (TFPI) is a factor Xa-dependent feedback inhibitor of the tissue factor-factor VIIa complex. In the present study the effect on DIC of a two-domain TFPI analogue (2D-TFPI), consisting of the first two Kunitz domains of TFPI but lacking the third domain, was tested. DIC was induced in rabbits by two intravenous bolus injections of endotoxin from Escherichia coli (10 and 50 micrograms/kg) 24 h apart. Simultaneously with the last endotoxin injection an infusion of 2D-TFPI (0, 0.3, 1.0 or 3.0 mg/kg/h) was given. Blood samples were obtained at 0 h, 24 h and 31 h. At 31 h the animals were sacrificed and the kidneys were submitted to histological examination. The degree of fibrin deposition in glomeruli was scored blindly using an arbitrary scale from 0 to 3. Between 24 and 31 h the group receiving endotoxin alone showed a significant decrease in platelet count (65%), plasma fibrinogen (41%), antithrombin III (25%), and factor VIII (63%), and a significant prolongation of the aPTT (14%). Furthermore, massive fibrin deposition was detected in the renal glomeruli at 31 h. Infusions of 2D-TFPI inhibited all the endotoxin-induced changes in a dose-dependent manner. In conclusion, the data demonstrate that inhibition of the TF/FVIIa complex by infusion of 2D-TFPI significantly counteracts endotoxin-induced coagulopathy in rabbits, and might thus be an attractive drug for treatment of endotoxin-induced DIC in humans.

Tissue factor pathway inhibitor reduces mortality from Escherichia coli septic shock

This study was designed to test the hypothesis that tissue factor pathway inhibitor (TFPI) plays a significant role in vivo in regulating coagulation that results from exposure of blood to tissue factor after vascular injury as in the case of gram negative sepsis. Highly purified recombinant TFPI (6 mg/kg) was administered either 30 min or 4 h after the start of a lethal intravenous Escherichia coli infusion in baboons. Early posttreatment of TFPI resulted in (a) permanent seven-day survivors (5/5) with significant improvement in quality of life, while the mean survival time for the controls (5/5) was 39.9 h (no survivors); and (b) significant attenuations of the coagulation response and various measures of cell injury, with significant reductions in pathology observed in E. coli sepsis target organs, including kidneys, adrenals, and lungs. TFPI administration did not affect the reduction in mean systemic arterial pressure, the increases in respiration and heart rate, or temperature changes associated with the bacterial infusion. TFPI treated E. coli infected baboons had significantly lower IL-6 levels than their phosphate buffered saline-treated controls, however tumor necrosis factor levels were similarly elevated in both groups. In contrast to the earlier 30-min treatment, the administration of TFPI at 4 h, i.e., 240 min, after the start of bacterial infusion resulted in prolongation of survival time, with 40% survival rate (2/5) and some attenuation of the coagulopathic response, especially in animals in which fibrinogen levels were above 10% of normal at the time of TFPI administration. Results provide evidence for the significance of tissue factor and tissue factor pathway inhibitor in bacterial sepsis, and suggest a role for blood coagulation in the regulation of the inflammatory response.

Prevention of thrombosis by topical application of tissue factor pathway inhibitor in a rabbit model of vascular trauma

The extrinsic pathway of coagulation is initiated when tissue factor complexes with factor VII. A naturally occurring protein inhibitor of this complex, tissue factor pathway inhibitor (TFPI), has recently been isolated and the cDNA coding for this protein cloned. We used a rabbit ear artery model of crush/avulsion injury and microvascular repair to investigate the efficacy of TFPI as a topically applied antithrombotic agent. Traumatized arteries treated through lumenal irrigation with normal saline vehicle (controls) achieved patency rates of 8% and 0% at 1 and 7 postoperative days, respectively. Heparin irrigation (10 U/ml) resulted in patencies of 40% at both evaluation times. In contrast, TFPI at a dose of 20 micrograms/ml (0.2 ml total volume; 10 minute exposure) yielded a 91% patency rate at 1 day and 73% at 7 days postoperatively (p < 0.0005 vs controls). Prothrombin time and activated partial thromboplastin time values were not altered after topical treatment with TFPI. Scanning electron microscopy revealed dramatically inhibited thrombogenesis upon the injured surfaces of TFPI-treated vessels. These results suggest that TFPI used as a topically applied antithrombotic agent is effective for the prevention of thrombosis in microvascular anastomoses.

Antithrombotic properties of a truncated recombinant tissue factor pathway inhibitor in an experimental venous thrombosis model

The aim of this study was to investigate whether a truncated recombinant tissue factor pathway inhibitor (rTFPI1-161) had an antithrombotic effect comparable to low-molecular-weight (LMW) heparin. A randomized double-dummy study was conducted with 40 rabbits in 6 groups. An experimental thrombosis was induced in the jugular veins by a combination of destroyed endothelium and restricted blood flow. Group 1 was given placebo; group 2, LMW heparin 60 anti-factor Xa units/kg; group 3, rTFPI1-161 0.1 mg/kg; group 4, rTFPI1-161 1.0 mg/kg and group 5, rTFPI1-161 10.0 mg/kg. rTFPI1-161 reduced the thrombus weights in all treated groups, with a significant effect in doses between 1.0 and 10.0 mg/kg compared to placebo. The frequency of thrombosis was significantly reduced in all treated groups. No hemorrhagic side effects were noted. In conclusion, rTFPI1-161 (1.0-10.0 mg/kg) has an antithrombotic effect comparable to that of LMW heparin.

Management of vitiligo

Vitiligo is a disease of unknown origin that causes destruction of melanocytes in the skin, mucous membranes, the eyes, and occasionally in hairbulbs and in the ears. The loss of melanocytes alters both structure and function of these organs. The goals of therapy are multifold. The primary goal is to restore melanocytes to the skin so that the epidermis has a normal morphology. Such repigmented skin regains its normal immune/inflammatory functions.

Recombinant lipoprotein-associated coagulation inhibitor inhibits tissue thromboplastin-induced intravascular coagulation in the rabbit

Lipoprotein-associated coagulation inhibitor produces feed-back inhibition of tissue factor (tissue thromboplastin)-induced coagulation in the presence of factor Xa Recombinant lipoprotein-associated coagulation inhibitor (rLACI) was tested for its ability to modify thromboplastin-induced intravascular coagulation in a rabbit model that allows monitoring of iodine-125 fibrin accumulation/disappearance in the lung and sampling of blood for the measurement of coagulation parameters. Infusion of thromboplastin into the rabbit caused a rapid increase of radioactivity over the lungs, possibly due to the accumulation of 125I fibrin in the lungs, followed by a rapid decline of radioactivity, suggestive of removal of fibrin from the lungs. Thromboplastin also caused a rapid decrease of systemic fibrinogen that was accompanied by a lengthening of the activated partial thromboplastin time and prothrombin time. The effect of coinfusion of rLACI with thromboplastin or bolus injection of rLACI before thromboplastin infusion was studied. At a high dose of rLACI (800 micrograms/kg body weight), the thromboplastin-induced radioactivity increase in the lungs and the systemic fibrinogen decrease were completely suppressed. The activated partial thromboplastin time and prothrombin time of the plasma samples lengthened, possibly due to the presence of thromboplastin in circulation. The thromboplastin-induced radioactivity increase over the lungs was not completely suppressed by lower doses of rLACI (135 to 270 micrograms/kg body weight), but these doses of rLACI prevented systemic fibrinogen decrease. At a bolus dose of 23 micrograms/kg body weight, rLACI provided 50% protection of the fibrinogen consumption (fibrinogen decreased to 82% compared with 65% in rabbits treated with thromboplastin alone). These results show that rLACI is effective in the inhibition of thromboplastin-induced coagulation in vivo.

Antibacterial therapy: problems and promises, Part II

Numerous antibacterial agents recently or soon to be available are reviewed: new quinolones, macrolides, aminoglycosides, glycopeptides, and lipopeptides. Overall, these agents do much to improve antibacterial activity against problem organisms, overcome resistance, and reduce toxicity and frequency of administration. Many are orally administered and will shorten hospital stays.

A54145 a new lipopeptide antibiotic complex: microbiological evaluation

A54145 complex is made up of eight factors; A, A1, B, B1, C, D, E, and F which were active in vitro (MIC 0.25 approximately greater than 32 micrograms/ml) against Gram-positive aerobic organisms. The complex, factor B and B1 were found to be active against two strains of Clostridium perfringens. A calcium dependence study on some of the factors showed that their in vitro antibacterial activity was greatly enhanced by the presence of calcium (50 mg/liter) in the media. Resistance build-up was seen when Staphylococcus sp. and Streptococcus sp. were passed seven times in the presence of sublethal concentrations of A54145 antibiotics. This resistance disappeared immediately when the resistant organisms were passed in the absence of the antibiotics. Factor A was very effective against Staphylococcus aureus and Streptococcus pyogenes infections in mice (sc ED50s of 3.3 approximately 2.4 mg/kg x 2, respectively). Factor B was more active against S. pyogenes in vivo (sc ED50, 0.9 mg/kg x 2). Acute mouse toxicities were determined with these antibiotics. Semisynthetic derivatives were evaluated.

Type-III Hyperlipoproteinaemia ("remnant removal disease"). Insight into the pathogenetic mechanism

The metabolism of very-low-density lipoprotein (V.L.D.L.) was studied in a patient with type-III hyperlipoproteinaemia. After injection of radioiodinated V.L.D.L. from a donor with endogenous hypertriglyceridaemia (in a type-IV pattern), clearance of radioactivity from the apoprotein-B moiety of V.L.D.L. was slow and appearance in low-density lipoprotein (L.D.L.) was delayed, suggesting defective catabolism of V.L.D.L. in type-III hyperlipoproteinaemia. Despite a 60% increase in the rate of V.L.D.L. production, therapy with oestrogen (ethinyloestradiol 1 microng/kg/day) resulted in a decrease in plasma-lipid concentrations, normalisation of lipoprotein composition, and correction of the defect in V.L.D.L. catabolism with increased conversion to L.D.L. Thus, in type-III hyperlipoproteinaemia, the primary defect seems to be impaired catabolism of V.L.D.L., which is corrected with oestrogen therapy.