GDKV-induced antiphospholipid antibodies enhance thrombosis and activate endothelial cells in vivo and in vitro

Antiphospholipid (aPL) Abs are associated with thrombosis, pregnancy loss, and thrombocytopenia in patients with systemic lupus erythematosus or primary antiphospholipid syndrome (APS). beta2-Glycoprotein I (beta2GPI), a phospholipid-binding serum protein, is involved in aPL binding to phospholipids. aPL can be generated in mice by immunization with beta2GPI, and these Abs are thrombogenic and cause pregnancy loss in mice. The objective of this study is to determine whether aPL induced by immunization with the phospholipid-binding site of beta2GPI are thrombogenic and whether they activate endothelial cells (EC) in vivo and in vitro. Murine monoclonal aPL were generated from spleen cells of a mouse immunized with GDKV, a synthetic 15-aa peptide spanning Gly274-Cys288 in the fifth domain of human beta2GPI, which represents the phospholipid-binding site of beta2GPI. The Abs generated had aPL and anti-beta2GPI activities. The effect of these Abs on thrombus formation and on EC activation in vivo was determined using a mouse model of thrombosis and microcirculation that enables examination of the adhesion of leukocyte to EC as an indication of EC activation as well as adhesion molecule expression using in vitro ELISA analysis. Mice injected with this monoclonal aPL showed a significant increase in leukocyte sticking and also produced larger thrombi that persisted longer. Exposure to GDKV-induced aPL for 4 h significantly increased surface Ag expression of E-selectin, ICAM-1, and VCAM-1. These data indicate that aPL induced by immunization with the phospholipid binding site of beta2GPI are thrombogenic and activate endothelial cells.

Tissue distribution of recombinant human tumor necrosis factor alpha derivative in mice

AIM

To study the tissue distribution and its mechanism of a new recombinant tumor necrosis factor alpha derivative (rhTNF alpha Da) in mice.

METHODS

125I-rhTNF alpha Da was prepared by Iodogen method. Tissue distribution of 125I-rhTNF alpha Da in mice was studied by determining radioactivity of tetrachloroacetic acid (TCA)- precipitable fraction in tissues. The isolated heart-lung perfusion study using 125I-rhTNF alpha Da perfusate was carried out to study the distribution characteristics of 125I-rhTNF alpha Da in lung.

RESULTS

Except for thyroid, AUC of the TCA-precipitable 125I-rhTNF alpha Da in tissues was highest in lung, which was 12.2-fold of that in serum, while concentrations in other tissues were all lower than that in serum. Perfusion study in vitro revealed that the concentration of radio-labeled peptide in lung was higher than that in perfusate. On the contrary, level in heart was much lower than that in perfusate. The overall distribution of 125I-rhTNF alpha Da in lungs showed rapidly equilibratory, dose-dependent, saturable, competitive, and highly affinitive, with Kd 47.6 pmol.L-1 and Bmax 348 fmol.g-1 (lung tissue).

CONCLUSION

The specific distribution of rhTNF alpha Da in lungs was its distinctive characteristics.

Pharmacokinetics and peripheral platelet counts after a single dose of recombinant human thrombopoietin in rhesus monkeys

AIM

To study the pharmacokinetics and the change of peripheral platelet counts after a single dose of recombinant human thrombopoietin (rhTpo).

METHODS

After i.v. or s.c. injections of rhTpo in 12 rhesus monkeys, rhTpo concentration in serum was determined by ELISA. Platelets were counted by automatic microcell counter.

RESULTS

The terminal half-lives of rhTpo were 12-18 h. AUC following s.c. were linearly increased with dose, while Cls were 0.061, 0.08, and 0.07 L.kg-1.h-1 in s.c. 0.5, 2, and 8 micrograms.kg-1 groups, respectively. Bioavailability was 0.50 +/- 0.18 after s.c. Single dose of rhTpo was associated with an increase in platelets (55.9%-107.4%, P < 0.05) in a dose-related manner. The peak response and the sustained days of platelet increase were dose-related. The degree of platelet increase (% x time) correlated with the systemic exposure to rhTpo (C x time).

CONCLUSION

rhTpo behaved as a linear pharmacokinetics in the monkey within dose range of 0.5-8 micrograms.kg-1.

Predictive chemotherapy of advanced breast cancer directed by MTT assay in vitro

In order to investigate the predictive value of in vitro MTT assay for directing chemotherapy of breast cancer patients, from 1992 to 1995, 156 advanced breast cancer patients who had evaluable lesions were recruited for a prospective study. Of them 83 had MTT assay before chemotherapy; the 73 patients in the MTT sensitive group received chemotherapy according to the result of the MTT assay. The other 10 patients in the MTT resistant group and 73 patients in the control group were given chemotherapy according to clinicians' discretion. The response rate in the MTT sensitive group was 76.7% (56/73). There was statistically significant difference as compared with 0 (0/10) in the MTT resistant group and 43.8% (32/73) in the control group. Between in vitro and in vivo, the overall coincident rate was 79.5% [(56 + 10)/83]. In the MTT sensitive group, the response rate of the subgroups of lesions and the chemotherapy regiments tended to be higher than that in the control group. Patients in the MTT sensitive group had longer response and survival than those in the control group. However, there was no statistical difference in the median response duration and the median survival between the two groups. Further exploration of in vitro chemosensitivity testing by MTT assay for patients with advanced breast cancer is warranted.

Thrombogenic properties of antiphospholipid antibodies do not depend on their binding to beta2 glycoprotein 1 (beta2GP1) alone

Immunization of mice with beta2glycoprotein 1 (beta2GP1) induces production of antiphospholipid (aPL) antibodies, which were shown to have thrombus enhancing properties in an experimental mouse model, indicating that these antibodies are thrombogenic in vivo. To determine whether the thrombogenic effect of murine antiphospholipid antibodies is due to their aPL or their anti-beta2GP1 activity, we injected mice with murine monoclonal anticardiolipin (aCL) and anti-beta2GP1 antibodies. Effects of these antibodies on thrombus formation, was evaluated utilizing a mouse model which enables kinetics of thrombus formation to be studied. The results of this study showed that the size of the thrombus in animals injected with murine aCL antibodies was larger than that in control groups. There was no difference in thrombus kinetics between anti-beta2GP1 injected mice and controls, suggesting that the thrombogenic effect of aPL antibodies is not related to their anti-beta2GP1 activity alone. Mice receiving monoclonal antibodies with both aCL and anti-beta2GP1 activity, also increase thrombus size when compared with controls. These data indicate that murine aCL, but not anti-beta2GP1, antibodies are thrombogenic in vivo.

An indirect effect of Stat5a in IL-2-induced proliferation: a critical role for Stat5a in IL-2-mediated IL-2 receptor alpha chain induction

Stat5a was identified as a prolactin-induced transcription factor but also is activated by other cytokines, including interleukin-2 (IL-2) and IL-7. We have now analyzed the immune system of Stat5a-deficient mice. Stat5a-/- splenocytes exhibited defective IL-2-induced expression of the IL-2 receptor alpha chain (IL-2R alpha), a protein that together with IL-2R beta and the common cytokine receptor gamma chain (gamma(c)) mediates high-affinity IL-2 binding. Correspondingly, Stat5a-/- splenocytes exhibited markedly decreased proliferation to IL-2, although maximal proliferation was still achieved at IL-2 concentrations high enough to titrate intermediate-affinity IL-2R beta/gamma(c) receptors. Thus, defective Stat5a expression results in diminished proliferation by an indirect mechanism, resulting from defective receptor expression. Correspondingly, we show that Stat5a is essential for maximal responsiveness to antigenic stimuli in vivo, underscoring the physiological importance of IL-2-induced IL-2R alpha expression.

Pharmacokinetics of recombinant human granulocyte colony-stimulating factor in rabbits and mice

AIM

To study the pharmacokinetics of recombinant human granulocyte colony-stimulating factor (rhGCSF) in rabbits and mice.

METHODS

125I-rhGCSF was prepared by iodogen method and determined by size exclusive HPLC (SEHPLC).

RESULTS

Concentration-time curves after i.v. 125I-rhGCSF in rabbits were best fitted with 2-compartment open model. The alpha and terminal elimination T1/2 were 0.25-0.33 and 3.2-4.6 h, respectively. AUC increased with doses, and Cls and K10 were similar. Tpeak was 0.59 +/- 0.25 h after s.c., and elimination T1/2 was similar to that after i.v. The bioavailability after sc was 1.0. In mice the highest level was found in renal system, the next was bile-enteric system. Levels in lymph nodes, bone marrow, and spleen were approximately equal to or slightly lower than that in plasma, while the levels in brain, fat, and muscles were the lowest. About 68%-86% were recovered in urine and feces.

CONCLUSION

Pharamcokinetics of 125I-rhGCSF in rabbits and mice provided a useful index for clinical trial.

[Effect of hedgehog hydnum on the delay of fatigue in mice]

Two groups of mice were fed with either hedgehog hydnum powder or extract for sixty days. For the assay of fatigue, the activity of serum lactate dehydrogenase, the serum urea nitrogen content, blood lactic acid, hepatic and muscular glycogen, and the physical stamina of the mice were determined. The activity of serum lactate dehydrogenase and the hepatic and muscular glycogen content in the experimental mice were evidently higher than that in the control mice (P < 0.05 or P < 0.01). After exercise, the increase in blood lactic acid and serum urea nitrogen in the experimental mice was significantly lower than that in the control mice (P < 0.05 or P < 0.01), but the rate of elimination of blood lactic acid in the experimental mice was significantly higher than that in the control mice (P < 0.05). In the physical stamina swimming, the experimental mice drowned after a longer period of time than the control mice (P < 0.05). In conclusion hedgehog hydnum had a significant effect on raising physical stamina and delaying fatigue in mice.

Induction of thrombosis in a mouse model by IgG, IgM and IgA immunoglobulins from patients with the antiphospholipid syndrome

Antiphospholipid syndrome is a disorder of recurrent thrombosis and pregnancy losses associated with production of anticardiolipin antibodies and lupus anticoagulant positivity. Recently, we have adapted a mouse model of induced venous thrombosis to study the role of autoantibodies in thrombus formation. To determine whether immunoglobulins from patients with the antiphospholipid syndrome play a role in thrombosis, we injected groups of CDI mice either with immunoglobulins purified from seven patients with the antiphospholipid syndrome (nine preparations studied: four IgG, three IgM and two IgA) or with immunoglobulins of the same isotype from healthy controls. Seventy-two h after injection, a non-occlusive thrombus was induced in the femoral veins of experimental mice by a pinch injury; the thrombus areas as well as times of formation and disappearance of the thrombi were measured. Eight of the nine antiphospholipid syndrome immunoglobulin preparations caused a significant increase in mean thrombus area and a significant delay in mean thrombus disappearance time as compared with normal controls. To determine whether anticardiolipin antibodies might be involved, separate groups of mice were injected with affinity-purified IgG (n = 2) or IgM (n = 2) anticardiolipin antibodies or with normal immunoglobulins of the same isotype, and the effects on thrombus formation compared. Mean thrombus area and mean disappearance times were again significantly increased in all four groups injected with affinity-purified antibodies. This is the first study to show that anticardiolipin antibodies of IgG, IgM and IgA isotypes may play a role in thrombosis in vivo.

Pharmacokinetics and tissue distribution of human recombinant interleukin-2 in mice

125I-labeled human recombinant interleukin-2 (125I-rIL-2) was prepared by iodogen method with rIL-2 and Na125I. Product was purified by Sephacryl S-200 gel filtration. Eluate fractions were identified by SDS-PAGE and compared with standard rIL-2. Radioactive 95% purified 125I-rIL-2 fractions were selected for pharmacokinetic study, with a specific activity of 56 PBq.mol-1. Concentration-time curves after iv 75, 530, 603, and 6767 ng of 125I-rIL-2/mouse were fitted to a 3-compartment model: with a fast distribution phase T1/2 of 2 min, a slow distribution phase T1/2 of 30-120 min, and a terminal elimination T1/2 of 6-15 h. AUC was linearly related to the dosage (r = 0.9998). Systematic clearances were independent of the dosages. SDS-PAGE of plasma and urine samples showed that radioactivities due to 125I-rIL-2 were 81 +/- 13% (n = 16) and 91 +/- 8% (n = 3, at 4 h), respectively. Levels of 125I-rIL-2 after im were lower than those after i.v., with bioavailability of 0.57. Time to peak concentration was about 1.1 h. The highest levels were seen at 15 min after i.v. in liver, bile and kidneys, the concentration gradients were blood > adrenals > plasma > lungs > thyroid > spleen > jejunum > mesenteric lymph nodes > jejunum contents > ovaries > heart > bladder > thymus > feces in colon > thigh skeletal muscle > testes > brain > fat. Peak concentration time in most tissues were found at 15 min, but at 4 h in the feces.(ABSTRACT TRUNCATED AT 250 WORDS)

Mössbauer effect studies on some bioinorganic complexes of europium

The bioinorganic complexes of europium with N-acetyl-DL-alanine, N-acetyl-DL-valine, and DL-alanyl-DL-alanine have been synthesized and the Mössbauer spectra at room temperature have been measured for these solid state complexes. The Mössbauer parameters indicate that the water molecules in these complexes are not directly linked to the central europium ion and are outside the coordination sphere of europium and biological ligands, and that the chemical bond between the europium ion and the ligands may be predominantly ionic in character, with the possibility of partial covalent contribution.

[Measurement of free silica concentration in the dust by small X-ray diffractometer]

X-ray diffraction method was applied to measure free silica concentration in the dust and the procedure of analysis have been established. The filter used was the polyvinyl chloride filter. Good linear relationship was shown to exist between the amount of silica and the intensity of its diffracted rays (r = 0.99). The standard deviation of repeated tests was 3.199%. The coefficient of variation was 4.43. An amount of 0.015 mg silica collected on the filter (d = 9 mm) can be detected. This method is suitable for monitoring and investigating silica contents in labour hygiene studies.

Marginal zinc deficiency and changes in behavioral salt taste threshold and salt preference in mice

An animal model of marginal zinc deficiency was tested in mice, and salt taste threshold and salt preference were investigated in the state of marginal zinc deficiency. Two experiments were conducted. In Experiment 1, four-week-old male ICR mice were fed diets of three different levels of zinc content (3.17, 9.27, or 48.13 micrograms Zn/g) for 60 days. Food intake, growth, zinc levels in tissues, hepatic metallothionein (MT) content, and activities of selected enzymes (hepatic and RBC delta-amino-levulinic acid dehydratase (ALAD) and plasma alkaline phosphatase (ALP] did not differ among the groups throughout the experiment, and no overt signs of zinc deficiency were manifested in any group. In Experiment 2, four-week-old male ICR mice were fed a zinc-deficient diet (1.98 micrograms Zn/g) or a zinc-adequate diet (49.14 micrograms Zn/g) for 56 days. Food intake and growth did not differ between the two groups, and no overt signs of zinc deficiency were observed throughout the experiment. Zinc levels in the plasma and femur--but not those in the brain, kidneys, liver, and red blood cell (RBC)--and plasma ALP activities were significantly lower on Day 42 and Day 56 of the experiment in the mice fed the zinc-deficient diet (ZnD group) than in those fed the zinc-adequate diet (ZnA group). Hepatic MT contents were lower in the ZnD group than in the ZnA group on Day 56 only. Salt taste threshold was 0.05% in the ZnA group, while it was 0.1% in the ZnD group, between Day 30 and Day 38, and between Day 44 and Day 52 of the experiment. Preference for 0.9% NaCl solution was no different in the two groups when tested between Day 38 and Day 40 or between Day 52 and Day 54, but that for 1.6% NaCl solution was significantly higher in the ZnD group than in the ZnA group between Day 40 and Day 42, and between Day 54 and Day 56.