Fibrinogen γ-chain peptide-coated, ADP-encapsulated liposomes rescue thrombocytopenic rabbits from non-compressible liver hemorrhage

BACKGROUND

We developed a fibrinogen γ-chain (dodecapeptide HHLGGAKQAGDV [H12])-coated, ADP-encapsulated liposome (H12-[ADP]-liposome) that accumulates at bleeding sites via interaction with activated platelets via glycoprotein IIb-IIIa and augments platelet aggregation by releasing ADP.

OBJECTIVE

To evaluate the efficacy of H12-(ADP)-liposomes for treating liver hemorrhage in rabbits with acute thrombocytopenia.

METHODS

Thrombocytopenia (platelets < 50 000 μL(-1)) was induced in rabbits by repeated blood withdrawal (100 mL kg(-1) in total) and isovolemic transfusion of autologous washed red blood cells. H12-(ADP)-liposomes with platelet-poor plasma (PPP), platelet-rich plasma (PRP), PPP, ADP liposomes with PPP or H12-(PBS)-liposomes/PPP, were administered to the thrombocytopenic rabbits, and liver hemorrhage was induced by penetrating liver injury.

RESULTS

Administration of H12-(ADP)-liposomes and of PRP rescued all thrombocytopenic rabbits from liver hemorrhage as a result of potent hemostasis at the liver bleeding site, although rabbits receiving PPP or ADP liposomes showed 20% survival in the first 24 h. Administration of H12-(ADP)-liposomes and of PRP suppressed both bleeding volume and time from the site of liver injury. H12-(phosphate-buffered saline)-liposomes lacking ADP also improved rabbit survival after liver hemorrhage, although their hemostatic effect was weaker. In rabbits with severe thrombocytopenia (25 000 platelets μL(-1)), the hemostatic effects of H12-(ADP)-liposomes tended to be attenuated as compared with those of PRP treatment. Histologic examination revealed that H12-(ADP)-liposomes accumulated at the bleeding site in the liver. Notably, neither macrothombi nor microthrombi were detected in the lung, kidney or liver in rabbits treated with H12-(ADP)-liposomes.

CONCLUSIONS

H12-(ADP)-liposomes appear to be a safe and effective therapeutic tool for acute thrombocytopenic trauma patients with massive bleeding.

Skin formation and bubble growth during drying process of polymer solution

When a polymer solution with volatile solvent is dried, skins are often formed at the surface of the solution. It has been observed that after the skin is formed, bubbles often appear in the solution. We conducted experiments to clarify the relation between the skin formation and the bubble formation. We measured the time dependence of the thickness of the skin layer, the size of the bubbles, and the pressure in the solution. From our experiments, we concluded that i) the gas in the bubble is a mixture of solvent vapor and air dissolved in the solution, ii) the bubble nucleation is assisted by the pressure decrease in the solution covered by the skin layer, and iii) the growth of the bubbles is diffusion limited, mainly limited by the diffusion of air molecules dissolved in the solution.

Altered immunoglobulin A and M levels associated with changes in BAFF and APRIL after administration of intravenous immunoglobulin to treat Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is an acute vasculitis of unknown etiology. Immunoregulatory abnormalities have been thought to contribute to its pathogenesis. Although treatment with intravenous immunoglobulin (IVIG) effectively prevents significant cardiac morbidity, the mechanism by which IVIG produces an effect in KD has yet to be fully elucidated.

OBJECTIVE

To investigate the effects of IVIG on the immune system of patients with KD.

PATIENTS AND METHODS

Eleven patients with KD (mean [SD] age, 2.2 [1.5] years) were enrolled in this prospective study and treated with high-dose IVIG therapy (2 g/kg in 1 or 2 infusions) during the acute phase of the disease. We examined immunological changes, with special reference to Ig levels and 2 previously unassessed cytokines: B cell-activating factor belonging to the tumor necrosis factor family (BAFF), and a proliferation-inducing ligand (APRIL).

RESULTS

Clinical symptoms disappeared quickly in all cases, with no coronary artery abnormalities. IgA and IgM levels responded more rapidly than previously reported and reached a peak between the 3rd and 10th day after the start of IVIG treatment. The mean (SD) BAFF level was high before IVIG treatment (3234 [1904] pg/mL) and decreased significantly (1085 [257] pg/mL) after IVIG treatment, whereas the mean (SD) APRIL level before IVIG treatment (18.0 [10.0] ng/mL) rose significantly (120.6 [41.2] ng/mL). A significant inverse correlation between BAFF and APRIL was observed in patients with KD.

CONCLUSIONS

These results suggest that IVIG may affect the pathogenesis of KD through alteration of BAFF/APRIL.

Inter-comparison of absorbed dose rates for non-human biota

A number of approaches have been proposed to estimate the exposure of non-human biota to ionizing radiation. This paper reports an inter-comparison of the unweighted absorbed dose rates for the whole organism (compared as dose conversion coefficients, or DCCs) for both internal and external exposure, estimated by 11 of these approaches for selected organisms from the Reference Animals and Plants geometries as proposed by the International Commission on Radiological Protection. Inter-comparison results indicate that DCCs for internal exposure compare well between the different approaches, whereas variation is greater for external exposure DCCs. Where variation among internal DCCs is greatest, it is generally due to different daughter products being included in the DCC of the parent. In the case of external exposures, particularly to low-energy beta-emitters, variations are most likely to be due to different media densities being assumed. On a radionuclide-by-radionuclide basis, the different approaches tend to compare least favourably for (3)H, (14)C and the alpha-emitters. This is consistent with models with different source/target geometry assumptions showing maximum variability in output for the types of radiation having the lowest range across matter. The intercomparison demonstrated that all participating approaches to biota dose calculation are reasonably comparable, despite a range of different assumptions being made.

Action mechanism of bis(allixinato)oxovanadium(IV) as a novel potent insulin-mimetic complex: regulation of GLUT4 translocation and FoxO1 transcription factor

Bis(allixinato)oxovanadium(IV), VO(alx)(2) (alx is 3-hydroxy-5-methoxy-6-methyl-2-pentyl-4-pyrone), has been reported to act as an antidiabetic agent in streptozotocin-induced type-1-like and obesity-linked KKA(y) type 2 diabetic model mice. VO(alx)(2) is also proposed as a candidate agent for treating metabolic syndromes in animals. However, its functional mechanism is yet to be clarified. In this study, we examined whether VO(alx)(2) contributes to both the activation of the insulin signaling cascade that activates glucose transporter 4 (GLUT4) translocation and the regulation of the forkhead box O1 (FoxO1) transcription factor that controls the gene transcription of gluconeogenesis genes. The following three important results were obtained: (1) intracellular vanadium concentration in 3T3-L1 adipocytes is higher after treatment with VO(alx)(2) than with VOSO(4); (2) VO(alx)(2) stimulates the translocation of GLUT4 to the plasma membrane following activation of the tyrosine phosphorylation of the insulin receptor beta-subunit (IRbeta) and insulin receptor substrate (IRS) as well as Akt kinase in 3T3-L1 adipocytes; and (3) the mechanism of inhibition of glucose-6-phosphatase (G6Pase) catalytic subunit gene expression by vanadium is due to disruption of FoxO1 binding with the G6Pase promoter, which indicates that FoxO1 is phosphorylated by VO(alx)(2)-stimulated Akt in HepG2 cells. On the basis of these results, we propose that the critical functions of VO(alx)(2) involve the activation of phosphatidylinositol 3-kinase-Akt signaling through the enhancement of tyrosine phosphorylation of IRbeta and IRS, which in turn transmits the signal to activate GLUT4 translocation, and the regulation of the DNA binding activity of the FoxO1 transcription factor.

Debonding dynamics of pressure-sensitive adhesives: 3D block model

We develop a 3-dimensional mechanical model which describes cavity expansions in a viscoelastic solid medium during the debonding phase of the probe-tack test. The stress-strain curves are in good agreement with experiments for the typical pressure-sensitive adhesives. We also show that the separation speed dependence can be explained by viscous dissipations due to large strain rates around the cavities.

The role of endoscopic endonasal approach to pituitary tumours: HUKM experience

Surgery for pituitary tumours at our institution was performed by rhinosurgical route by combined procedure by otolaryngologist and neurosurgeons. A retrospective review of case records of patients who had endonasal endoscopic transphenoidal approach for pituitary tumours from September 1998 to December 2004 was performed. A total of 81 trans-sphenoidal surgeries were performed during this study period. Only 68 case records with adequate information were available for review, 56 patients were included in the study and 12 were excluded. There were 24 males (42%) and 32 females (58%). The ethnic distribution, were 29 Malays, 24 Chinese, 2 Indian and 1 others. The age ranged from 16 years to 76 years, with a mean of 46 years. The majority of our patients presented with visual symptoms (38), headache (28), menstrual cycle disturbance or impotence (14) and acromegalic features (16). Forty patients had macroadenoma (71%) and 16 had microadenomas (29%). Thirty-six patients out of 40 macro-adenomas had suprasellar extensions (90%). Only eleven patients had lumbar drain inserted prior to commencement of the surgery and the majority of these were macroadenomas. The common complications encountered were diabetes insipidus (4), cerebrospinal fluid leak (2), meningitis (3), epistaxis (2), septal perforation (2), intercavernous sinus haemorrhage (3) and anterior pituitary insufficiency (2). Our study reveals that endonasal trans-sphenoidal approach is a safe and effective method of management of pituitary adenomas.

Modeling on debonding dynamics of pressure-sensitive adhesives

We propose a simple mechanical model describing viscoelasticity and cavitation during the debonding process in pressure-sensitive adhesives (PSA). Our calculation qualitatively reproduces typical stress-strain curves in the probe-tack test, such as the steep stress maxima and the following plateau region. It is shown that in the thin-film geometry the stress-strain curve is essentially determined by the cavities created by the large negative pressure. Effects of pre-existent air bubbles due to surface roughness are also discussed.