Volume expansion of albumin, gelatin, hydroxyethyl starch, saline and erythrocytes after haemorrhage in the rat

OBJECTIVE

To compare the colloids 5% albumin, 4% gelatin and 6% hydroxyethyl starch (HES) 130/0.4 with each other and with saline, regarding their plasma-expanding effects after haemorrhage; these were also compared with the intravascular volume-expanding effect of re-transfusion with erythrocytes.

DESIGN

Controlled, prospective, randomised laboratory study.

SETTING

University research laboratory.

SUBJECTS

Thirty-five adult rats.

INTERVENTIONS

Plasma volume was determined (I(125) albumin tracer technique) after haemorrhage of 20 ml/kg and 3 h after a bolus infusion of 20 ml/kg of each of the colloids or 80 ml/kg of saline, or 6.7 ml/kg of erythrocytes diluted in 9 ml/kg of saline. Blood pressure, haematocrit (Hct), blood gases and physiological parameters were measured.

MEASUREMENTS AND RESULTS

Plasma volume after haemorrhage was 29.6+/-2.6 ml/kg (n=35). With the bolus infusion, plasma volume increased by 21.1+/-3.6 ml/kg in the albumin group (n=7), by 13.1+/-2.9 ml/kg in the gelatin group (n=7), by 13.8+/-2.2 ml/kg in the HES group (n=7), by 16.0+/-2.4 ml/kg in the saline group (n=7) and by 6.9+/-2.3 ml/kg in the erythrocyte group (n=7) 3 h after the infusion. In the latter group, there was a total increase in intravascular volume of 13.6+/-2.5 ml/kg including the erythrocyte volume. Arterial pressure was better preserved in the albumin and erythrocyte groups than in the other groups.

CONCLUSION

Albumin 5% was a more effective plasma volume expander than gelatin and HES. Saline, with a four times larger volume, and erythrocytes in about 1/3 of the volume had a similar volume-expanding effect to gelatin and HES.

Involvement of cyclic AMP in the production of the acid protease Acp1 by Sclerotinia sclerotiorum

The acid protease Acp1 is produced by Sclerotinia sclerotiorum during plant infection. We explored the mechanism involved in the triggering of that production and found that cyclic AMP played a positive role. Acp1 could be produced in the sole presence of exogenous cyclic AMP. The use of molecules known to increase or decrease the intracellular cyclic AMP levels confirmed the impact of this nucleotide on the protease production and suggested its endogenous site of action. Further pharmacological studies showed the specific effect of cyclic AMP on Acp1 production and suggested that protein kinase A would be its likely target. Together, these results provide the first indication that the production of a pathogenesis-related fungal protease could depend on a cyclic AMP/Protein kinase A signalling pathway.

Three-dimensional cardiac tissue engineering using a thermoresponsive artificial extracellular matrix

The purpose of this study was to try to reconstitute three-dimensional cardiac tissue using a thermoresponsive artificial extracellular matrix, poly (N-isopropylacrylamide)-grafted gelatin (PNIPAM-gelatin), as the scaffold. PNIPAM-gelatin solution gels almost immediately when heated above 34 degrees C. We thought this property could become advantageous as scaffolding for reconstituting three-dimensional tissue. Because PNIPAM-gelatin solution gels so quickly, all seeded cells in PNIPAM-gelatin solution would become entrapped and uniformly distributed toward three dimensions. Thus it would be possible to reconstitute three-dimensional tissue by a very simple method of mixing cells and PNIPAM-gelatin solution. Fetal rat cardiac cells were mixed with PNIPAM-gelatin solution, incubated at 37 degrees C to allow the mixture to gel, and cultured in vitro. To define suitable culture conditions the following parameters were tested: (1) PNIPAM-gelatin concentration, 0.04 approximately 0.125 mg/ml; (2) cell seeding density, 1 approximately 50 x 10(6) cells/ml; and (3) addition or not of hyaluronic acid. With a PNIPAM-gelatin concentration of 0.05 mg/ml, a cell seeding density of 50 x 10(6) cells/ml, and the addition of hyaluronic acid, tissue was reconstituted and it contracted synchronously. After hematoxylin and eosin staining, the cells reconstituted three-dimensional tissue, and the tissue cross-section was approximately 60 microm thick.

Effect of cellular uptake of gelatin nanoparticles on adhesion, morphology and cytoskeleton organisation of human fibroblasts

The aim of present study was to prepare nanometer sized particles of gelatin via water-in-oil microemulsion system for drug and gene delivery applications. In this study, cross-linked gelatin nanoparticles encapsulating a fluorescent marker molecule fluorescein isothiocyanate-dextran (FITC-Dex, Mol. Wt. 19.3kDa) have been prepared, characterized and their influence on human fibroblasts has been assessed in terms of cell adhesion, cytotoxicity, light microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and observation of cytoskeleton organisation. Gelatin nanoparticles were prepared inside the aqueous cores of sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-hexane reverse micelles. Transmission electron microscopy image showed that the particles are spherical in shape with size of 37+/-0.84 nm diameter. The release of FITC-Dex from the nanoparticles in phosphate buffer saline (pH 7.4) is found to increase with time and about 80% of the encapsulated dye is released in 6 h. Cell adhesion studies with human fibroblasts have shown that gelatin nanoparticles do not affect the number of cells adhered to glass as compared to control cells with no particles. Standard cell viability assay demonstrated that cells incubated with gelatin nanoparticles remained more than 100% viable at concentration as high as 500 microg/ml. From SEM image, it was observed that the nanoparticles were internalised and the fibroblasts exhibited vacuoles in the cell body with cell membrane abnormalities. Endocytosis of nanoparticles was confirmed from TEM studies and it resulted in disruption of F-actin and beta-tubulin cytoskeleton. These studies show that the gelatin nanoparticles prepared by water-in-oil microemulsion systems are endocytosed by the fibroblasts without being toxic to cells even at high concentration of nanoparticles.

Safety of Curcuma aromatica oil gelatin microspheres administered via hepatic artery

AIM: To evaluate the safety of Curcuma aromatica oil gelatin microspheres (CAO-GMS) infused via hepatic artery against primary liver cancer.

METHODS: The safety of CAO-GMS was evaluated in view of its acute toxicity in rats, long-term toxicity in Beagle dogs and general pharmacology in rats and mongrel dogs.

RESULTS: The 50% lethal dose (LD₅₀) of CAO-GMS infused via the hepatic artery was 17.19 mg/kg, and the serum biochemical indices of dying rats after the administration changed markedly while those of survived rats did not. Subsequent pathological examination of the tissues from the dead rats indicated improper embolism. Similar edema and small necrotic foci in the hepatic lobule were found in the hepatic tissue of rats receiving 10 and 5 mg/kg CAO-GMS and GMS 60 d after the last administration, while not in the rats of the blank control group, indicating that microspheres infused via the hepatic artery may induce irreversible liver damage dose-dependently. General pharmacological study showed that the activities (posture and gait), respiration frequency, blood pressure or heart rate of the dogs were not affected by CAO-GMS, nor were salivation, tremor or pupil changes of the rats observed or their balancing ability compromised, suggesting CAO-GMS infused via the hepatic artery did not significantly affect the nervous, respiratory and cardiovascular systems.

CONCLUSION: CAO-GMS embolization administered via the hepatic artery is safe but undesired embolization induced by vascular variation should be given due attention in its clinical application. Individualized embolization dosage and super-selective catheterization technique are recommended to avoid undesired embolism and reduce complications.

Reducing friction by chemically modifying the surface of extrasynovial tendon grafts

In this study we evaluated methods to reduce the friction of an extrasynovial tendon under a pulley in vitro. The surface of canine peroneus longus (PL) tendons was modified with gelatin and/or hyaluronic acid (HA) under different conditions. The gliding resistance between treated or control tendons and the canine digital flexor pulley was measured during 500 cycles of simulated flexion/extension. After 500 cycles, the gliding resistance of normal PL tendon increased 10-fold (p<0.05), while the gliding resistance of tendons coated with carbodiimide derivatized gelatin (cd-gelatin) or carbodiimide derivatized gelatin/HA (cd-gelatin-HA) did not increase significantly. The PL tendon treated with cd-gelatin-HA had a similar friction response during the repetitive motion as the intrasynovial flexor digitorum profundus (FDP) tendon. Scanning electron microscopy after 500 cycles of motion showed that the tendon surface in the group treated with cd-gelatin-HA appeared smoother than tendons in the other groups.

Tissue-engineered trachea from sheep marrow stromal cells with transforming growth factor β2 released from biodegradable microspheres in a nude rat recipient

OBJECTIVE

The purpose of this study was to evaluate the feasibility of using autologous sheep marrow stromal cells cultured onto polyglycolic acid mesh to develop helical engineered cartilage equivalents for a functional tracheal replacement. We also explored the potential benefit of local delivery of transforming growth factor beta 2 with biodegradable gelatin microspheres.

METHODS

Bone marrow was obtained by iliac crest aspiration from 6-month-old sheep and cultured in monolayer for 2 weeks. At confluence, the cells were seeded onto nonwoven polyglycolic acid fiber mesh and cultured in vitro with transforming growth factor beta 2 and insulin-like growth factor 1 for 1 week. Cell-polymer constructs were wrapped around a silicone helical template. Constructs were then coated with microspheres incorporating 0.5 microg transforming growth factor beta 2. The cell-polymer-microsphere structures were then implanted into a nude rat. On removal, glycosaminoglycan content and hydroxyproline were analyzed in both native and tissue-engineered trachea. Histologic sections of both native and tissue-engineered trachea were stained with hematoxylin and eosin, safranin-O, and a monoclonal anti-type II collagen antibody.

RESULTS

Cell-polymer constructs with transforming growth factor beta 2 microspheres formed stiff cartilage de novo in the shape of a helix after 6 weeks. Control constructs lacking transforming growth factor beta 2 microspheres appeared to be much stiffer than typical cartilage, with an apparently mineralized matrix. Tissue-engineered trachea was similar to normal trachea. Histologic data showed the presence of mature cartilage. Glycosaminoglycan and hydroxyproline contents were also similar to native cartilage levels.

CONCLUSIONS

This study demonstrates the feasibility of engineering tracheas with sheep marrow stromal cells as a cell source. Engineering the tracheal equivalents with supplemental transforming growth factor beta 2 seemed to have a positive effect on retaining a cartilaginous phenotype in the newly forming tissue.

17β-Estradiol enhances neuronal differentiation of mouse embryonic stem cells

Existing protocols show a variety in the percentage of neurons that can be generated from mouse embryonic stem (ES) cells. In the current study, we compared effects of various differentiating conditions, including gelatin and poly-l-ornithine/fibronectin coatings, and NGF and 17beta-estradiol treatments on the total yield of neurons, as well as, neurite growth and branching. Here, we show that combination of fibronectin coating with 17beta-estradiol increased number of generated neurons over 50%. Poly-l-ornithine/fibronectin increased the percent of neurons in all cultures, suggesting its direct influence on neurogenesis. Addition of 17beta-estradiol reduced mean neurite length in culture, but significantly increased branching. Our results indicate a substrate-dependent regulation of estrogen-induced ES cells differentiation into neuronal cells.

Recombinant hepatocyte growth factor accelerates cutaneous wound healing in a diabetic mouse model

We examined effects of recombinant hepatocyte growth factor (HGF) on cutaneous wound healing, using a full-thickness cutaneous excision model in diabetic mice. Topical administration of HGF, as well as basic fibroblast growth factor (bFGF), promoted the rate of wound closure and re-epithelialization. Both HGF and bFGF enhanced expansion of the granulation tissue and stimulated neovascularization on day 7 postwounding, wherein the increase in microvessel density in HGF-treated wounds was higher than that in bFGF-treated wounds. Matrix metalloproteinases (MMP-2 and MMP-9) activities involved in cell migration, angiogenesis, and extracellular matrix (ECM) remodeling, were enhanced by HGF-treatment on day 7. On day 28 postwounding (later stages of wound healing), granulation tissue in bFGF-treated wounds remained to a greater extent than that seen in saline- and HGF-treated wounds. Likewise, bFGF- but not HGF-treatment stimulated DNA synthesis of fibroblasts in granulation tissue, suggesting that HGF stimulates wound healing with lesser degree of susceptibility to cutaneous scarring. We propose that supplement of HGF may be a potential therapeutic approach for treatment of cutaneous ulcer.

Ringer's solution but not hydroxyethyl starch or modified fluid gelatin enhances platelet microvesicle formation in a porcine model of septic shock †

BACKGROUND

Sepsis is associated with volume deficit and clotting system activation. Platelet activation in sepsis results in an increased formation of microvesicles, which in turn, have been associated with increased mortality. We hypothesized an effect of different volume replacement solutions on platelet-derived microvesicle formation in septic shock.

METHODS

Anaesthetized, mechanically ventilated and multi-catheterized pigs received 1 g kg(-1) body weight faeces into the abdominal cavity to induce sepsis and were observed over 8 h. Five animals in each group received volume replacement therapy with modified fluid gelatin 4% or 8% (MFG4%, MFG8%), 6% hydroxyethylstarch (HES) 200/0.5 or Ringer's solution (RS) to maintain a central venous pressure of 12 mm Hg. Flow cytometry was used for determination of microvesicles before induction of sepsis (baseline) and after 8 h. Platelets and microvesicles were identified with an anti-platelet monoclonal Ab and a secondary antibody. Microvesicles were determined as the smallest 1-3% positive cells in forward scatter. Intergroup comparisons were performed using Wilks-Lambda and Ryan-Einot-Gabriel-Welsh F-test. Differences within groups were compared using a two-tailed Student's t-test.

RESULTS

Baseline values were considered as 100%. While microvesicle formation was reduced in HES (73 (sd 19)%), MFG4% (63 (41)%) and MFG8% groups (53 (17)%), an increase in the RS-group (210 (121)%) was observed. Eight hours after induction of sepsis, formation of microvesicles was significantly higher in the RS group compared to all colloid-treated groups.

CONCLUSION

In this porcine septic shock model the formation of platelet-derived microvesicles was significantly increased by volume replacement with Ringer's solution in comparison to colloid solutions.

Development of a varicella virus vaccine stabilizer containing no animal-derived component

Various stabilizers containing no animal-derived components were assessed for their efficacy in stabilizing live attenuated varicella virus under various storage temperatures. Stabilizers containing carrageenan, soy protein hydrolysates, or sucrose had a satisfactory performance to maintain infectivity of the cell-free virus when compared to control stabilizer containing animal-derived gelatin/gelatin hydrolysate.

The effects of perioperatively administered crystalloids and colloids on concentrations of molecular markers of activated coagulation and fibrinolysis

To explore whether intravenous administration of routinely used crystalloid or colloid solutions differently affects the coagulation system, we investigated orthopaedic patients. Since crystalloid solutions might cause hypercoagulability, we here present our results on molecular markers of coagulation and fibrinolysis. Patients undergoing knee replacement surgery randomly received isovolemic amounts of lactated Ringer's solution, 6% hydroxyethyl starch 200/0.5 or 4% modified gelatine. Arterial blood samples for determination of specific molecular markers of activated coagulation (thrombin/antithrombin complex, D-dimer, prothrombin fragment F1 + 2), fibrinolysis (plasmin/alpha 2-antiplasmin complex, tissue plasminogen activator, plasminogen activator inhibitor-1), and concentrations of coagulation factor XIII were obtained at baseline, before tourniquet release, at the end of surgery and 2 h after operation. During the observation period, thrombin/antithrombin complex increased from 4.8 to 54.7 microg/l, D-dimer increased from 0.3 to 6.0 mg/ml, prothrombin fragment F1 + 2 increased from 1.7 to 5.9 nmol/l, tissue plasminogen activator decreased from 7.3 to 6.7 ng/ml, plasminogen activator inhibitor-1 increased from 68.4 to 71.0 ng/ml, plasmin/alpha 2-antiplasmin complex increased from 281.5 to 884 microg/l and factor XIII decreased from 89.0 to 58.5%. All parameters changed significantly but without any detectable difference in the response profile between the groups receiving different intravenous fluids. During knee replacement surgery a pronounced activation of the coagulation/fibrinolytic system was observed, regardless of whether patients received crystalloid or colloid fluids. Thus, these results cannot confirm the hypothesis that crystalloid fluids per se cause hypercoagulability in vivo.

The effects of a polymerized bovine-derived hemoglobin solution in a rabbit model of arterial thrombosis and bleeding

Hemoglobin-based oxygen carriers (HBOCs) have been developed primarily for their oxygenating function and possible use as an alternative to red blood cells during surgery or after major trauma. However, their effect on hemostasis has not been studied extensively. We compared the effects on hemostasis of bovine-derived hemoglobin solution (HBOC-201) with gelatin solution and saline infusion in an experimental model of arterial thrombosis and bleeding. After anesthesia, the Folts model was constructed in 30 rabbits. The common carotid artery was exposed, and a 60% stenosis was induced. A compression injury of the artery was then produced, which triggered a series of cyclic episodes of thrombosis (cyclic flow reductions [CFRs]). After the number of baseline CFRs was counted, animals were assigned randomly to one of three groups (n = 10 each): saline (control), gelatin, or HBOC-201 solution. The effect of studied solutions was observed by recording the number of CFRs during another period and was compared with that of saline. Ear immersion bleeding time was recorded after each CFR period. Gelatin and HBOC-201 had similar effects, manifested by significantly decreased CFRs (from median of 7 to 1 and 6 to 1, respectively) and significantly lengthened bleeding time (from 88 to 98 s and 81 to 102 s, respectively; P < 0.05). Saline infusion had no significant effect on CFRs or bleeding time. HBOC-201 and gelatin had similar effects marked by a reduction in the arterial thrombosis rate and increased bleeding time in rabbits.

IMPLICATIONS

In a rabbit thrombosis and hemorrhagic model, a polymerized bovine-derived hemoglobin solution and a gelatin solution infusion decreased arterial thrombosis and lengthened bleeding time.

Effect of adhesion or collagen molecules on cell attachment, insulin secretion, and glucose responsiveness in the cultured adult porcine endocrine pancreas: a preliminary study

The effect of either adhesion or collagen molecules on cell attachment, insulin secretion, and glucose responsiveness was investigated in adult porcine pancreatic endocrine (PE) cells that were cultured for a longer term in vitro. Six different types of molecules--laminin, fibronectin, poly-L-lysine (PLL), type I collagen, gelatin, and Matrigel--were used. Approximately 2.0 x 10(5) cells per dish of each molecule type were cultured for 4 weeks. In the laminin group, the insulin accumulation was maintained at a significantly higher level than in the control group at 4 weeks of culture, and glucose-stimulated insulin secretion and the insulin-positive rate were also higher than in the control group. In the Matrigel group, islet-like cell clusters were formed, but insulin accumulation rapidly decreased at 3-4 weeks of culture. A large number of PE cells attached tightly and spread in the fibronectin group until the fourth week of culture, but their function was not better than those in the control group. In the PLL and gelatin groups, the PE cell function was not significantly different from that of the control group. In the type I collagen group, insulin secretion was inferior to that of the other groups. The results of this study suggest that laminin is the most suitable extracellular matrix for the long-term culture preservation of PE cells.

Isolation and clonal analysis of human epidermal keratinocyte stem cells in long-term culture

We developed a procedure for growing normal epidermal keratinocyte stem cells isolated from a single punch biopsy of adult human skin in long-term culture. Primary skin epithelial cells were maintained in collagen-coated plates with irradiated human neonatal foreskin fibroblasts (line HPI.1) as a feeder for more than 120 days, approximately 115 population doublings, without signs of replicative senescence. Clonal analysis revealed the presence of holoclones, meroclones, and paraclones. Only emerging colonies with high proliferative potentials and extensive capacities for division (holoclones and meroclones) were subcultured, favoring the expansion of stem cells and progenitors capable of prolonged self-maintenance when subcloned, thus accounting for the prevailing long-term proliferation of the original culture. We found that meroclones included bipotent progenitors capable of generating both keratinocytes and mucin-producing cells. The numbers of these cells were greater after confluence, suggesting that commitment for their differentiation occurred late in the life of a single clone. On a three-dimensional gelatin matrix and on a collagen layer containing the fibroblast feeder, cells isolated from the expansion of holoclones and meroclones formed stratified cohesive layers of keratinocytes that were able to further differentiate, as in normal skin. These results indicate that our procedure will serve as a valuable tool to study expansion of epidermal stem cells as well as the growth mechanisms and cell products associated with their growth and differentiation.

Enzymatic stabilization of gelatin-based scaffolds

The definitive goal of this research is to develop protein-based scaffolds for use in soft tissue regeneration, particularly in the field of dermal healing. The premise of this investigation was to characterize the mechanical properties of gelatin cross-linked with microbial transglutaminase (mTGase) and to investigate the cytocompatibility of mTGase cross-linked gelatin. Dynamic rheological analysis revealed a significant increase in the storage modulus and thermal stability of gelatin after cross-linking with mTGase. Static, unconfined compression tests showed an increase in Young's modulus of gelatin gels after mTGase cross-linking. A comparable increase in gel strength was observed with 0.03% mTGase and 0.25% glutaraldehyde cross-linked gelatin gels. In vitro studies using 3T3 fibroblasts indicated cytotoxicity at a concentration of 0.05% mTGase after 72 h. However, no significant inhibition of cell proliferation was seen with cells grown on lower concentrations of mTGase cross-linked gelatin substrates. The mechanical improvement and cytocompatibility of mTGase cross-linked gelatin suggests mTGase has potential for use in stabilizing gelatin gels for tissue-engineering applications.

Disulfide-crosslinked hyaluronan-gelatin sponge: growth of fibrous tissue in vivo

The modification of hyaluronan (HA) and gelatin using dithiobis(propanoic dihydrazide) (DTP) has provided two thiolated macromolecular components of the extracellular matrix (ECM), specifically HA-DTPH and gelatin-DTPH. Blends of these thiolated ECM components were crosslinked in air to form hydrogels that were interpenetrating disulfide-crosslinked networks. Lyophilization of the hydrogels afforded sponge-like macroporous scaffolds suitable for cell attachment and proliferation. Increasing percentages of gelatin-DTPH (0, 25, 50, and 75%) were blended with HA-DTPH, and the resulting sponges were evaluated in vitro and in vivo as scaffolds for tissue engineering by seeding with human tracheal scar (HTS) fibroblasts. While cells failed to attach and grow in HA-only sponges, the gelatin-modified HA sponges promoted cell adhesion, proliferation, and spreading in vitro. Optimal attachment and growth was observed with 50% gelatin-HA sponges. Cell attachment to the gelatin-HA sponge could be blocked by preincubation of cells with a soluble fibronectin peptide Gly-Arg-Gly-Asp (GRGD). Finally, HTS fibroblast-seeded gelatin-HA sponges were implanted into the flanks of nude mice and evaluated at 2 and 8 weeks postimplantation. The sponges were fully biocompatible and new fibrous tissue formed, gradually replacing the sponge-like scaffold. The gelatin-HA sponges act as synthetic, macroporous, covalent mimics of the ECM and constitute novel scaffolds for cell growth and tissue augmentation.

Efficacy and cytotoxicity of cationic-agent-mediated nonviral gene transfer into osteoblasts

Ex vivo gene transfer into osteoblastic cells is an advantageous strategy for bone tissue engineering. This study investigated the efficacy and cytotoxicity of in vitro cationic-agent-mediated nonviral gene transfer into osteoblasts. Various cationic agents, lipid, gelatin, and polyethylenimine (PEI) were tested. Each was formulated in various concentrations to form a complex with plasmid DNA encoding red fluorescent protein. The cationic agent/DNA complexes were transfected into human fetal osteoblastic cell line and rat bone-marrow-derived primary osteoblasts, as well as NIH 3T3 fibroblast controls. Rat primary osteoblasts were transfected more with cationic lipid and PEI agents than with gelatin carrier, yielding transfection efficacy up to 18.1% and 12.7 %, respectively. In contrast, human fetal osteoblastic cell line was transfected more with cationic lipid and gelatin than with PEI. There was a positive correlation between the lipid and PEI doses and cytotoxicity. When the lipid and PEI were used to transfect the rat primary osteoblasts in a dose that yielded the highest transfection efficacy, cell survival rates decreased as low as 40%. When their transfection efficacies into primary osteoblasts were compromised at two thirds of the highest value, that is, 12.6% and 8.3% for the lipid and PEI, respectively, the cell survival rate was nearly 80%. Cationic gelatin was associated with cell survival rates over 60 % in any cell type, regardless of the doses tested. These results suggest that different types of osteoblastic cells may possess different ability to the uptake and expression of cationic-agent-bound DNA. There seemed to be agent-specific threshold doses that dropped the cell survival rate. Cationic-agent-mediated nonviral gene transfer into osteoblastic cells may be successful when the agent- and dose-dependent transfection efficacy and cytotoxicity are optimized.

Expression of matrix metalloproteinase-2 and -9 in exudates associated with polydimethyl siloxane and gelatin tubes implanted in mice

The expression of matrix metalloproteinases (MMPs), MMP-2 and -9, during the inflammatory response to two implanted biomaterials was determined. To illustrate this phenomenon, polydimethyl siloxane (PDMS), weakly crosslinked gelatin, and highly crosslinked gelatin tubes were implanted subcutaneously in mice for up to 3 weeks. Latent MMP-2 (pro-MMP-2) was seen in exudates throughout the experimental period and did not show any apparent changes in time or among the three biomaterials. The expression of MMP-9, however, showed a very different pattern. At days 4 and 8, the predominant form of MMP-9 is pro-MMP-9 (the latent form) and its level is much higher for the PDMS tube than either of the gelatin tubes. The active form of MMP-9, initially low, rose progressively over the 3-week period and reached its peak at week 2 for PDMS and highly crosslinked gelatin and at week 3 for the more degradable, weakly crosslinked gelatin. Data from the histological and cytological analysis also showed that the PDMS tube induced a much stronger cellular response than gelatin tubes, although endotoxin contamination precludes a conclusion related to biomaterial effects. We concluded that MMP-9 is a useful marker of the host inflammatory response to the implanted biomaterials and it may be useful in the assessment of biomaterial biocompatibility. Perhaps more importantly, the consequences of MMPs on matrix remodeling may become of concern in biomaterials used for tissue engineering.

Resuscitation with modified gelatin causes higher bacterial translocation in experimental sublethal hemorrhagic shock

The effect of colloidal solutions on bacterial translocation was studied. Sublethal hemorrhagic shock was established by blood withdrawal until the mean arterial pressure fell to 40 mmHg within 15 min on 36 adult Wistar Albino rats. Resuscitation was performed using four different solutions with the same amount of blood. Group I (n = 9) 0.9% NaCl, Group II (n = 9) 10% dextran 40, Group III (n = 9) 6% hydroxyethyl starch, Group IV (n = 9) 4% modified fluid gelatin. Before resuscitation and after anesthesia blood samples were drawn to analyze pH, PCO2, PO2, SaO2, HCO3 and ABE values. Twenty-four hours after anesthesia laparotomy was performed to obtain tissue samples of the liver, spleen and mesenteric lymph nodes. Samples were cultured on EMB and blood agar media. Results were analyzed with the one-way ANOVA and Post-hoc test (Tukey's HSD). The translocated bacteria were mainly Eschericia coli and three grew in Group I, two in Group II, three in Group III and six in Group IV. Although there was a trend in difference in bacterial translocation rates among groups, statistical analyses revealed no difference among groups (p < 0.05). It can be concluded that resuscitation with modified gelatin causes higher bacterial translocation in an experimental sublethal hemorrhagic shock model.

Effects of oxypolygelatin and dextran 70 on hemostatic variables in dogs

OBJECTIVE

To evaluate and compare coagulation variables following the administration of oxypolygelatin and dextran 70 to clinically healthy dogs.

STUDY DESIGN

Randomized cross-over experimental study.

ANIMALS

A total of eight healthy adult female Beagles aged 2-4 years old and weighing 11.8 +/- 2.7 kg.

METHODS

The dogs received a 15-minute intravenous (IV) infusion of 5 mL kg-1 oxypolygelatin or 10 mL kg-1 6% dextran 70. Before (PRE) and at 2, 5, and 24 hours after administration, packed cell volume (PCV), total solids concentration (TS), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen concentration (FIB), platelet numbers (Plat), factor VIII coagulant activity (VIII:C), von Willebrand factor antigen concentration (vWf:Ag) and platelet function and buccal mucosal bleeding time (BMBT) were measured. Platelet function was assessed using aggregation and by measuring ATP release from aggregating platelets over 6 minutes, with 20, 10, and 5 micro m ADP and 5 and 10 micro g of collagen mL-1 as platelet activation agonists.

RESULTS

All baseline values were within our normal ranges, except for one dog that had low vWf:Ag PRE values prior to both dextran and oxypolygelatin administration. Following dextran and oxypolygelatin administration, the PCV and TP were significantly (p < 0.05) decreased. Plat, FIB, and vWf:Ag decreased, while BMBT and VIII:C increased following dextran administration. Dextran also caused a significant decrease in platelet aggregation in response to ADP. Oxypolygelatin caused a significant decrease in vWf:Ag, Plat, and FIB compared to PRE values. The total amount of ATP released, standardized to platelet number, did not vary significantly for either group at any sampling time from PRE values. No significant changes from PRE values were noted at any time in either group for PT or APTT.

CONCLUSION

At the doses administered, both dextran and oxypolygelatin can interfere with hemostatic variables in healthy dogs, but dextran's effect is more profound and prolonged when compared to oxypolygelatin.

CLINICAL RELEVANCE

Oxypolygelatin causes fewer hemostatic abnormalities when compared to dextran, making it a superior colloid for administration at the doses tested.

Transcriptional up-regulation of endothelial cell matrix metalloproteinase-2 in response to extracellular cues involves GATA-2

Matrix metalloproteinase-2 (MMP-2) plays a critical role in endothelial cells during the processes of angiogenesis and vascular remodeling. Endothelial cell production of MMP-2 is greatly enhanced when cells are cultured within a three-dimensional type I collagen matrix coinciding with the increased invasive and migratory phenotype of the cells. To define the transcriptional regulation of MMP-2 in rat microvascular endothelial cells, we performed promoter-reporter assays with a series of promoter truncations. Activity of the full promoter was significantly greater in cells cultured within three-dimensional type I collagen compared with cells cultured as a monolayer (two-dimensional) on type I collagen. Truncation of the region encompassing base pairs -1562 to -1375 (relative to the start codon) of the MMP-2 promoter resulted in loss of this differential activity of the MMP-2 promoter. Analysis of this region indicated two putative GATA-2 binding domains between -1437 and -1387. Southwestern blot analysis and electrophoretic mobility shift assays confirmed the binding of GATA-2 to this region of the MMP-2 promoter. Overexpression of GATA-2 in COS-7 cells significantly increased the activity of the full-length MMP-2 promoter-luciferase construct. Endothelial cells expressed greater levels of GATA-2 protein in three-dimensional compared with two-dimensional cultures, and activity of the -1437/-1387 region of the MMP-2 promoter was significantly greater in three-dimensional cultured endothelial cells. Together, these results indicate GATA-2 regulation of the MMP-2 promoter in endothelial cells and that the GATA-2 binding domain is sufficient to drive increased activity of the MMP-2 promoter in response to an extracellular matrix stimulus.

Viability of microencapsulated bifidobacteria in simulated gastric juice and bile solution

Microencapsulated cells of Bifidobacterium longum B6 and Bifidobacterium infantis CCRC 14633 were prepared by spray drying the cell suspension containing the test organism and 10% (w/w) of the carrier material of either gelatin, soluble starch, skim milk or gum arabic. Survival of these microencapsulated and free cells of bifidobacteria in simulated gastric juice (pH 2.0 and 3.0) and bile solution (0.5% and 2.0%) was then examined. B. infantis CCRC 14633 was more susceptible than B. longum B6 to the simulated gastric environment and bile solution tested. Microencapsulated bifidobacteria exhibited a lower population reduction than free cells during exposure to simulated gastric environment and bile solution. This phenomenon was most pronounced when the test organism was exposed to gastric juice at pH 2.0 or 2.0% bile solution. Moreover, it was also observed that the protective effect exerted by encapsulation with spray drying varied with the carriers used and the strains of bifidobacteria.

Gelatin degradation at elevated temperature

Four gelatin types (A, B, C and AB), two different samples of each, were subjected to temperature treatments with the incubation temperature, incubation time, gelatin concentration and solvent (type and concentration of salt ions and pH) as variables. Degradation was studied by means of fast protein liquid chromatography and sodium dodecylsulphate polyacrylamide gel electrophoresis. All the variables tested seemed to be critical. Addition of a protease inhibitor cocktail confirmed that the observed degradation was not due to the action of proteases.Fluorescence measurements indicated that during the temperature treatment pentosidine and pyridinoline cross-links can be broken, while the cleavage of peptide bonds was verified by ninhydrin tests and N-terminal amino-acid analyses with phenyl isothiocyanate.