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.

In vivo biocompatibility of gelatin-based hydrogels and interpenetrating networks

The in vivo host response to two gelatin-based hydrogel systems of varying crosslinking modalities and loaded with the anti-inflammatory agent dexamethasone sodium phosphate was investigated. Either gelatin was chemically crosslinked with glutaraldehyde, or polyethyleneglycol diacrylate was photopolymerized around gelatin to form interpenetrating networks. The subcutaneous cage implant system was utilized to determine differential leukocyte concentrations in the inflammatory exudate surrounding the materials as indices for biocompatibility and drug efficacy in vivo. Most of the crosslinked gelatin-based materials, either via glutaraldehyde fixation or interpenetrating network formation, elicited stronger inflammatory responses than either of the starting materials, gelatin and polyethyleneglycol diacrylate. In general, dexamethasone delayed and intensified the inflammatory response. The loss of material mass did not correlate directly with the degree of cellular inflammatory response, but increased with longer implantation time and decreased with more extensive fixation.

Effect of isoflurane on skin-pressure-induced vasodilation

Since general anesthesia has been shown to attenuate endothelium-dependent vasodilation, it was of interest to verify whether general anesthesia would modify skin vasodilation in response to local pressure application, which is endothelium dependent. To study the effect of general anesthesia on pressure-induced vasodilation development, we examined the effects of low- and high-dose isoflurane. Skin blood flow was measured by laser Doppler flowmetry during 11.1 Pa s(-1) increases in locally applied pressure in anesthetized rats treated with low or high doses of isoflurane. Following the administration of low doses of isoflurane, skin blood flow increased from baseline, with increasing local pressure application (+37 +/- 10% at 2.0 kPa). The increase in skin blood flow was absent in rats treated with high doses (-20 +/- 5% at 2.0 kPa), even when the anesthesia-induced hypotension was corrected by gelofusine infusion (-20 +/- 10% at 2.0 kPa). Whereas sodium-nitroprusside-induced vasodilation developed following low and high doses of isoflurane, acetylcholine-induced vasodilation was impaired with high doses compared to low doses. These data show that pressure-induced vasodilation is abolished with high doses of anesthetics. It is not the anesthesia-induced hypotension, but the depth of anesthesia, which can lead to the disappearance of pressure-induced vasodilation by an alteration in endothelial function.

Functional barrier principle for growth-factor-based articular cartilage repair

OBJECTIVE

Induction of growth-factor-based repair in full-thickness articular cartilage defects can be impaired by the upgrowth of blood vessels and new bone into the cartilaginous compartment. We postulated that if an antiangiogenic factor (suramin) is included in the chondrogenic matrix applied to the cartilaginous compartment of a full-thickness defect, vascular upgrowth and therefore bone formation will be inhibited (functional barrier principle).

DESIGN

Full-thickness defects were created in miniature pigs and the bony portion filled with a chondrogenic matrix. The cartilaginous compartment was filled with the same matrix which additionally contained suramin, either in a free form or in free and liposome-encapsulated forms. Animals were sacrificed 8 weeks after surgery and the extent to which bone tissue had encroached on the cartilaginous compartment was graded semiquantitatively using light microscopy.

RESULTS

In 63% of the control defects, bone represented more than 50% of the repair tissue present. In 10% of the defects treated with free suramin, bone upgrowth was completely inhibited; in 55%, osseous tissue occupied 1-10% of the cartilaginous space and in the other 35%, it represented 11-50% of the repair tissue present in this compartment. In 69% of the defects treated with free and liposome-encapsulated suramin, bone upgrowth into the cartilaginous compartment was completely inhibited; in the remaining 31%, osseous tissue occupied no more than 1-10% of this space.

CONCLUSIONS

To be effective, an antiangiogenic factor needs to be present at a sustained level throughout the chondrogenic treatment course.

Rhizosecretion of a monoclonal antibody protein complex from transgenic tobacco roots

The secretion of a functional, full-length monoclonal antibody complex from transgenic Nicotiana tabacum roots has been demonstrated. Initially, seeds were germinated on nitrocellulose membranes and antibody secretion detected from the developing roots. Plants were then established in hydroponic culture and secretion into the growth medium measured over 25 days. Western blotting indicated that full-length antibody was present in the medium along with other fragments. Secreted antibody was shown to be functional by binding to antigen in ELISA studies. In contrast, no antibody could be detected from transgenic Nicotiana in which the same antibody was expressed as a membrane protein in the plasmalemma. These results indicate that antibody accumulation in the growth medium is genuinely caused by rhizosecretion and not cell damage. Addition of gelatin to plant growth medium markedly increased levels of antibody accumulation. The mean antibody yield per plant was calculated to be 11.7 microg per gram root dry weight per day. Rhizosecretion may be a viable alternative to agricultural production or cell culture for the generation of monoclonal antibodies in transgenic plants. It may also give rise to novel applications for antibodies expressed in plants such as removal or neutralisation of environmental pollutants and attenuation of pathogens which infect the plant via the rhizosphere.

Identification of a region of beta-amyloid precursor protein essential for its gelatinase A inhibitory activity

Because beta-amyloid precursor protein (APP) has the abilities both to interact with extracellular matrix and to inhibit gelatinase A activity, this molecule is assumed to play a regulatory role in the gelatinase A-catalyzed degradation of extracellular matrix. To determine a region of APP essential for the inhibitory activity, we prepared various derivatives of APP. Functional analyses of proteolytic fragments of soluble APP (sAPP) and glutathione S-transferase fusion proteins, which contain various COOH-terminal parts of sAPP, showed that a site containing residues 579-601 of APP(770) is essential for the inhibitory activity. Moreover, a synthetic decapeptide containing the ISYGNDALMP sequence corresponding to residues 586-595 of APP(770) had a gelatinase A inhibitory activity slightly higher than that of sAPP. Studies of deletion of the NH(2)- and COOH-terminal residues and alanine replacement of internal residues of the decapeptide further revealed that Tyr(588), Asp(591), and Leu(593) of APP mainly stabilize the interaction between gelatinase A and the inhibitor. We also found that the residues of Ile(586), Met(594), and Pro(595) modestly contribute to the inhibitory activity. The APP-derived decapeptide efficiently inhibited the activity of gelatinase A (IC(50) = 30 nm), whereas its inhibitory activity toward membrane type 1 matrix metalloproteinase was much weaker (IC(50) = 2 microm). The decapeptide had poor inhibitory activity toward gelatinase B, matrilysin, and stromelysin (IC(50) > 10 microm). The APP-derived inhibitor formed a complex with active gelatinase A but not with progelatinase A, and the complex formation was prevented completely by a hydroxamate-based synthetic inhibitor. Therefore, the decapeptide region of APP is likely an active site-directed inhibitor that has high selectivity toward gelatinase A.

Potential involvement of IL-8 and its receptors in the invasiveness of pancreatic cancer cells

The purpose of the present study was to examine the expression of interleukin (IL)-8 and IL-8 receptors and to evaluate the effects of IL-8 on human pancreatic cancer. We examined the expression of IL-8 and its two receptors (CXCR1 and CXCR2) in 40 surgically resected human pancreatic cancer tissues and in three different human pancreatic cancer cell lines (PANC-1, MIAPaCa-2 and Capan-2). The immunohistochemical analysis using specific antibodies demonstrated that positive staining for IL-8, CXCR1 and CXCR2 in surgically resected human pancreatic cancer was 50, 55 and 65%, respectively. Moreover, 40% of these cases were positive for both IL-8 and IL-8 receptors. In contrast, immunoreactive signals for those proteins were extremely suppressed in normal pancreatic tissues. All of the pancreatic cancer cell lines expressed IL-8 and IL-8 receptors at the RNA and protein levels. Receptor binding experiments using 125I-labeled IL-8 showed that PANC-1 cells had specific binding sites for IL-8. The cell proliferation assay demonstrated that IL-8 did not affect the growth of the three cell lines. However, treatment with IL-8 enhanced the invasiveness into Matrigel and increased the activity of matrix metalloproteinase (MMP)-2 in supernatants of the PANC-1 cells. These results demonstrate that IL-8 and IL-8 receptors are over-expressed in pancreatic cancer, and suggest that IL-8 regulates MMP-2 activity and plays an important role in the invasiveness of human pancreatic cancer.

Effect of gelatins on human cancer cells in vitro

Three types of gelatins were tested for their antiproliferative activities in vitro against three human tumor cell lines (K-562; erythroleukemia, HCT-15; colon carcinoma, AGS; gastric carcinoma) with viable cell count and tritium-thymidine ((3)H-TdR) uptake by those cells. Porcine skin (PS) gelatin exerted the strongest antiproliferative activity of all three gelatins. Bovine bone (BB) gelatin did not exert such an activity. PS gelatin exerted antiproliferative activity against K-562 cells also in a serum-free medium. The serum-free medium contains two growth factors, insulin and transferrin, as well as nutrients. The activity of PS gelatin was not interfered by addition of insulin and transferrin to the medium. Effect of diluting a K-562 cell-concentration on the activity of PS gelatin was tested. Diluting the cell concentration did not affect the activity of PS gelatin. Moreover, the conditioned medium in which K-562 cells had been cultured did not stimulate the proliferation of K-562 cells. In conclusion, PS gelatin suppress the proliferation of human tumor cell lines in vitro. The antiproliferative activity of PS gelatin might not be attributed to trapping growth factors or autocrine mediators.

[Protective effect of Gastrodia elata and E-gelatin on lead-induced damage to the structure and function of rat hippocampus]

OBJECTIVE

To observe the counteraction of Gastrodia elata and E-gelatin on the effect of subchronic lead poisoning on the ability of learning and memory and the ultrastructure in hippocampus.

METHODS

Subchronic lead acetate exposure was given to rats (0.2 g x kg(-1) x d(-1)). Single and combined administration of Gastrodia elata (4 g x kg(-1) x d(-1)) and E-gelatin (1 g x kg(-1) x d(-1)) were conducted at the same time. Pb concentration in blood, and the ability of learning and memory (Y-maze test) of rats were measured. Ultrastructure of CA3 pyramidal cells in hippocampus under transmission electron microscope was observed.

RESULTS

Blood Pb concentrations in each group (Pb group: 690.6 micro g/L, Pb + Gastodiae eleta group: 688.8 micro g/L, Pb + E-gelatin group: 663.8 micro g/L, Pb + combined group: 667.2 micro g/L) were higher than that in the control (28.24 micro g/L, P < 0.01). But there was no significant difference (P > 0.05) among these groups. In Y-maze test, the number of electric stroke in Pb group is higher than that in control (P < 0.01). Gastrodia elata or E-gelatin used singly could significantly reduce the number of electric stroke of lead-exposed groups (P < 0.05 in the first month and P < 0.01 in the second and third month). And the effect of combined use of them was more efficient than single use (P < 0.01). Under electron microscope, no anomaly was seen in the pyramidal cells of CA3 area in hippocampus of control group. But there was significant anomaly such as neucleus separation in the cells of Pb exposed group. In Pb-Gastrodia elata group, there were some stress response phenomena such as the occurrence of huge mitochondria while in Pb-E-gelatin group, the anomaly was mild. The cells in the CA3 area in hippocampus of the pb-Gastrodia-E-gelatin group were almost normal, and also showed some stress response phenomena.

CONCLUSION

Gastrodia elata and E-gelatin may protect the neurons in CA3 area of hippocampus against damage induced by lead to improve the ability of learning and memory, and they have synergistic effect.

[The antagonistic action of Gastrodia elata combined with E-gelatin on lead-induced down regulation of c-fos expression in rat brain]

OBJECTIVE

To observe the effect of lead on the expression of c-fos mRNA in hippocampus and cerebellum and the ability of learning and memory in rat, and to observe the antagonistic action of Gastrodia elata and E-gelatin on the effect mentioned above.

METHODS

Rats were exposed to lead acetate (0.2 g x kg(-1) x d(-1) and 0.1 g x kg(-1) x d(-1)). The single and combined administration of Gastrodia elata (4 g x kg(-1) x d(-1)) and E-gelatin (1 g x kg(-1) x d(-1)) were conducted at the same time. Blood lead concentration in rats were measured. The ability of learning and memory by Y-maze test were examined. The expression of c-fos mRNA in hippocampus and cerebellum during Y-maze test were observed by in situ hybridization (ISH).

RESULTS

(1) Blood lead concentrations were significantly increased in both high and low doses of lead-exposed rats (P < 0.01). But there were no differences among high dose groups or low dose groups (P > 0.05). (2) In Y-maze test, the number of electric stroke during learning in lead-exposed group was significantly increased (P < 0.01) while that in Gastrodia elata and E-gelatin groups was significantly decreased (P < 0.05), and that in combined use group was more significantly decreased (P < 0.01). (3) There were much more deep-colored c-fos positive cells in CA3 area of hippocampus in low dose of Pb-exposed with Gastrodia elata + E-gelatin group. These cells were also found in high Pb with combined use or single use group, but which were not so densely distributed as the former. And they were hardly found in high and low doses of Pb alone groups. The changes of expression of c-fos cells in cerebellam were similar to those in hippocampus.

CONCLUSION

The down regulation of c-fos expression may be one of the molecular mechanism of lead-induced impairment of learning and memory. Gastrodia elata and E-gelatin may antagonize the effect of lead on c-fos expression, and combined use of both drugs may potentiate the antagonism.

Induction of cyclooxygenase-1 and -2 modulates angiogenic responses to engagement of alphavbeta3

Prostaglandins and cyclooxygenase (COX) have been implicated in the angiogenesis that occurs around tumours, but how they are induced is unclear. Prostaglandin formation is regulated by the availability of arachidonic acid and/or COX activity that in turn are controlled by activation of G-protein-coupled receptors or kinase receptors. Adhesion receptors provide another potential level of control as they transduce a variety of "outside-in" signals implicated in inflammation. We examined whether engagement of the vitronectin receptor (alphavbeta3) modulated prostacyclin (PGI2) formation in human umbilical vein endothelial cells (EC). Engagement of EC alphavbeta3 by vitronectin (versus fibronectin or gelatin) or by monoclonal antibodies (mAbs) LM609 and LIBS6, enhanced PGI2 generation and also induced expression of both COX-1 and -2 isoforms. Alphavbeta3 engagement also led to vascular endothelial cell growth factor (VEGF) generation and EC proliferation that was attenuated by inhibition of both COX-1 and COX-2. COX-1 inhibition also prevented new vessel formation in an in vitro model of angiogenesis that is alphavbeta3 dependent. Inhibition of angiogenesis by the COX-1 inhibitor was partially reversed by removal of the inhibitor or by addition of the stable analogue of PGI2, iloprost. These findings strongly indicate that alphavbeta3-mediated angiogenesis is partly due to induction of both isoforms of COX.

Expression and secretion of the heterodimeric protein interleukin-12 in plant cell suspension culture

It has been suggested that plant cell culture is the most suitable system for producing small-to-medium quantities of specialized, expensive, and high-purity proteins. Here, we report that a heterodimeric protein, human interleukin-12 (hIL-12), was expressed and secreted into culture medium in a biologically active form. A transgenic plant expressing hIL-12 was constructed by sexual crossing of plants that expressed each subunit of the protein. From a piece of transgenic plant, callus was induced and cell suspension culture was established. The biological activity and amount of hIL-12 secreted into culture medium were analyzed using bioassays and ELISA. Analysis of cellular localization demonstrated that the protein was secreted into the culture medium together with its intrinsic signal peptide.

Decreased plasminogen activator inhibitor-1 secretion in hypoxic corneal epithelial cells is associated with increased urokinase plasminogen activator activity

The aim of this study was to determine the effects of hypoxia on mRNA levels, cell-associated and -secreted protein concentration, activity, and protein complex formation of urokinase-type plasminogen activator, its receptor, and plasminogen activator inhibitor type-1 in corneal epithelium. Non-transformed human corneal epithelial cells were cultured in 20% oxygen (normoxic conditions) or 2% oxygen (hypoxic conditions) for 1, 3, 5, or 7 days. Relative changes in mRNA levels of plasminogen activator, receptor, and plasminogen activator inhibitor-1 were determined using a cDNA expression array, chemiluminescence, and densitometry. Protein concentrations were determined using enzyme linked immunosorbent assays. Activity assays were also used. Protein complex formation was assayed using cell surface biotinylation, immunoprecipitation, and Western blot analysis. Hypoxic corneal epithelial cells demonstrated no significant differences in plasminogen activator or receptor mRNA. Cell-associated plasminogen activator and membrane-associated receptor protein levels were unchanged. In contrast decreases in mRNA and secreted plasminogen activator inhibitor-1 protein were observed in hypoxic cells. Concurrently, increased cell-associated plasminogen activator activity was observed in hypoxic cells. The formation of plasminogen activator/receptor/plasminogen activator inhibitor-1 complex at the cell surface was not inhibited by hypoxia. However, in hypoxic cells less plasminogen activator inhibitor-1 was associated with receptor. It is concluded that in corneal epithelium cultured in 2% oxygen plasminogen activator inhibitor-1 may be an important regulatory factor of the plasminogen activator system resulting in increased urokinase plasminogen activator activity.

Synthesis and physicochemical analysis of gelatin-based hydrogels for drug carrier matrices

This study examined the interrelated effect of environmental pH, gelatin backbone modification and crosslinking modality on hydrogel morphology, surface hydrophilicity, in vitro swelling/degradation kinetics, in vitro drug release kinetics and in vivo degradation, inflammatory response and drug release activity. The percent glutaraldehyde fixation had a greater impact on the morphology of the dehydrated hydrogels than gelatin modification. Any decrease in percent glutaraldehyde fixation and/or modification of gelatin with polyethylene glycol dialdehyde (PEG-dial) and/or ethylenediaminetetraacetic dianhydride (EDTAD) increased hydrogel surface hydrophilicity. Swelling/degradation studies showed that modification of gelatin with PEG-dial generally increased the time to reach the maximum swelling weight ratio (T(max)) and the time to failure by hydrolysis (T(fail)), but had little effect on the maximum swelling weight ratio (R(max)) and the weight ratio at failure (R(fail)). Modification of gelatin with EDTAD generally had no effect on T(max) and T(fail), but increased R(max) and R(fail). Modification of gelatin with PEG-dial and EDTAD increased R(max), but had no effect on T(max), R(fail), or T(fail). Decreasing percent glutaraldehyde fixation generally increased R(max) and R(fail) but decreased T(max) and T(fail). Decreasing environmental pH from 7.4 to 4.5 had no effect on any swelling/degradation properties. In vitro drug release studies showed that modification of gelatin with PEG-dial and/or EDTAD generally decreased the maximum mass ratio of drug released (D(max)) and the time to reach D(max) (T(dmax)). Percent glutaraldehyde fixation did not significantly affect D(max) or T(dmax) (except for EDTAD-modified gelatin hydrogels). In vivo studies showed that gelatin-based hydrogels elicited comparable levels of acute and chronic inflammatory response as that of the empty cage control by 21 d.

Evaluation of hemolysis in the VentrAssist implantable rotary blood pump

The VentrAssist implantable rotary blood pump (IRBP) is an implantable centrifugal blood pump with a hydrodynamically suspended impeller; optimal efficiency requires small running clearances (70-300 microm). The effect of running clearance and polish on hemolysis was evaluated in vitro. Three different human blood suspensions were compared: phosphate buffered saline (PBS), plasma volume expander (Hemaccel), and whole blood. The test conditions were: blood hematocrit 30%, flow rate 5 L/min, pressure across pump 100 mm Hg, 6 h flow period, and 37 degrees C. Normalized Index of Hemolysis (NIH) for the Biomedicus BP-80, used as a control, was: 0.0040 +/- 0.0023 (n = 9; x +/- SD) and 0.00014 +/- 0.00009 (n = 5) for pooled blood suspensions in PBS and Hemaccel respectively, and 0.00053 +/- 0.0002 (n = 3) in whole blood. Hemolysis was reduced by improved surface finish and unaffected by running clearance. NIH for the VentrAssist IRBP with 0.2 microm Ra surface finish was 0.000167 +/- 0.00007 (n = 4) g/100 L in whole human blood, demonstrating minimal hemolysis.

Effects of gelatin concentration on the growth parameters of Listeria innocua in a model gel system

In this work, the growth of Listeria innocua was studied responding to the addition of different concentrations of gelatin (see text) model gel system in a modi_ed Brain Heart Infusion medium at 12 C and an initial pH of 6.2. The global number of viable cells as a function of incubation time and the corresponding pH, lactic acid concentration and glucose concentration were measured. Each set of data was fitted with the growth model of Baranyi and Roberts (1994) to estimate the maximum specific growth rate and the maximum cell concentration. Gelatin had a significant e_ect on the growth rate of Listeria innocua, which reduced as the gelatin concentration increased. A tail was observed after a certain concentration of gelatin indicating that there exists a maximum concentration beyond which no further reduction could be observed. There was, however, within the gelatin concentration range studied, no appreciable effect on the maximum cell concentration. A distinct morphological change of colonies was also observed with increasing gelatin concentration.

Stimulation of Pro-MMP-2 Production and Activation by Native Form of Extracellular Type I Collagen in Cultured Hepatic Stellate Cells

Cultured hepatic stellate cells (HSCs) are known to change their morphology and function with respect to the production of extracellular matrices (ECMs) and matrix metalloproteinases (MMPs) in response to ECM components. We examined the regulatory role of the native form of type I collagen fibrils in pro-MMP-2 production and activation in cultured HSCs. Gelatin zymography of the conditioned media revealed that pro- and active form of MMP-2 was increased in the HSCs cultured on type I collagen gel but not on type I collagen-coated surface, gelatin-coated surface, type IV collagen-coated surface, or Matrigel, suggesting the importance of the native form of type I collagen fibrils in pro-MMP-2 production and activation. The induction of active MMP-2 by extracellular type I collagen was suppressed by the blocking antibody against integrin beta1 subunits, indicating the involvement of integrin signaling in pro-MMP-2 activation. RT-PCR analysis indicated that MMP-2, membrane type-1 MMP (MT1-MMP) and tissue inhibitor of metalloproteinase-2 (TIMP-2) mRNA levels were elevated in HSCs cultured on type I collagen gel. The increased MT1-MMP proteins were localized on the cell surface of HSCs cultured on type I collagen gel. In contrast to the expression of MMP-2, HSCs showed a great decline in MMP-13 expression in HSCs cultured on type I collagen gel. These results indicate that the native fibrillar (polymerized) but not monomeric form of type I collagen induced pro-MMP-2 production and activation through MT1-MMP and TIMP-2 in cultured HSCs, suggesting an important role of HSCs in ECM remodeling in the hepatic perisinusoidal spaces.

Oxygen transport and myocardial function after the administration of albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% to rabbits

BACKGROUND AND OBJECTIVE

The effects of administering albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% on oxygen transport and left ventricular function were prospectively investigated in different experimental conditions: baseline, fluid load, after 10 min of myocardial ischaemia and after reperfusion.

METHODS

Twenty-seven rabbits received at random one of three colloids in escalating boluses over 10-15 min to achieve left ventricular end-diastolic pressures (LVEDP) between 8 and 10mmHg. A branch of the left anterior descending coronary artery was then temporarily occluded by a ligature and released after 10 min. Myocardial function was assessed using left ventricular pressure recordings and dimension data obtained from ultrasound crystals inserted onto the ventricular wall. Blood was sampled for the determination of oxygen delivery and consumption, the oxygen extraction ratio, acid-base status, and glucose and lactate concentrations.

RESULTS

Administration of the colloids similarly increased oxygen delivery and improved left ventricular function in all groups. Peak rate of pressure development (dP/dt(max)) and oxygen delivery were reduced during ischaemia and reperfusion. The decrease in dP/dt(max) was more pronounced in the hydroxyethylstarch group.

CONCLUSIONS

Administration of albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% had similar effects on oxygen delivery and myocardial function. After ischaemia and during reperfusion, the decrease in myocardial function was most pronounced with hydroxyethylstarch 6%.

The isolated blood-perfused rat heart: an inappropriate model for the study of ischaemia- and infarction-related ventricular fibrillation

1. Well-characterized in vivo and in vitro models exist for the study of ischaemia- and infarction-related ventricular fibrillation (VF). In rats in vivo, VF appears to occur in distinct acute ischaemia- (early) and infarction-related (late) phases. Interestingly, isolated buffer-perfused rat hearts do not develop late VF. This raises the possibility that unidentified components of the blood may be responsible for late VF. We thus sought to characterize an isolated blood-perfused rat heart in order to investigate the possible influence of blood components on arrhythmias arising from ischaemia and infarction. 2. Hearts, excised from male Wistar rats, were perfused in the Langendorff mode with blood from support rats (male Wistar, 350-430 g) via an extracorporeal circuit. Perfused hearts underwent left coronary artery occlusion for 240 min or a sham procedure (n=10 group(-1)). 3. Only 10% of ischaemic hearts developed late VF (90-240 min). Tissue myeloperoxidase activity (an index of neutrophil accumulation) increased during ischaemia from 0.017+/-0.004 (six fresh hearts) to 0.056+/-0.005 units mg protein(-1) (P<0.05) at 240 min, but values were similar in sham hearts (0.083+/-0.013). Likewise, the decline (-1 vs 240 min of ischaemia shown) in circulating total white blood cells from 6.8+/-0.5 to 1.9+/-0.2 x 10(3) micro l(-1) and in platelets from 441+/-32 to 274+/-16 x 10(3) micro l(-1) (both P<0.05) was similar in time-matched sham hearts (data not shown). 4 Surprisingly, only 10% of ischaemic hearts developed early VF (0-90 min), although the incidence of early ventricular tachycardia was 100% in these hearts (P<0.05 vs sham hearts). Blood K+ values were normal (hyperkalaemia suppresses VF). 5 Although late VF was absent in blood-perfused hearts, it would be premature to conclude from this that late VF is not mediated by blood components. This is because the similar neutrophil accumulation in ischaemic and sham hearts, the decline in numbers of circulating blood components, and the unexpected paucity of early VF all question the validity of the model.

When food becomes a drug: nonanabolic nutritional supplement use in athletes

The use of nonanabolic nutritional supplements for the sake of improving athletic performance is common, and the types of supplements used can have significant implications for the medical care of athletes. This review will address the most common and most controversial nonanabolic nutritional supplements, including recommendations regarding their use. Many supplements are marketed and promoted based on various theoretical benefits, often derived from limited animal studies, without any basis for recommending their human use. Physicians are trained to not recommend a nutritional supplement unless it is known to be effective, whereas athletes are oriented toward trying any supplement or ergogenic aid as long as it is safe, with the hope that it may be effective. The built-in error in most study designs is larger than the difference between winning and not qualifying at elite levels of competition, such that research may not always answer the questions raised by athletes. An honest discussion of the limitations of most supplements, and acknowledgment that some supplements may work some of the time in some athletes, may lead the physician to be more credible and useful to athletes in providing medical care and guidance that support their desire to improve their performance.