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PubMed2004

Neovascularization of poly(ether ester) block-copolymer scaffolds in vivo: long-term investigations using intravital fluorescent microscopy.

Poly(ether ester) block-copolymer scaffolds of different pore size were implanted into the dorsal skinfold chamber of balb/c mice. Using intravital fluorescent microscopy, the temporal course of neovascularization into these scaffolds was quantitatively analyzed. Three scaffold groups (diameter, 5 mm; 220-260 thickness, microm; n = 30) were implanted. Different pore sizes were evaluated: small (20-75 microm), medium (75-212 microm) and large pores (250-300 microm). Measurements were performed on days 8, 12, 16, and 20 in the surrounding normal tissue, in the border zone, and in the center of the scaffold. Standard microcirculatory parameters were assessed (plasma leakage, vessel diameter, red blood cell velocity, and functional vessel density). The large-pored scaffolds showed significantly higher functional vessel density in the border zone and in the center (days 8 and 12) compared with the scaffold with the small and medium-sized pores. These data correlated with a larger vessel diameter and a higher red blood cell velocity in the large-pored scaffold group. Interestingly, during the evaluation period the microcirculatory parameters on the edge of the scaffolds returned to values similar to those found in the surrounding tissue. In the center of the scaffold, however, neovascularization was still active 20 days after implantation. Plasma leakage and vessel diameter were higher in the center of the scaffold. Red blood cell velocity and functional vessel density were 50% lower than in the surrounding tissue. In conclusion, the dorsal skinfold chamber model in mice allows long-term study of blood vessel growth and remodeling in porous biomedical materials. The rate of vessel ingrowth into poly(ether ester) block-copolymer scaffolds is influenced by pore size and was highest in the scaffold with the largest pores. The data generated with this model contribute to knowledge about the development of functional vessels and tissue ingrowth into biomaterials.

Animals↗
PubMed1989

Leukocyte function in Pelger-Huët anomaly of dogs.

Leukocyte function was evaluated in five dogs with Pelger-Huët (P-H) anomaly and in five control dogs. No significant differences were found between groups in neutrophil adherence, random movement, chemotaxis, phagocytosis, or bacterial killing of Staphylococcus intermedius. Neutrophils migrated rapidly into inflammatory sites where progressive nuclear lobulation was noted over time. Antibody titers to exogenous antigens were similar in the P-H and control groups indicating B- and T-lymphocyte cooperation in humoral immunity. Lymphocyte blastogenesis to phytohemagglutinin also was similar in both groups suggesting the presence of a responsive T-lymphocyte population. These findings indicate that no apparent predisposition to infection or immunodeficiency exists in dogs with P-H anomaly.

Animals↗
PubMed1992

Effect of aspirin on photodynamic therapy utilizing chloroaluminum sulfonated phthalocyanine (CASP).

The efficacy of photodynamic therapy (PDT) is mediated through a direct vascular effect. Interference with platelet function and resulting vascular stasis have been recently demonstrated utilizing the photosensitizer dihematoporphyrin ether (DHE). We examined the effect of aspirin, a known inhibitor of both cyclooxygenase and platelet activity, on PDT using chloroaluminum sulfonated phthalocyanine (CASP). Thirty-six rats implanted with a window chamber were given either 0.1 mg/kg (low dose) or 10 mg/kg (high dose) aspirin immediately before, immediately after, or 6 hours after the completion of CASP-PDT. Aspirin in either dosage did not appear to have any effect on the window vasculature when given immediately after light exposure. A moderate inhibition of vascular response was seen in animals treated with aspirin pre-PDT, whereas high-dose aspirin completely abrogated the CASP-PDT vascular response when given 6 hours post-PDT. These data indicate that aspirin can effect CASP-PDT in both time-dependent and dose-dependent fashions.

Animals↗
PubMed1995

Interaction of activated natural killer cells with normal and tumor vessels in cranial windows in mice.

A mammary carcinoma, MCa IV, was grown in syngeneic C3H mice in a cranial window preparation which permitted the in vivo observation of the growth and microcirculation of the tumors. Fluorescently labeled activated natural killer (A-NK) cells were injected into the external carotid artery and their interactions with normal and tumor vessels were quantified by video microscopy. Cells which entered the tumor vessels adhered heterogeneously to these vessels, regardless of vessel size or blood flow rates and bound with an efficiency ranging from 0 to 82% of the incoming cell flux. Normal brain tissue showed significantly fewer binding cells per microscopic field (9 +/- 5 vs 85 +/- 27 cells/1.3 mm2) and the few cells which were retained by the normal tissue were highly deformed, suggesting mechanical rather than adhesive entrapment. These studies indicate that A-NK cells bind in high numbers to segments of the vessels of mammary tumors growing in an intracranial site when administered through an arterial route; however, some tumor vessels may escape recognition by these cells. These findings suggest that A-NK cells may be used as carriers of genes for anti-cancer agents.

Animals↗
PubMed1985

The behaviour of the tissue pO2 in transparent chambers of rats with and without tumour implantations.

Changes of tissue pO2 levels in chronic subcutis wounds with and without heteroplastic tumour spheroid implants in thoraco-lumbal rat skinfolds covered by transparent chambers were followed in crosscut analysis by pO2 surface electrodes as a function of post-operative age using constant normoxic, hypoxic, post-hypoxic breathing conditions and intervals for each measured area. The tissue pO2 showed significantly higher values in the edematous phase of wound healing than in the granulation and differentiation phase. Tumour implantations induced even higher pO2 values in the edematic phase. This difference vanished in later phases. The hypoxic reactivity of non-tumour and tumour tissue improved with post-operative age indicating a sufficient vessel outgrowth.

Age Factors↗
PubMed1990

Microvascular ultrastructure in non-freezing cold injuries.

The effects of repeated local exposure to cold on the integrity of the subcutaneous microcirculation were studied in a model using a transparent tissue chamber implanted into a dorsal skin fold of Syrian hamsters. A detailed study of the vascular ultrastructure within the chamber revealed the following features: Endothelial damage was prominent in true capillaries and venous vessels, while arterioles remained unaffected. The endothelial lining appeared extremely attenuated around the entire vascular perimeter causing the development of "gaps", some of which contained leukocytes or platelets. Smaller vessels were often completely filled with blood cells with leukocytes integrated into the endothelial wall. Fibrin was never observed within these occluded vessels. Finally, only veil-like remnants of the endothelium persisted, and compressed erythrocytes were still mimicking the original vascular outline. It is concluded that the ultrastructural changes observed after a repeated non-freezing cold injury closely resemble those observed during ischemia/reperfusion injury.

Animals↗
PubMed1992

Effect of cetirizine, ketotifen and chlorpheniramine on the dynamics of the cutaneous hypersensitivity reaction: a comparative study.

Allergic cutaneous challenge causes mast cell and basophil mediator release which recruit inflammatory cells to the site of antigen administration. This secondary cell infiltration and mediator release is responsible for the changes seen during the late phase of allergic diseases. In this randomised, double-blind, cross-over, placebo controlled study, it was demonstrated that, at steady-state drug concentrations, chlorpheniramine reduced the wheal-and-flare reaction by about 50% compared to the 75% reduction, on average, by cetirizine and ketotifen. Cetirizine significantly reduced eosinophil vacuolisation at all observation periods, i.e. 2,6,10 and 24 h, and also inhibited basophil accumulation significantly at 10 h (75% reduction), while chlorpheniramine had a negligible effect on these variables. These changes would indicate that the late phase reaction was modified, especially as eosinophil vacuolisation is known to correlate with late phase intensity, T-lymphocyte infiltration and subsequent tissue damage. It further supports previous speculation that cetirizine inhibit late histamine release by acting on basophils. The extent of induration in the late phase reaction did not differ significantly among the three treatments. Cetirizine and ketotifen, noticeably although not significantly, reduced eosinophil and lymphocyte recruitment. As these two antihistamines differ structurally and in regard to receptor specificity, it is possible that they exert their actions on other, unspecified, receptors.

Basophils↗
PubMed1980

Defective phagocytosis confined to Staphylococcus aureus in a female infant with recurrent infections.

Defective chemotaxis and phagocytosis of Staphylococcus aureus was identified in a female infant with marked hepatosplenomegaly and recurrent infections. Neutrophil mobilization from the marrow and marginal pool; random mobility; phagocytosis of yeast particles, latex beads and carbon particles; phagocytosis and intracellular killing capacity of Streptococcus pyogenes and E. coli; and NBT dye reduction were normal. Infiltration of neutrophils was depressed in the skin window test. The complement system and cellular immunity were intact. The patient also had a persistent EB virus infection. Defective phagocytosis limited to Staphylococcus aureus seems to be caused by an intrinsic cellular defect, such as congenital defect in neutrophil receptors for Staphylococcus aureus.

Bacterial Infections↗
PubMed1993

Factor-specific changes in oxidative burst response of human neutrophils in skin-window exudates.

Human neutrophils were isolated from blood and aseptic inflammatory exudates. The respiratory burst response was measured as superoxide (O2-) production by a microplate assay system and polarographically as oxygen consumption. Exudate cells exhibited a respiratory burst in response to n-formyl-methionyl-leucyl-phenyl-alanine (FMLP) that was two- to threefold higher than the burst exhibited by peripheral blood cells. The O2- production induced by substance P was also found to be fivefold higher in exudate cells, while the metabolic response to other stimulants such as concanavalin A (con A), phorbol-myristate acetate (PMA), NaF, and immunocomplexes was not primed. Serum-treated zymosan (STZ)-stimulated activity was primed by only 11%. In contrast, superoxide production in response to tumor necrosis factor-alpha (TNF) was decreased in exudate versus blood cells by about 50%. Therefore, the skin-window cells, compared to blood cells, appear to be at the same time primed, unmodified, and desensitized, according to the different stimulants employed.

Concanavalin A↗
PubMed1989

In vivo and in vitro HeNe laser effects on phagocyte functions.

The goal of this work was to evaluate the effect of helium-neon (HeNe) laser irradiation on immunocompetent cells. We used the in vivo skin window method and in vitro granulocyte function tests. The study of cellular migration showed a marked decrease in vitro and in vivo in a dose-independent manner. Superoxide release was not modified by laser irradiation. The granulocyte's aggregation, when using PHA and PMA, presented a reduction that was statistically very significant, not as a subordinate dose. An increase of the release of ATP was demonstrated only at 4 joules and precedes granulocyte aggregation. When using Ca2+ ionophore A23187 as stimulus, laser irradiation at 1, 2 or 4J did not show any modification of granulocyte aggregation. The monoclonal antibody 60.1, which identifies a membrane antigen fundamental for aggregation and chemotaxis, is expressed in normal amounts on granulocyte membranes both before and after irradiation with a HeNe laser. In fact, Laser irradiation preferentially attacks the area of the cellular centrosome that determines a modification of cellular morphology. The electron microscope and immunofluorescence study with a monoclonal antibody have pointed out a disorganization of the microtubules. The alteration of some of the granulocyte functions is correlated to the damage in the centrioles. The granulocyte mitochondrial system and surface membrane remain intact, and this explains the normal production and release of free radicals. Further experiments are necessary to evaluate the clinical application of lasers in various diseases with immunophagocytic pathogenesis.

Adenosine Triphosphate↗
PubMed1996

Changes of fatty acid composition and oxidative metabolism of human neutrophils migrating into an inflammatory exudate.

The peripheral blood neutrophils and the neutrophils accumulated into a skin-window experimental exudate were compared for their ability to release superoxide anion (O2-) and for their fatty acid composition, determined by capillary gaschromatography. The basal O2- release and the phorbol myristate acetate (PMA)-induced O2- release were not significantly different in the two neutrophil populations, while in response to formyl-methionyl-leucyl-phenylalanine (fMLP) the exudate cells showed an activity that was two fold higher than that of blood cells. The most significant changes of fatty acid composition of exudate versus blood cells were the following: i) increase of C16:0 (palmitic acid) from 21.3 +/- 1.2% to 23.5 +/- 1.3% (+ 10.2%) of total fatty acids (p < 0.001),ii) increase of C18:2 (linoleic acid) from 9.3 +/- 1.7% to 11.0 +/- 2.1% (+ 18.3%) (p = 0.005), iii) decrease of C20:4 (arachidonic acid) from 12.8 +/- 1.6% to 10.6 +/- 1.2% (-17.3%) (p < 0.001), whereas C18:1 (oleic acid) did not change. The total content of saturated or unsaturated fatty acids did not change. In exudate cells, a strong negative correlation was found between palmitic acid content and O2- release in response to both fMLP and PMA (r = -0.52, p < 0.02 and r = -0.49, p < 0.05, respectively) whereas arachidonic acid correlated positively, but weakly, with O2- (r = 0.40, p = 0.07 and r = 0.47, p = 0.05, with fMLP and PMA as stimulants respectively). A positive correlation was also found between the arachidonic acid content of blood cells and the number of cells that migrated into the inflammatory exudate. These results indicate that the process of extravasation from blood into the exudate causes specific and consistent modifications of the fatty acid composition of neutrophils and suggest that these modifications have a role in the activation and the regulation of the O2- forming system.

Chemotaxis, Leukocyte↗