Cytokines and matrix metalloproteinases mRNA expression in archival human tissues from failed total hip arthroplasty using in situ hybridization and color video image analysis

Reports on the histological and biochemical nature of periprosthetic fibrous/granulomatous tissue has, to date, been largely limited to frozen tissue sections. This study reports the cytokine and matrix metalloproteinase profiles found in periprosthetic interface tissues in THA which have failed due to aseptic loosening and in capsular tissues obtained at primary surgery. The study employs immunohistochemistry, in situ hybridization, and color video image analysis on formalin fixed and paraffin embedded sections.

Influence of Aloe vera on collagen characteristics in healing dermal wounds in rats

Wound healing is a fundamental response to tissue injury that results in restoration of tissue integrity. This end is achieved mainly by the synthesis of the connective tissue matrix. Collagen is the major protein of the extracellular matrix, and is the component which ultimately contributes to wound strength. In this work, we report the influence of Aloe vera on the collagen content and its characteristics in a healing wound. It was observed that Aloe vera increased the collagen content of the granulation tissue as well as its degree of crosslinking as seen by increased aldehyde content and decreased acid solubility. The type I/type III collagen ratio of treated groups were lower than that of the untreated controls, indicating enhanced levels of type III collagen. Wounds were treated either by topical application or oral administration of Aloe vera to rats and both treatments were found to result in similar effects.

Nerve and blood vessel growth in response to grafted dermis and cultured keratinocytes

The aim of this study was to study innervation and angiogenesis in response to grafts of dermis and cultured keratinocytes using immunohistochemical techniques. In a porcine model, fresh autologous de-epidermalized dermis and cultured autologous keratinocytes were combined using a two-stage technique, to produce keratodermal grafts. Wounds were encased within skin graft chambers that prevented the influence of the surrounding skin. As grafts contracted, a peripheral rim of granulation tissue became exposed, allowing us to compare the wound bed beneath grafts with that beneath the raw granulating surface. Grafts were studied for 6 weeks. Angiogenesis was studied using antisera to von Willebrand factor to detect endothelial cells. Nerve growth was studied using antisera to S-100, a Schwann cell marker, and to four axonal markers: protein gene product 9.5, C-flanking peptide of neuropeptide Y, calcitonin gene-related peptide, and vasoactive intestinal peptide. In kerato-dermal grafts (n = 28), organization of blood vessels and nerve growth occurred only beneath areas with epidermal cover as compared with the surrounding granulation tissue. Initially, the immunoreactivity to von Willebrand factor was high, but in areas with epidermal cover it assumed a more orderly pattern with fewer blood vessels. Innervation was first detected by S-100 immunoreactivity seen at 1 to 2 weeks, closely followed by that to protein gene product 9.5 and much later to calcitonin gene-related peptide. C-flanking peptide of neuropeptide Y and vasoactive intestinal peptide immunoreactivity were detected in the wound depth surrounding large blood vessels at 4 to 6 weeks. In control wounds that had been either grafted with de-epidermalized dermis alone (n = 10) or allowed to granulate (n = 10), persistently there was high immunoreactivity to von Willebrand factor but minimal immunoreactivity to the neural markers. In conclusion, kerato-dermal grafts become innervated, and beneath their surface there is also vascular organization to resemble normal skin. Keratinocytes themselves may influence angiogenesis and innervation, as both processes failed to occur beneath granulating areas.

Pathological features of healing of a ruptured human round window membrane

Pathology of a round window membrane rupture was demonstrated in a human temporal bone from a case in which labyrinthotomy had been performed through the round window membrane. Proliferation of mesothelial cells was seen in the inner layer of the membrane, and it appeared to be reinforced from the inside by these reactive cells. The middle layer of the membrane was thickened by increased collagen and elastin. The pathologic changes which take place during healing of the ruptured round window membrane are discussed.

Tenascin-C expression in ultrastructurally defined angiogenic and vasculogenic lesions

Tenascin-C (TN) is an extracellular matrix glycoprotein expressed during embryogenesis. Its distribution is restricted in normal adult tissues and is upregulated in tumors and inflammatory conditions. Twenty-five specimens were studied, including 7 reactive vascular lesions (6 cases of granulation tissue and 1 case of bacillary angiomatosis), and 18 vascular tumors (6 angiosarcomas, 7 hemangioendotheliomas, and 5 AIDS-related nodular type Kaposi's sarcomas). Formalin fixed-paraffin-embedded tissues were stained with monoclonal antibody to TN (DAKO) and with MIB-1 (AMAC). Heterogeneous expression of TN immunoreactivity was seen in all cases, with a diffuse pattern in bacillary angiomatosis and most granulation tissue cases and a focal pattern in angiosarcoma and most hemangioendothelioma cases. Kaposi's sarcoma cases showed both a focal and diffuse pattern of distribution. In most cases proliferation indices (PI) did not correlate with TN expression. Electron microscopy demonstrated active angiogenesis in bacillary angiomatosis and granulation tissue and vasculogenesis in angiosarcoma and hemangioendothelioma. The study demonstrated positive TN expression in reactive lesions with angiogenesis (granulation tissue and bacillary angiomatosis) and neoplastic lesions showing vasculogenesis (angiosarcoma and hemangioendothelioma), although with a different pattern of distribution. These results suggest that TN might be an important extracellular matrix glycoprotein in angiogenesis and vasculogenesis.

Dynamic distribution of basic fibroblast growth factor during epulis formation: an immunohistochemical study in an enhanced healing process of the gingiva

Basic fibroblast growth factor (bFGF) is thought to play an important role in wound healing. However, its histological localization, both in normal and pathological conditions in the oral mucosa, has not been well documented. We have studied the immunolocalization of bFGF in normal gingiva and gingival epulis specimens corresponding to different organizing stages. In normal gingiva, bFGF was detected in subpopulations of macrophages, mast cells and most endothelial cells in the lamina propria. Granulation tissue in epulides was histopathologically classified into six organizing stages. In stages 1 and 2, a small number of bFGF-positive macrophages was seen at the periphery of ulcer bases. In stages 3 and 4, histologically characterized by prominent capillary proliferation, large numbers of bFGF-positive macrophages and mast cells were located within granulation tissue. A positive reaction for bFGF was also found in some endothelial cells and in myxoedematous stroma that was rich in heparan sulfate proteoglycan. In stages 5 and 6, when fibrosis was accelerated, bFGF-positive macrophages and mast cells decreased in number and were localized only at the periphery of the fibrous tissue. These findings suggest that maximum amounts of bFGF are synthesized and released from some macrophages and mast cells into the extracellular matrix during neovascularization of granulation tissue.

Significance of granulation tissue in torn supraspinatus insertions: an immunohistochemical study with antibodies against interleukin-1 beta, cathepsin D, and matrix metalloprotease-1

The pathophysiology of rotator cuff tears can be elucidated by examining the tendinous insertion of the supraspinatus muscle. As seen by light microscopy, the granulation tissue around the insertion of a torn supraspinatus tendon appears to induce osteochondral destruction by means of multinucleated giant cells and chemical mediators. The purpose of this study was to examine the contribution of certain chemical mediators to osteochondral destruction using immunohistochemical analysis of interleukin-beta, cathepsin D, and matrix metalloprotease-1. Sixteen supraspinatus insertions with portions of the greater tuberosity, including eight complete-thickness tears and eight incomplete-thickness tears, were obtained during surgery. Six fresh cadaveric supraspinatus tendons without grossly evident tears served as normal controls. Strong immunoreactivity was found in all 16 torn supraspinatus insertions but not in the six insertions of apparently intact tendons. Macrophages and multinucleated giant cells, which showed immunoreactivity for all three chemical mediators, were often found at the interface between the osteochondral margin of the enthesis and the granulation tissue, suggesting that they may be involved in osteochondral destruction. We therefore concluded that, in addition to repetitive subacromial impingement, this granulation tissue may contribute to the development of rotator cuff tears by weakening the insertion.

Ultrastructure of collagen fibers in the outer membrane of recurrent chronic subdural hematoma

The three-dimensional structure of the collagen fibers in the outer membrane of recurrent chronic subdural hematoma was studied by scanning electron microscopy (SEM). Specimens obtained at surgery were treated with NaOH at room temperature to digest away all cellular components and expose the collagen fibers. SEM observation of the dural side of the outer membrane showed the collagen fibers were woven into a compact feltwork with a dense arrangement. The fiber bundles had a honeycomb structure framed by the collagen fibers. Observation of the hematoma side found the collagen bundles had a sparse wavy appearance. The arrangement of the collagen fibers on the dural side is different from that on the hematoma side. The thick outer membrane may be formed by granulation resulting from inflammatory reaction. Collagen fibrillar networks are not fragile, and may reinforce the outer membrane of the recurrent hematoma.

[Cholesterol granuloma of the temporal lobe]

Cholesterol granuloma is a histological term used to describe a non-specific inflammatory reaction produced by the presence of cholesterol crystals, which may originate a foreign-body reaction. Cholesterol granuloma of the temporal bone is silent for years and not preceded by a history of otitis media. The diagnosis is made by CT and MRI, which reveal an expansive, isodense lesion brain tissue and increased signal intensity on both T1 and T2-weighted images respectively. A case of cholesterol granuloma of the petrous apex is presented. The granuloma was excised completely using an infra-retrolabyrinthine approach.

Transient functional expression of alphaVbeta 3 on vascular cells during wound repair

During early granulation tissue formation of wound repair, new capillaries invade the fibrin clot, a process that undoubtedly requires an interaction of vascular cells with the wound provisional matrix composed mainly of fibrin, fibronectin, and vitronectin. Integrin alphaVbeta3 is the vascular cell receptor for these wound-associated adhesive proteins. Therefore, we investigated the expression of this receptor on new capillaries of healing full-thickness cutaneous porcine wounds. During granulation tissue formation, alphaVbeta3 was expressed specifically on capillary sprouts invading the central fibrin clot whereas the closely related integrin alphaVbeta5 failed to localize to these cells. Cyclic peptides or antibody antagonists of alphaVbeta3 specifically inhibited granulation tissue formation in a transient manner during the period of invasive angiogenesis. Immunolocalization studies revealed that alphaVbeta3 became aggregated and lost from sprouting vessels after treatment with a peptide antagonist. In contrast, beta 1 integrins were not modulated by this treatment. Once granulation tissue filled the wound and invasive angiogenesis terminated, the alphaVbeta3 showed little or no expression in the granulation tissue microvasculature. These data demonstrate that integrin alphaVbeta3 plays a fundamental, but transient, role during invasive angiogenesis and granulation tissue formation in a healing wound.

Strong induction of activin expression after injury suggests an important role of activin in wound repair

Activins are members of the transforming growth factor beta (TGF beta) superfamily, which comprises a growing group of dimeric proteins. TGF beta and several other members of this superfamily are known to play an important role in wound healing. However, expression of activin during wound healing has not been demonstrated so far. In this study we have analyzed the expression pattern of activin and activin receptors in normal and wounded skin. We found a large induction of activin A and a minor induction of activin B mRNA expression 1 day after skin injury and high expression levels of activin A and B were found within the first 7 days after wounding. At 13 days after injury, expression of activin A mRNA had returned to the basal level, whereas high levels of activin B persisted. In situ hybridization studies revealed expression of activin A in the granulation tissue below the wound and activin B in the hyperproliferative epithelium at the wound edge and in the migrating epithelial tongue. All known types of activin receptors as well as the activin binding protein follistatin were expressed in normal and wounded skin. However, no significant induction of receptor gene expression was seen during the repair process. The distribution of activins and activin receptors in the wound suggests multiple autocrine and paracrine activities of the ligands during wound healing. Our data provide evidence for a novel function of activin and indicate that--besides TGF beta s themselves--other members of this superfamily might also play an important role in tissue repair.

Evaluation of a porous bovine collagen membrane bandage for management of wounds in horses

OBJECTIVE

To evaluate the effect of a porous bovine-derived collagen membrane (PBCM) on the rates of wound healing, cellular events, presence of granulation tissue, and appearance at termination of the study in surgically created full-thickness cutaneous wounds of the distal portion of the extremities of horses.

DESIGN

Treated wounds (n = 12) received a PBCM dressing and control wounds were covered with a nonadherent dressing. Forelimbs and hind limbs were cross paired; the right forelimb and left hind limb always received the same dressing application, as did the left forelimb and right hind limb. Limbs pairs were then randomly assigned to 1 of the 2 dressings.

ANIMALS

Six healthy male horses (3 sexually intact, 3 geldings) ranging from 2 to 10 (mean, 6.5) years and weighing between 278 and 568 (mean, 408.5) kg were studied.

PROCEDURE

Full-thickness skin wounds (6.25 cm2) were created on the dorsal metatarsi and metacarpi of the experimental animals. A preformed PBCM dressing was evaluated in half the wounds (n = 12). Control wounds (n = 12) were dressed with a nonadherent gauze dressing. At each bandage change, wounds were subjectively assessed and were photographed, and measurements of horizontal and vertical wound dimensions were documented. Wound biopsy specimens obtained on days 2, 5, 7, 10, 21, and 31 were evaluated for presence of collagen, fibrin, inflammation, epithelium, and cellular elements of healing. Planar morphometry was used to determine total wound area and granulation area from the wound photographs. Percentage of contraction and epithelialization were calculated from these values. Linear regression analysis of the square root of the total wound area and the granulation area was performed. Wound area measurements were analyzed, using ANOVA for repeated measures. Regressions were compared, using covariance analysis and ANOVA. Significance was considered at P < 0.05.

RESULTS

Fibrin score, neutrophil score, and degree of inflammation were significantly greater in the PBCM-treated wounds. No significant differences in the total wound, epithelialized, or contraction areas were detected between the PBCM-treated and control (nonadherent-treated) wounds. Rates of wound healing were not statistically different between the 2 treatment groups, though they were significantly slower in the hind limbs, compared with the forelimbs. Scabs were formed more frequently in the PBCM-treated wounds.

CONCLUSIONS

Application of a porous collagen bandage was not detrimental to full-thickness cutaneous wound healing in horses.

Plasticity of myofibroblasts appearing in granulation tissues after acetic acid treatment. Effect of bFGF

To clarify the origin of the myofibroblasts appearing in the healing process of the acetic acid-induced ulcer and effect of basic fibroblast growth factor (bFGF) on these myofibroblasts, we conducted an immunohistochemical study using antibody to intermediate filaments, desmin and vimentin. The binding sites of bFGF on the regenerative tissues were also studied by the radioautographic study of soluble compounds. As a result, the binding sites of bFGF were accumulated on the fibroblasts and myofibroblasts as well as on endothelial cells. The effect of CS23, acid-stable human recombinant bFGF was shown on distribution of myofibroblasts and regeneration of the microvascular system in the mucosal and submucosal layers.

Expression of proteoglycans and hyaluronan during wound healing

We investigated the expression of proteoglycans (PGs) and hyaluronan (HA) during healing of human mucosal wounds. Biopsy specimens of experimental wounds were taken 1, 3, and 7 days after wounding. Frozen sections were used for immunolocalization of CD44, syndecan-1, basement membrane-associated heparan sulfate proteoglycan (BM-HSPG), decorin, and biglycan. HA was localized in paraffin sections with a specific HA-binding probe. Epithelium showed first signs of migration on Day 1, more progressive migration on Day 3, and epithelial sheets confronted on Day 7. CD44 surrounded migrating keratinocytes at all stages of wound healing. In epithelium, CD44 and HA remarkably localized to the same region. Expression of syndecan-1 was switched from the suprabasal cell layer of unwounded epithelium to the basal cell layer of the migrating wound epithelium. BM-HSPG was absent under migrating keratinocytes. It started to reappear at the basement membrane zone on Day 7. The area under the wound epithelium containing newly synthesized collagen fibers first became positive for decorin on Day 7, whereas staining of biglycan was negative. Granulation tissue was also strongly positive for CD44 and hyaluronan. Our results indicate that migrating keratinocytes express both CD44 and syndecan-1 but not BM-HSPG. During differentiation of keratinocytes, expression of CD44 preceded that of syndecan-1. The results suggest that different HSPGs have multiple functions in keratinocyte migration and differentiation during reepithelialization.

Topical zinc oxide treatment increases endogenous gene expression of insulin-like growth factor-1 in granulation tissue from porcine wounds

Application of zinc oxide has been shown to accelerate the healing of both chronic and acute wounds, but the mechanisms are unknown. We quantified the gene expression (mRNA) for one important growth factor, insulin-like growth factor-1 (IGF-1) in 12 full-thickness wounds in each of three domestic pigs treated with or without topical zinc oxide. We used a RNAase protection/solution hybridisation technique to measure IGF-1 mRNA concentrations, which were 50% higher in the granulation tissue in wounds treated with zinc oxide compared with control wounds on days 3-4 (p < 0.05), but not thereafter (up to postoperative day 11). Topical zinc oxide increased the healing rate of wounds compared to the control group (p < 0.01). The cell composition of the granulation tissue was similar in the two groups. The increased gene expression of IGF-1 may be one mechanism by which topical zinc oxide enhances wound healing.

Human wound healing fibroblasts have greater contractile properties than dermal fibroblasts

Contractile and phenotypic properties of human fibroblasts from healing wounds were compared to those of dermal fibroblasts using in vitro models. Wound fibroblasts were recovered from implants, made of a polyvinyl alcohol sponge threaded into a perforated silicone tube, 12 days after their subcutaneous implantation in human volunteers. Dermal fibroblasts were isolated from the skin of healthy subjects. Two morphologically different fibroblast populations were observed in cells cultured from implants. In order to characterize these fibroblast populations, intracellular alpha-actin expression was studied by immunofluorescence labeling of cells cultured in monolayer. This protein was detected in less than 1% of the dermal fibroblasts. By contrast, 30 to 40% of wound fibroblasts were labeled and contained fiber networks of alpha-actin. These results confirm the presence of myofibroblasts in human wound healing tissues. The contractile property of fibroblasts and myofibroblasts was evaluated using a three-dimensional cell culture model (fibroblast populated collagen gels). Cells were incorporated in a collagen matrix and cultured for 14 days. The surface area of collagen gels was measured every day. Our results show that wound fibroblasts strongly contract collagen gels during the first 24 hr (surface area at 24 hr = 20-55% of initial surface area) in comparison to dermal fibroblasts (surface area at 24 hr = 70-75% of initial surface area). This superior level of contraction was observed until the fifth day of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical study of purulent wounds treated with King crab collagenase

Immunohistochemical study of tissues from purulent wounds in rats after treatment with the collagenase isolated from the King crab Paralithodes camtschatica was undertaken. The enzymotherapy resulted in a rapid and efficient removal of necrotic debris. It was accompanied by fibrin elimination from the wound bed and subsequent formation of new capillaries. Cellular fibronectin with ED-A sequence was identified in the newly formed granulation tissue, which points to its active synthesis in situ. Polyclonal antibodies against two isozymes of the crab collagenolytic protease were obtained. By their use it was shown that, after application of the collagenase, both isozymes accumulated in fibrin deposits at the wound bed but did not penetrate adherent granulation tissue.

Complement component C3-derived neutrophil chemotactic factors purified from exudate of rat carrageenin-induced inflammation

Two neutrophil chemotactic factors have been purified from the exudate of chronic-phase of rat carrageenin-induced inflammation. Both the factors were derived from the third component of complement (C3); one was an NH2-terminal fragment (C3a) of alpha chain of C3 and another chemoattractant was a COOH-terminal fragment of beta chain, which was referred to as C3 beta c, on the basis of their molecular masses and NH2-terminal amino acid sequences. C3a exhibits potent chemotactic activity for rat neutrophils, and C3 beta c is a novel basic neutrophil chemoattractant with molecular mass of about 11 kDa, suggesting that both chemoattractants play a role in the neutrophil infiltration into inflammatory site of carrageenin-induced inflammation in rats.

Immunohistochemistry of fibronectin and actin in ungrafted wounds and wounds covered with full- and split-thickness skin grafts

Fibronectin and actin content were measured with immunochemistry in excised wounds in 18 rats. In six rats, wounds were allowed to granulate and contract. Wounds were grafted with full-thickness skin in six rats and with split-thickness skin grafts in the remaining six. Multiple biopsies were taken for immunochemistry and electron microscopy. Actin and fibronectin content was greatest in ungrafted wounds. This content was reduced in wounds by skin grafting, with full-thickness grafts having a generally more inhibitory effect than split. In grafted wounds, actin was observed primarily in the wound bed, whereas fibronectin was present in both the wound bed and graft. Fibronectin appeared coincidently with actin in split-thickness skin grafts and their wounds. In contrast, full-thickness skin grafts had fibronectin staining before actin. The degree of wound contraction inhibition by different types of skin grafts appears to correlate with the fibronectin and actin staining patterns.

Immunoelectron microscopic localization of transforming growth factor beta 1 and latent transforming growth factor beta 1 binding protein in human gastrointestinal carcinomas: qualitative difference between cancer cells and stromal cells

Transforming growth factor beta 1 (TGF-beta 1) is secreted as an inactive complex associated with latent TGF-beta 1 binding protein (LTBP). Tissue localization of these proteins has not been fully understood in human pathological conditions. We examined the immunohistochemical localization of TGF-beta 1 precursor (proTGF-beta 1) and LTBP in carcinomas and granulation tissue in the human gastrointestinal tract at the light and electron microscopic levels. In normal tissue, endothelial cells and granulocytes sporadically showed immunoreactivity for proTGF-beta 1, while epithelial cells were all negative. In cancer tissue, both cancer cells and stromal cells (fibroblasts, macrophages, and endothelial cells) were positive for proTGF-beta 1, more frequently in diffuse-type gastric carcinomas than in differentiated-type adenocarcinomas. Immunoelectron microscopy revealed that proTGF-beta 1 was localized in rough endoplasmic reticulum and perinuclear cisternae in fibroblasts, macrophages, and endothelial cells in cancer stroma and in fibrous granulation tissue. In contrast, the intracellular localization of proTGF-beta 1 in carcinoma cells was predominantly observed in the cytosol (cytoplasmic matrix). This finding suggests disarranged or blocked intracellular transportation of proTGF-beta 1 in cancer cells. The immunoreactivity for LTBP was not observed in the normal epithelial cells. It was localized in cancer stroma, not in cancer cells. Ultrastructurally, LTBP was located in the extracellular matrix around fibroblasts and smooth muscle cells. The intracellular immunoreactivity for LTBP was observed in rough endoplasmic reticulum of fibroblasts and smooth muscle cells, the same as in granulation tissue. These results suggest that gastrointestinal carcinoma cells produce no or a small amount of LTBP in vivo. Our investigation suggests that extensive fibrosis in both cancer stroma and granulation tissues may be promoted by TGF-beta 1 mainly secreted from stromal cells.

Time-dependent appearance of myofibroblasts in granulation tissue of human skin wounds

Human skin wounds (66) inflicted between 20 h and 7 months prior to biopsy were studied. In order to identify the type of cellular differentiation of the fibroblastic cells in the granulation tissue, alpha-smooth muscle actin and desmin were immunohistochemically localized. The value of any presumed time-dependent appearance and/or disappearance of positively stained cells was tested for the estimation of wound age. In skin specimens with a wound age less than 5 days (n = 15) no typical granulation tissue had developed and no alpha-actin-positive myofibroblasts could be detected. The first appearance of positively reacting myofibroblasts was noted in a 5-day-old wound. In 57% of the lesions with a wound age between 5 and 31 days (25 out of 44 cases) typical granulation tissue formation was present and myofibroblasts with positive reaction for alpha-smooth muscle actin could be identified. Numerous positively reacting cells could generally be found in wounds aged between 16 and 31 days, but also in wounds less than 16 days old. In 29% of the cases with a wound age of more than 31 days (2 out of 7 cases) alpha-sma-positive myofibroblasts also occurred. Fibroblastic cells positive for desmin could not be seen at all in our series. Our results demonstrate the appearance of alpha-sma-positive myofibroblasts with the initial formation of typical granulation tissue in human skin lesions as early as approximately 5 days after wounding. In contrast to recent experimental results these cells remained detectable in wounds aged more than 2 months in some cases.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro and in vivo evaluation of antibiotic diffusion from antibiotic-impregnated polymethylmethacrylate beads

The elution of antibiotics from antibiotic-impregnated polymethylmethacrylate (PMMA) beads was measured in mongrel dogs. The antibiotics, used in mixture with Simplex cement, included cefazolin (Ancef; 4.5 g/40 g cement powder), ciprofloxacin (Cipro; 6 g/40 g powder), clindamycin (Cleocin; 6 g/40 g powder), ticarcillin (Ticar; 12 g/40 g powder), tobramycin (Nebcin; 9.8 g/40 g powder), and vancomycin (Vancocin; 4 g/40 g powder). After a pneumatic drill was used to dredge a trough in the tibia, five beads were implanted. During the next 28 days, seroma samples and serum samples were taken for antibiotic measurements. On Day 28, the dogs were killed, beads removed, and the seroma, serum, bone, and granulation tissue sampled. The results of the study showed that clindamycin, vancomycin, and tobramycin exhibited good elution characteristics and had consistently high levels in bone and granulation tissue.

Immunocytochemically detectable metallothionein in granulation tissue surrounding mucosal ulceration

Metallothioneins (MTs) are low-molecular-weight heavy metal binding proteins which are effective free oxygen radical scavengers in vitro. Free oxygen radicals have been implicated in the pathogenesis of stress-induced acute gastric mucosal ulceration and ischaemic injury in rat and man. Experimentally, MTs can have a protective role in stress-induced ulceration in rats. The possible cytoprotective role of MTs in chronic mucosal ulceration in man has not been previously studied. Evidence for locally produced MTs in human chronic gastric and small bowel ulcers has been sought by immunocytochemical staining using a monoclonal antibody (E9) to MT. At the base of ulcers MT has been localized to spindle cells (fibroblasts) in granulation tissue. Labelling of macrophages with a pan-macrophage marker KP1, and double labelling with KP1 and E9 showed two distinct populations, and MT appeared to be localized primarily in fibroblast-like cells.

c-ets1 proto-oncogene is a transcription factor expressed in endothelial cells during tumor vascularization and other forms of angiogenesis in humans

The c-ets1 proteins are transcriptional activators expressed within endothelial cells during blood vessel development in chick embryos. The authors show by in situ hybridization that c-ets1 is transcribed in the endothelia during angiogenesis in human embryos, in granulation tissue, and especially during tumor vascularization. c-ets1 mRNAs were also detected in the fibrocytes of tumor stroma and in the spindle cells of Kaposi's sarcomas, regarded as cells of endothelial origin. It has been shown that the c-ets proteins activate transcription through a PEA3 motif that plays a role in the stimulation of transcription of urokinase-type plasminogen-activator (u-PA), stromelysin and collagenase genes. The authors demonstrate in vitro that the angiogenic factor TNF alpha increases transiently the amount of both c-ets1 and u-PA mRNA in confluent human umbilical vein endothelial cells. Therefore, the authors suggest that the c-ets1 proteins might regulate the transcription of the genes coding for matrix-degrading proteases, which are necessary for both angiogenesis and tumor invasion.

Detection of undegraded fibrin and tumor necrosis factor-alpha in venous leg ulcers

The pathogenesis of venous leg ulcers is based on the leakage of fibrinogen leading to pericapillary fibrin cuff and plugging of capillaries by white blood cells. Eight patients with venous leg ulcers have been studied with a panel of antibodies reactive for fibrinogen, fibrin, fibrin degradation products, and various cell-associated markers for polymorphonuclear cells, monocytes, and B and T lymphocytes. Our results showed that pericapillary fibrin cuff was mainly composed of undegraded fibrin and that, in the granulation tissue, tumor necrosis factor-alpha and elastase activities were detectable in monocytes and polymorphonuclear cells, respectively. Only few activated lymphocytes were present. On the basis of these results, it is assumed that inflammation generated by activated white blood cells that accumulate under unrelieved pressure is the key event. Tumor necrosis factor-alpha synthesized by activated monocytes may therefore induce the formation of pericapillary fibrin cuffs. Pericapillary fibrin cuffs and toxic metabolites released by polymorphonuclear cells may explain the absence of wound repair.