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Biomedical subjects

J Glowacki

Publications and source records attributed to J Glowacki.

At least 91 records · Page 5Linked to original sources
PubMed1982

Cells of the mononuclear phagocytic system resorb implanted bone matrix: a histologic and ultrastructural study.

Implantation of mineral-containing bone fragments into calvarial defects in rats initiates a rapid and reproducible resorption of the bone matrix. After 7 days, a dense tissue develops with mononucleated as well as multinucleated cells surrounding and between the bone fragments. Electron microscopy revealed that these cells belong to the mononuclear phagocytic system: they were identified as macrophages, epithelioid cells, foreign body giant cells, and Langerhans cells. In addition to the common ultrastructural characteristics, these cells had electron-dense, focal specializations along their cell membrane with a coating on the exterior, corresponding to subplasmalemmal linear densities. Small, unidentified cells with electron-dense ground cytoplasm were often seen in close proximity to more differentiated cells. No halisteresis had occurred on the surfaces of the bone fragments. Indentations resembling Howship's lacunae were frequent; these contained mononucleated as well as multinucleated cells. Some surfaces were frayed and collagen fibers were exposed, but the cells apposed to these surfaces did not have ruffled borders as are seen in osteoclasts. Some bone fragments were broken up and cell processes had penetrated deep into the cracks, separating pieces of matrix. Small matrix particles were phagocytosed by macrophages, but not by epithelioid cells or giant cells. It appears that enzymes capable of degrading bone matrix components were secreted by the more differentiated cells of the mononuclear phagocytic system. They eroded the bone surface in a way reminiscent of osteoclastic bone resorption. They also entered the canaliculi to act from within the bone fragment, a process possible only in dead bone. We suggest a possible relationship of these cells with osteoclasts.

Animals↗
PubMed1982

Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics.

Forty-nine specimens from a variety of vascular lesions were analyzed for cellular characteristics. Two major categories of lesions emerged from this investigation: hemangiomas and vascular malformations. This classification and its implications are justified by several considerations. Hemangiomas in the proliferating phase (n = 14) were distinguished by (1) endothelial hyperplasia with incorporation of [3H]thymidine, (2) multilaminated basement membrane formation beneath the endothelium, and (3) clinical history of rapid growth during early infancy. Hemangiomas in the involuting phase (n = 12) exhibited (1) histologic fibrosis and fat deposition, (2) low to absent [3H]thymidine labeling of endothelial cells, and (3) rapid growth and subsequent regression. The endothelium in hemangiomas had many characteristics of differentiation: Weibel-Palade bodies, alkaline phosphatase, and factor VIII production. Vascular malformations (n = 23) demonstrated no tritiated thymidine incorporation and normal ultrastructural characteristics. These lesions were usually noted at birth, grew proportionately with the child, and consisted of abnormal, often combined, capillary, arterial, venous, and lymphatic vascular elements. This cell-oriented analysis provides a simple yet comprehensive classification of vascular lesions of infancy and childhood and serves as a guide for diagnosis, management, and further research.

Adolescent↗
PubMed1982

Mast cells in hemangiomas and vascular malformations.

Common pediatric vascular birthmarks, classified as hemangiomas or malformations, were analyzed for the presence of mast cells. Hemangiomas in the proliferative phase contained large numbers of mast cells (27 +/- 15 cells/high-power field [HPF]) in comparison with hemangiomas in the involuting phase (2.6 +/- 2.9), vascular malformations (1.7 +/- 3.2), and normal skin (5.0 +/- 1.0). Inasmuch as hemangiomas are characterized by endothelial proliferation and increased numbers of mast cells, these data raise the possibility that mast cells may have an important role in the formation and/or maintenance of these lesions.

Adolescent↗
PubMed1981

Application of the biological principle of induced osteogenesis for craniofacial defects.

Demineralised bone implants were used for cranio-maxillofacial reconstruction and construction in 34 patients, 28 with congenital deformities and 6 with acquired defects. The patients' ages ranged from 15 months to 59 years (mean 18 years). In 33 cases, the implants were obtained from cadaver femurs; in 1 case, the implant was prepared from the patient's own skull. Early healing was assessed by clinical and radiographic examination and, when appropriate, by biopsy. Longer follow-up will be required to determine whether resorption has been avoided. The clinical advantages are rapid union, healing of large defects, avoidance of harvesting procedures, and the potentially unlimited supply of banked material.

Adolescent↗
PubMed1981

Self assembly of mixtures of collagen alpha-chains.

As part of an effort to understand the mechanism of assembly of collagen polypeptide chains into triple-helical rod shaped molecules, we have assessed the role of the proportions of alpha 1 to alpha 2 chains in the starting solutions in determining the compositions of renatured collagen. Solutions of different ratios of alpha 1 and alpha 2 chains, one of which was labelled with [14C]- or [3H]glycine, were renatured to form triple-helical, rod-shaped molecules, then cross-linked intramolecularly with formaldehyde. Specific radioactivity measurement and chromatographic elution profiles demonstrated that the composition of the resultant molecules, (alpha 1)3, (alpha 1)2 alpha 2, alpha 1(alpha 2)2 and (alpha 2)3, depended on a relative proportions of alpha chains in the starting solution.

Animals↗
PubMed1981

Fate of mineralized and demineralized osseous implants in cranial defects.

We have evaluated the fate of mineralized osseous implants placed into cranial defects in rats. By 2 weeks, 100% of the defects that had been filled with demineralized bone powder (DBP, 75-250 micrometer) showed bony repair as judged by histomorphometric analysis and incorporation of 45Ca. The DBP was not appreciably resorbed but rather was amalgamated within the new bone. Histomorphometric evaluation of osteo-genesis induced by equal masses of demineralized bone powders of various particle sizes (less than 75, 75-250, 250-450 micrometer) revealed that the smaller particles induced more bone per field than did the larger particles. In contrast, mineralized bone powder (BP) was completely resorbed by 3 weeks, without bony repair of the cranial defect. These specimens contained large multinucleated cells within 7 days and completely resorbed by 3 weeks. It is concluded that (a) demineralized bone powder predictably induces a osteogenic healing of cranial defects, (b) demineralized bone powder is not appreciably resorbed prior to bone induction, (c) the extent of bone induction is a function of the surface area of the demineralized bone implant, and (d) mineralized bone powder undergoes obligatory resorption.

Animals↗
PubMed1981

Use of demineralized allogeneic bone implants for the correction of maxillocraniofacial deformities.

Two major problems in maxillocraniofacial surgery are the limited amount of fresh autogenous bone, the standard material for bone grafting, and the resorption of the grafted bone. Experimental studies with demineralized, devitalized bone matrix have shown induction of endochondral ossification. Fifty-five demineralized allogeneic implants have been used in 44 patients over the past two years for a variety of congenital (n = 37) and acquired (n = 7) defects. The allogeneic bone was obtained from cadavers, prepared as powders, chips or blocks, and was demineralized. After having been sterilized by irradiation, they were used to augment contour, fill defects, or construct bone within soft tissue. Of implanted sites that could be evaluated by physical examination, 31 of 31 were solid by three months. By radiographic examination three of 19 were healed by three months, and an additional 11 were positive by six months. Induced bone was seen in four of four biopsy specimens. Infection occurred in four of 44 patients (9%), comparable with conventional grafts. Implant resorption occurred in four instances. Allogeneic demineralized implants offer several advantages over conventional bone grafting, such as avoidance of a harvesting operation, ease of manipulation, and potentially unlimited material in banked form. In addition, healing by induced osteogenesis may bypass the resorption seen with healing of mineral-containing grafts.

Adolescent↗
PubMed1981

Neocartilage derived from transplanted perichondrium: what is it?

The articular surfaces of rabbit patellae were completely eburnated and resurfaced with ear perichondrium or fascia lata or left unresurfaced. Both mature and immature animals were used and were sacrificed at 3, 6, and 12 months postoperatively. Only those joints resurfaced with perichondrium formed neocartilage. The neocartilage was composed of variable amounts of chondroitin sulfate; histologic appearances ranged from hyaline cartilage to fibrocartilage to fibrous tissue. Scanning electron microscopy revealed that the neocartilage surface was irregular, fibrillated, and disorganized. Biochemical analyses documented the variability of the neocartilage, one specimen being quite similar to normal articular cartilage. Cell-culture experiments with isolated rabbit periochondrocytes, chondrocytes, and fibroblasts were conducted to determine whether those cell types could produce cartilage matrix in vitro. The ability of sparse cultures of perichondrocytes to synthesize chondroitin sulfate under serum-free conditions is evidence that these cells are unlike fibroblasts and more like chondrocytes in their in vitro behavior. These in vitro and in vivo studies show that perichondrocytes are relatively differentiated cells with the potential to make cartilage. Elucidation of the factors contributing to the variable results of perichondral transplantation is essential before clinical applications will be predictably successful.

Animals↗
PubMed1981

Induced osteogenesis in the repair of experimental mandibular defects in rats.

In order to investigate the repair of mandibular defects, we have devised a nonhealing model in the ramus of the rat mandible. The large full thickness defects, devoid of periosteum, were filled with demineralized bone powder (DBP), lyophilized bone chips, and un-demineralized bone powder (BP) or were irrigated with Ringer's lactate. Healing was judged by gross and histologic examination and by incorporation fo 45 calcium into hydropyapatite. DBP produced more rapid and complete healing than did BP or lyophilized chips. DBP did not undergo appreciable resorption prior to bone formation and was a more potent osteogenic stimulus than was BP or lyophilized chips.

Animals↗
PubMed1980

Povidone-iodine and tensile strength of wounds in rats.

The present study was designed to test the hypothesis that povidone-iodine would inhibit the recovery of tensile strength in a healing wound. Clean, incised dorsal wounds in rats were soaked in 1% povidone-iodine solution for 15 minutes; control wounds were soaked in lactated Ringer's solution before closure. Tensile strength measurements and histologic studies were conducted at 1, 2, and 6 weeks. No statistical differences in the rate of gain of tensile strength or histological appearance were noted between control and experimental wounds. It is concluded that brief irrigation of clean incised wounds with povidone-iodine solution does not affect factors important in the recovery of tensile strength during would healing, such as fibroplasia and collagen cross-linking.

Animals↗
PubMed1980

Induced osteogenesis for repair and construction in the craniofacial region.

Solid and powdered forms of undemineralized and demineralized bone grafts were implanted in rat cranial defects. Demineralized calvarial discs healed the defects as well as did the fresh discs, as judged by histology and 45Ca incorporation. Gross and histologic evaluations demonstrated predictable endochondrial osteogenesis by demineralized bone powder (DBP). Undemineralized grafts, in contrast, showed poor and unpredictable bony healing. Construction of facial bones was achieved by implantation of demineralized bone powder within the soft tissues. The phenomenon of induced osteogenesis by demineralized implants was not species specific. These studies of osseous transformation provide insight into the mechanism of, and possible answers to, the problems of osseous transplantation.

Animals↗
PubMed1980

A microangiographic study of hematoma-associated flap necrosis and salvage with isoxsuprine.

Rat dorsal skin flaps predictably underwent full-thickness necrosis by 48 hours when hematoma had been placed beneath the flap. Microangiographic studies demonstrated failure of filling of the distal vasculature of these flaps. This was in marked contrast to the complete reestablishment of circulation in control flaps, overlying equal volumes of serum. The circulation of failing flaps overlying hematoma was restored with isoxsuprine given parenterally 1 hour preoperatively and every 4 hours for 24 hours postoperatively. This pharmacologic regimen gave consistent reestablishment of flap perfusion and flap survival. The toxic component of hematoma acts on the circulation to a skin flap. This may be at the same level of the vasculature as the vasodilating action of isoxsuprine.

Angiography↗