Cellular isolation, culture and characterization of the marrow sac cells in human tubular bone.

The goal of this study is to characterize the epithelioid-like human marrow sac cells that separate the myeloid and osteoblast populations in situ and to determine if they express osteoblast cytoplasmic markers. Tubular segments of femoral diaphyseal bone were obtained from healthy young (4-8 yr) male and female patients undergoing femoral shortening surgeries. The interface between bone and marrow was examined by scanning (SEM) and transmission electron microscopy (TEM). The marrow sac cells were isolated and cultured in a-MEM medium with and without dexamethasone, glycerophosphate, and ascorbic acid [DGPA]. Alkaline phosphatase (ALP), bone morphogenetic protein-2 (BMP-2) and osteocalcin were evaluated. In the SEM, the marrow sac presented a distinctive pattern of large overlapping cells. TEM studies showed that marrow sac was one or two cells thick, which were attenuated with elongated nuclei, few cellular organelles, and appeared to display intercellular gap junctions. In culture, the marrow sac cells stained positively for ALP and BMP-2, and their expression was enhanced two- to three- fold when the cells were grown in DGPA. DGPA did not enhance osteocalcin expression. The cells of the human marrow sac reside proximate to endosteal osteoblasts and express osteoblastic markers. It is possible that these stromal cells constitute an osteoprogenitor pool from which replacement osteoblasts are recruited, and that they are involved in normal bone formation and in bone diseases (e.g., osteoporosis and osteopenia).

Comparative morphology of the marrow sac.

Electron microscopic techniques have been used to profile the morphologies of marrow sacs in different laboratory species. These structures all comprise a condensed layer of overlapping fibroblast-like stromal cells and apparently confine the medullary and endosteal osteoblast/lining cells to separate histiotypic compartments. There were some variations in the morphology of the sac cells in the different species. In rats, cats, and sheep, scanning electron microscopy (SEM) showed a seamless arrangement of marrow sac cells which resembled a thin, flat simple squamous epithelium; they displayed few intercellular cytoplasmic processes. In the rabbit and pigeon, the sac comprised a more woven, multilayered fabric of broadly elongate flat fibroblast-like cells which displayed numerous intercellular processes. Transmission electron microscopy (TEM) showed that all marrow sac cells were attenuated with elongated nuclei, a few small round mitochondria, and a sparse rough endoplasmic reticulum. In the majority of animals, the sac was one to two cell layers thick. The rabbit and pigeon sacs were multilayered, and never less than three to four cells deep. The cell layers were not closely apposed. Tight or gap junctions were absent at the points of intercellular contact. These morphological results suggest that marrow sacs are common elements of the vertebrate skeleton with species specific morphologies.

The origin of bone formed by heterotopic periosteal autografts.

PURPOSE: This study tested the hypothesis that a significant amount of the new bone produced by heterotopic periosteal autografts is derived osteoinductively because proliferating periosteal cells express the bone morphogenetic protein (BMP). MATERIALS AND METHODS: Rabbit ulnar and radial periosteum were autografted as free grafts (FGs) to the forelimb musculature, and as millipore diffusion chambers grafts (MDCGs) to the rectus abdominus muscle. The grafts were recovered at 3, 5, 7, 14, and 28 days postoperation, fixed in 4% paraformaldehyde, demineralized in 0.6N HCL, and 4.0 microns paraffin-embedded sections were immunostained with monoclonal antibody against recombinant human (rh) BMP-2. RESULTS: Sections from FGs recovered 5 to 28 days postoperatively exhibited cartilage and bone; fibrous tissue, cartilage, bone, and osteochondroid differentiated within MDCGs. Although BMP-2 was expressed by mesenchymal cells, osteoblasts, osteocytes, and osteoclasts, none of the MDCGs produced the osteoinductive signature of transmembrane bone formation. CONCLUSIONS: These observations indicated that the larger fraction of the new bone produced by heterotopic periosteal autografts is derived from the graft cells.

Correction of the deficient alveolar ridge.

The success of a denture is dependent on a good foundation; therefore, construction of the prosthesis begins with extraction of the teeth. The teeth should be maintained as long as possible if they can be restored. When the teeth are extracted, bone resorption usually starts, owing to systemic and local factors. Good communication between the prosthodontist and the oral and maxillofacial surgeon must exist during the diagnostic procedure, must be maintained through the various stages of treatment, and must prevail through the follow-up care of the patient. Each clinician must be aware of both the objectives and the possible limitations of the treatment the other will provide, to ensure optimal care for the edentulous patient. The development of the osteointegrated titanium implant system opens an exciting new avenue with respect to total rehabilitation of the edentulous patient. This is the future, and in our opinion, the preferred technique for mandibular reconstruction.

Propofol as an intravenous agent in general anesthesia and conscious sedation.

Propofol has been shown in clinical studies to be a safe, effective, hypnotic, and amnesic anesthetic agent at induction doses of 2-2.5 mg/kg and maintenance doses of approximately 9mg/kg per hour. Significant post-induction hypotension reported earlier can be reduced to a all in MAP of less than 25% when the drug is used alone (without nitrous oxide or narcotic premedication). Post-induction apnea is minimized by avoidance of pre-induction hyperventilation. Acute and long term venous tolerance is acceptable. Emergence from anesthesia induced and maintained with propofol is rapid, predictable and relatively free of postoperative complications. Incidence of drug interaction is low. Propofol causes no adrenocortical suppression and is not potentiated by ethanol, diazepam, amitriptyline or phenelzine. Preliminary investigation of propofol as an intravenous sedative agent at subanesthetic doses has been favorable.

The treatment of radiation necrosis with hyperbaric oxygen (OHP).

Sixty-nine patients with radiation necrosis were received by the authors from January 1, 1969 through August 1, 1975. The patients were categorized according to site of injury. Full treatment protocol is discussed including local wound care, antibiotic coverage, surgical procedures, and the administration of hyperbaric oxygen. Results indicate that the combination of hyperbaric oxygen, properly timed surgery, and antibiotic therapy has resulted in improvement in all cases of radiation necrosis and full healing in most.

Hyperbaric oxygen treatment of mandibular osteomyelitis in osteopetrosis.

A patient was successfully treated with hyperbaric oxygen for chronic osteomyelitis of the mandible associated with osteopetrosis. This mode of therapy appears to have a definite place in the management of such patients. There was no clinical, radiographic, or laboratory evidence that the osteopetrosis was made worse by the hyperbaric oxygen.

Lingual mandibular bone concavity.

The lingual mandibular bone concavity is not pathognomonic but is a radiographic bone entity. The origin of the entity and the histologic picture of the contents found within the concavity are probably related to the size and growth of the structures located in the submandibular space and the contiguous area. This accounted for the presence of normal submandibular space tissue contents in this patient and in nine of the ten patients whose conditions are reviewed in the literature. The question of whether a surgical exploration is indicated should be decided in terms of each individual case by the oral surgeon. However, only by performing a surgical exploration and submitting the tissue contents for a histopathologic examination can an accurate diagnosis be made. The general practitioner of dentistry should be aware of this bone entity and be prepared to discuss the condition with the patient and to refer the patient for exploration of the area if appropriate.

Osteoradionecrosis of the mandible. Treatment with hyperbaric oxygen.

Hyperbaric oxygen used in the treatment of 14 patients with intractable osteonecrosis of the mandible produced a favorable response in relief of pain, elimination of extraoral draining sinus tracts, the return of osseous union in areas of the abnormal fracture, and the rapid dissolution of sequestrum without suppuration, so that further loss of hard and soft tissue was minimized. This treatment is a more conservative approach in the management of osteoradionecrosis.