gests that it might be possible to replace missing teeth with dental implants anchored in alveolar bone by a normal periodontal ligament.-D.C. BURCHFIELD Reprint requests to Dr Buser: Department
Harvard School of Dental Medicine, Boston, MA 02115.
of Periodontology, 188 Longwood Avenue,
Wartbin’s Tumor. Bat&is JG, El-Naggar AK. Ann Otol Rhino1 Laryngol99588, 1990 A lesion of the parotid gland and environs, including lymph nodes, Warthin’s tumor is a monomorphic adenoma, second to pleomorphic adenoma in incidence of benign neoplasms of the parotid gland. Histopathologic diagnosis requires an oncocytic (mitochondria-rich) epithelium and lymphoid stroma. Malignancy is rare, producing carcinomas from the ductal component, or nonHodgkin’s lymphomas arising from the lymphoid tissue. Multifocality is responsible for the 5% to 25% “recurrence rates” of the tumor after surgery that includes excisional biopsy, enucleation, subtotal and total parotidectomy.-G.H. SPERBER Reprint requests to Dr Batsakis: Department of Pathology, MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030.
Tissue Expansion Technique and the Transposition Flap. Joss GS, Zoltie N, Chapman P. Br J Plast Surg 43:328, 1990 The shape and volume of tissue expanders have previously been considered essential when determining optimal expander size. Clinical calculations are presented to estimate ideal expander size based on width instead of volume; an expander twice as wide as the defect to be covered will produce enough tissue to reconstruct both defect and donor site, irrespective of expander shape. Previous descriptions of reconstruction using tissue expansion imply the use of advancement flaps, which can waste normal tissue. The use of a transpositional advancement flap is discussed and several cases are presented. Advantages of the transpositional flap include facilitated closure of the donor site without loss of expansion as the flap is raised. The authors conclude that the transpositional flap has increased the success of reconstruction with tissue expansion when an expander twice the width of the defect is used.-KS. SWANSON Reprint requests to Mr Zoltie: 16 The View, Alwoodley, Leeds LS17 7NB, England.
nents contribute to histological variety of the stroma. The purpose of this study was to demonstrate the presence of specific basement membrane molecules in stromal areas of this tumor. Immunohistochemical studies were carried out in 30 cases of pleomorphic adenoma for four specific molecules: type IV collagen, laminin, enactin, and heparan sulfate proteoglycan. Immunohistochemically, type IV collagen and laminin were more intensively localized in hyalin, fibrous, and chondrial types of stroma, whereas heparan sulfate proteoglycan was more prominent in myxoid areas. The results suggest that the stroma does indeed contain these basement membrane components, which are possibly synthesized by epithelial tumor cells. Furthermore, the histological variety of the stroma may depend on the proportion of local contents of each basement membrane molecule.-C.M. WORLEY Reprint requests to Dr Saku: Dept of Pathology, Nagasaki University School of Dentistry, F-l Sakamoto-machi, Nagasaki 852, Japan.
Tritiated Tbymidine Autoradiographic Study on the Influence of Sensory and Sympathetic Innervation on Periodontal Wound Healing in the Rat. Wucherpfennig AL, Chiego JR, Avery JK. Arch Oral Biol 35:6, 1990 The influence of sympathetic and sensory denervation on gingival response to injury is assessed at the cellular level by autoradiographic studies in rats. Inferior alveolar nerve (IAN) resection, superior cervical ganglion (SCG) extirpation, or trauma to those structures or sham operations were performed. Experimental gingival wounds were created and followed by tritiated thymidine pulsing at various times. General wound healing followed patterns previously described by other investigators. However, SCG resection profoundly positively influenced proliferation of epithelial, fibroblast, and alveolar crest cells. IAN resection had a smaller overall effect, with statistically significant changes affecting only fibroblasts. Postulates of the observed effects include effects related to vasodilatation, such as increased blood flow and delivery of growth factor and insulin. Gingival denervation may cause local increases in neurotrophic growth factors. Alternatively there may be removal of physiological suppression. The effects on proliferation involving different cell types suggest several interacting factors rather than a single stimulating factor. This information may be useful in determining therapeutic methods to treat gingival wounds.-S. CROWLEY Reprint requests to Dr Wucherpfennig: Department of Immunology, Forsyth Dental Center, 140 The Fenway, Boston. MA 02115.
Immunolocalization of Basement Membrane Molecules in the Stroma of salivary Gland Pleomorpbic Adenoma. Saku T, Cheng J, Okabe H, et al. J Oral Path01 Med 19:208, 1990
Pulse Oximeter Failure Thresholds in Hypotension and Vasoconstriction. Severinghaus JW, Spellman BA. Anesthesiology 73:532, 1990
The pleomorphic adenoma (“mixed tumor”) is known for its varied and abundant stroma. Various terms have been used to describe this neoplastic stroma; these include fibrous, hyaline, myxoid, and chondroid, the proportion of each type depending on individual cases. Myoepithelial cells are thought to play an important role in producing the pleomorphic extracellular matrix. Past studies have indicated that basement membrane compo-
Pulse oximeters are programmed to cease reporting oxygen saturation (Sao,) when pulsatile blood flow decreases below certain limits. This study examined three pulse oximeters (CSI [Criticare], Nellcor, Ohmeda) to determine their functional thresholds. Nine healthy adult males had arterial pressure cannulae placed in the right radial artery, with attachment of three reusable pulse oximeter probes to different fingers of the right hand. Ox-