Arie Shteyer

The cannabinoid CB1 receptor regulates bone formation by modulating adrenergic signaling

We have recently reported that in bone the cannabinoid CB1 receptor is present in sympathetic terminals. Here we show that traumatic brain injury (TBI), which in humans enhances peripheral osteogenesis and fracture healing, acutely stimulates bone formation in a distant skeletal site. At this site we demonstrate i) a high level of the main endocannabinoid, 2‐arachidonoylglycerol (2‐AG), and expression of diacylglycerol lipases, enzymes essential for 2‐AG synthesis;ii) that the TBI‐induced increase in bone formation is preceded by elevation of the 2‐AG and a decrease in norepinephrine (NE) levels. The TBI stimulation of bone formation was absent in CB1‐null mice. In wild‐type animals it could be mimicked, including the suppression of NE levels, by 2‐AG administration. The TBI‐ and 2‐AG‐induced stimulation of osteogenesis was restrained by the β‐adrenergic receptor agonist isoproterenol. NE from sympathetic terminals is known to tonically inhibit bone formation by activating osteoblastic β2‐adrenergic receptors. The present findings further demonstrate that the sympathetic control of bone formation is regulated through 2‐AG activation of prejunctional CB1. Elevation of bone 2‐AG apparently suppresses NE release from bone sympathetic terminals, thus alleviating the inhibition of bone formation. The involvement of osteoblastic CB2 signaling in this process is minimal, if any.— Tam, J., Trembovler, V., Di Marzo, V., Petrosino, S., Leo, G., Alexandrovich, A., Regev, E., Casap, N., Shteyer, A., Ledent, C., Karsak, M., Zimmer, A., Mechoulam, R., Yirmiya, R., Shohami, E., Bab, I. The cannabinoid CB1 receptor regulates bone formation by modulating adrenergic signaling. FASEB J. 22, 285–294 (2008)

Resorption of the crown in impacted maxillary canine: A clinical, radiographic and histologic study

Thirty-six maxillary impacted canines which showed coronary resorption were selected out of 252 impacted canines. Clinical, radiographic and histologic observations were performed. In the majority of the cases (31) a local inflammatory factor was present and only in five cases was the resorption idiopathic. The incidence of resorption was highest in the later decades of life. In all cases bone replacement was found.

Interdisciplinary treatment of multiple unerupted supernumerary teeth. Report of a case.

Abstract A case of multiple supernumerary teeth is presented. The dentition exhibited retained deciduous teeth, unerupted permanent teeth, and a palatally displaced maxillary canine. Cooperation of the individual practitioners of three branches of the profession is considered mandatory in all aspects of the treatment, and emphasis is placed on correct timing of treatment. Patient motivation in relation to the specific problem is also discussed.

Radiographic and clinical manifestations of the impacted mandibular third molar

Observations were made on 200 impacted mandibular third molars that were removed from 200 unselected patients under local anesthesia. Sixty percent of the teeth were found to be in apparent relationship with the inferior dental canal: 19 % in true relationship and 41 % in superimposition. The vertical impacted molars were mainly found to be in true relationship with the inferior dental canal. On comparison of the clinical postoperative diagnosis with the radiographic preoperative findings an error of only 0.8 % was shown. Most of the molars showed fully developed roots in the third decade of life. Most of the teeth in this series were vertically impacted having mostly fully developed roots. There was a significant correlation between the patients suffering from pain, trismus, and swelling. Swelling and trismus were the mostly affected postoperative sequelae.

Mental nerve neuropathy associated with compound odontoma

An instance of anesthesia of the lower lip caused by a compound odontoma in the mental foramen region is described. Removal of the odontoma was followed by a full recovery of the sensation.

Sarcoidosis of the parotid salivary glands.

Salivary gland abnormalities in sarcoidosis are thought to be unusual-a conclusion based on a general lack of symptoms. Recently, however, thorough investigations by means of biopsies,’ objective tests of exocrine function such as quantitative saliva collection, biochemical studies,* 67galium citrate scan,3-4 and scintigraphy with ggtechnetium5 have suggested that salivary gland involvement may be much more prevalent than has been supposed. The purpose of this article is to present the case of a patient with bilateral large swellings in the parotid region that culminated in the diagnosis of sarcoidosis.

Median mandibular cyst

Since the median mandibular cyst is an extremely rare lesion, there is difficulty in determining the nature and origin of this entity. An additional case of a median mandibular cyst is described and an attempt is made to clarify the confusion associated with the diagnosis of this lesion. After a review of the literature it is suggested that the median mandibular cyst is a much rarer entity than was previously believed.

The diagnostic value of computed tomography in temporomandibular joint synovial chondromatosis

Synovial chondromatosis of the temporomandibular joint was diagnosed and location of dens particles was assessed by means of computed tomography. Based upon the data collected, the joint was operated conservatively and most of the calcifications were removed leaving the patient symptom free. The importance of an accurate preoperative diagnosis of synovial chondromatosis by use of CT scan is stressed in view of numerous unnecessary condylectomies and parotidectomies reported in the literature.

Submandibular tuberculous lymphadenitis (scrofula): Report of two cases

Two cases of scrofula are presented. These cases were very different in terms of age of the patient, duration of the lesion, and the clinical course. The final diagnosis was based on the histologic findings and tuberculin tests.

Characteristics of a neutral amino acid transport system (system A) in osteoblastic rat osteosarcoma cells

Transport of alpha-aminoisobutyric acid (AIB) in the clonal, osteoblastic-like cell line, ROS 17/2, was characterized. AIB transport was time-, temperature- and Na+-dependent. Both ouabain and monensin inhibited AIB transport in these cells. AIB uptake followed Michaelis-Menten kinetics with an apparent Km = 0.57 mM and a Vmax = 4.07 nmol/30 min/plate. These characteristics are consistent with the presence of system A neutral amino acid transport in ROS 17/2 cells. Exposure of ROS 17/2 cells to either parathyroid hormone or dibutyryl cyclic AMP (db-cAMP), but not to dibutyryl cyclic GMP (db-cGMP), markedly stimulated AIB transport. This suggests that extracellular stimuli which enhance osteogenic responses in this cell type, coordinately upregulate system A transport.