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Biomedical subjects

T M Levine

Publications and source records attributed to T M Levine.

10 recordsLinked to original sources
PubMed1996

Authentic 17 kDa tumour necrosis factor alpha is synthesized and released by canine mast cells and up-regulated by stem cell factor.

BACKGROUND: Previous studies have suggested varying molecular weights for mast cell derived tumour necrosis factor alpha (TNF alpha ) and little data exist upon the factors which may regulate the control of this cytokine in these cells. OBJECTIVE: To determine the molecular weight of canine mastocytoma-derived TNF alpha, to determine whether it is pre-formed within the granule and whether is expression could be up-regulated by stem cell factor (SCF). METHODS: Molecular sizing was assessed by immunoblot. The cellular localization of the TNF alpha was determined by immunocytochemistry before and after stimulation by A23187 and passive sensitization. Subcellular localization was performed by immunogold immunocytochemistry. Changes in the level of mastocytoma mRNA for TNF alpha in response to stimulation with SCF or fibroblast conditioned media for up to 12 weeks were studied using Northern analysis and changes in the level of TNF alpha protein expression on immunoblot and immunocytochemistry. RESULTS: Mast cells contained authentic 17 kDa TNF alpha as identified by immunoblotting. Immunocytochemical studies demonstrated preformed TNF alpha which was released by stimulation with antigen after passive sensitization, or by the calcium ionophore A23187. Further confirmation of the preformed nature of this TNF alpha was provided by immunogold electron microscopy which localized this cytokine to the granule of the inactive mast cell. Northern blotting revealed a constitutive message for TNF alpha, which increased in response to fibroblast conditioned media (FCM) and to recombinant human SCF. Immunocytochemical studies of mast cells cultured long-term with FCM or with recombinant SCF showed increased expression of TNF alpha over the course of 12 weeks incubation with these stimuli. CONCLUSION: Mastocytoma derived-TNF alpha is a preformed, granule-associated 17 kDa cytokine which is released on stimulation with A23187 or passive sensitization. It is up-regulated by stem cell factor and by FCM over the course of 12 weeks.

Animals↗
PubMed1993

Mitogen-inducible prostaglandin G/H synthase is expressed in canine mastocytoma cells.

A mitogen-inducible prostaglandin G/H synthase (PGHS-2 or cyclooxygenase-2) has recently been cloned from chicken and mouse fibroblasts. This protein is distinct from classic prostaglandin G/H synthase (PGHS-1 or cyclooxygenase-1) but has a similar enzymatic activity. Because PGHS-1 is a rate-limiting enzyme in the synthesis of prostaglandins, PGHS-2 may also play an important role in prostaglandin production. To examine whether PGHS-2 is induced by phorbol ester in mast cells, we studied mRNA expression of PGHS-2 and also measured prostaglandin D2 (PGD2) production when canine mastocytoma cells were incubated with phorbol myristate acetate (PMA). PGHS-2 mRNA was induced by PMA, with a maximal induction after 4 h of incubation with 10 nM PMA. There was concentration-dependent production of PGD2 after incubation with PMA. In contrast, PGHS-1 mRNA was expressed in resting cells, and the expression of PGHS-1 mRNA was down-regulated by PMA. Dexamethasone inhibited PMA-induced mRNA expression of PGHS-2 and PGD2 production. Aspirin had no effect on mRNA expression of PGHS-2 but inhibited PGD2 production. In conclusion, PGHS-2 is induced by phorbol ester in canine mast cells. We speculate that PGHS-2 may be important in airway inflammation in which mast cells are activated.

Animals↗
PubMed1989

Laser lingual tonsillectomy.

Diseases of the lingual tonsils are generally overlooked in both clinical practice and medical literature. Infections of the lingual tonsils are usually treated medically, although in patients with symptomatic chronic inflammation or hyperplasia of the lingual tonsils, surgical intervention may be indicated. Eighty-two patients with benign inflammatory problems of the lingual tonsils, who were not improved by medical management, underwent laser lingual tonsillectomy at four different medical centers, between 1984 and 1987. The procedure was tolerated well by all of the patients, with no significant operative complications. Short- and long-term results were satisfactory. Laser surgery is an effective method for the treatment of benign hyperplastic and inflammatory diseases of the lingual tonsils.

Adolescent↗
PubMed1988

Surgical management of aspiration.

Chronic recurrent aspiration can occur in patients suffering from a diverse group of pathologic processes. Many innovative surgical procedures are available to compensate for severe functional deficits. Some of these procedures can be reversed if the patient recovers from his or her underlying disability. An open-minded, eclectic approach is the best way of preventing the disastrous sequelae of chronic aspiration.

Gastroesophageal Reflux↗
PubMed1988

Swallowing disorders following skull base surgery.

The modern otolaryngologist-head and neck surgeon has the technical ability to perform a wide range of surgical procedures at the skull base. Associated with some of these operations are swallowing deficits secondary to cranial nerve paralyses or anatomic disturbances. The skull base surgeon must physically and emotionally prepare patients preoperatively for these functional disabilities.

Cranial Nerves↗
PubMed1987

Sublabial transseptal repair of choanal atresia or stenosis.

Bilateral choanal atresia in newborns and infants carries significant morbidity and mortality, therefore, prompt correction is required. The transnasal route is usually preferred in the infant age group. This approach, however, carries significant incidence of restenosis. The transpalatal correction of choanal atresia has been the definitive approach in older children and adults. We are introducing a new procedure for correction of choanal atresia or stenosis that can be used at any age. The sublabial transseptal repair was performed in four infants without complications or restenosis. Two of our patients previously underwent different types of repair with persistent choanal stenosis. The sublabial transseptal approach provides wide exposure to the nasal cavity and the floor leading to the choanae. The operating microscope and various otologic micro-instruments were used in the surgical dissection. Preservation of the anterior inferior cartilaginous septum and the maxillary crest and spine is mandatory in order not to disturb the nasal growth pattern of the nose and premaxilla. The infants were evaluated with a computed tomography (CT) scan, preoperatively. The posterior inferior portion of the vomer is uniformly wide, increasing the degree of stenosis or atresia. Removal of the vomer is an essential part of this procedure in order to open and enlarge the choanae. Both choanae were stented with polyvinyl tubes. Every attempt was made to keep the stents in position for a minimum of 8 to 10 weeks. Follow-up has been for 2 to 4 years, and no recurrent choanal stenosis has been experienced.

Choanal Atresia↗
PubMed1986

Surgical aptitude test for otolaryngology-head and neck surgery resident applicants.

The search for a convenient, rapid manual dexterity examination, which could be used at the time of the otolaryngology resident applicant's interview, led us to assess the following areas: purposeful hand direction, depth perception, tactile discrimination, finger pressure coordination, finger visual tracking of moving objects, spatial visualization, finger strength, speed of movements, fine control precision, finger dexterity, steadiness during movement, steadiness without movement, and neatness. With the astronomical increase in applicants to a limited number of positions in the field of otolaryngology-head and neck surgery, the application of an accurate, efficient manual dexterity assessment at the time of applicant interview is desirable. Presently, dental school applicants are screened by a series of manual dexterity tests. To develop our screening test, we integrated manual performance tests currently in use by private industry, occupational therapists, and dental school admission committees. Thus, applicants who are able to master fine microsurgical and macrosurgical techniques common in our specialty will be preferentially selected.

Aptitude Tests↗
PubMed1986

Mediastinitis occurring as a complication of odontogenic infections.

Mediastinitis occurring from a descending odontogenic infection occurs rarely. The diagnosis is sometimes difficult to make and is often delayed until the patient is in extremis. The physical examination is often nondiagnostic, but may include brawny edema of the neck and chest. CT scanning provides the most accurate diagnostic information. The treatment is always surgical, in combination with appropriate antibiotics. Five patients with mediastinitis secondary to odontogenic infections are presented, and the technique of transcervical drainage of the anterior and posterior mediastinum is reviewed.

Adult↗
PubMed1986

Skull base chordomas.

Chordomas are rare, benign tumors of the nasopharynx. Because of their location at the skull base, removal of these tumors is usually subtotal. Described is the transcervical-transmandibular approach to the skull base which can be employed in removing these tumors.

Chordoma↗