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Biomedical subjects

S P Davison

Publications and source records attributed to S P Davison.

8 recordsLinked to original sources
PubMed1999

Improved nerve regeneration with neutralization of transforming growth factor-beta1.

OBJECTIVES: Recovery of injured peripheral nerves depends on a balance between Schwann cell regeneration and scar formation. Transforming growth factor-beta1 (TGF-beta1) has been implicated as a humoral stimulus in scar formation. The neutralization of TGF-beta1 has been beneficial in the reduction of fibrosis. This study was to identify the presence of TGF-beta1 in regenerating peripheral nerve and to measure motor nerve regeneration by the neutralization of TGF-beta1 in neural wounds. STUDY DESIGN: A randomized study of rat sciatic nerve regeneration. METHOD: Sciatic nerve axotomy was performed, followed by serial immunohistochemical staining by anti-TGF-beta1 at 12 to 216 hours (n = 5). Two groups (n = 10) with sciatic axotomy and epineural repair were treated with a 7-day perineural administration of neutralizing antibody of TGF-beta1 or saline carrier via subcutaneous silicone infusion port. A control group (n = 10) without axotomy with anti-TGF-beta1 administration was established. At 12 weeks the compound muscle action potential amplitude (CMAP) and the muscle twitch strength generated by the gastrocnemiussoleus muscle complex were measured. RESULTS: TGF-beta1 was qualitatively present with maximal concentration by 72 to 144 hours. CMAP amplitude in the anti-TGF-beta1/axotomy group was 49.6% of the control and the axotomy/saline group was 31% of the control. Muscle twitch strength was 74% and 46.5%, respectively. These differences were statistically significant, P = .05. CONCLUSIONS: The presence of TGF-beta1 at regenerating nerve sites was confirmed. The benefit of neutralization of transforming growth factor on CMAP and muscle twitch strength was shown. These results suggest improved regeneration at nerve injury sites with neutralization of TGF-beta1.

Action Potentials↗
PubMed1998

An algorithm for maxillectomy defect reconstruction.

A maxillectomy defect creates a communication from oral cavity to nasal cavity that may extend to the orbit. Functional deglutition and speech problems with a significant soft tissue deficit ensue. This paper defines the reconstruction options for the spectrum of inferior partial maxillectomy defects to midface-orbital exonerations. Treatment protocols from maxillectomy patients treated in January 1991 to February 1996 at a major tertiary care institution were reviewed (n = 108). An ascension of care from dental obturator, nonvascularized graft, local flap, regional flap, and free tissue grafts (n = 28) is described. These data and experience were organized to provide a treatment algorithm to assist in presurgical planning for maxillectomy reconstruction.

Algorithms↗
PubMed1998

Sensorineural hearing loss caused by NSAID-induced aseptic meningitis.

Aseptic meningitis is a rare complication of nonsteroidal anti-inflammatory drug (NSAID) use. Otologic symptoms may include sensorineural hearing loss and tinnitus. A 66-year-old woman sought the care of an otologist for sudden bilateral sensorineural hearing loss and a substantial increase in baseline tinnitus. The patient had previously undergone a left tympanoplasty secondary to cholesteatoma and had been treated for atypical face pain with ibuprofen taken every six hours for three months. Magnetic resonance imaging (MRI) with gadolinium demonstrated abnormal enhancement of the dura mater and the surrounding basal cisterns, with extension of enhancing dura mater into the internal auditory canals. Cerebrospinal fluid examination revealed evidence of aseptic meningitis. An audiogram confirmed new bilateral sensorineural hearing loss. Hearing loss and tinnitus resolved and no abnormalities were observed with MRI when nonsteroidal anti-inflammatory medication was discontinued. Otolaryngologists are well aware of the otologic sequelae in patients with meningitis. However, NSAIDs need to be considered as possible causal agents in the evaluation of meningitis with otologic symptoms.

Aged↗
PubMed1997

Use of magnetic resonance imaging and magnetic resonance angiography in diagnosis of sigmoid sinus thrombosis.

Magnetic resonance angiography is an established radiologic technique which is rapidly becoming useful in imaging the head and neck. Currently, this imaging modality is important in the diagnosis of sigmoid sinus thrombosis caused by otologic disease. Since the introduction of antibiotic therapy, the percentage of deaths attributed to intracranial complications from otitic disease has decreased from 2.5 to approximately 0.25% of documented deaths. Also, the incidence of sinus thrombosis within this group has decreased, but it is still a serious and potentially lethal condition. Sinus thrombosis is suspected clinically when mastoid disease progresses, with picket fence fever pattern, chills, headaches and signs of papilledema. Definitive diagnosis is necessary before surgical treatment. The Queckenstedt test is unreliable, computed tomography is better suited for demonstrating thrombosis of the sagittal sinus rather than the sigmoid sinus, and conventional angiography (although it provides excellent visualization) has the hazard of ionizing radiation and requires vessel puncture and the use of intraarterial contrast agents. We present two cases of thrombosis of the sigmoid sinus as an intracranial otologic complication which were diagnosed definitively with magnetic resonance imaging and magnetic resonance angiography. The combination of magnetic resonance imaging, which showed the thrombosis displaying abnormal signal intensity, and magnetic resonance angiography, which demonstrated the absence of flow in the sinus, was an ideal diagnostic tool. For both patients, treatment consisted of mastoidectomy, sigmoid sinus decompression and antibiotics.

Adolescent↗
PubMed1996

Nasal and nasopharyngeal angiocentric T-cell lymphomas.

Thirty patients (24 mean and 6 women) with a median age of 44.5 years who had angiocentric T-cell lymphoma were studied. The neoplastic cells in each had a T-cell phenotype. Epstein-Barr virus RNA was detected in the neoplastic cells in 29 of 30 patients. The most common presenting symptom was nasal obstruction followed by purulent rhinorrhea. Patients with early presentation had only a friable nasal or nasopharyngeal mucosa; late clinical signs included septal perforation in 40%. Twenty-one of 30 patients received radiation therapy as initial treatment; 22 of 30 patients achieved a complete remission. Fifteen patients relapsed: 10 with local recurrence and 5 with systemic disease. In long-term follow-up, 10 patients were alive and disease free, 6 patients died of unrelated causes, and 12 patients died of disease.

Adult↗
PubMed1995

A Clostridium acetobutylicum regulator gene (regA) affecting amylase production in Bacillus subtilis.

Plasmid pMET7C containing a 6.05 kb DNA insert from Clostridium acetobutylicum P262 made Escherichia coli F19 cells sensitive to metronidazole. The nucleotide sequence of the C. acetobutylicum DNA controlling metronidazole sensitivity in E. coli F19 revealed an ORF of 972 bp which encoded a protein of 324 amino acids with a calculated Mr of 35,000. The amino acid sequence encoded by the ORF contained a helix-turn-helix DNA-binding domain and was homologous to the catabolite control protein, CcpA, from Bacillus subtilis and Bacillus megaterium, a tRNA repressor of E. coli encoded by the shl gene, and the GalR, Lacl and PurR repressors of E. coli. The C. acetobutylicum ORF, which was termed regA, complemented a B. subtilis ccpA mutant and an E. coli shl mutant, but was unable to complement E. coli galR, lacl or purR mutants. To determine whether the regA gene product was involved in the regulation of amylase gene expression in C. acetobutylicum, a starch-degrading enzyme gene (staA) from C. acetobutylicum NCIMB 8052 was cloned. The RegA protein inhibited the degradation of starch by the C. acetobutylicum staA gene product in E. coli.

Acetoin↗
PubMed1990

Shade selection by color vision-defective dental personnel.

This investigation studied the impairment of Hue, Value, and Chroma matching by color vision-defective dental personnel. Color-defective dental personnel were found to make significantly greater errors in Hue and Chroma selection than normal-vision dental personnel. Value, the component of shade selection considered the most important, was uneffected. Color-normal dental assistants were significantly more accurate in Hue and Chroma selection than color-defective dental personnel and could assist affected dentists in clinical situations.

Adult↗