Search PubMed⌕ Search

Biomedical subjects

C McNeill

Publications and source records attributed to C McNeill.

At least 37 records · Page 2Linked to original sources
PubMed1994

31P-magnetic resonance spectroscopy of the rabbit masseter muscle.

Dynamic biochemical changes in the masseter muscle were studied in 14 New Zealand adult male rabbits by 31P-nuclear magnetic resonance (NMR) spectroscopy. NMR spectra were obtained during rest and electrical stimulation of the muscle in the anaesthetized animal at 33 recording sessions. Electrical stimulation was applied by a pair of copper wires placed separately with hypodermic needles into the muscle. NMR spectra were acquired with a 2 x 3 cm, double-turn, copper transmit/receive coil. Sixteen spectra were averaged over 30 s to obtain averaged spectra continuously during a 30-min recording. The spectra were processed automatically using a non-linear 'least-squares' fitting program on the spectrometer. A Lorentzian line shape was assumed for the peaks, and values of peak height, area and chemical shifts were generated. Each averaged spectrum consisted of five peaks: inorganic phosphate (Pi), creatine phosphate (PCr), and three peaks related to ATP. Data were analysed as to absolute changes in Pi and PCr, in the ratio of Pi/PCr, and the shift of Pi to PCr to estimate pH. Several protocols were used in which ranges of frequency, intensity and duration of electrical stimulation were tested. The protocol for detailed studies involved stimulating the muscle twice at 5 Hz for 3 min separated by a 3-min rest period, then stimulating twice at 50 Hz for 3 min separated by a rest period. During contraction of the muscle, there was a significant increase in the Pi/PCr ratio (p < 0.05) as compared to the resting level. The ratio reached a plateau over a 3-min contraction using 5-Hz stimulation, then increased significantly more with the 50-Hz stimulation but decayed during the 3 min. Sustained stimulation with 50 Hz for 15-45 min evoked an initial sharp change in Pi/PCr, which then reached a steady plateau that remained over the entire stimulation. These findings indicate that the rabbit masseter muscle is relatively fatigue resistant in maintaining a steady-state equilibrium in the relation of Pi to PCr.

Adenosine Triphosphate↗
PubMed1992

Effect of an anesthetic injected into the temporomandibular joint space in patients with TMD.

Twenty-three adult female patients were studied before and after injection of one temporomandibular joint to relieve pain. These patients had exhibited a persistent history of pain within their mandibular, neck, and somatic muscles, despite repeated treatment involving occlusal splints, physical therapy, and biofeedback. Patients were also screened for possible condylar degeneration using corrected tomograms. Initially, patients rated their pain on a linear scale from 0 to 10 and designated the site of the pain on a full-body-profile chart. The presence and location of the pain was determined by manual palpation using a rating scale of 0 to 10, and by the patients designating those regions perceived as painful by marking a full-body-profile chart. After this initial screening, subjects received an injection of 1% lidocaine (1:100,000) to the upper intracapsular space of one joint. The pain profile chart was completed by the patients 15 minutes after injection. Twenty of the 23 patients demonstrated a significant decrease in pain located in facial, head, and neck regions. These data suggest that injection of a local anesthetic to the temporomandibular joint will decrease pain for a short time in ipsilateral and contralateral regions of the head and neck.

Adolescent↗
PubMed1991

Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry.

Subjects of the past decade in the dental literature are reflected in this year's Committee report. We note the decrease in the prevalence of caries, the influence of dental implants, the advancements in dental materials, and the continued efforts to control adhesive events in the oral cavity. This year we included comments from and about many significant review articles published this past year. The Committee continues to be concerned about the quality of some of the work reported and the quality of the reporting. We have attempted to select the distinguished work, that which provides new information to our profession. The subjects covered include pulp biology, caries prevention, periodontics, implants, craniomandibular function and dysfunction, occlusion, and dental materials.

Dental Bonding↗
PubMed1991

Signs and symptoms in samples with and without temporomandibular disorders.

Factors commonly associated with signs and symptoms of temporomandibular disorder were investigated in two groups. The patient group consisted of 41 subjects seeking treatment at the UCSF Temporomandibular Disorders Clinic, and the control group consisted of 40 incoming and first-year students. Questionnaires and clinical examinations were used to identify and measure factors in the areas of history, functional signs, and occlusion. Only four factors emerged as statistically significant between groups: frequent headaches, masticatory muscle tenderness, cervical muscle tenderness, and maximum opening.

Adult↗
PubMed1990

Adaptation of craniofacial muscles in subjects with craniomandibular disorders.

The purpose of this study was to examine muscle function in subjects with muscle pain. Forty-three subjects with pain in the craniomandibular muscles, clinically determined by manual palpation, were studied for alteration in recruitment of temporalis, masseter, and suprahyoid muscles during a series of phasic movements. Seventeen normal subjects were used as controls. The subjects with muscle pain were divided into three subgroups: (1) those with pain in both mandibular and neck muscles; (2) those with pain in these two muscle groups with joint degeneration; and (3) those subjects with pain only in mandibular muscles. Surface electromyographic (EMG) recordings were taken as each subject performed 16 different responses in which mandibular incisor movement was tracked simultaneously. The results show that the subjects with muscle pain use their anterior temporalis muscles with less frequency (i.e., probability) and with less intensity in several responses than normal subjects. These responses include rapid vertical closing movements, retrusion, ipsilateral laterotrusion, and natural as well as contralateral mastication. The masseter muscle is impaired much less in its function, and the recruitment of the suprahyoid muscles is not affected in the patients with muscle pain. Comparison of the bilateral activity in the anterior temporalis muscles during intercuspal clenching shows that the subjects with muscle pain often demonstrate a more severe asymmetrical recruitment of these muscles than the more symmetrical recruitment seen in normal subjects. Similar observations were made for the masseter muscle. These studies demonstrate that subjects with muscle pain in craniomandibular muscles alter the recruitment of their jaw muscles, thus supporting the concept that the neuromuscular system is altered in patients with craniomandibular disorders.

Adult↗
PubMed1990

Psychological factors that predict AIDS high-risk versus AIDS precautionary behavior.

Men (N = 526) who patronized gay bars in three cities completed measures of sexual behavior covering the previous 3 months and psychological measures theoretically pertinent to AIDS risk. Thirty-seven percent of the sample reported engaging in unprotected anal intercourse, the behavior most strongly associated with transmission of human immunodeficiency virus (HIV) infection. Perceived peer norms concerning the acceptability of safer sex practices, AIDS health locus of control scores, risk behavior knowledge, age, and accuracy of personal risk estimation, but not personal HIV serostatus knowledge, were associated with high-risk and precaution-taking behavior.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Temporomandibular joint: morphology and signal intensity characteristics of the disk at MR imaging.

Magnetic resonance (MR) imaging has been used in the temporomandibular joint (TMJ) primarily to define the disk position. This report examines altered morphology and signal intensity characteristics of the TMJ disk as they relate to the severity of internal derangement. Two hundred sixteen joints in 133 patients with a history of such derangement. were imaged with MR. Disk position, signal intensity, morphology, and the presence of osteoarthritis were determined for each joint. The normal disk was not anteriorly displaced and had a normal "bow-tie" shape. A grade 1 disk was anteriorly displaced and had a normal shape; a grade 2 disk was anteriorly displaced and had an abnormal shape. Forty (19%) joints were considered normal; none of these exhibited osteoarthritis. One hundred thirty-nine (64%) joints were grade 1; osteoarthritis was found in 17%. Thirty-seven (17%) were grade 2; osteoarthritis was found in 95%. All forty normal joints had high or intermediate signal intensity in the disk. Osteoarthritic joints had a higher percentage of disks with diminished intensity (P less than .0001). Severe or untreated osteoarthritis is known to be a complication of TMJ internal derangements; hence this grading system seems to correlate with the severity of internal derangement.

Adult↗
PubMed1989

Staging of internal derangements of the TMJ with magnetic resonance imaging: preliminary observations.

Although MRI has been reported to be accurate in diagnosing displaced TMJ menisci, it has not been used to characterize the condition of the meniscus. A staging system of internal derangement of the TMJ using MRI signal characteristics and morphology of the meniscus is presented. A normal meniscus has the appearance of a small "drumstick" and is positioned superiorly on the mandibular condyle. It produces a small amount of intermediate signal on the MRI. A grade 1 displaced meniscus has normal shape and signal; a grade 2 meniscus has normal shape and absent signal; a grade 3 meniscus has abnormal shape and absent signal. There was a significant correlation between meniscus grade and chronicity of symptoms, severity of pain, and presence of degenerative joint disease in 62 joints (39 patients).

Adolescent↗