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Biomedical subjects

E Ellis

Publications and source records attributed to E Ellis.

At least 145 records · Page 8Linked to original sources
PubMed1991

Histologic examination of the temporomandibular joint after mandibular advancement with and without rigid fixation: an experimental investigation in adult Macaca mulatta.

This study evaluated the histologic response of the temporomandibular joint (TMJ) following mandibular advancement using rigid and nonrigid fixation in monkeys. Twelve adult female rhesus monkeys underwent sagittal ramus osteotomies with advancement. Six of them were placed into maxillomandibular fixation (MMF); six underwent bicortical bone-screw fixation without MMF. Changes in condylar position were quantified using lateral cephalograms with the aid of bone markers. The animals were killed at 6 weeks and the TMJs were prepared for histologic analysis. Three measures of condylar cartilage thickness were obtained for each animal and were correlated to changes in position of the condyle. Animals who underwent MMF showed a tendency for anterior movement of the condyles; animals who underwent rigid fixation showed a tendency for posterior condylar position. Thicker cartilage layers were found in the MMF animals. Animals who had posterior displacement of the condyles showed evidence of resorption of the posterior surface of the condyle and anterior surface of the postglenoid spine. There was a significant correlation between a change in the horizontal position of the condyle and the thickness of the posterior aspect of the condylar cartilage. The results of this study indicate that alterations in condylar position may induce remodeling changes within the TMJ.

Animals↗
PubMed1991

Effects of local anesthesia on bite force generation and electromyographic activity.

Maximum voluntary bite force has been used to evaluate functional changes following orthognathic surgery. It has been proposed by others that maximum voluntary bite force may depend, in part, on sensory input from the dentition. However, results from previous studies have shown contradictory effects of local anesthesia on bite force following anesthetization of the dentition. The purpose of this study was to investigate the effects of drug-induced local anesthesia on the generation of first molar bite force and electromyographic (EMG) activity in adults. Twenty normal adults (3 women, 17 men) were evaluated. Electromyographic activity was monitored from four muscles of mastication bilaterally, and bite force was concurrently recorded at the right and left first molars. Maximal and submaximal bite forces were then measured after sequential unilateral anesthetization of the right mandible and maxilla with 2% lidocaine containing 1:100,000 epinephrine. No statistically significant differences in bite force or integrated EMG levels were observed between the unanesthetized and anesthetized sides, nor on the anesthetized side at different levels of anesthesia.

Adult↗
PubMed1991

An assessment of the predictability of maxillary repositioning.

The purpose of this investigation was to compare our ability to perform the surgery that is planned in the prediction tracing and model surgery when using the mandible as a guide to maxillary repositioning, using internal and external reference points to establish the vertical dimension at the time of surgery. A total of 146 consecutive patients who underwent maxillary repositioning by means of Le Fort I osteotomy were selected. In all patients the unoperated mandible was used to provide anteroposterior and transverse maxillary position. In 100 patients, measurements made on the lateral wall of the maxilla (internal reference points--IRP) were used to determine the maxillary vertical dimension. In 46 patients, the vertical dimension was established by measuring between a Kirschner wire in the nasal bridge and a maxillary incisor (external reference points--ERP). Comparison between the predicted and actual change in the position of the incisor was calculated. Statistical analysis showed that there were significant differences between the predicted and actual change in vertical and horizontal position of the incisor (p less than 0.0001) for both experimental groups. However, there was a significant difference between the 2 experimental groups (p less than 0.001) for the accuracy of vertical repositioning. The use of an external reference point proved to be a more accurate method for vertical maxillary repositioning. The results of this investigation indicate that the ability to determine vertical repositioning of the maxilla with internal reference lines is limited.

Bone Nails↗
PubMed1991

Treatment options for hairy-cell leukemia.

In 1991, there are numerous proven therapies for the treatment of hairy-cell leukemia. Since none have been proven to be curative, it is important that all be considered, as individual patients might need to undergo a series of sequential treatments with each. In fact, some elderly patients with minimal splenomegaly and relatively normal blood counts might require no therapy. Splenectomy has a role in rapid reversal of severely depressed blood counts in association with a systemic infection; however, growth factors might soon replace this role of emergency splenectomy. Treatment with recombinant interferon results in few complete remissions, but with normalization of peripheral blood counts in over 80% of patients. In the original interferon alfa-2b study of 195 patients, only three of the 159 patients achieving a normalization of their blood counts have subsequently died. Treatment with deoxycoformycin either after interferon or initially has resulted in an apparent complete remission rate of approximately 60%, but recent follow-up analyses suggest that hairy cells persist within the bone marrow; however, patients seem to remain in a clinical remission. Treatment with 2-chlorodeoxyadenosine shows little toxicity and a high apparent complete remission rate. However, review of the posttreatment bone marrow specimens remains to be done, and longer follow-up is necessary to assess true differences in the degree of response from interferon or deoxycoformycin treatment. Advances in therapy over the past decade have led to significant benefits for patients with hairy-cell leukemia.

Humans↗
PubMed1990

Response of rat cerebral cortical astrocytes to freeze- or cobalt-induced injury: an immunocytochemical and gap-FRAP study.

Astrocytic response in the immediate vicinity of freeze- and cobalt-induced lesions has been examined at the light and ultrastructural level. However, the temporal and spatial distribution of astrocytic reactivity throughout the rat cerebral cortex, using glial fibrillary acidic protein (GFAP) immunolabeling, has not been examined. The first purpose of this study was to establish the chronological distribution of astrocytic reactivity, as measured by changes in GFAP immunoreactivity, following freeze- or cobalt-induced injury to the rat cerebral cortex. Cobalt metal also has been proposed to have a direct effect on astrocytes and has been shown to stimulate in vitro astrocytes to become reactive. The second purpose of this report was to determine if cobalt had an effect on in vitro astrocytic gap junctional dye coupling as measured by fluorescence recovery after laser-photobleaching (gap-FRAP). Although the chronological development of the increased GFAP immunoreactivity was different for the freeze- and cobalt-induced lesions, astrocytes initially showed an increase in GFAP immunoreactivity in the region surrounding these lesions. This initial response was followed by a spread of increased GFAP immunoreactivity throughout certain regions of the ipsilateral cerebral hemisphere and then by a restriction of the increased immunolabeling to the lesion site. Cobalt also had a direct effect on in vitro astrocytes as demonstrated by the inhibition of astrocytic gap junctional dye coupling. Based on gap-FRAP analysis, cobalt significantly blocked fluorescence recovery (2.5%) as compared to the fluorescence recovery in control astrocytes (26%). It is proposed that the initial increase in GFAP immunoreactivity may be due to decreased gap junctional activity.

Animals↗
PubMed1990

An assessment of the predictability of maxillary surgery.

The purpose of this investigation was to determine the ability to perform the surgery that is planned based on the prediction tracing and model surgery when using the mandible as a guide to maxillary repositioning and internal reference points to establish the vertical dimension at the time of surgery. One hundred consecutive patients who underwent maxillary repositioning by means of Le Fort I osteotomy were selected. In all patients the unoperated mandible was used to provide anteroposterior and transverse maxillary position and measurements made on the lateral wall of the maxilla (internal reference points, IRP) to determine the maxillary vertical dimension. Tracings of all cranial structures were made of the preoperative cephalograms and superimposed on the postoperative cephalogram and on the prediction tracing using cranial base structures. Points were digitized to compare the preoperative, postoperative, and predicted position of the maxillary central incisor and first molar of each patient by computer. Comparison between the predicted and actual change in the position of the incisor and molar was calculated. Statistical analysis showed that there were significant differences between the predicted and actual change in vertical and horizontal position of both the incisor and the molar (P less than .0001). The results of this investigation indicate that the ability to determine vertical repositioning of the maxilla with internal reference lines is limited.

Analysis of Variance↗
PubMed1990

Electromyography of the suprahyoid musculature following mandibular advancement with and without rigid fixation.

The purpose of this investigation was to determine if the activity of the suprahyoid musculature changes following advancement of the mandible and the use of rigid or nonrigid fixation. Ten monkeys underwent mandibular advancement; six underwent 6 weeks of maxillomandibular fixation (MMF), and four had rigid fixation without MMF. Electromyography (EMG) of the suprahyoid musculature was performed preoperatively, and at 3, 7, and 10 weeks postoperatively. The results of this study fail to demonstrate an increase in suprahyoid EMG activity following mandibular advancement. Furthermore, there were no differences between the groups with different types of fixation.

Analysis of Variance↗
PubMed1990

Histochemical analysis of the masseter and temporalis muscles in macaca mulatta after mandibular advancement using rigid or nonrigid fixation.

This study compared the histochemical characteristics of the temporalis and masseter muscles in monkeys who underwent mandibular advancement with and without immobilization of the mandible. The results showed, when compared with controls, that the animals who underwent maxillomandibular fixation (MMF) following advancement of the mandible had significant atrophy in both temporalis and masseter muscles. In contrast, much less myoatrophy was noted in the animals who underwent rigid internal fixation and no MMF following advancement of the mandible.

Analysis of Variance↗
PubMed1990

Accuracy of model surgery: evaluation of an old technique and introduction of a new one.

This article evaluates the ability of 4th-year residents to accurately perform maxillary model surgical repositioning in the conventional manner. Using a special model surgery--measuring platform, measurements of the maxillary dental casts were recorded before and after model surgery was performed by residents in 20 bimaxillary cases. The model surgery was performed in the usual manner described in several texts, using reference lines scored on the casts and measurements made to the incisal pin and upper member of the articulator. Analysis of the differences between the planned movements and the postsurgical position of the maxillary model surgery casts showed statistically significant errors in maxillary repositioning for all measures. This indicates that the manner in which model surgery was performed by the residents, as reported in the literature, was inaccurate. A new technique and instrument for more accurately recording measurements and repositioning the maxillary cast is introduced.

Audiovisual Aids↗
PubMed1990

Enhancement of infusion-induced brain edema by mediator compounds.

Mediator compounds such as bradykinin, arachidonic acid, and LT are released in the brain in conditions causing cerebral swelling. The potential of these compounds to enhance this process was studied in the infusion-induced model of brain edema. Cats subjected to chloralose anesthesia were infused with 400 microliters of artificial CSF into the right and left frontal white matter within 2.5 hr. CSF infused into the left hemisphere contained either bradykinin (40 microM), arachidonic acid (3 mM), LTB4 (15 microM), or LTC4 (16 microM), respectively. Evans blue was administered as blood-brain barrier indicator. Water content of gray and white matter was microgravimetrically determined in serial coronal brain slices. Infusion of CSF only led to an increase in water content from 69 to between 75% and 79%. Addition of bradykinin effectively enhanced the infusion edema but did not open the barrier to Evans blue. Arachidonic acid even more effectively led to an increase in water content and opened the barrier to Evans blue, in addition. Infusion of LT (LTB4, as well as LTC4) was not found to increase further the infusion edema and did not open the blood-brain barrier to Evans blue. It is concluded that the infusion edema model is suitable for studying the edema-enhancing potential of mediator compounds. Marked enhancement of vasogenic brain edema by bradykinin or arachidonic acid again demonstrates a pathophysiological function of these compounds as mediators of secondary brain damage, although LT are unlikely to be specifically involved in vasogenic edema formation.

Animals↗
PubMed1990

Diagnosis and treatment planning for the surgical-orthodontic patient.

Contemporary orthognathic surgery has made it possible to reposition either or both jaws in one piece or as segmental osteotomies. This has provided the patient, who has a severe dentofacial problem, with the option of having all components of their malocclusion and facial aesthetic concerns addressed. The close collaboration between the orthodontist and the surgeon provides a comprehensive diagnosis and treatment plan to be generated. The goal of the presurgical phase of orthodontics is to remove the dental compensations and allow optimum surgical correction of the jaw discrepancy. A short phase of orthodontic treatment postoperatively is usually necessary to detail the final occlusion. A systematic approach to diagnosis and treatment planning is discussed in the context of the problem-oriented approach. The application of this approach is illustrated in a case report of the combined orthodontic-surgical treatment of a patient who benefited from a two-jaw surgical procedure with pre- and postoperative orthodontic treatment. The principles of presurgical orthodontic treatment are discussed and should avoid any counterproductive tooth movements that can be part of the surgical correction. Tooth movements done as part of the postoperative treatment should avoid compromising the surgical outcome. Illustrations of the cephalometric prediction tracing and its application to the diagnosis and treatment plan of the patient discussed in the case report is an important aspect in providing the dentofacial patient with a representation of the expected treatment outcome.

Clinical Protocols↗