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Biomedical subjects

M D Russell

Publications and source records attributed to M D Russell.

At least 37 records · Page 2Linked to original sources
PubMed1986

Cutmarks on the Engis 2 calvaria?

An examination of the surface morphology of the juvenile Neandertal calvaria, Engis 2, has resulted in the discovery of several series of incised striations. The purpose of this paper is to describe and discuss these striations. A preliminary interpretation of at least some of the striations as cutmarks, made at or near the time of the child's death, is offered.

Child, Preschool↗
PubMed1986

A ten-year experience with fiberoptic bronchoscopy for mycobacterial isolation. Impact of the Bactec system.

From January 1974 to December 1983, positive mycobacterial isolates from all sources were reviewed to determine the impact of fiberoptic bronchoscopy (FB) on retrieval and identification of these organisms. There were 112 patients with positive cultures obtained during FB, 25 with Mycobacterium tuberculosis and 87 with mycobacteria other than tuberculosis (MOTT). We reviewed the results of prebronchoscopy and postbronchoscopy sputum specimens, bronchial washings, brushings, and transbronchial biopsy to determine the yield from each specimen in patients with M. tuberculosis. The bronchial washings provided positive cultures in 24 of 25 and were exclusively positive in 10 of 25 (40%). We also reviewed the clinical presentation, chest roentgenogram, bronchoscopy findings, and culture data for the 87 patients with MOTT isolated. The isolation of MOTT from bronchoscopy specimens increased throughout the study, most notably with the introduction of a rapid radiometric method (the Bactec system) for the recovery of mycobacteria to our laboratory in June 1983. Active disease could be established in only 13 of 87 cases (15%). Our findings confirm the sensitivity of Bactec in the isolation of MOTT from bronchoscopic specimens. The Bactec system, on the other hand, does not differentiate saprophytic colonization from clinical disease. To avoid expensive, time-consuming biochemical identification necessary to evaluate these MOTT isolates, careful selection of patients prior to obtaining mycobacterial cultures during FB is a critical factor.

Bacteriological Techniques↗
PubMed1985

A diagnostic X ray field verification device for a 10 MV linear accelerator.

The quality of portal films taken at megavoltage energies is frequently poor, despite the use of various techniques such as lead screens to improve the image. When critical structures, such as the spinal cord, are to be blocked out of the treatment field, it is frequently difficult to determine whether the block is correctly placed. To solve this problem, a diagnostic X ray source has been mounted on the side of a 10 MV linear accelerator to provide accurate verification of patient positioning and location of shielding blocks. The coincidence between the mechanical, 10 MV and diagnostic X ray isocenters is about 1 mm. The system has been designed so that procedures to monitor this coincidence, and adjustment procedures to maintain it, are easily performed.

Humans↗
PubMed1983

An investigation into the presence of secondary electrons in megavoltage photon beams.

The presence of secondary electrons in photon beams of 60Co and 4, 8, 10, 15 and 25 MV x-rays has been studied by measuring surface charge using thin window ionisation chambers. Measurements have been made for square fields from 4 X 4 cm2 to 35 X 35 cm2 for locations from the collimator head to a distance of 4 m from the target. In addition, measurements have been made for rectangular fields at 10 MV and 25 MV for fields of equivalent area from 5 X 5 cm2 to 25 X 25 cm2. By eliminating the inverse square effect, the presence of contaminants from the head and the effect of build-up in air are clearly seen and well separated. Comparison between the curves at different energies indicates an increasing effect of contamination from the head with energy and a decreasing effect of electron production in air with increasing energy.

Cobalt Radioisotopes↗
PubMed1983

The relationship of occlusal wear to occlusal contact area.

It has been suggested that masticatory efficiency is directly related to the area of the occlusal surfaces that make contact. However, little work has been carried out to determine if occlusal wear increases the area of contact, and controversy exists as to whether this would be an advantage. Using a wax registration method, occlusal contact area was measured in a group of individuals with either local or generalized wear, before and after treatment. The changes in occlusal contact area were statistically significant for the group exhibiting generalized wear but not for the group exhibiting localized war.

Dental Occlusion↗
PubMed1982

Tooth eruption and browridge formation.

One of the most reasonable hypotheses regarding the functional significance of the browridge is that the supraorbital torus forms in response to masticatory stress during development. Oyen, Walker, and Rice (1979) have recently proposed a model that tests this hypothesis: if browridges are functionally related to masticatory stresses on the cranial vault, then changes in the biomechanics of the masticatory system ought to be reflected by changes in the browridge. To test their model they attempted to relate biomechanical discontinuities resulting from tooth eruption to episodes of bone deposition on the supraorbital tori of a developmental series of dry Papio crania. This paper reports on a parallel test of the model on a cross-sectional sample of Australian Aboriginal juvenile crania. This sample showed no relation between tooth eruption and the supraorbital surface morphology thought to be indicative of active bone deposition. It is also demonstrated that no significant relationship between tooth eruption and episodes of bone deposition is shown by the Papio sample. It is concluded that the use of small cross-sectional samples of dry crania does not provide a valid test of the model.

Adolescent↗
PubMed1982

Use of 10 MV spoiled x ray beam for treatment of head and neck tumors.

The employment of a 10 MV X ray beam for treatment of head and neck tumors has been investigated. A 1.2 cm thick beam spoiler positioned 7 cm from the patient surface was used to achieve adequate dose to the superficial region. This technique provides at least 90% depth dose at 0.5 cm depth, which is clinically required for the treatment. For departments able to acquire only one megavoltage machine, the technique can provide an option to treat adequately both shallow as well as deep-seated tumors by choosing a high megavoltage machine; a low megavoltage machine cannot provide an equivalent option to treat deep-seated tumors.

Acrylic Resins↗
PubMed1981

Anterior dental cutting at Laetolil.

No evidence supports the interpretation of malocclusion in the LH-14 right P3. The pattern of anterior cutting shown in the younger laetolil specimens has its analogue in the deciduous dentitions of Pongo.

Animals↗
PubMedDate not supplied

The efficacy of practical participation in undergraduate dental education.

OBJECTIVE: This paper investigates the efficacy of practical participation as a vehicle for conveying knowledge of the subject of dental occlusion. METHODS: A fourth-year class of students was divided into two groups: one had benefited from a series of practicals focusing on the re-organized approach to occlusion, and the other had attended routine clinical sessions in conservative dentistry. Both had attended the same course of four lectures. Their knowledge was tested by means of a short answer question paper. RESULTS: The group attending the focused practicals out-performed the control group at the 0.01 level of significance. CONCLUSION: Practical participation would appear to enhance students' understanding of the subject of dental occlusion.

Clinical Clerkship↗