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Biomedical subjects

R A Reynolds

Publications and source records attributed to R A Reynolds.

At least 55 records · Page 3Linked to original sources
PubMed1976

Application of a multiwire proportional chamber to the detection of axoplasmic transport.

A new technique for the detection of the axoplasmic transport of beta-radioactively labelled materials is described wherein a multiwire proportional chamber is used to measure the distribution of activity along peripheral nerve fibers which are maintained in vitro. The operating principles of the chamber are described and basic construction parameters given. Potential radiolabels are discussed. Two types of studies were performed at room temperature in vitro using sciatic nerves of the amphibian Xenopus laevis: static and dynamic. In the static study the nerve ganglion was incubated for a suitable period of time in either L-(U-14C) leucine or L-(35S) methionine after which the ganglion was removed and the activity in the remaining nerve assayed with the chamber. In the dynamic study the nerve activity was assayed by the chamber while incubation proceeded so that a dynamic picture of transport could be observed. Using the second approach, transport rates were observed which are in agreement with others which have been reported in the literature. Some advantages and limitations of the technique are discussed.

Animals↗
PubMed1976

Improving access to health care among the poor--the neighborhood health center experience.

Utilization, cost, and productivity patterns at neighborhood health centers (NHCs) are examined on the basis of data from 82 centers. Minority groups and residents of the South and rural areas are found to have achieved levels of care and benefits closer to equality with other groups at NHCs than has been their health care experience generally. Continuity and comprehensiveness of care and the use of paramedical personnel are shown to be important contributory factors to utilization of NHCs. The impact of alternative cost-saving devices at NHCs is considered. It appears unlikely that professional productivity can be markedly improved. Increasing third-party payments is the most likely means of reducing dependence on operating grants without deleterious effects on utilization. The problem NHCs have had in maintaining stable professional staffs is shown to be a problem which needs further attention if the program is to expand.

Community Health Centers↗
PubMedDate not supplied

Techniques for the rapid display and manipulation of 3-D biomedical data.

The use of fully interactive 3-D workstations with true real-time performance will become increasingly common as technology matures and economical commercial systems become available. This paper provides a comprehensive introduction to high speed approaches to the display and manipulation of 3-D medical objects obtained from tomographic data acquisition systems such as CT, MR, and PET. A variety of techniques are outlined including the use of software on conventional minicomputers, hardware assist devices such as array processors and programmable frame buffers, and special purpose computer architecture for dedicated high performance systems. While both algorithms and architectures are addressed, the major theme centers around the utilization of hardware-based approaches including parallel processors for the implementation of true real-time systems.

Algorithms↗
PubMedDate not supplied

Variability in gait analysis interpretation.

The purpose of this study was to assess the reliability of interpretation of gait analysis data between physicians and institutions. Gait analysis data from seven patients were reviewed by 12 experienced gait laboratory physicians from six institutions. Reviewers identified problems and made treatment recommendations based on the data provided. Agreement among physicians for the most commonly diagnosed problems was slight to moderate (kappa range, 0.14-0.46). Physicians agreed on identification of soft tissue more than bony problems (intraclass correlation, 0.56 vs. 0.37). Variability regarding surgical recommendations for soft-tissue procedures (kappa range, 0.20-0.64) was similar to that for diagnosis of both soft-tissue and bone problems, although recommendation for hamstring lengthening showed substantial agreement (kappa = 0.64). There was less agreement in recommendation of osteotomies (kappa range, 0.13-0.22). Physicians agreed more on the number of soft-tissue procedures than bone procedures recommended (intraclass correlation, 0.65 vs. 0.19). There was an interinstitutional difference in the frequency of soft-tissue (p = 0.0152) and osseous problem identification (p = 0.0002), as well as in the frequency of recommendations for soft-tissue surgery (p = 0.0004) and osteotomies (p < 0.0001). Although gait analysis data are themselves objective, this study demonstrates some subjectivity in their interpretation. The interobserver variability reported here is similar to that reported for established classification systems of various orthopedic conditions.

Adolescent↗
PubMedDate not supplied

Titanium elastic nails for pediatric femur fractures: a multicenter study of early results with analysis of complications.

Titanium elastic nailing is used instead of traction and casting in many European centers, but limited availability has prevented widespread use in North America. Before a planned general release in America, titanium elastic nails (TENs) were trialed at several major pediatric trauma centers. This multicenter study is a critical analysis of early results and complications of the initial experience. Overall, TENs allowed rapid mobilization with few complications. The results were excellent or satisfactory in 57 of the 58 cases. No child lost rotational alignment in the postoperative period. Irritation of the soft tissue near the knee by the nail tip occurred in four patients, leading to a deeper infection in two cases. As indications, implantation technique, and aftercare are refined, TENs may prove to be the ideal implant to stabilize many pediatric femur fractures, avoiding the prolonged immobilization and complications of traction and spica casting.

Adolescent↗
PubMedDate not supplied

An algorithm for three-dimensional visualization of radiation therapy beams.

A computer algorithm to display radiation beams superimposed on three-dimensional (3-D) views of patient anatomy has been developed. It may be implemented as a postprocessing step to existing software for 3-D presentation and display. The algorithm takes as input a shaded 3-D view (reconstructed, for example, from computed tomography scans), together with the associated depth map, and generates as output an enhanced 3-D view highlighting in color the visible points which lie within the projected beam outlines. The algorithm is independent of the method used to generate the 3-D view (surface or volume rendering techniques may be used) and is independent of beam shape (beams may be modified with shielding blocks). It is not restricted to external surfaces and will correctly show radiation beams projected onto cut-away views of internal organs. The method is illustrated by application to a tangential pair for breast malignancy, using 3-D views generated with volume rendering software.

Algorithms↗
PubMedDate not supplied

A technique to determine proper pin placement of crossed pins in supracondylar fractures of the elbow.

Supracondylar humerus fractures are the most common elbow injury in children. Stable fractures can be closed, reduced, and casted, whereas unstable fractures require percutaneous pinning. Studies have shown that there is a biomechanical advantage of crossed pin fixation as opposed to two lateral pin fixation. However, medial pin placement has the risk of injuring the ulnar nerve. This modification of technique was used on 46 patients, aged 12 months to 14 years (median age, 3.6 years). Two patients had an ulnar sensory and motor neurapraxia, and two patients had cubitus varus deformities postoperatively. Thus, a safe, easy, and reproducible technique of crossed pin fixation is described here.

Adolescent↗