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Biomedical subjects

R A Mann

Publications and source records attributed to R A Mann.

At least 109 records · Page 6Linked to original sources
PubMed1981

Hallux valgus--etiology, anatomy, treatment and surgical considerations.

The etiology of hallux valgus, method of patient selection, technique of carrying out a modified McBride procedure, and possible surgical pitfalls associated with the procedure are discussed. The results of the McBride procedure and the limitations that the authors feel should be placed upon the procedure were stressed. The authors believe that the modified McBride procedures is biomechanically sound and offers patients a most satisfactory correction of their deformity. The procedure has a very low incidence or postoperative complications, and if a complication arises, the surgeon has many good alternatives with which to correct the problem.

Biomechanical Phenomena↗
PubMed1980

Arthrodesis of the first metatarsophalangeal joint.

A series of 41 first toe metatarsophalangeal joint arthrodeses performed in 28 patients was subjectively and objectively evaluated by personal interview, physical examination, and follow-up X-rays. The length of the post-operative follow-up ranged from 5 to 58 months, with an average of 35 months. The overall rate of fusion was 95%. Excellent or good results were obtained in 28 procedures, representing 68% of the study of the patients. Utilizing this procedure in the treatment of severe forefoot deformities, secondary to rheumatoid arthritis, demonstrated that 85% of the patients obtained excellent or good results, and, in the treatment of patients with failed bunion surgery, 53% obtained excellent or good results.

Arthrodesis↗
PubMed1979

Morphology of experimental spina bifida in the chick embryo.

Open malformations of the central nervous system may involve the brain or spinal cord, or both. Preliminary experiments in which a window was cut in the shell overlying early chick embryos (with removal of 2 ml of albumen) produced a range of neural and non-neural malformations. Exposure of Stage 5--10 embryos at 26 hours of incubation produced open brain and cord defects. Embryos were recovered at 11--12 days for gross examination. Open cord defects in 12 day experimental embryos could be divided morphologically into 2 types. One group showed an everted symmetrical plaque of neural tissue. In the other group the cord defect was more irregular, partly covered by skin, and often combined with rump and trunk defects. Skeletal staining showed that vertebral lesions increased in severity in a cranio-caudal sequence. Spina bifida occulta was found in the cervical and upper thoracic regions; spina bifida manifesta, associated with open cord defects, occurred from the lower thoracic to the sacral regions; vertebral deletions were almost confined to the caudal region. Spina bifida manifesta at the site of open cord defects also showed 2 distinct patterns. Regular cord defects were associated with regular spinal defects, showing loss of spinous processes, reduction of laminae and eversion of the pedicles. Irregular cord defects were associated with more irregular spinal defects showing vertebral deletions or fusions, rumplessness, and pelvic reduction. Neither group, however, showed local kyphosis or scoliosis. Early neurogenesis in the avian and human embryos is very similar with development of the spinal cord from neural plate and tail bud materials which fuse in an overlap zone. These experimental defects in the chick embryo, separable into regular and irregular types thus provide a useful model for investigation of the embryogenesis of spina bifida.

Abnormalities, Multiple↗
PubMed1979

The initiation of gait.

The initiation of gait was studied utilizing electromyography, force-plate data, measurements of walking velocities, and ranges of motion of joints, all of which demonstrated that gait is initiated by the body becoming unbalanced in such a way as to permit a subject to pick one foot the ground in order to take the first step. The subsequent transition of the body to the steady gait pattern occurs rapidly over a period of appproximately three steps. This transition involves rapid changes in the measured forces and activities of the muscles of the lower extremity and the motion of the joints reflects these changes.

Adult↗
PubMed1979

Histogenesis of experimental open neural defects in the early chick embryo.

The chick embryo is a useful experimental model for investigating neural dysraphism. Windowing at 26 h incubation is by itself teratogenic, resulting in predominantly neural tube defects. A histological study of a regular series of specimens between pre-neurulation and later stages was undertaken. Open brain defects occurred at every stage after the expected closure of the anterior neuropore, suggesting that they arose by non-closure, myeloschisis was preceded by a characteristic triangular shape of the rhomboid sinus. Serial sections revealed regular open defects, with separation between the neural plate and tail-bud sources of neural tissue, but continuity of the neural plate into the caudal region. These findings suggest that myeloschisis arises by nonclosure of the neural folds. The establishment of myeloschisis was followed by local separation of the notochord from an open area of neural tube, but not by overgrowth of neural tissue. Myelodysplasia appeared at about the time of expected closure of the rhomboid sinus. Serial sections revealed irregular open defects, with complete absence of neural plate material and formation of the cord tissue from tailbud material alone. The lesions were accompanied by extensive cystic and hemorrhagic changes in local mesoderm, with reduction in somite volume. There was no associated notochordal separation.

Animals↗
PubMed1978

Teratogenic effect of windowing eggs at early stages of avian development.

The chick embryo is widely used as an experimental model for embryological and teratological studies. Treatment may be iether across the intact shell or through a window cut in the shell above the embryo. However, it is apparent from the present investigation that merely windowing eggs at early stages of development is highly teratogenic. Abnormal development can be attributed to the presence of an introduced air space above the early embryo. Obliteration of this artificial air space by three different methods significantly reduced the teratogenic response.

Air↗
PubMed1978

Role of the posterior calf muscles in normal gait.

The role of the calf muscles during the single-limb stance phase of gait was assessed in fifteen normal subjects and in seven with either an amputation or a neuromuscular deficit. Normal activity of the muscles, paralysis by nerve blocks, and stability versus instability of the ankle were studied. Pelvic displacement and velocity, step length, and step time were evaluated for each limb during the gait cycle, and the contribution of activity of calf muscles to each was determined. Limb-segment position, lower-limb joint angles, over-all cadence, velocity, and stride length were measured to reveal compensatory mechanisms in the absence of muscle strength in the calf. The results indicate that the force produced by activity of calf muscles is used to restrain the body's own forward momentum and not used to propel it further. Absence of the calf muscle causes an immediate compensatory reaction directed toward maintaining over-all stability rather than speed.

Adolescent↗
PubMed1977

The popliteus muscle.

The popliteus muscle was studied during both normal gait and a series of planned exercises. Its activity during the walking cycle was shown to begin shortly before heel-strike and to continue throughout three-quarters of the stance phase. During the exercises the muscle was active during internal rotation of the tibia on the femur, and during normal gait the phasic activity of the popliteus coincided with internal rotation of the tibia on the femur. It was concluded that the basic function of the popliteus is to help to bring about and maintain internal rotation of the tibia on the femur.

Adult↗
PubMed1972

The behavior-therapeutic use of contingency contracting to control an adult behavior problem: weight control.

Items considered valuable by the subject and originally his property were surrendered to the researcher and incorporated into a contractual system of prearranged contingencies. Each subject signed a legal contract that prescribed the manner in which he could earn back or permanently lose his valuables. Specifically, a portion of each subject's valuables were returned to him contingent upon both specified weight losses and losing weight at an agreed-upon rate. Furthermore, each subject permanently lost a portion of his valuables contingent upon both specified weight gains and losing weight at a rate below the agreed-upon rate. Single-subject reversal designs were employed to determine the effectiveness of the treatment contingencies. This study demonstrated that items considered valuable by the subject and originally his property, could be used successfully to modify the subject's weight when these items were used procedurally both as reinforcing and as punishing consequences. In addition, a systematic analysis of the contingencies indicated that punishing or aversive consequences presumably were a necessary component of the treatment procedure.

Journal Article↗