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Biomedical subjects

P F Harris

Publications and source records attributed to P F Harris.

At least 19 recordsLinked to original sources
PubMed1995

Assessment of basic medical sciences in an integrated systems-based curriculum.

Basic medical sciences at Sultan Qaboos University (SQU) are taught in a systems-based curriculum. During the development of the courses different formats have been used for the written examinations and also different types of questions. This paper compares students' performance in relation to examination format and to types of questions used. The formats were non-coordinated (NCAs), each discipline having a separate paper; coordinated (CAs), questions from various disciplines being given in the same paper but with separate sections for each discipline; and integrated assessments (IAs), questions being grouped under structure, function, and problem-based integrated long essays. The types of questions used were multiple choice (MCQs), short essays (SEQs), and structured integrated long essays (SILEQs). Students performed better in SEQs than in MCQs. Our analyses also show that SILEQs measure skills similar to those of MCQs and SEQs combined. Students performed best in NCAs. In CAs, students concentrated on those disciplines carrying most weight in the final grade. Currently we use IAs consisting of two parts: part I, comprising MCQs and SEQs, and part II, comprising SILEQs. To date, students are performing better in part II than in part I. We suggest that it is prudent to use different types of questions to measure students' knowledge and skills when IAs are used for systems-based courses.

Analysis of Variance↗
PubMed1995

Cytogenetic analysis of children suspected of chromosomal abnormalities.

Karyotypes were examined in 122 Omani children suspected of having chromosomal abnormalities. A total of 50 (41 per cent) had an abnormal karyotype: 38 (31 per cent) were Down's syndrome whilst a further 12 (10 per cent) had other types of chromosomal abnormalities. These findings suggest that cytogenetic analysis is useful in the investigations of children with congenital anomalies of unknown origin; to confirm clinical diagnosis in children with known cytogenetic syndromes and for genetic counselling.

Adolescent↗
PubMed1995

Teaching of human anatomy: a role for computer animation.

Computer-assisted learning fulfils an important need for pictorial representation of the functions of organs and systems. The various computer techniques of animation and morphing provide promising horizons for medical educational technology. Image acquisition is one of the most resource-intensive components of animation sequence development. Images can be drawn as originals or can be copied/scanned from various sources. By standardizing the initial (starting) image to the particular/basic need of the teacher and projecting the end-point image by using a vector animation package, 'films' can be created to demonstrate any form of movement. In the Anatomy Department, Sultan Qaboos University in Muscat, computer-animated tutorials are being introduced to illustrate normal and abnormal functional anatomy. The heart and its valve mechanisms have been selected as a pilot study. The student response is very positive and the technique has great potential. Embryology animations showing the formation and growth of organs such as the brain and spinal cord are also being developed.

Anatomy↗
PubMed1990

Diagnosis and management of paragangliomas of the skull base.

In appropriately selected patients, glomus tumors of the head and neck are best treated surgically. Unresectability is not a factor in therapeutic planning for local disease control. Existing techniques and exposures for tumor removal can be reliably applied to these paragangliomas, with acceptable morbidity and mortality. A team approach to this problem is mandatory.

Adult↗
PubMed1987

Pharyngocutaneous fistulas in advanced cancer: closure with musculocutaneous or muscle flaps.

Two hundred cases of head and neck cancer were reviewed and 16 pharyngocutaneous fistulas identified, for an incidence of 6 percent. The fistulas were closed with pectoralis major muscle flaps in four patients, pectoralis musculocutaneous flaps in seven patients, sternocleidomastoid muscle flaps in four patients, and latissimus dorsi flaps in two patients. Four types of fistulas were identified, and flap selection was determined by fistula location. Successful closure was obtained in 15 patients (88 percent), although one patient died from recurrence with a persistent fistula.

Combined Modality Therapy↗
PubMed1986

Comparison of the structure of human intervertebral discs in the cervical, thoracic and lumbar regions of the spine.

Posterior and anterior heights, cross-sectional area and shape were measured for all the intervertebral discs in four spines from elderly human cadavers. Disc height was a minimum at the T4-5 level; thoracic discs were less wedge-shaped than those in the cervical and lumbar regions. Cross-sectional area increased from the cranial to caudal extremity; at the L5-S1 level the nucleus pulposus occupied a high proportion of this area. Cervical discs tended to have an elliptical cross-sectional shape, thoracic discs were more circular and lumbar discs tended to have an elliptical cross-section which was flattened or re-entrant posteriorly. This shape distribution was quantified by defining a shape index which had a maximum value of 1 for a circular cross-section. Orientations of the reinforcing fibres in the outer lamellae of the anterior annulus fibrosus were measured from 27 discs by X-ray diffraction. For these measurements, C3-4, T7-8 and L2-3 were chosen as representative of cervical, thoracic and lumbar discs. The fibre tilt, with respect to the axis of the spine, was significantly less in the cervical discs (at 65 degrees) than in the thoracic and lumbar discs (about 70 degrees). These findings are interpreted in relation to differing functional requirements and possible mechanisms of failure in the cervical, thoracic and lumbar regions of the spine in the light of current knowledge on the biomechanics of the intervertebral disc.

Humans↗
PubMed1986

Skull-base surgery: operative refinements.

Advances in microsurgical techniques, with the use of the laser and the ultrasonic suction aspirator, have paved the way for even more aggressive surgical approaches to large skull-base lesions, such as glomus tumors, adenocarcinomas of the temporal bone, and cranial nerve neuromas. Postoperative morbidity of multiple cranial nerve dysfunction has been aggravated in the past by cerebrospinal fluid leakage and/or gastro-intestinal dysfunction. At the Otology Group, P.C., in the course of dealing with more than 86 skull-base tumors, we have developed a standardized, multispecialty approach to such extensive skull-base lesions, including tracheotomy, gastrostomy, "ventriculoatrial" shunt placement, and rotated temporalis muscle flap closure. This article presents cases that illustrate the evolution of the current, "standard skull-base" operative procedure and the rationale for incorporation of the shunt and the muscle flap closure as operative refinements. Their beneficial effects upon postoperative morbidity are detailed.

Adolescent↗
PubMed1984

A radiographic study of variations of the human fetal spine.

Variations of the vertebral column were considered to be those deviations from the norm which were still compatible with normal life and not pathological. The incidence of these variations is described as seen radiographically in a group of normal human fetuses. Ossification centers for the costal processes of cervical vertebra 7 were found to be common (19%), being present in approximately one-fifth of the total number of fetuses studied. They were mostly present as bilateral centers (15%), but because of the cross-sectional nature of the study, it could not be determined whether these centers would have developed into actual cervical ribs. Far less common were the presence of lumbar ribs (1%). Ossification of the vertebral centra was found to be confusing with no clearly defined pattern being evident. In particular, there was a suggestion that some of the vertebral centra might well develop at least initially from bilateral centers. There was also evidence that the vertebral body was the product of four centers and this was supported by other literature. No variations were found which suggested that the vertebra develops from two somite levels, and this appears to be in conflict with the commonly accepted resegmentation theory.

Fetus↗
PubMed1982

Glomus Tumors. Diagnosis, classification, and management of large lesions.

Glomus tumors of the temporal region and skull base can range in size from small microscopic lesions confined to the promontory to large destructive and neurologically aggressive agents of substantive incapacitation. Contemporary diagnostic and surgical technology has made definitive management of these historically dreaded management of these historically dreaded lesions confidently practical. Prompted by these advances, a new classification of glomus tumors is disclosed. The specific problem of the large chemodectoma at the skull base is addressed and a series of such cases reviewed. Surgical therapy is viewed as definitive, and the technique employed by the members of The Otology Group, PC, is described.

Airway Obstruction↗
PubMed1982

A radiographic study of the longitudinal growth of primary ossification centers in limb long bones of the human fetus.

This paper describes an extensive study of the growth of ossification centers in limb long bones of the human fetus from 8 to 26 weeks of conceptual age. Longitudinal measurements were made of the femur, tibia, fibula, humerus, radius, and ulna. Comparisons were made between bones on the left and right sides of the body and between the sexes. Standards are presented for the growth of these centers. They compare well with previous studies, any differences being accounted for by different methods of aging and measurement. A complicated picture of growth of the two sides of the fetal body is presented. Growth of the humerus, tibia, and fibula appears to be dominant on the left side of the body while growth in the femur is dominant on the right. At present, no explanation is available, but it is possible that factors such as manual dominance may be related. Evidence also is presented which suggests that the female fetus is in advance of the male in terms of ossification but only ater 21 weeks gestation.

Bone and Bones↗
PubMed1982

A radiographic study of the growth in width of the human fetal vertebral column.

Only a few studies have concerned themselves with the development of the fetal vertebral column, and this paper attempts to extend the literature. Standards are presented for the growth in width of the human vertebral column between 10 and 26 weeks of conceptual age. The growth patterns show that cervical and lumbar enlargements are not present at 8 weeks but develop slowly and become clearly present at 26 weeks. The growth equations also show that groups of vertebrae have their own growth patterns, indicating that the vertebral column could be separated into five groups: C1-C5, C6-C7, T1-T12, L1-S1, and S2-S5. Furthermore, comparisons with growth patterns available for growth in length from other studies reveal that some vertebrae appear to develop in one dimension independently of another.

Cervical Vertebrae↗
PubMed1982

Disruption of passive avoidance memory by REM sleep deprivation: methodological and pharmacological considerations.

The present experiments were designed to examine more closely the variables responsible for the disruption of passive avoidance memory produced by REM sleep deprivation. In the pharmacological study it was found that imipramine could reverse the memory disruption exhibited by rats maintained on large platforms (presumably not REM-deprived) while both imipramine and physostigmine were required to reverse the memory disruption exhibited by rats maintained on small platforms. In the methodological study it was found that those animals maintained on the smallest platforms and therefore having the largest weight to area ratio exhibited the greatest degree of memory disruption. It is concluded that further modification and verification of the platform techniques of REM deprivation is required before firm conclusions about its neurochemical basis and behavioural functions can be made.

Animals↗
PubMed1980

A morphological and histological study of the postnatal development of intervertebral discs in the lumbar spine of the rabbit.

Some basic features in the development of the structure of the annulus fibrosus and nucleus pulposus in the rabbit, as described by previous workers, have been confirmed in the present study. However, the greater thickness of the anterior part of the disc, as compared with the posterior region, and the distinctive arrangement of lamellae in the posterior part of the disc, cannot be attributed, as conventionally claimed from studies of the human spine, to a secondary curvature in the lumbar spine associated with an upright posture: for these features are present in the lumbar spine of the quadrupedal rabbit with its primary curvature. Secondary ossification produces a plate-like epiphysis separating the growth cartilage from the intervertebral disc. A distinct cartilaginous plate, limiting the nucleus pulposus in the rabbit intervertebral disc, only becomes apparent when collagen fibres cease to traverse the area above and below the nucleus pulposus.

Animals↗
PubMed1979

A radiographic study of the human fetal spine. 3. Longitudinal growth.

Regression equations are presented which describe the growth in length of the various regions of the vertebral column in the human fetus. From 8 weeks on the thoracic is always the longest region and the sacral the shortest, while the lumbar region is longer than the cervical. From the regression equations predictions of fetal vertebral length can be made from fetal age: this should be useful in obstetric practice when diagnostic ultrasound techniques are being employed for the diagnosis of growth disorders and skeletal abnormalities. A different developmental pattern emerges when average 'vertebral units' for each region are compared. The lumbar vertebrae are always the largest with the thoracic, cervical and sacral vertebrae being progressively smaller.

Anthropometry↗
PubMed1977

Adaptation of museum specimens for use in anatomical teaching aids.

Colour transparencies are prepared of a re-colourized anatomical specimen after placing labels temporarily in position to indicate specific structures. The specimen is also radiographed to show skeletal and soft tissue structures and radio-opaque materials and letters may used to indicate certain parts. Having mounted the specimen it can then be placed in a teaching carrel together with the radiographs and a back-slide projector for viewing the colour transparencies. The student is guided through an examination of the specimen using a script or soundtape. Frequent cross-reference is made between the actual specimen, the colour transparencies on which certain parts of the specimen have been labelled, and also the radiographs. The examination is followed by self-assessment questions relevant to the specimen and these may include identification of structures on a photograph of the specimen and on duplicate radiographs. In the final section of the aid, the answers of the self-assessment questions are given.

Anatomy↗