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Biomedical subjects

P D Byers

Publications and source records attributed to P D Byers.

At least 19 recordsLinked to original sources
PubMed2005

Cell columns in articular cartilage physes questioned: a review.

OBJECTIVE: To report the outcome of a search of the literature for evidence in support of the published [Brown RA, Blunn GW, Salisbury JR, Byers PD. Two patterns of calcification in primary (physeal) and secondary (epiphyseal) growth cartilage. Clin Orthop1993;294:318-24] observation that there are differences in the cellular organisation and ossification between the articular growth cartilage and the metaphyseal physis, i.e., dual patterns of ossification. METHOD: The search of the journal literature was by Medline. Many references came from found articles, and from textbooks. The source texts were at the libraries of the Royal Society of Medicine, The Wellcome Trust and the British Library. RESULTS: (1) The search produced nine authors whose observations make up the bulk of the paper, which support the dual pattern of physes. (2) But there were also articles in favour of the single pattern of cellular organisation and ossification, in which, nevertheless, there were illustrations which were inconsistent with this, and favoured the duality. (3) The third section of the results mainly concerns the role of osteoclasts in the ossification process in articular physes. They are generally regarded as insufficient in number to play a solo part. Quantitative data about osteoclasts are limited; mathematical modelling is proposed as a more objective test. CONCLUSION: Objective, assessable criteria are presented in favour of a modification in our understanding of articular cartilage, and could, and should be augmented by further testing of the hypothesis. Some lines of enquiry are suggested.

Animals↗
PubMed1994

Histomorphometric study of intratrabecular osteons in the iliac bone in three metabolic bone diseases.

Full-thickness biopsy specimens of iliac bones were submitted to morphometric analysis of intratrabecular osteons to study whether and how much the number and density of osteons increase in some metabolic bone diseases such as osteomalacia (OM), primary hyperparathyroidism (PHPT) and renal osteodystrophy (ROD). The biopsies were taken from 16 patients with OM of various causes, 18 with PHPT, 12 with ROD, and from 41 control cases. All the specimens were methacrylate-embedded, sectioned undecalcified and stained with solochrome cyanine or HE. Morphometry included measurements of the density of osteons and the volume of bone and osteoid, partially assisted with a semiautomatic digital image analyzer. Intratrabecular osteons were found to be more numerous in patients with metabolic disorder than in control. It was shown by discriminant analysis that the elevated number of osteons/cm2 tissue area contributes to the differentiation of abnormal from normal bones. The presence of blood vessels in the osteons indicated the biological significance of osteon formation which extends the metabolic surface of trabeculae, providing a basis for trabecular hypertrophy.

Adolescent↗
PubMed1993

Two patterns of calcification in primary (physeal) and secondary (epiphyseal) growth cartilage.

It is generally stated that the process of cartilage calcification and ossification is the same in the physeal (primary growth center) and epiphyseal (secondary growth center) growth plates. Reexamination of osteophyte growth led to the proposal that these growth plates differ. This proposition was tested by examining rabbit and human material from both sites before and after maceration; both tissue preparations were processed for light microscopy, and the macerated tissues were also studied by scanning electron microscopy (SEM). The physis showed the well-recognized, longitudinal calcified tubal structures in which capillaries make direct contact with and resorb the nonmineralized, transverse septal cartilage. In the epiphysis, the transverse septal cartilage was also mineralized, producing a continuous calcified sheet, perforated only by a limited number of channels and susceptible only to osteoclastic removal. This variation in mineral distribution modifies the way in which the primary spongiosa is formed during growth.

Animals↗
PubMed1992

Tests on hypotheses about osteoarthritis and hip joints.

Hypotheses suggesting that hip joints which develop osteoarthritis are congruent, have a single area of peak pressure, and have peak pressure which exceeds normal values were tested. Of 100 hip joints examined on necropsy; two showed an early stage of osteoarthritis and the geometry and pressure distribution under load were assessed in these joints. One joint was congruent, in agreement with the hypotheses, but the other was incongruent. In both joints there were several areas of high pressure, the number and location of which depended on the orientation of the joint. The measured values of pressure in the congruent joint exceeded values found previously in normal hip joints. In the incongruent hip joint the peak pressures were within normal limits.

Aged↗
PubMed1989

Development and involution of the notochord in the human spine.

The availability of a collection of fetal and embryonic spines made possible a review of the involution of the notochord. Results of this histological, histochemical and immunohistochemical study are in accord with the dominant view in the literature that the notochord does not contribute materially to the adult nucleus pulposus. It is also consonant with the expectation that, normally, all chordal cells have disappeared during early childhood, but is not sufficiently detailed to assess the possibility of occasional survivors.

Child↗
PubMed1987

Contact pressures in the human hip joint.

The pressure distribution between the cartilaginous surfaces in the human hip joint was measured using pressure-sensitive film. Five cadaveric hip joints (aged between 58 and 87 years) were measured at three positions and loads, representing three instants in the stance phase of the walking cycle. The pressure distribution was not uniform, indicating that the cartilage did not, to any great extent, distribute the applied load. The maximum pressures recorded were about 10 MN/m2. The anterosuperior surface of the cartilage was identified as an area of high pressure.

Aged↗
PubMed1987

Pathogenesis of membranous lipodystrophy. Case report and review of the literature.

Membranous lipodystrophy occurred in a 35-year-old woman and membrane-like material was found in her epiphyses and short bones. Electron microscopy allowed a study of the relationship between the pathologic tissue and normal fat, suggesting that the membrane-like material is derived from degenerated cells. Nucleation of hydroxyapatite crystals was also observed in the membranous material. Because basal ganglia calcifications were demonstrated with the use of computed tomography, brain and bone lesions may be assumed to share the same pathogenesis. Lipid and mucopolysaccharide metabolism was found to be normal.

Adipose Tissue↗
PubMed1986

Histomorphometric study of trabecular channels in normal iliac bone.

Cancellous bone channels in the normal iliac crest have been studied histologically and by histomorphometry, and their biological role has been considered. Eighty percent of trabecular channels were typical osteons with the same structural and remodeling features as cortical osteons. The similarity of osteons in these two locations was corroborated by the comparability of morphometric features. The points of difference between osteons in the two types of bone were irregular configurations of trabecular osteons and marrow cells in the central canal in some. Since the number of trabecular osteons decreases with age, and since active trabecular resorption cavities were few in number, it is unlikely that additional osteons are formed in normal bone after the active modeling phase of bone growth. It is improbable that they make a significant contribution to bone remodeling since their number decreases with age, and since the available surface of trabecular channels for remodeling is extremely small. However, it is probable that they aid the intraosseous microcirculation and mineral exchange in thick trabecula and bifurcations, where they are mainly located. The demarcation curves at the 95% confidence interval, which suggest the normal range for numbers of channels, was calculated from the scatter diagram against bone area.

Adolescent↗
PubMed1984

Synovial fluid circulation in the hip joint.

Early in our study of the role of incongruency in the hip (Ref. 1) we observed by x-ray screening that, under load, a drop of barium sulphate placed between the articular surfaces spread out between them and a substantial portion was extruded from the intercartilage space into the fossa; all the barium was drawn back as load was reduced. This observation and others (Ref. 2) which demonstrated the location, size and behaviour of intercartilage space with movement and load, prompted exploration of the hypothesis that the space due to joint incongruency serves as a pump to transport synovial fluid in the articular cavity in aid of nutrition and lubrication. This had already been suggested by others (Ref. 3); but none have closely studied the hypothesis. The following is an expansion of this idea, which leads to the concept of a systematic circulation of fluid through the hip joint.

Adult↗
PubMed1984

The incongruous hip joint: a loading study.

Hip incongruency was studied by load-displacement and casting methods. Twenty-five joints were loaded in 5 different positions of the walking cycle. Seventeen of them had a space at the apex in all positions, while 3 were congruent at low loads, and the remaining 5 had femoral heads smaller than their acetabula. No trends with age were apparent.

Adult↗