Biomedical subjects

C A Poole

Publications and source records attributed to C A Poole.

At least 55 records · Page 3Linked to original sources

PubMed1990

Chondrons from articular cartilage (II): Analysis of the glycosaminoglycans in the cellular microenvironment of isolated canine chondrons.

A chondron rich preparation was isolated from mature canine tibial cartilage using low-speed homogenization techniques. Proteoglycans were extracted from this preparation by exhaustive treatment with 4M guanidine-HCl. A significant proportion of the total proteoglycan, measured as uronic acid, was resistant to extraction and represented 27.9% in intact cartilage chips and 18.6% in the chondron fraction. Histochemical examination of chondrons confirmed that extraction resistant proteoglycans remained within the capsule of the chondron after 4M guanidine-HCl treatment. Electrophoretic analysis of the glycosaminoglycans extracted from intact cartilage chips and the chondron fraction showed approximately equivalent amounts of chondroitin sulphate (79.3%), keratan sulphate (16.3%) and hyaluronic acid (4.3%) present. In contrast, the extraction resistant residue in the chondron fraction was significantly enriched for hyaluronic acid (10.5%, p less than 0.05) but was depleted of chondroitin sulphate (70.9%, p less than 0.05). The major chondroitin sulphate isomer in the resistant fraction was chondroitin 6-sulphate while in the soluble fraction, the quantities of the two isomers were approximately equivalent. Comparison with previously published data suggests a role for minor collagens in the retention of proteoglycans in the cellular microenvironment.

Animals↗

PubMed1989

MR technique for localization and verification procedures in episcleral brachytherapy.

Spatial definition of an intraocular tumor and subsequent determination of the actual position of an implanted eye plaque are essential for adequate ocular brachytherapy treatment planning. However, a method for verification of the plaque placement which would provide required 3-dimensional information is not available at present. In addition, tumor localization procedures, including ultrasonography and CT techniques, cannot always offer the precision needed for 3-dimensional definition of an intraocular target. This communication describes a magnetic resonance imaging technique specifically developed for both localization and verification procedures. A 1.5 Tesla magnetic resonance scanner, spin-echo pulse sequence (echo time 30 msec, repetition time 700 msec), and commercially available surface coil were used to obtain a series of transverse, coronal, and sagittal images of a slice thickness of 3 mm. Usually, eight scans in each of the three planes were needed for adequate coverage of the orbit. The required patient set-up and data acquisition time did not exceed 40 minutes. With a data matrix size of 256 X 256 pixels and 13 cm field of view, localization and verification were accomplished with a precision of 0.5 mm. Our results suggest that the magnetic resonance imaging technique permits precise integration of diagnostic and therapeutic procedures, and in addition provides adequate data for accurate treatment planning. We conclude that magnetic resonance imaging is the preferred diagnostic technique for episcleral brachytherapy.

Brachytherapy↗

PubMed1988

Chondrons extracted from canine tibial cartilage: preliminary report on their isolation and structure.

We report on the morphology and structure of single and multiple chondrons isolated from homogenized samples of fresh and fixed canine tibial cartilage. Phase contrast, Nomarski, and scanning electron microscopy observations show each chondron to be composed of a chondrocyte and its pericellular matrix enclosed within a "felt-like" pericellular capsule. The extraction of intact chondrons from cartilage homogenates confirms the structural validity of the chondron concept and emphasizes the intrinsic mechanical strength of the capsule. Frayed collagen fibers radiate from multiple chondron columns suggesting a shear-resistant, structural interrelationship between capsular components and type II collagen fibers. Future development of chondron extraction procedures could provide a unique model with which to study the structure, biochemistry, and function of articular cartilage chondrocytes and their pericellular microenvironment.

Animals↗

PubMed1988

Localization of type IX collagen in chondrons isolated from porcine articular cartilage and rat chondrosarcoma.

Chondrocytes, each with their pericellular matrix bounded by a fibrous capsule, can be extracted singly or in groups from both mature pig articular cartilage and chondrosarcoma tissue. These structures, termed chondrons, are thought to anchor the chondrocytes in the matrix and protect them from the compressive forces experienced when articular cartilage is under load. The capsule of these chondrons contains both type II and type IX collagens and is composed of fine fibrillar material, unlike the large banded fibres of type II collagen found in the rest of the matrix. This suggests a role for type IX collagen in regulating the diameter of type II fibres to produce the fine fibrillar structure of the chondron capsules.

Animals↗

PubMed1988

MR characterization of brain and brain tumor response to radiotherapy.

This paper describes our experience in using the T1 and T2 relaxation times for quantitative evaluation of brain and brain tumor response to radiation therapy. Twenty-two computed T1 and 22 computed T2 images were obtained from 66 routine inversion-recovery and spin-echo magnetic resonance (MR) brain scans. The relaxation times of the brain tissues, determined from the computed images, were examined as a function of the absorbed dose. Statistical evaluation of the results showed no significant difference between the relaxation times of irradiated and not irradiated tissues, including tumor and normal white matter. Influence of the magnetic field strength and imaging techniques on the computed T1 and T2 values was confirmed. We conclude that the relaxation time values, as obtained today using conventional MR scanner and standard software, are not specific enough to warrant a correct assessment of the acute radiation effect on the brain tissues.

Adolescent↗

PubMed1988

Chondrons from articular cartilage: I. Immunolocalization of type VI collagen in the pericellular capsule of isolated canine tibial chondrons.

A heterogenous population of intact chondrons extracted from low-speed homogenates of canine tibial cartilage were stained by indirect immunofluorescence methods with a polyclonal antibody to type VI collagen. In each of the four chondron groups examined, anti-(type VI collagen) anti-serum was concentrated in the capsule immediately adjacent to the chondrocyte complex. A constant but weaker fluorescent reaction persists in 'tail-like' extensions common to single and double chondrons and in the medial connections between adjacent chondrons in linear columns and aggregated clusters. Frayed collagen bundles typical of chondron preparations did not react with the antibody. Similarly, chondrons reacted with normal rabbit serum, or treated by type VI collagen extraction procedures, showed no staining reaction. The differential localization of type VI collagen in the pericellular capsule is discussed in relation to the maintenance of the chondron's integrity and to the protection of the chondrocyte during dynamic compressive loading.

Animals↗

PubMed1988

The efficacy of subcutaneous goretex implants in monitoring wound healing response in experimental protein deficiency.

This combined biochemical and histological study demonstrated that subcutaneously implanted Goretex tubing can be used to monitor and detect variations in wound healing potential in rats subjected to experimental hypoproteinaemic and normal refeeding conditions. Induced hypoproteinaemia was observed to be associated with a marked diminution in cellular infiltration, collagen synthesis and fibrous deposition within the implant. All these effects were completely reversed by subsequent refeeding of normal diet. Although regional variations in fibroblastic response attributable to biologic variability, were observed within individual control implants, or between paired controls, they were relatively minor as compared to the marked differences observed at the macroscopic, microscopic and biochemical level between implants removed from normally fed and protein deficient animals.

Animals↗

PubMed1987

Chondrons in cartilage: ultrastructural analysis of the pericellular microenvironment in adult human articular cartilages.

A combination of scanning and transmission electron microscopy was used to investigate the morphology and ultrastructure of normal human articular cartilage sampled from adult amputation specimens. This study confirms our previous observations on canine articular cartilage, which showed middle and deep layer chondrocytes surrounded by a pericellular matrix and enclosed within a pericellular capsule composed of filamentous and fine fibrillar materials. Pores in the "felt-like" organization of the capsular weave progressively decreased in size from the inner to the outer border of the capsule. Matrix vesicles were found embedded within the capsular weave and distributed throughout the territorial matrix. It is suggested that the chondrocyte, its pericellular matrix, and capsule together constitute the "chondron," a primary functional and metabolic unit of cartilage that acts hydrodynamically to protect the integrity of the chondrocyte and its pericellular microenvironment during compressive loading.

Adult↗

PubMed1986

Horseshoe lung: clinical, pathologic, and radiologic features and a new plain film finding.

Horseshoe lung is a rare congenital malformation in which an isthmus of pulmonary parenchyma extends from the right lung base across the midline behind the pericardium and fuses with the base of the left lung. Six cases are presented and eight previously published case reports are reviewed. Eleven of these 14 cases occur in conjunction with scimitar syndrome, the complex of anomalies including hypoplasia of the right lung, anomalous right pulmonary venous return, and anomalous arterial supply to the right lung. Differentiation of scimitar syndrome from horseshoe lung can be made on the plain chest film, if, in addition to the typical radiographic findings of scimitar syndrome, there is evidence of a fine linear density in the medial aspect of the left base representing the lateral extent of the pulmonary isthmus. Recognition of horseshoe lung is important because children present in the first few years of life with significant respiratory symptoms, whereas the scimitar syndrome alone is usually discovered fortuitously after the first decade of life.

Angiography↗

PubMed1985

Analysis of the morphology and function of primary cilia in connective tissues: a cellular cybernetic probe?

More than 300 primary cilia have been identified electronmicroscopically in a variety of embryonic and mature connective tissue cells. To further define the enigmatic function of these cilia, we examined the interrelationships between the basal apparatus and cytoplasmic organelles and the ciliary shaft and the extracellular matrix. The basal diplosome was consistently associated with the secretory organelles including the maturing face of the Golgi complex, Golgi vacuoles and vesicles, the microtubular network, the plasma membrane, and coated pits and vesicles. Small vesicles and amorphous granules were also observed within the ciliary lumen and adjacent to the ciliary membrane. Microtubule-membrane bridges linked axonemal tubules to the ciliary membrane. The position, projection, and orientation of the axoneme were influenced by the structural organisation and mechanical properties of the matrix and frequently caused angulation of the ciliary shaft relative to the basal body. Located midway between the secretory apparatus and the extracellular matrix, primary cilia would appear ideally situated to mediate the necessary interaction between the cell and its surrounding environment prerequisite to the formation and maintenance of a functionally effective matrix. We propose that primary cilia in connective tissue cells could act as multifunctional, cellular cybernetic probes, receiving, transducing, and conducting a variety of extrinsic stimuli to the intracellular organelles responsible for effecting the appropriate homeostatic feedback response to changes in the extracellular micro-environment.

Animals↗

PubMed1985

Morphology of the pericellular capsule in articular cartilage revealed by hyaluronidase digestion.

To allow a more valid comparison between our previous ultrastructural data and the immunolocalization of type IX and other minor collagen species in cryosectioned cartilage, we examined both normal and testicular hyaluronidase-digested canine tibial cartilage by electron microscopy. Removal of matrix proteoglycans caused the pericellular capsule to collapse against the cell surface, suggesting that its normal anatomical position is mediated by pericellular matrix hydration. Detailed examination of the pericellular capsule and pericellular channel revealed fine, faintly banded fibrils and an amorphous component somewhat similar in structure to basement membrane collagens. Matrix vesicles and the electron-dense material of the interterritorial matrix were only partially digested by hyaluronidase. We propose that the pericellular capsule is composed of a "felt-like" network of minor collagen species which act synergistically to maintain both the composition of the pericellular matrix and the integrity of the chondrocyte/pericellular matrix complex during compressive loading.

Animals↗

PubMed1984

Morphological and functional interrelationships of articular cartilage matrices.

The pericellular, territorial and interterritorial matrices of canine tibial cartilage have been identified ultrastructurally on the basis of their collagen fibre density and organisation, proteoglycan distribution and their structural response to experimentally applied compressive loads. In addition, a discrete pericellular capsule composed of fine, faintly banded fibrils is described which surrounds and encloses the pericellular matrix and chondrocytes of the middle and deep layers but not of the superficial layer. It is suggested that the fine fibrils which comprise this pericellular capsule represent some of the new minor collagen species recently localised in a similar position in hyaline cartilages. The densely compacted cupola which forms the articular pole of the capsule is frequently penetrated by a clearly defined pericellular channel, consistently orientated in the direction of the articular surface. Membrane-bound vesicles are observed in the pericellular matrix, within the lumen of the pericellular channel and accumulated in the territorial matrix immediately beyond the pericellular channel. The constancy of this distribution pattern strongly suggests a flow of material through the pericellular channel from the pericellular matrix to the territorial matrix and beyond, possibly in response to minute pressure gradients generated during compressive deformation of the non-distensible capsule. Furthermore, it is suggested that the random dispersal and subsequent rupture of matrix vesicles may represent a mechanism whereby chondrocytes, with limited mobility, could exercise homeostatic control over the cartilage matrix at some distance from the cell. Chondrocytes in the deeper layers of canine tibial cartilage are each surrounded by three distinct compartments, a pericellular matrix and capsule, a territorial matrix and an interterritorial matrix. The response of each of these concentric compartments to experimental load suggests that they function synergistically to produce an integrated, biological, hydro-elastic suspension system capable of resisting physiological compression.

Animals↗

PubMed1983

Articular cartilage collagen and proteoglycans. Their functional interdependency.

By use of an in vitro experimental system which permits the observation at high resolution of articular cartilage in a physiologic condition, its biomechanical response to compression was investigated before and after enzymatic digestion of the proteoglycan components with testicular hyaluronidase. The study provides further insight into the functional interplay between the collagen network and the hydrated proteoglycans. Certain structural features associated with age-related and osteoarthritic changes occurring in vivo in human articular cartilage were mimicked in the compressive response of the enzymatically digested tissue.

Animals↗

PubMed1982

The adverse effects of HEPES, TES, and BES zwitterion buffers on the ultrastructure of cultured chick embryo epiphyseal chondrocytes.

Chick embryo epiphyseal chondrocytes cultured in media containing HEPES, TES, and BES zwitterion buffers, used in combination or independently, consistently developed cytoplasmic vacuoles. This cytoplasmic vacuolation was resolved when the zwitterion buffered media was replaced by media containing bicarbonate:CO2 enriched air buffer. Vacuoles were infrequent or absent in cultures grown in bicarbonate:CO2 enriched air. Chondrocytes with an established extracellular matrix showed less vacuolation than fibroblastlike and polygonal shaped cells that lacked such a matrix. The granular endoplasmic reticulum and Golgi dictyosomes of zwitterion buffered chondrocytes were distended and contained a flocculent amorphous material. Cytoplasmic vacuoles (0.5 to 3.0 micron diam) formed by the fusion and intracellular accumulation of Golgi vesicles and vacuoles also contained a flocculent material enhanced by ruthenium red. Membrane bound extracellular vacuoles containing ruthenium red stained proteoglycan aggregates were common in the extracellular matrix of zwitterion buffered cultures but were generally absent from bicarbonate treated cultures. Electron dense calcium deposits seemed much larger and more numerous in the presence of zwitterion buffers. It is suggested that HEPES, TES, and BES buffers, used alone or in combination, may adversely affect cell membrane systems, and thus the transport or secretory mechanisms operative in cultured chondrocytes, or both, resulting in vacuole formation and the intracellular accumulation of synthesized export material. Although the mechanism by which HEPES, TES, and BES induce these changes remains unclear, the use of zwitterion buffers in biological preparations should be treated with caution.

Alkanesulfonates↗

PubMed1982

A functional-morphological study of the tidemark region of articular cartilage maintained in a non-viable physiological condition.

Composite samples consisting of articular and calcified cartilage maintained in a non-viable physiological condition have been subjected to static compression using a system of simultaneous micromechanical testing and interference light microscopy. This, combined with transmission electron microscopy following glutaraldehyde fixation of the tissue under sustained load, has provided a unique observation of the response of the collagen framework in the tidemark region of articular cartilage to sustained compression loading. The tidemark in mature articular cartilage is seen to be highly variable in its morphological features, when viewed ultrastructurally. It incorporates variable amounts of internal stress which are relieved when the articular cartilage is separated from the calcified cartilage. Deformation of the articular cartilage can terminate abruptly at the tidemark. There is no evidence that the tidemark or calcified cartilage provided an intermediate layer between the complaint articular cartilage and the rigid subchondral bone. However, morphological evidence presented suggests that a smooth transfer of stress from the complaint to the rigid tissues could be achieved through changes in orientation and packing density of the collagen fibres in the articular cartilage adjacent to the tidemark. A variety of morphological responses of the collagen framework was observed in the tidemark region of articular cartilage following static compressive loading. In any given region, these responses were determined by (a) the local form and orientation of the tidemark; (b) the organisation of the collagen fibres; (c) the position of this region with respect to the compressive anvil. No evidence was obtained which suggested that the collagen fibres near the tidemark had a predominantly tensile role during direct compression. The observed process of compaction and collapse via a 'crimp' formation is clearly non-tensile. However, deformation involving lateral shear in regions nearer the extremities of joint contact would require that the collagen fibres provide an anchoring role and thus be subjected to tensile loading.

Animals↗

PubMed1981

A congenital abnormality in the arrangement of muscle bundles in a segment of the distal ileum, producing obstruction: a variant of the so-called "giant Meckel's diverticulum".

This 4-year-old male child was diagnosed at birth as having several minor congenital anomalies. X-rays taken during the first year of his life showed a single, massively dilated loop of bowel in the upper abdomen, not appreciated at the time. In 1980 he was admitted to Jackson Memorial Hospital with the diagnosis of small bowel obstruction. An upper gastrointestinal series showed one tremendously dilated loop of distal ileum. At laparotomy, the patient was found to have extreme segmental dilatation of one loop of distal ileum which ended abruptly; there was no evident external cause for obstruction. The resected loop contained in excess of 200 cc of watery brown liquid. The mucosal folds and underlying smooth muscle bundles, in the dilated portion only, were not arranged circumferentially but rather in a distinctive finger-print-like pattern with trifurcations, whorls, and intricate interdigitations which had probably produced contractions of a circus type rather than normal peristaltic waves. We have been able to find only three reports in the literature in which, as was the case here, the so-called "giant Meckel's diverticulum" presented as a single tremendously dilated segment of ileum, sharply demarcated at its distal end. In none of them is there any description of the orientation of muscle bundles. We believe that the abnormal arrangement of smooth muscle in the muscular coat in this specimen, and perhaps in the others, probably represents the underlying cause for the extreme localized dilatation.

Child, Preschool↗

PubMed1981

Mesenteric vascular gas secondary to ischemic bowel in transmesenteric hernia.

A transmesenteric herniation of bowel with subsequent bowel ischemia in a thirteen-year-old boy is reported. Radiographic findings were that of abdominal mass and branching radiolucencies secondary to gas within the mesenteric vasculature. The unusual distribution of vascular gas (mesenteric rather than portal) is thought to be secondary to obstruction of mesenteric veins by strangulation.

Adolescent↗

PubMed1980

Extracranial complications of cerebrospinal fluid shunt function in childhood hydrocephalus.

There were 112 separate hospital evaluations in 84 patients for suspected shunt malfunction: 96 evaluations were of ventriculoperitoneal shunts, 13 were of ventriculoatrial shunts, and three were of both types of shunts. In 45 (47%) of 96 ventriculoperitoneal shunts, complications eventually led to surgical revision; 20 (44%) of these were problems of the peritoneal end and therefore peculiar to this type of shunt. Peritoneal end problems included tubing disconnection, bowel obstruction, perforation, and abdominal cerebrospinal fluid pseudocyst. Of the 13 ventriculoatrial shunts, 10 (79%) required revision; eight (61%) of these were due to problems of the atrial end. These problems included relative shortening of the tubing due to patient growth, superior vena cava thrombosis, and disconnection. Ventriculoperitoneal shunts were used most frequently and had a lower complication rate (47%). Ventriculoatrial shunts were used less often and had a higher complication rate (79%) and more serious problems.

Cerebrospinal Fluid Shunts↗