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Biomedical subjects

C A Poole

Publications and source records attributed to C A Poole.

18 recordsLinked to original sources
PubMed1992

Microbiological assay of avoparcin in animal feeds and pre-mixes--co-operative study.

A microbiological method for the determination of the antibiotic growth promoter avoparcin in animal feeds and pre-mixes was first published in 1979. The existing method has been applied to new matrices as commercial use of avoparcin has spread. Problems with the existing analytical procedure have been reported, particularly in Germany. This paper identifies the causes of the problems and includes revisions to the existing analytical procedure. The testing of these revisions in co-operative studies with up to five German official laboratories is also reported.

Animal Feed↗
PubMed1992

Chondrons from articular cartilage. V. Immunohistochemical evaluation of type VI collagen organisation in isolated chondrons by light, confocal and electron microscopy.

The pericellular microenvironment around articular cartilage chondrocytes must play a key role in regulating the interaction between the cell and its extracellular matrix. The potential contribution of type VI collagen to this interaction was investigated in this study using isolated canine tibial chondrons embedded in agarose monolayers. The immunohistochemical distribution of an anti-type VI collagen antibody was assessed in these preparations using fluorescence, peroxidase and gold particle probes in combination with light, confocal and transmission electron microscopy. Light and confocal microscopy both showed type VI collagen concentrated in the pericellular capsule and matrix around the chondrocyte with reduced staining in the tail region and the interconnecting segments between adjacent chondrons. Minimal staining was recorded in the territorial and interterritorial matrices. At higher resolution, type VI collagen appeared both as microfibrils and as amorphous deposits that accumulated at the junction of intersecting capsular fibres and microfibrils. Electron microscopy also showed type VI collagen anchored to the chondrocyte membrane at the articular pole of the pericellular capsule and tethered to the radial collagen network through the tail at the basal pole of the capsule. We suggest that type VI collagen plays a dual role in the maintenance of chondron integrity. First, it could bind to the radial collagen network and stabilise the collagens, proteoglycans and glycoproteins of the pericellular microenvironment. Secondly, specific cell surface receptors exist, which could mediate the interaction between the chondrocyte and type VI collagen, providing firm anchorage and signalling potentials between the pericellular matrix and the cell nucleus. In this way type VI collagen could provide a close functional interrelationship between the chondrocyte, its pericellular microenvironment and the load bearing extracellular matrix of adult articular cartilage.

Animals↗
PubMed1992

Characteristics of indigent women with ruptured and unruptured tubal pregnancies.

The diagnosis of tubal pregnancy, whether ruptured or unruptured, often requires a surgical procedure, such as laparoscopy or laparotomy, for confirmation. We compared women with ruptured and unruptured tubal pregnancies to determine whether the clinical presentations, morbidity and surgical complications in the two groups were significantly different. We compared the demographic characteristics, clinical presentations, laboratory findings, morbidity and complications from surgical management in the two groups. Women with ruptured tubal pregnancies had a higher incidence of abdominal pain lasting less than 24 hours, adnexal tenderness and positive culdocentesis from hemoperitoneum as compared to women with unruptured tubal gestations. Abnormal uterine bleeding was observed less frequently in women with ruptured tubal pregnancies as compared to women with unruptured ones despite similar gestational ages at presentation. All the patients with a tubal pregnancy were managed surgically. The morbidity and surgical complication rates in the two groups were not significantly different.

Adult↗
PubMed1991

Chondrons from articular cartilage. III. Morphologic changes in the cellular microenvironment of chondrons isolated from osteoarthritic cartilage.

Chondrons were isolated from human and canine osteoarthritic cartilage using low-speed homogenization techniques. Changes in chondron morphology were evaluated using differential interference-contrast microscopy, phase-contrast microscopy, and histochemical and ultrastructural methods. Chondrocyte viability was assessed using fluorescein diacetate staining, and chondron metabolism was investigated using autoradiography. The results suggest that initial changes in the collagen and proteoglycan distribution within the chondron are followed by chondrocyte proliferation to form clusters. These techniques offer the potential to study cell matrix interactions in degenerative osteoarthritis.

Aged↗
PubMed1991

Chondrons from articular cartilage. (IV). Immunolocalization of proteoglycan epitopes in isolated canine tibial chondrons.

Chondrons have recently been extracted from adult articular cartilages and techniques developed to study their structure and composition in isolation. This study introduces methods to immobilize isolated canine chondrons in thin layers of agarose gel for immunohistochemistry and future in vitro studies. An antibody to Type VI collagen which stained the chondron in suspension was used to successfully validate the system and its feasibility for immunoelectron microscopy. Monoclonal and polyclonal antibodies to a variety of epitopes on the proteoglycan molecule were tested on fresh and fixed plugs cored from chondron-agarose gels. Plugs were immunolabeled with peroxidase-diaminobenzidine before or after digestion with testicular hyaluronidase or chondroitinase ABC. Trypsin/chymotrypsin were used to challenge epitopes of the core protein. The results indicate that epitopes to keratan sulfate, chondroitin sulfate, hyaluronate binding region, and core protein are localized in the chondron. Consistent staining was found in the tail and interconnecting segments between chondrons, whereas staining of the pericellular matrix and capsule adjacent to the chondrocyte varied according to the enzyme pre-treatment employed. We conclude that isolated chondrons are rich in proteoglycan monomer, which is particularly concentrated in the tail and interconnecting segments of the chondron where it could function to protect and stabilize the chondrocyte.

Animals↗
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

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

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↗
PubMed1979

Cerebrospinal fluid shunt function and hydrocephalus in the pediatric age group: a radiographic/clinical correlation.

Eighty-four pediatric patients were evaluated clinically and radiographically on 112 separate admissions for suspected increased intracranial pressure and possible shunt malfunction. The shunt system was tested clinically in each patient and correlated with the ventricular size as determined by CT. Of the patients with enlarged ventricles, 87% had an improperly functioning shunt and 13% had a normally functioning shunt. Of the patients with normal or small ventricles, 93% had a normally functioning shunt. Thus the "false negative" rate was 4% (small ventricles with a nonfunctioning shunt) and the "false positive" rate was 13% (large ventricles with a functioning shunt).

Adolescent↗
PubMed1978

Surgical resection for pulmonary interstitial emphysema in the newborn infant.

Three patients with pulmonary interstitial emphysema are presented in whom the course was similar and progressive. Eventually all three infants developed respiratory insufficiency and chronic dependence on mechanical ventilation, cardiovascular complications of patent ductus arteriosus with congestive heart failure, and seizures probably secondary to intermittent periods of asphyxia and hypoxemia. All infants underwent lobectomy and recovered rapidly. Follow-up examinations have shown some residual pulmonary abnormalities. All three infants are progressing within the normal range for motor development.

Follow-Up Studies↗
PubMed1976

Distal neonatal intestinal obstruction: the choice of contrast material.

The use of barium sulfate as the contrast agent of choice in the radiographic evaluation of distal neonatal intestinal obstruction is advocated. The advantages of Gastrografin or other water-soluble contrast materials are far outweighed by their disadvantages, which include the hazards of hypertonic dehydration and the danger of missing the diagnosis of Hirschsprung's disease. Five patients are presented, all of whom had the diagnosis of Hirschsprung's disease missed in the neonatal period with one use of Gastrografin enemas. All five were subsequently admitted to the Surgical Neonatal Intensive Care Unit, critically ill with enterocolitis of Hirschsprung's disease.

Barium Sulfate↗
PubMed1976

Renal cyst puncture: a non-diagnostic procedure in the infant.

A case of metastatic Wilms tumor in a newborn is presented. Cyst puncture was included in the preoperative evaluation and the merits of this procedure in infants are questioned. The differential diagnosis of intrarenal masses in the neonate is discussed.

Female↗
PubMed1976

Clinical evidence of intestinal absorption of Gastrografin.

Experimental evidence suggests that Gastrografin in the neonatal gastrointestinal tract leads to hypertonic dehydration by two mechanisms: loss of water from the circulating blood volume, and absorption of osmolarly active substances across intact, normal mucosa of the gastrointestinal tract. Clinical documentation of absorption of Gastrografin is presented. Renal excretion of contrast material was seen following its use in the treatment of meconium ileus.

Diatrizoate↗
PubMed1976

Neonatal diaphragmatic dysfunction.

Several unusual diaphragmatic problems in the neonate are presented and a new potential complication of the negative pressure respirator is illustrated. The association of bilateral diaphragmatic eventrations with chromosome anomalies is emphasized. In our experience the appearance of the chest on frontal and lateral views is usually so characteristic that no further evaluation is required. The relationship between several neuromuscular disorders and diaphragmatic dysfunction is discussed. A case of congenital myotonic dystrophy with unilateral eventration is illustrated.

Chromosomes, Human, 13-15↗
PubMed1976

The association of Wilms' tumor with second primary malignancies.

Medulloblastoma occurs uncommonly in the neonatal period. Metastatic Wilm's tumor in a newborn is extremely rare. The coincidence of these two neoplasms in one infant, and an equally uncommon combination of Wilms' tumor and a cerebellar medulloephithelioma in another child prompted this report. The authors speculate on the mechanism of oncogenesis in these and other infants with neonatal malignancies.

Cerebellar Neoplasms↗