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Biomedical subjects

P Heap

Publications and source records attributed to P Heap.

12 recordsLinked to original sources
PubMed1994

Submicroscopic crystals in osteoarthritic synovial fluids.

OBJECTIVES: To investigate the hypothesis that synovial fluid (SF) from patients with osteoarthritis (OA) may contain calcium phosphate crystals that are either too small, or too few in number to be identified by conventional light microscopy techniques. METHODS: Twelve SF from 11 patients with established knee OA, five SF from patients with rheumatoid arthritis (RA), and two control samples of SF from patients with pseudogout were subjected to an enzyme/hypochlorite extraction procedure. The patients with OA and RA had no radiographic evidence of chondrocalcinosis, or SF crystals on polarised light microscopy. Extracted material was examined and analysed by analytical electron microscopy (AEM) and x ray powder diffraction (XRD). RESULTS: Mineral was found in 11 of 12 OA samples, ranging from 2-120 micrograms/ml SF. Analytical electron microscopy revealed calcium pyrophosphate dihydrate (CPPD) crystals in five (confirmed by XRD in three) and basic calcium phosphates (BCP) in eight (five on XRD). Two samples with confirmed CPPD contained some rods with a mean length below 100 nm. The majority of BCP clusters were also less than 100 nm in diameter. BCP was detected in 1/5 RA samples. Control samples contained CPPD crystals of the expected size range of 0.42-17.9 microns. CONCLUSIONS: The data indicate that many OA SF may contain CPPD or BCP crystals which are too small or too few in number to be identified by conventional techniques. Crystal deposition is not an 'on-off' phenomenon in OA.

Aged↗
PubMed1993

A method for isolating rabbit atrioventricular node myocytes which retain normal morphology and function.

This report describes a method for isolating single rabbit atrioventricular (AV) node myocytes which retain their normal morphology when exposed to millimolar levels of calcium. Previous attempts to isolate cells from the AV node have produced myocytes that "round up" (i.e., go into contracture) when exposed to calcium. We show that the cells isolated with our technique possess properties similar to those described for intact AV nodal tissue. We find that single AV node myocytes are shorter and thinner (mean dimension = 103.5 +/- 2.3 by 7.8 +/- 0.2 microns; mean +/- SE, n = 90) than atrial or ventricular cells. Many of the cells produced by this isolation procedure generate spontaneous action potentials (188 +/- 9 beats/min; n = 6), which resemble action potentials recorded previously from the intact AV node. Voltage-clamp recordings from spontaneously active cells revealed similar membrane currents to those seen in intact tissue: fast sodium current and a L-type calcium current, followed by a delayed outward current. However, we found little evidence for the hyperpolarization-activated current (I(f)). Because the cells responded normally to concentrations of acetylcholine and isoproterenol within the physiological range, their cholinergic and adrenergic receptors appear to be well preserved by the isolation procedure. The ability to isolate morphologically and functionally normal AV myocytes may represent a significant advance for the investigation of nodal physiology at the cellular level.

Acetylcholine↗
PubMed1992

Systemic distribution of wear debris after hip replacement. A cause for concern?

The production of particulate wear debris is a recognised complication of joint arthroplasty, but interest has concentrated on local tissue reactions and a possible association with implant loosening. The fate of wear products in the body remains unknown, although some of the metals used in the construction of orthopaedic implants are known to have toxic and oncogenic properties. We report histological and electron-microscopic evidence from two cases which shows that metallic debris can be identified in the lymphoreticular tissues of the body distant from the hip some years after joint replacement. The increase in the use of total arthroplasty in younger patients, the development of new alloys and the use of porous coatings must raise concern for the long-term effects of the accumulation of wear debris in the body.

Aged↗
PubMed1988

Effect of aerosol challenge with sensitising antigen on the permeability of the surface of the rat trachea in life.

A rat model of immediate pulmonary hypersensitivity was used to investigate the permeability changes in the tracheal epithelium produced by aerosol challenge with antigen. The rats were sensitised by the intraperitoneal injection of antigen (dinitrophenyl (DNP19) ovalbumin). Sensitised and control animals were then challenged for 60 minutes with an aerosol of the same antigen, which also contained the electron dense pore marker lanthanum. Histological examination and x ray probe microanalysis showed a greater intercellular concentration of lanthanum in the tracheal epithelium in sensitised than in control animals. The results show that in sensitised rats increased intercellular penetrance of antigen can occur after antigen challenge.

Animals↗
PubMed1987

Antigenic challenge via the airway alters the permeability of the trachea in sensitized rats.

Inbred rats were sensitized by intraperitoneal injection of DNP19 ovalbumin (DNP-OA) or saline. The rats were subsequently challenged by exposure to an aerosol of DNP-OA or bovine gamma globulins (BGG) for 10 min. Tracheal tissue was processed immediately after challenge in fixative containing 1% lanthanum. Planimetry of transmission electron micrographs showed 59% of the intraepithelial membranes were stained with lanthanum in the DNP-OA-sensitized and DNP-OA-challenged group; 39% in the saline-sensitized, DNP-OA-challenged group, and 26% in the DNP-OA-sensitized, BGG-challenged group. X-ray static probe microanalysis confirmed that most lanthanum penetrated in the DNP-OA-sensitized and DNP-OA-challenged group. In this group, the magnitude of the mechanical response, measured by body plethysmography, correlated directly (r = 0.74) with the lanthanum penetration. Our results confirm that increased permeability of the intercellular spaces occurs in immediate pulmonary hypersensitivity. They suggest that this change in permeability may be involved in producing the mechanical response.

Aerosols↗
PubMed1986

Lanthanum penetration of the trachea after the immediate response of sensitized rats to aerosol antigen.

Inbred rats were sensitized by the intraperitoneal injection of 10 micrograms DNP19-ovalbumin (DNP-OA). These rats were compared both in their responses to 10 min of aerosol challenge with DNP-OA or bovine gamma globulins (BGG) and with other rats similarly 'sensitized' with saline and subsequently challenged with DNP-OA. Lanthanum (1%) in the fixative permitted the identification by transmission electron microscopy of electron-dense lanthanum in the tracheal epithelium. Planimetry showed 59% of the intercellular membranes in the tracheal epithelium of the group sensitized and challenged with DNP-OA were stained with lanthanum versus 39% in the saline-sensitized and 26% in the BGG-challenged. X-ray energy probe microanalyses confirmed that significantly more lanthanum had penetrated in the group sensitized and challenged with DNP-OA than in the other two groups. In this group the magnitude of the change in respiratory pattern produced by challenge was directly related to the quantity of the lanthanum in the epithelium. Our findings show that increased permeability of the intercellular spaces occurs in immediate pulmonary hypersensitivity, probably as a result of the opening of the tight intercellular junctions and suggests that this change of permeability may be involved in producing the physiological response.

Animals↗
PubMed1985

Effect of enzootic pneumonia of pigs on growth performance.

Growing pigs were naturally infected with a field strain of Mycoplasma hyopneumoniae to assess the effect of enzootic pneumonia on production. Both the initial ("breakdown") and endemic stages of infection were evaluated. The pigs were reared under environmental and management conditions commonly found on commercial piggeries in South Australia. Growth rate of pigs held in-contact with inoculated pigs was reduced by 12.7% (p less than 0.01) between 50 to 85 kg bodyweight. In the second trial inoculated gilts were used to naturally infect piglets during suckling. Growth rate of infected pigs was reduced by 15.9% (p less than 0.001) between 8 to 85 kg bodyweight, while feed conversion was depressed by 13.8% (p less than 0.05) between 10 to 25 kg bodyweight. At current feed and production costs this reduced performance added approximately $2.80 to the cost of every pig produced. These losses were recorded in groups of pigs in which enzootic pneumonia was present. At slaughter, 40% of lungs contained gross lesions of enzootic pneumonia which were free of significant secondary bacteria. The nature of the infection was established by gross and microscopic pathology and confirmed by the detection of specific complement fixing antibody in infected pigs and the demonstration of M. hyopneumoniae by direct immunofluorescent staining of lung sections.

Animals↗
PubMed1985

Enzootic pneumonia of pigs in South Australia--factors relating to incidence of disease.

Environmental and management conditions of 15 herds with a high-prevalence (greater than 70%) of enzootic pneumonia of pigs at slaughter were compared with 16 herds with a low-prevalence (less than 30%) to determine factors commonly predisposing pigs to enzootic pneumonia in South Australia. Comparisons were made of herds having greater than 100 sows (fully intensive units) and also small herds having 20 to 70 sows (sideline units). Half the herds were visited in summer and half in winter to detect seasonal factors. In small herds, factors commonly found associated with a high prevalence of enzootic pneumonia were larger numbers of pigs per shed section (p less than 0.001), larger group sizes (p less than 0.01) and draughty farrowing and weaner accommodation (p less than 0.01). In large herds, factors associated with a high prevalence were higher pen stocking rate (p less than 0.05) and airspace stocking rate (p greater than 0.05), and a trend toward higher atmospheric ammonia levels in summer (p less than 0.1).

Air↗
PubMed1982

An ultrastructural study of glycosaminoglycans associated with collagen and other constituents of the cat anulus fibrosus.

It has been confirmed that glycosaminoglycan is associated with collagen and other constituents of the anulus fibrosus. In cells, it appears to be present on the rough endoplasmic reticulum and is removed by hyaluronidase digestion and thus may consist of chondroitin sulphate. In pericellular material it appears as fibrils and granules, is unaffected by hyaluronidase and may consist of keratan sulphate or dermatan sulphate. Collagen fibrils contain hyaluronidase-digestable glycosaminoglycan (such as chondroitin sulphate) in the form of peripheral rings that appear as bands in longitudinal sections of the fibrils.

Animals↗