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J G Pickering

Publications and source records attributed to J G Pickering.

46 records · Page 3Linked to original sources
PubMed1991

Quantitative assessment of the age of fibrotic lesions using polarized light microscopy and digital image analysis.

Reliable histologic methods for gauging the maturity of fibrotic lesions are limited, making interventions in the healing process difficult to assess. As collagen ages there is enhanced birefringence due to increased molecular and fibrillar organization. The purpose of this study was to develop a microscopal technique to quantify this process and to determine its ability to distinguish scars of varying ages. Fibrosis in the rat gracilis muscle was studied 5 to 63 days after superficial injury. Sections were stained with picrosirius red and illuminated with monochromatic, polarized light. The microscope fields were digitized using a computer-video system yielding an image in which noncollagenous material was dark (gray level 0) and collagen was depicted by grey levels 1 to 255. In the fibrosis model used, the collagen area fraction plateaued at 80% by day 21. The median collagen grey level increased progressively as the scar aged. It is concluded that this histologic, nondestructive technique can reliably quantify age-related optical properties of fibrotic collagen and that this could be used to determine the maturity of fibrotic lesions.

Aging↗
PubMed1990

Fibrosis in the transplanted heart and its relation to donor ischemic time. Assessment with polarized light microscopy and digital image analysis.

Long-distance procurement of cardiac allografts is commonly used to increase the supply of donor organs but has recently been associated with the development of impaired diastolic function. Therefore, the effect of the total ischemic duration on myocardial fibrosis was quantitatively evaluated in 36 cardiac transplant recipients in whom the ischemic time ranged from 70 to 363 (mean, 189 +/- 83) minutes. Interstitial collagen was quantified with polarization microscopy and digital image analysis in 115 endomyocardial biopsy specimens taken 5-10 days after surgery. The technique, developed for this study, showed excellent correlation with hydroxyproline analysis (r = 0.98, p less than 0.001). Collagen volume fraction in biopsy specimens from the transplanted hearts was significantly greater than that in biopsy samples from seven normal, age-matched autopsy hearts (4.7 +/- 1.9% vs. 2.9 +/- 0.6%, p less than 0.02). The degree of fibrosis correlated with the total ischemic time (r = 0.60, p less than 0.001). Donor age ranged from 10 to 51 years and did not correlate with the degree of fibrosis. No relation was found between the corresponding collagen content and right atrial pressure, pulmonary artery wedge pressure, or cardiac output measured at the time of biopsy. Myocyte damage was observed in eight of the 36 patients and was characterized by a striking loss of muscle birefringence. We conclude that cardiac allograft fibrosis may be identified shortly after transplantation and is dependent on the total ischemic duration.

Adult↗
PubMed1989

Focal right atrial dysplasia and atrial flutter in a patient with myotonic dystrophy.

Focal dysplasia of the right atrium was identified postmortem in a 22-year-old man with myotonic dystrophy and sudden death. Antemortem cardiac abnormalities included a single syncopal episode associated with atrial flutter with exercise-induced 1:1 atrioventricular conduction, sinus node dysfunction, and mild mitral valve prolapse. Pathologically there was only mild conduction system disease and the ventricular myocardium was normal. Right atrial dysplasia, previously unreported in myotonic dystrophy, appears to have been an arrhythmogenic lesion in this patient, serving as a morphological substrate for reentry.

Adult↗
PubMedDate not supplied

Quantitative assessment of myocardial collagen with picrosirius red staining and circularly polarized light.

Collagen plays a major role in the structural organization of the heart and therefore direct visualization of collagen fibers is a crucial component of cardiac analysis. Although linearly polarized light has proven an effective tool for the examination of myocardial collagen in histologic sections, the use of circularly polarized light may offer advantages and additional possibilities. We examined the potential enhancement of collagen analysis using circularly polarized light in two ways. We first measured the brightness, and hence indirectly assessed the birefringence, of collagen fibers in scars examined at different times after myocardial infarction. Secondly, we measured collagen content in myocardial tissue and compared results obtained from brightfield analysis of trichrome stained sections with those obtained from circularly polarized light analysis of picrosirius red stained sections. We observed a progressive increase in the maximum brightness of collagen fibers in the scar with time, and a time-dependent shift in the relative distribution of collagen fiber brightness from lower to higher levels. We found consistently lower values of collagen content in trichrome stained versus picrosirius red stained tissue, and concluded that trichrome staining underestimated collagen content. The information provided by these studies could not be obtained by brightfield analysis and could be only partially obtained from linearly polarized light analysis. Thus, analysis using circularly polarized light has the ability to enhance histologic assessment of tissue and can provide additional insights into the composition and structure of myocardial collagen.

Animals↗
PubMedDate not supplied

Enhanced detection of cardiac myocyte damage by polarized light microscopy. Use in a model of coxsackievirus B3-induced myocarditis.

Although accurate detection of cardiac muscle damage is critical in the diagnosis of acute myocarditis or acute cellular rejection in both clinical and experimental settings, the histologic evaluation is frequently uncertain without specialized stains. In a study of adult male A/J mice infected with 2x10(5) plaque-forming units of myocarditic coxsackievirus B3, cardiac muscle injury causing myofibrillar disruption was detected as a loss of muscle birefringence by polarized light microscopy. The technique was corroborated by comparison with Masson's trichrome stain and was helpful for histologic examination especially at the early preinflammatory stages of lesion development or in fringe territories of focal lesions. Polarized light microscopy is thus an available means to enhance the histologic determination of cardiac myocyte damage and has specific advantage in an absence of specialized stains.

Animals↗