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Biomedical subjects

M J Kern

Publications and source records attributed to M J Kern.

At least 145 records · Page 8Linked to original sources
PubMed1995

Immunohistochemical characterization of immune cell composition and cytokine receptor expression in human coronary atherectomy tissue.

BACKGROUND: Prior histologic studies have examined smooth muscle cell, macrophage and thrombus constituents of atherosclerotic coronary atherectomy specimens. Lymphocytes and mononuclear leukocytes are also detectable in atherosclerotic surgical pathology specimens utilizing immunocytochemical techniques. METHODS: In order to quantify the histological contribution of cytokine receptor-expressing immunocompetent cells to human coronary artery stenoses, 30 directional atherectomy catheter biopsy specimens (wet weight < or = 10 mg) from 16 patients were snap frozen (-70 degrees C) for quantitative immunocytochemical studies. Following computer-assisted quantification of total intimal nuclei per tissue section (mean 297 +/- 177; cell density 7 +/- 5/10(4) microns 2), monoclonal antibody cytochemistry was used to identify the percentage of these cells expressing antigenic clusters of differentiation (CD) characteristic of T-lymphocytes, B-lymphocytes and monocytes. Identification of alpha (low affinity) and beta (intermediate affinity) interleukin-2 receptors on intimal cells was accomplished using a three-step streptavidin-biotin method. RESULTS: A significant percentage of intimal cells were of lymphocytic (11 +/- 13%) or monocytic (12 +/- 14%) origin, with helper T-cells (9 +/- 12%) outnumbering both suppressor T-cells (2 +/- 4%) and B-lymphocytes (1 +/- 2%). Interleukin-2 receptors were noted on 9 +/- 12% of intimal cells, including cells with a vascular smooth muscle phenotype. CONCLUSIONS: These quantitative immunocytochemical data conclusively demonstrate that lymphocytes and monocytes account for over 20% of coronary plaque cells obtained by in-vivo atherectomy, and that helper (CD4) T-cells predominate over suppressor (CD8) T-cells and B-lymphocytes. Variable interleukin-2 receptor subtype expression occurs in mononuclear leukocytes infiltrating chronic human atheroma. By applying these techniques, the therapeutic effects of cytotoxic agents on selectively targeted cytokine receptor-expressing cells may now be evaluated in vivo in small human directional coronary atherectomy specimens.

Adult↗
PubMed1994

Genomic organization and chromosome localization of the murine homeobox gene Pmx.

Homeobox genes are expressed in very specific temporal and spatial patterns and function as transcriptional regulators of developmental processes. The murine homeobox gene, Pmx (paired mesoderm homeobox), is expressed in a mesodermally restricted pattern in embryos and most abundantly in cardiac, skeletal, and smooth muscle tissues in adults. Previously, this murine gene was named K-2 and mHox, while the human homolog was named Phox1. In this report, the localization of Pmx has been determined by interspecific backcross analysis. The Pmx gene is located on Chromosome 1, approximately 3.3 cM distal to the Gsh-4 homeobox locus. The sequence of the Pmx transcript has been extended toward the 5' end and corresponds in size to one of the transcripts previously detected by Northern blot analysis. Sequence analysis indicates that Pmx is the first characterized mammalian gene to encode a paired type homeodomain, but not a paired domain. The Pmx gene includes at least five exons spanning a minimum of 60 kb of genomic DNA, making this the largest known murine homeobox gene.

Animals↗
PubMed1994

Translesional pressure-flow velocity assessment in patients: Part I.

Interventional physiology presents the operator with objective data to facilitate decision making. A thorough and validated understanding of the alterations of pressure and flow in the human coronary circulation is currently in progress. As illustrated in the case studies, some situations have data which may initially appear contradictory or unhelpful to clinical practice. These data should provide a framework to understand the dynamic physiology producing the clinical syndromes in patients undergoing coronary interventional procedures. Future Interventional Physiology Rounds will examine coronary pressure-flow responses during directional atherectomy, stents, and acute myocardial infarction.

Adult↗
PubMed1994

Coronary flow velocity during coronary angioplasty in regions of myocardial infarction.

In patients undergoing angioplasty for angina after myocardial infarction, patterns of post-stenotic coronary blood flow velocity depend not only on satisfactory dilation of the flow-limiting lesion, but also on the vasoregulatory capacity of infarcted myocardium. The case examples demonstrate both normal and persistently abnormal flow velocity patterns following successful coronary angioplasty for post-infarction ischemia. Recognition of collateral flow patterns, easily available using the Doppler angioplasty guidewire, may provide valuable information predicting the viability of post-infarcted myocardium and the resolution of abnormal distal coronary flow patterns.

Adult↗
PubMed1994

Alterations of coronary flow velocity during intervention for acute myocardial infarction: responses to complications of intracoronary thrombolysis and angioplasty.

Alterations, either an increase or decrease, in the distal flow velocity over time are associated with alterations in vessel diameter and/or unstable flow velocity. Unexplained unstable flow velocity patterns should act as early warning signs to prompt the interventionalist to assess continued coronary patency and need for renewed interventions.

Angioplasty, Balloon, Coronary↗
PubMed1994

Limitations of translesional pressure and flow velocity for long ostial left anterior descending stenoses.

Translesional pressure and flow velocity can be used to assess angiographically intermediate or indeterminate lesions. Ostial narrowings and long lesions represent situations that may require both pressure and flow velocity assessment. In patients with hypertension, diabetes mellitus, and chronic renal failure, distally measured absolute and regional coronary reserve values alone may not be helpful in selecting lesions requiring intervention.

Adult↗
PubMed1994

Approach to total occlusion of an aorto-ostial "Y" saphenous vein graft with anterior descending graft limb stenosis by serial balloon angioplasty and elective stent deployment.

Coronary revascularization using balloon angioplasty and stent placement for unstable angina was performed in a 74-year-old woman with an aorto-ostial occlusion of a "Y-type" saphenous vein graft and a severe stenosis in the body of a 14-year-old left anterior descending saphenous vein graft. Multiple prior coronary bypass graft surgeries, location of branch graft lesions, and length of the ostial stenosis must be considered in selecting the approach to revascularization.

Aged↗
PubMed1994

Role of side holes in guide catheters: observations on coronary pressure and flow.

When performing coronary angioplasty, guide catheter intubation of the ostium often leads to a damping of the pressure tracing. In contrast, when a guide catheter with side holes is used, the pressure tracing is most often superimposable to the pressure wave recorded through the side arm of a femoral artery sheath introducer. This pressure wave gives the reassuring impression of normal hemodynamics in the coronary artery. To illustrate the role of guide catheter side holes and that guide catheter pressure does not necessarily equal the actual coronary artery perfusion pressure, we report observations on trans-ostial pressure gradients at rest and during increased coronary flow rates. An abbreviated in vivo study of side holes on the maximal achievable blood flow, employing timed blood flow collections in 7F and 8F side hole guide catheters, was made in 10 patients. At high mean aortic pressure levels, the blood flow through the side holes did not exceed 80 and 60 mL/min for 8 and 7F guide catheters, respectively. These observations suggest that, under some conditions, the guide catheter may produce a resting or hyperemic trans-ostial gradient and that the flow provided only by the side holes of guide catheter is limited. Guide catheter interference with normal flow should be considered in interventional procedures even when arterial pressure appears normal.

Adult↗
PubMed1994

Part XII: Assessment of serial lesions in the proximal right coronary artery following intracoronary thrombolysis.

Assessment of angiographically serial coronary lesions at the time of diagnostic catheterization remains a difficult clinical problem. Doppler flow velocity data is easily obtainable and allows physiologic interrogation of the distal coronary microcirculation, but has limitations in the detection of some flow-limiting stenoses. In cases of serial lesions or distal arterial disease, particularly after thrombolysis, flow velocity data may be insufficient to identify the hemodynamic significance of the coronary lesions. Translesional pressure measurements may be combined with flow velocity data to support an appropriate physiologically based therapeutic approach.

Adult↗
PubMed1994

Improved left ventriculography with the new 5F helical-tip Halo catheter.

The purpose of this study was to evaluate the incidence of ventricular ectopy and catheter movement during left ventriculography with a new 5F halo angiographic catheter that has a unique helical-tip design unlike the design of standard 5F and 6F pigtail catheters. The pigtail catheter is presently preferred for left ventriculography, although its use is associated with a high incidence of ventricular ectopy, which often limits precise interpretation of data. In this study, 155 patients (in 145 unpaired and 10 paired studies) underwent left ventriculography during diagnostic cardiac catheterization. In the unpaired group, the 5F Halo catheter was used in 63 studies and standard 5F and 6F pigtail catheters in 40 and 42 studies, respectively. An additional 10 patients had two consecutive left ventriculograms with 5F Halo and pigtail catheters. Ventriculograms were performed with the same technique in the 30-degree right anterior oblique projection. The left ventricle was divided into a basal zone, midzone, and apical zone. Catheter movement within the ventricle was scored as significant if there was at least one zone change. Ventricular ectopy was quantified by a simultaneous electrocardiographic recording during contrast injection. There were no significant differences in the left ventricular systolic or end-diastolic pressures, left ventricular score, or diagnostic quality of the ventriculograms between the 5F Halo catheter group and the 5F and 6F pigtail catheter groups. Mean ventricular ectopy with the 5F Halo catheter was significantly less (0.9 +/- 1.4 ventricular premature beats [VPBs]) than with the 5F pigtail catheter (2.3 +/- 2.5 VPBs, p < 0.001) or the 6F pigtail catheter (2.9 +/- 2.9 VPBs, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗