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Biomedical subjects

J F Cornhill

Publications and source records attributed to J F Cornhill.

At least 37 records · Page 2Linked to original sources
PubMed1996

A medical workstation for the display and analysis of multi-frame digital cineradiographic data.

A medical workstation has been developed for the efficient display and analysis of large sets of digital cineradiographic images. Various features aid the clinician in quickly identifying and extracting the image information relevant for diagnosis: animated viewing of image frames, a digital magnifying glass for local image enlargement and enhancement, a special review queue for critical image frames, and task-oriented image processing. Double frame buffering and direct memory addressing ensure fast, artifact-free image display and transfer. Much freedom is provided for adapting the system to one's own preferences. A statistical analysis of extensive tests conducted by eight clinical expert reviewers is given.

Cineradiography↗
PubMed1996

Effect of age, race, body surface area, heart weight and atherosclerosis on coronary artery dimensions in young males.

Compensatory arterial enlargement in response to atherosclerosis has been demonstrated for the left main coronary artery. Only limited data is available on the interaction of patient characteristics and atherosclerosis with coronary artery dimensions. The purpose of the present study was to evaluate the influence of age, race, body habitus, heart weight and atherosclerosis on coronary artery dimensions of young males. Hearts from 137 young men (age 32 +/- 8 years; 78 black, 59 white) with unnatural deaths (homicide, suicide, accident, drug overdose) were perfusion-fixed, and histologic sections were obtained from the left main, proximal left anterior descending and left circumflex coronary arteries. Computerized planimetry was performed on Movat stained sections. Multiple regression analysis was used to evaluate the relative contribution of plaque size, age, race, heart weight and body surface area on coronary dimensions and compensatory enlargement in response to atherosclerosis. In the left anterior descending and left main coronary arteries, black race, body surface area and age were independent predictors of increased lumen area. In the left circumflex, age was a predictor of lumen area. Plaque area, black race and body surface area independently predicted increased area enclosed by the internal elastic lamina area. There was compensatory enlargement of internal elastic lamina with increasing plaque size in both races in the three arteries, but the percent luminal stenosis was greater in whites due to smaller artery size. Luminal narrowing did not develop until plaques occupied 30% of internal elastic lamina area. Among a population of young men with non-cardiac deaths, blacks have larger lumen and area enclosed by internal elastic lamina than whites. Age and body surface area are major determinants of lumen areas, and compensatory arterial enlargement was seen in all examined arteries in the present study.

Adolescent↗
PubMed1996

Immunization with cholesterol-rich liposomes induces anti-cholesterol antibodies and reduces diet-induced hypercholesterolemia and plaque formation.

Immunization of rabbits with a protein-free formulation consisting of liposomes containing 71% cholesterol and lipid A as an adjuvant induced anticholesterol antibodies that caused complement-dependent lysis of liposomes lacking lipid A. The antibodies, immunoglobulin G (IgG) and immunoglobulin M (IgM), also recognized nonoxidized crystalline cholesterol as an antigen by enzyme-linked immunosorbent assay (ELISA). The effects of immunization against cholesterol on elevations in serum cholesterol and development of atherosclerosis were examined in rabbits fed a diet containing 0.5% to 1.0% cholesterol. Although the mean serum cholesterol level, mainly in the form of very-low-density lipoprotein cholesterol, rose as much as 60-fold in the nonimmunized rabbits, the elevation was significantly less--as much as 35% lower--in the immunized rabbits. Elevation of serum cholesterol was accompanied by an apparent drop in the level of antibodies on initiating the diet, followed by a rebound on stopping the diet, thus suggesting that the antibodies were adsorbed to cholesterol that was present in circulating lipoproteins. When lipoprotein fractions--composed of either very-low-density and intermediate-density lipoproteins derived from cholesterol-fed nonimmunized rabbits or human low-density lipoproteins--were tested as capture antigens by solid-phase ELISA, reactivity was observed with IgG and IgM antibodies present in the serum of immunized rabbits. Immunization also resulted in a marked decrease in the risk of developing atherosclerosis. Analysis of aortic atherosclerosis by quantitative histologic examination and fatty streaks by automated morphometric probability-of-occurrence mapping showed diminished atherosclerosis in most areas of the aorta in vaccine recipients. It is proposed that immunization with liposomes containing 71% cholesterol and lipid A can reduce diet-induced hypercholesterolemia and atherosclerosis.

Animals↗
PubMed1996

Hypercholesterolemia in the rabbit induced by feeding graded amounts of low-level cholesterol. Methodological considerations regarding individual variability in response to dietary cholesterol and development of lesion type.

While a number of studies have presented detailed examinations of lesion development in the cholesterol-fed rabbit, individual variability in response to cholesterol feeding and type of lesion produced relative to the degree of cholesterol exposure is not well defined. This study analyzed such critical parameters in an attempt to further characterize the model and establish a baseline for future testing of treatments targeted at limiting atherosclerosis. For these experiments, male New Zealand White rabbits were fed atherogenic diets consisting of 0.05%, 0.10%, 0.15%, 0.20%, or 0.25% cholesterol dissolved in 6% peanut oil for 31 to 32 weeks. Raising dietary cholesterol from 0.05% to 0.15% resulted in a less than twofold stepwise increase in total plasma cholesterol (TPC) exposure (area under plasma cholesterol versus time curve), whereas further increases in cholesterol intake resulted in an exponential four- to fivefold increase in TPC exposure. Regression analysis of TPC exposure with aortic sudanophilia demonstrated a threshold of approximately 5000 cholesterol weeks; below this limit lesions were minimal, and above this value the degree of plaque correlated with TPC exposure. Furthermore, a wide biological variability occurred among rabbits with respect to individual responsiveness to dietary cholesterol. In the aorta, various types of plaques, from fatty streaks to atheromatous lesions, were observed, depending on the degree of cholesterol intake. Diets consisting of < 0.15% cholesterol resulted in the development of fatty streak lesions, while transitional lesions and atheromatous plaques were mostly found with higher cholesterol feeding. Coronary artery atherosclerosis was present in > 50% of animals fed diets > or = 0.15% cholesterol. Despite the level of TPC exposure, coronary lesions in epicardial vessels were generally the fibrous type, whereas intramyocardial arteries demonstrated predominantly intimal foam cells. In conclusion, by adjusting dietary cholesterol intake and selecting rabbits with a similar responsiveness to cholesterol, the overall cholesterol exposure can be more closely controlled to minimize the inherent individual variability among animals in this model. The nature of the target lesion must also be carefully considered, because the efficacy of some treatments may depend on the type of atherosclerotic plaque.

Animals↗
PubMed1995

Flow characteristics of aortic cannulae.

Atheroembolism from the ascending aorta is an emerging cause of noncardiac complications after open heart surgery. We designed a new arterial cannula specifically to reduce the exit force and velocity of blood flow, thereby reducing the "sandblasting" effect of the exiting blood jet. The cannula has a closed tip and an internal cone that diffuses blood flow such that it enters the aorta via multiple side holes. Fluid dynamics of the cannula were tested against five frequently used cannulae: Sarns High-Flow (3M Sarns High-Flow, Ann Arbor, MI, USA), DLP 83024 (DLP Inc., Grand Rapids, MI, USA), RMI ARS 024C (Research Medical Inc. of Research Industries Corp., Midvale, UT, USA), Bard 1966 (C.R. Bard Inc., Haverhill, MA, USA), and Argyle THI (Sherwood Medical Co. Sub American Home Products Corp., St. Louis, MO, USA). All cannulae had an 8.0-mm external diameter. The new cannula demonstrated a similar pressure drop and internal tip diameter as the others. The exit force (newtons) of the Soft Flow cannula was significantly less than the Sarns High-Flow (p < 0.05), DLP (p < 0.001), RMI (p < 0.01), Bard (p < 0.001), and the Argyle (p < 0.001) cannulae. Peak velocity (cm/s) of the Soft Flow cannula was significantly less than the DLP (p < 0.01), RMI (p < 0.01), Bard (p < 0.01), and Argyle (p < 0.001). The cannulae all had similar hemolysis rates. The new arterial cannula produced the lowest exit force and flow velocity with no increase in hemolysis and may help to decrease the incidence of atheroemboli and its sequelae.

Cardiac Surgical Procedures↗
PubMed1995

Restenosis after experimental angioplasty. Intimal, medial, and adventitial changes associated with constrictive remodeling.

Predicting and preventing arterial restenosis after angioplasty has failed despite considerable research into mechanisms and techniques. We examined the roles of chronic constriction, neointimal-medial growth, and adventitial changes in restenosis in atherosclerotic rabbits. Angioplasty was performed on femoral artery lesions 4 weeks after lesion induction by air drying and cholesterol-supplemented diet. Angiographic and histological evaluation was conducted 3 to 4 weeks after angioplasty. The angiographic minimum luminal diameter (MLD) increased from 1.31 +/- 0.21 to 1.73 +/- 0.41 mm after angioplasty. Loss in MLD by 3 to 4 weeks was 0.95 +/- 0.64 mm. Initial gain and late loss correlated (P = .008). Late residual stenosis, defined histologically as the difference between the luminal areas of a proximal reference site and lesion site normalized by the luminal area of the reference site, was 52 +/- 32%. Histological indices of chronic constriction, neointimal-medial growth, and adventitial growth were defined on the basis of the areas of these arterial wall layers at the lesion site relative to the reference site. Another parameter defined as the ratio of adventitial area to the area of intima+media at the lesion site allowed evaluation of the relative importance of these layers. Surprisingly, late residual stenosis correlated with chronic constriction (P = .0003) but not with neointimal-medial growth or adventitial growth. The ratio of adventitial area to the area of intima+media at the lesion site also correlated with chronic constriction (P = .01). These findings suggest that factors related to arterial remodeling rather than neointimal-medial growth may dominate the response to angioplasty.

Angiography↗
PubMed1995

Effect of alpha-tocopherol on restenosis after angioplasty in a model of experimental atherosclerosis.

The ability of alpha-tocopherol to reduce restenosis after angioplasty was tested in a rabbit model in which angioplasty was performed on established atherosclerotic lesions. Lesions induced by 4 wk of cholesterol feeding after focal desiccation of femoral arteries were balloon dilated. 3 wk after angioplasty, angiographically determined minimum luminal diameters were less in the untreated group (0.80 +/- 0.51 mm) than in the group treated with oral alpha-tocopherol beginning 19 d before angioplasty (1.38 +/- 0.29 mm; P < 0.01). The cross-sectional area of the intima-media was greater in the untreated group (1.18 +/- 0.48 mm2) than in the alpha-tocopherol group (0.62 +/- 0.25 mm2, P < 0.0001). These differences were not due to vasoconstriction or altered plasma cholesterol. Alpha-tocopherol thus reduced restenosis after angioplasty in this model. In rabbit vascular smooth muscle cells, oxidized low density lipoprotein stimulated DNA synthesis. Alpha-tocopherol treatment inhibited DNA synthesis stimulated by oxidized low density lipoprotein, but not by serum. The findings are consistent with the hypothesis that oxidized lipids can stimulate hyperplasia and that antioxidants may limit hyperplasia by inhibiting either the oxidation or the proliferative effects of oxidants on cells.

Administration, Oral↗
PubMed1995

The clinical morphology of human atherosclerotic lesions. Lessons from the PDAY Study. Pathobiological Determinants of Atherosclerosis in Youth.

The PDAY study addresses the role traditional risk factors play in the development and progression of arterial lesions in youth (15 to 34 years of age). This autopsy based study indicates that in the aorta and in the right coronary artery, atherosclerosis is positively associated with cholesterol (LDL+VLDL), glucose intolerance, smoking, hypertension, and obesity and negatively associated with HDL-cholesterol. When a high cholesterol group (> 240 mg/dl) is compared to a low cholesterol group (< 200 mg/dl) early fatty sudanophilic lesions decrease in the aorta from 35% to 29% (p < 0.03) surface area, while raised atherosclerotic lesions are lowered (from 5%) in the high cholesterol group (to 3%) in the low cholesterol group; p < 0.02). Clearly, risk factors particularly cholesterol levels, directly affect the development of atherosclerosis in the coronary arteries and the aorta of young people. The data presented suggest that risk factor modification would be beneficial in young people as from 15 years of age.

Adolescent↗
PubMed1994

Gastric vascular ectasia in patients undergoing bone marrow transplantation.

The authors reviewed all gastric biopsy specimens from patients who had undergone bone marrow transplantation at our institution between 1986 and 1991. Ten of 28 patients had gastric vascular ectasia (GVE), a distinct lesion consisting of telangiectatic vessels within the superficial gastric mucosa. All patients undergoing bone marrow transplantation had received a standard chemotherapeutic transplantation regimen consisting of busulfan and cyclophosphamide without total-body irradiation. Eight of the 10 patients with GVE had evidence of upper gastrointestinal tract bleeding, as compared with 4 of 18 patients without GVE. In all 10 patients with GVE, the results of liver chemistry analyses were abnormal. Five patients had hepatic veno-occlusive disease, and 8 patients had graft-versus-host disease. Endoscopic biopsy samples of GVE showed markedly dilated vascular spaces similar to those seen in gastric antral vascular ectasia and diffuse antral vascular ectasia. However, no thrombi were identified in these enlarged vessels. Digital morphometry showed the mean cross-sectional area of GVE vessels was significantly greater (P < .001, Wilcoxon's rank-sum test) than the mean vessel areas of 10 chemical gastritis and 10 normal antral (control) biopsy samples. Gastric vascular ectasia may be a significant cause of gastrointestinal bleeding in patients undergoing bone marrow transplantation. The pathogenesis of GVE is unknown; transplantation regimen toxicity may play a role.

Adolescent↗
PubMed1994

Cholesterol-fed and casein-fed rabbit models of atherosclerosis. Part 1: Differing lesion area and volume despite equal plasma cholesterol levels.

One-month-old male New Zealand White rabbits were fed either a cholesterol-free casein diet (CAS; n = 10); low-level cholesterol-supplemented (0.125% to 0.5% by weight) chow (CH; n = 10); or standard laboratory rabbit chow (n = 3) for 24 weeks, during which total plasma cholesterol (TPC) levels were matched for the two experimental groups (TPCCAS = 475 +/- 39 mg/dL; TPCCH = 515 +/- 70 mg/dL). The percentage of cholesterol partitioned into each of the lipoprotein fractions except high-density lipoprotein (HDL) was significantly different for the experimental groups: casein-fed rabbits had a primarily low-density lipoprotein (LDL) hypercholesterolemia while cholesterol-fed rabbits had approximately equal levels of very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and LDL cholesterol. Despite matched TPC, lesions in CH animals covered twice the luminal surface area (as detected by oil red O staining; P < .05) and had three times the total volume compared with lesions in the CAS group (P < .05). Lesion volume was positively correlated with TPC and IDL and LDL cholesterol for the CAS group and with TPC and IDL cholesterol for the CH group. When the experimental groups were combined, TPC and VLDL and IDL cholesterol were positively correlated with the lesion volume. Probability of occurrence maps revealed, however, that both groups were virtually identical with respect to the topographic distribution of lesions in the thoracic and abdominal aortas. The data suggested that the differential partitioning of cholesterol into the lipoprotein fractions seen in CAS and CH rabbits influenced lesion area and volume but not topographic distribution.

Animals↗
PubMed1993

The expression of monocyte chemotactic protein (MCP-1) in human vascular endothelium in vitro and in vivo.

A monocyte chemotactic protein (MCP-1) is thought to play a major role in recruiting monocytes to the vascular endothelium where the adherence of monocytes is one of the earliest events in atherogenesis. We cloned MCP-1 cDNA from a lambda gt 11 cDNA library constructed from human aortic endothelial mRNA to test whether MCP-1 expressed in arterial endothelium is identical to those from other sources. A approximately 670 bp MCP-1 cDNA clone was identified and showed the identical sequence with the ones from other cell lines. Northern blot analysis using this cloned MCP-1 cDNA as probe revealed two hybridizing bands of RNA at 0.68 and 0.77 kb in human aortic, human pulmonary arterial, and human umbilical vein endothelial cell cultures. Primer extension analysis showed that the difference in size (approximately 90 bp) between the two transcripts is not due to a difference at the 5'-noncoding region. The amount of MCP-1 transcripts increased dramatically in aortic endothelial cells when stimulated with recombinant IL-1 alpha (100 units/ml), IL-1 beta (100 units/ml), or TNF-alpha (200 ng/ml). Northern blot and slot blot analysis of RNA isolated from both the endothelium and the underlying vessel wall of freshly removed human arteries and veins showed MCP-1 transcripts. This observation demonstrates for the first time that MCP-1 is expressed not only in atherosclerotic human arteries but also in symptom free arteries and veins in vivo.

Amino Acid Sequence↗
PubMed1992

Cocaine: an independent risk factor for aortic sudanophilia. A preliminary report.

Several recent autopsy reports indicate an increased prevalence of coronary atherosclerosis in ischemic heart disease temporally associated with cocaine abuse. The objective of this study was to conduct a retrospective analysis of sudanophilic lesions in young asymptomatic individuals who abused cocaine. Twenty-six cases (15-34-year-old black males) were examined from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. Sixteen subjects (mean age 25 +/- 1 years) had a positive toxicologic screen for cocaine and/or its major metabolites at autopsy and were confirmed habitual cocaine abusers. The remaining 10 cases (mean age 24 +/- 2 years) were subjects with a negative toxicologic screen at autopsy and no history of illicit drug abuse. Post-mortem blood was collected for lipoprotein analysis and determination of smoking status. The aorta and right coronary arteries were stained with Sudan IV and the degree and extent of sudanophilia was quantitated by image analysis. Multiple linear regression analysis of cocaine, age, smoking status, VLDL+LDL-C/HDL-C ratio and HDL-C as predictor variables of percentage intimal surface involvement, revealed an association between cocaine abuse and the extent of sudanophilia in both the thoracic and abdominal aorta (P = 0.002 and 0.049, respectively). Analysis of risk factors or of cocaine abuse as predictors of sudanophilia did not achieve statistical significance in the right coronary artery. These preliminary results suggest that habitual use of cocaine, through unknown mechanism(s), increases aortic sudanophilia independent of traditional risk factors.

Adolescent↗
PubMed1991

Increase in atherosclerosis and adventitial mast cells in cocaine abusers: an alternative mechanism of cocaine-associated coronary vasospasm and thrombosis.

Coronary vasospasm has been implicated as a cause of myocardial ischemia and sudden cardiac death in cocaine abusers. However, the mechanism or mechanisms remain unknown. Autopsy records (n = 5,871) from the medical examiner's files at Baltimore, Maryland and northern Virginia were examined and 495 persons (8.4%) were identified with positive toxicologic findings for cocaine. Of these, six subjects (1.2%) had total thrombotic occlusion, involving primarily the left anterior descending coronary artery. The mean number of adventitial mast cells per coronary segment and the degree of atherosclerosis were determined. These observations were compared with findings in age- and gender-matched subjects who died from cocaine overdose and in patients who had sudden cardiac death (acute thrombosis) without a history of illicit drug abuse. There were significantly more mast cells in subjects with cocaine-associated thrombosis than in the other groups. The number of mast cells showed a significant correlation with the degree of cross-sectional luminal narrowing (r = 0.68) in subjects with cocaine-associated thrombosis but not in subjects with sudden death due to thrombosis (r = 0.34, p less than 0.03). Subjects with cocaine-associated thrombosis also had significant coronary atherosclerosis without plaque hemorrhage (five had one or more vessels with greater than 75% cross-sectional area luminal narrowing) despite a mean age of 29 +/- 2 years. These findings suggest that adventitial mast cells may potentiate atherosclerosis and vasospasm, thrombosis and premature sudden death in long-term cocaine abusers.

Adult↗
PubMed1991

Effect of aging on aortic morphology in populations with high and low prevalence of hypertension and atherosclerosis. Comparison between occidental and Chinese communities.

A comparative morphologic study of aortic changes with aging was conducted in different populations in an attempt to separate the effects of hypertension and atherosclerosis. Chinese and the occidental populations were chosen, as they are known to have a high prevalence of hypertension and atherosclerosis, respectively. Aortic tissue was collected from occidental (American and Australian) and Chinese populations from three geographic locations. Postmortem specimens were obtained from four fixed locations: ascending aorta (A), descending thoracic aorta (B), and abdominal aorta (suprarenal [C] and above the aortic bifurcation [D]). Histologic sections were used to measure aortic circumference, medial thickness, intimal thickness, and grade of atherosclerosis. Kidney sections were used to confirm the presence or absence of hypertension. A total of 302 cases (age range, 19 to 104 years; Male-to-female ration, 2:1) were studied: 112 Americans, 80 Australians, and 110 Chinese. Cases were divided into three age groups: 19 to 44; 45 to 64; and 65 years and older. The aortic circumference progressively decreased from sites A to D in all populations and age groups. The aortic circumference increased with age, and the increase was independent of the aortic location. When the populations were separated, however, the greater increase was at location A in the Chinese (P = .008) and locations D in the occidental (P = .13), a population contrast that was significant only in location A. Intimal thickness increased with advancing age and was maximal in the abdominal aorta. The population differences also were significant for intimal thickness and were significantly greater in the occidental population in B, C, and D locations, whereas for atherosclerosis significance was only seen in location D. Hypertension (as defined by the morphologic changes in the kidney) after adjusting for age, height, and weight resulted in no statistical significant effect on aortic circumference or on intimal thickness, but did show a significant increase in atherosclerosis score at locations B, C, and D. Also after adjusting for age, height, and weight, the Chinese had a significantly larger aortic circumference in location A compared with the occidental population, whereas in location D the occidentals with hypertension had a significantly larger circumference compared with Chinese, probably due to an interaction of atherosclerosis and hypertension. After similar adjustments, the medial thickness in locations A and C, the intimal thickness in B, C, and D, and atherosclerosis score in D were significantly greater in occidental than Chinese populations.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

Topography of human aortic sudanophilic lesions.

The topographic distribution of sudanophilic lesions in the human aorta has been defined using probability-of-occurrence maps for a population dying of trauma (male, black and white, 15-29 years, n = 109). The maps demonstrate that sudanophilic lesions are localized with a characteristic topography. Regions of high probability (greater than 60%) occurred in close proximity to regions of low probability (less than 10%). Although some high-probability areas are associated with expected low wall shear stress regions, many other high probability areas are not and thus no specific causal hemodynamic localizing factors could be identified. The probability maps do however form an important basis for the development of rational strategies of tissue sampling in studies concerned with the characterization of localizing factors (biochemical, cellular, hemodynamic, and structural) and their relationship to putative atherogenic mechanisms.

Adolescent↗
PubMed1987

Hybrid color MR imaging display.

A novel computer-image processing method is described that combines and displays the data from two different MR sequences of the same anatomic slice in a single color image. The pixel intensities from one image are assigned varying spectral hues while the luminance of these hues is derived from the intensities of corresponding pixels of a second spatially aligned image. This technique provides a two-dimensional resolvable contrast scale that may produce images of improved information content. The versatility of the method, termed hybrid color display, is demonstrated by using T1-weighted, T2-weighted, chemical-shift, and gradient-recalled-acquisition-into-steady-state (GRASS) images. This technique may facilitate MR interpretation by enhancing anatomic and pathologic conspicuity and by expediting review.

Color↗