Compressive stress-relaxation of human atherosclerotic plaque

Knowledge of the mechanical properties of human atherosclerotic plaque is fundamental to understanding atherosclerosis and its treatment. Data are scant, however, particularly with respect to the time-dependent nature of plaque behavior. Previous experiments in our lab showed that human plaques do not exhibit the traditional preconditioning behavior common to most soft tissues. In particular, the behaviors of three classes of plaques differed fundamentally in response to multiple, successive, cyclic compression protocols. In this report, we demonstrate that plaques exhibit different responses to successive relaxation tests in uniaxial compression. Not only is there significant relaxation, but there are composition-dependent differences in the general character of the relaxation responses. Such information on the time-dependent behavior is important for the design of clinical protocols such as stenting or angioplasty wherein the atherosclerotic vessel is subjected to persistent or multiple short duration loadings. This study presents a step toward a better understanding of the biomechanical behavior of atherosclerotic plaques; however, the need for much more data remains.

Cocaine-induced increase in the permeability function of human vascular endothelial cell monolayers

The effects of cocaine on endothelial cell macromolecular transport, electrical resistance, and morphology were assessed. In confluent endothelial monolayers grown on microporus filters, cocaine (0.01 to 1 mmol/L) induced a rapid concentration-dependent increase in permeability to peroxidase and low density lipoprotein. Along with increased transport, the cocaine effect was paralleled by a decrease in transendothelial electrical resistance. Alterations in membrane resistance were fully reversible following washout of the drug, providing evidence that cocaine does not cause permanent injury to the integrity of the monolayer. Cocaines major metabolites, benzoylecgonine and ecgonine methyl ester, had minimal effect on electrical resistance properties, whereas monolayer impedance was markedly depressed by the novel cocaine/alcohol metabolite, cocaine ethyl ester (cocaethylene). Morphologic studies of cocaine-treated endothelial cells revealed a marked disruption of F-actin and the formation of intercellular gaps; no evidence of cell lysis and/or detachment was noted. Forskolin, a potent activator of adenylate cyclase known to promote the endothelial cell barrier function, impaired cocaine-induced changes in electrical resistance and morphology. Cocaine, however, had no effect on resting levels of intracellular adenosine 3',5'-cyclic monophosphate (cAMP) in confluent endothelial monolayers. In summary, the results indicate that cocaine directly induces structural defects in the endothelial cell barrier which enhance the transport of macromolecular tracers, the mechanism does not appear to involve intracellular cAMP.

Increased insulin-like growth factor-1 protein in human left ventricular hypertrophy

Animal models of cardiac hypertrophy demonstrated increased expression of insulin-like-growth factor-1 (IGF-1) in the heart. To study protein expression of insulin-like-growth factor 1 in left ventricular hypertrophy (LVH) in humans 11 hearts of autopsy cases with LVH were compared to 11 controls using immunohistochemical staining with anti-human IGF-1. LVH was defined as thickening of the left ventricular wall which ranged from 1.6 to 2.5 cm with hearts weights from 400 to 900 g. Immunohistochemical staining for IGF-1 was increased in the presence of LVH. In cases of LVH 37.9 +/- 3.5% of the cross-sectional myocardial area stained positively for IGF-1 compared to 6.8 +/- 2.9% in controls (P < 0.001). The findings support the hypothesis that IGF-1 has a role in the pathogenesis of LVH in humans. The increase of IGF-1 protein with LVH suggests reactivation of the cardiac IGF-1 genes in the hypertrophied adult cardiomyocyte.

Composition- and history-dependent radial compressive behavior of human atherosclerotic plaque

Invasive procedures to revascularize occluded blood vessels rely on the mechanical response of the diseased tissue. Failure rates associated with such procedures show the need for improvement. to understand the associated mechanics, the material properties of atherosclerotic plaque should be known; yet data are scant. The purpose of this study was to investigate the different mechanical responses exhibited by plaques with different compositions, focusing specifically on radial compressive behavior. A custom-built experimental system was developed that was fully computer controlled with a broad range of loading capabilities. A temperature-controlled, physiologic specimen bath allowed testing at 37 degrees C. Monotonically loaded specimens showed that plaque behavior was nonlinear under finite deformations. A multiple cycle protocol, executed in two phases, distinguished three types of mechanical response of different plaques. The differences in behavior were associated with histologic differences in plaque composition, and mechanically characterized by different "repeatability" (the stabilization of the cyclic response) and "recoverability" (the second loading phase retracing the first loading phase behavior). Type 1 behavior was categorized by repeatability and recoverability. Type 2 behavior displayed repeatability but only partial recovery during the second loading phase. Recovery was absent in type 3 behavior. The histologic observations demonstrated that calcified tissue was present only in specimens displaying type 1 behavior. Fibrous tissue and part of a modified media (due to disease) were present in specimens displaying type 2 behavior. An atheroma, along with a relatively thin modified media, was present in specimens displaying type 3 behavior. The differences in the maximum stretches attained at the end of phase I loading, the stretch offset from the first to the 15th cycle of phase I loading, and the hysteresis in the first and 15th cycles of phase I loading distinguished the specimen behaviors with statistical significance. These compression data showed that plaques exhibit composition- and history-dependent nonlinear and inelastic responses under finite deformations.

The use of bilateral adult renal allografts - a method to optimize function from donor kidneys with suboptimal nephron mass

Alternatives to traditional organ donor usage has allowed expansion of the organ donor pool to help compensate for the increasing disparity between recipients and donors. The use of bilateral adult renal transplants is a novel idea to salvage older donor kidneys with suboptimal nephron mass that would otherwise be destined for discard. Ten renal transplants were performed utilizing both kidneys from adult cadaver donors with diminished nephron mass determined by calculated glomerular filtration rate or biopsy evidence of significant glomerulosclerosis (>10%). Nine of ten (90%) recipients have satisfactory renal function at a mean follow-up of 7 months. The single case of graft failure was due to documented medical non-compliance. Mean serum creatinine at 6 months was 1.5 mg/dl. Mean measured creatinine clearance was 43.2+/-3.4. These preliminary findings suggest that the use of bilateral renal transplants provide satisfactory early function and allows salvage of older donor kidneys with suboptimal nephron mass.

Localization of thyrotropin-releasing hormone mRNA expression in the rat heart by in situ hybridization histochemistry

Our laboratory has recently detected mRNA of thyrotropin-releasing hormone (TRH) in the rat heart. The density of mRNA for TRH is five-fold higher in the atria than in the left and right ventricle. We also found TRH receptor mRNA and 3H-TRH-binding sites in both ventricles. Cardiac contractility was stimulated after intracoronary administration of TRH. This study was performed to investigate the localization of TRH in the heart. We utilized in situ hybridization histochemistry (ISHH) to localize TRH mRNA expression in the rat heart. ISHH was performed on fresh frozen heart tissue sections which were hybridized with a specific 35S-TRH oligo probe and subsequently processed by autoradiography. The autoradiographic signals corresponding to TRH mRNA were analyzed with an image program. For positive controls TRH mRNA was identified in the hypothalamic paraventricular nucleus. This test confirms the specificity of the TRH oligo probe. Cardiac hybridization signals were observed predominantly in the atria and localized preferentially in atrial connective tissues, vascular adventitia and atrial cardiomyocytes. No hybridization signals were found in ventricular cardiomyocytes. These observations suggest that TRH is synthesized in atrial myocytes and atrial vascular structures. Based on studies which show synthesis of the TRH receptors in ventricular cardiomyocytes, we hypothesize that atrial TRH is an endocrine source for the stimulation of ventricular contractility and that endothelial and adventitial TRH may play a role(s) in the regulation of the growth and/or vasomotor tome of the cardiac vascular system.

Role of atheroma liposomes and malondialdehyde-modified low-density lipoproteins in complement activation

We investigated the ability of atheroma-associated liposomes and malondialdehyde (MDA)-modified low-density lipoproteins (MDA-LDL) to activate complement. Complement activation markers C3a, Bb, C4d and SC5b-9 were measured in both normal and complement-deficient sera. We found that MDA-LDL was able to generate C3a and SC5b-9, predominantly by the alternative pathway. High-density lipoproteins modified with MDA were also capable of C3a generation although to a lesser degree. The presence of atheroma-associated liposomes did not result in detectable levels of complement activation markers. We conclude that MDA-modified lipoproteins may represent a possible source for complement activation within atherosclerotic lesions.

Intragenic mutations of CDKN2B and CDKN2A in primary human esophageal cancers

The CDKN2A and CDKN2B genes, encoding p16 and p15 respectively, are located on chromosome 9p21, a locus at which frequent homozygous and heterozygous deletions occur in many primary human tumors, including esophageal carcinoma. CDKN2A and CDKN2B inhibit cyclin dependent kinase 4 (CDK4) and CDK6 and control cellular proliferation by preventing entry into the S phase of the cell cycle. Their inactivation may contribute to uncontrolled growth in human cancer. We previously described CDKN2A exon 2 mutations in a pilot study of 43 esophageal cancers. In order to determine whether CDKN2A and CDKN2B are frequent targets of 9p21 deletion in esophageal carcinogenesis, we have now analyzed 60 primary esophageal cancers for mutations in both exons 1 and 2 of CDKN2A and CDKN2B by direct sequencing of PCR amplified genomic DNAs. In conjunction with our previously published data, we have identified a total of eight nucleic acid substitutions among 60 esophageal carcinomas; here, we describe one new CDKN2B nonsense mutation and one new silent CDKN2B mutation that occurred somatically. Taken together, these results suggest that intragenic mutations in CDKN2A and CDKN2B occur in esophageal cancer, but that they are infrequent events. In view of the known high frequency of loss of heterozygosity at the chromosome 9p21 locus in esophageal cancers, the current data suggest that intragenic mutation is not the predominant mode of inactivation of CDKN2A and CDKN2B or that other genes are targets of deletion at this locus in these cancers.

Studies on TGF-beta 1 gene expression in the intima of the human aorta in regions with high and low probability of developing atherosclerotic lesions

Certain regions of the human aorta are at greater risk for early and more severe atherosclerotic lesions development than others. Cornhill and coworkers (Cornhill FJ et al.: Arteriosclerosis 5:415, 1985) created maps for the probability of developing atherosclerosis defining the high-probability region (HPR) in the dorsal descending thoracic aorta and the low-probability region (LPR) in the ventral descending thoracic aorta. Our study examines the hypothesis that transforming growth factor beta -1 (TGF-beta 1), a well-known suppressor of growth and function in many human cell lines, is one of the inhibitors of human atherogenesis. The present experiment analyzes the expression of mRNA for TGF-beta 1 in both the HPR and the LPR of aortas from young (age 17 to 25 y) males of black (n = 8) and white (n = 7) race. The level of TGF-beta 1 gene expression was assessed in the aortic intima in both the HPR and the LPR, using National Institutes of Health Image 1.47, an Apple Macintosh application capable of digital image processing, analysis, and morphometric measurement. There was significantly lower (P = 0.002, alpha = 0.05) TGF-beta 1 gene expression in the HPR than in the LPR in the 22- to 25-y age group. There was no significant difference in the 17- to 21-y age group and between the HPR and the LPR in the entire study group.(ABSTRACT TRUNCATED AT 250 WORDS)

Rare incidence of human papillomavirus types 16 and 18 in primary and metastatic human prostate cancer

OBJECTIVES

The reported data regarding the incidence and significance of human papillomavirus (HPV) in prostate cancer have been inconsistent. In the present study the incidence of HPV 16 and 18 was evaluated in an expanded series of primary as well as metastatic prostate cancer specimens, in order to evaluate a potential role of HPV infection in development and progression of prostate cancer. This is the first study attempting to establish the significance of HPV in metastatic prostate cancer.

METHODS

The presence of high risk human papillomaviruses HPV 16 and 18 was analyzed using the polymerase chain reaction (PCR) amplification method and Southern blot hybridization analysis in a total of 61 prostatic tissue specimens: 43 primary prostate adenocarcinoma formalin-fixed, paraffin-embedded specimens, with varying degrees of differentiation (mean Gleason score 5.8, range 3 to 9); 17 pelvic lymph nodes positive for metastatic deposits; and 1 normal prostate specimen.

RESULTS

This human papillomavirus typing indicates that only 1 out of the 43 prostatic specimens analyzed was positive for HPV 16 and 1 metastatic lymph node was positive for HPV 18, as revealed by Southern analysis. These results demonstrate the infrequent detection of HPV 16 and 18 DNA in all the primary prostatic adenocarcinoma specimens and metastatic lymph nodes analyzed in this study population.

CONCLUSIONS

The negative HPV status for primary and metastatic prostate cancer demonstrated in this study provides a strong argument against an etiological role of HPV infection in the development and progression of the disease.

Dolichoectatic aneurysm of common carotid artery: an animal model with histological correlation

There is a limited understanding of the pathogenesis of dolichoectatic (dolicho = long; ectatic = dilated) aneurysms of elastic arteries. Therefore, we developed a model of dolichoectatic changes in elastic arteries by injecting porcine elastase into the media of the carotid artery of male New Zealand white rabbits. After 3 months, gross examination of the carotid arteries in vivo revealed dilated and tortuous vessels. The carotid arteries were then harvested, and cross-sections of the vessels were stained by the Verhoff-van Giesson stain. Histologically, the internal elastic lamina was dissolved in the most dilated areas. The elastic lamellae of the media were also digested and there was reorientation of the innermost medial smooth muscle layer. These gross and histologic changes were present in 80% of the treated carotid arteries and in none of the contralateral control vessels. Our study suggests the importance of the elastic lamellae for the maintenance of tubular shape and length of the carotid artery and describes a new chronic animal model of dolichoectatic aneurysm of the common carotid artery.

Increased prevalence of aortic fatty streaks in cholesterol-fed rabbits administered intravenous cocaine: the role of vascular endothelium

Several recent postmortem studies suggest an increased prevalence of atherosclerosis in young habitual cocaine abusers. However, little is known about the effects of cocaine abuse on the vascular endothelium and its relationship to atherosclerosis. Therefore, the consequence of chronic administration of intravenous cocaine on the induction of aortic sudanophilia was examined. Male New Zealand White rabbits were fed a 0.5% cholesterol diet for 10 wk. During this period, animals were randomized to receive either cocaine-hydrochloride (0.25 mg/kg) intravenously (n = 17) twice daily; or an equivalent volume of 0.9% physiologic saline, control group (n = 16). Mean values for total circulating leukocytes and platelets and total plasma cholesterol and triglycerides were similar in both groups throughout the protocol. At the completion of the study, aortic sudanophilia was measured and expressed as a percentage of regional involvement (R1 = proximal 4 cm, R2 = middle 6 cm, and R3 = distal 10 cm). Statistical significance among groups was achieved in the proximal thoracic aorta (p = 0.057). No significant differences in sudanophilia were noted in the middle and distal segments. When animals were placed in subgroups according to percent total plaque involvement, there was a significant increased distribution of rabbits with a greater extent of sudanophilia in the cocaine-treated group as compared with control (p = 0.01, chi-square analysis). Immunocytochemical studies using the macrophage-specific and muscle actin-specific monoclonal antibodies demonstrated that sudanophilic areas in both groups were predominantly composed of macrophage-derived foam cells. Evaluation of plaque morphology showed an increase in intimal plaque thickness and in the number of macrophages and smooth muscle cells in cocaine-treated animals; however, group differences were not statistically significant. Because no significant differences were found in the cellular composition of atherosclerotic plaques between groups, further studies were performed to assess the effects of cocaine on the permeability function of cultured endothelial cell monolayers as a possible mechanism of increased sudanophilia. Cocaine (100 microM)-treated endothelial cell monolayers demonstrated an increased permeability to horseradish peroxidase during all time intervals studied (0-6 hr). Permeability differences were statistically significant at 30 min and 1 hr (p = 0.003 and 0.02, respectively). Collectively, these observations suggest that administration of cocaine to cholesterol-fed rabbits increases the prevalence of aortic sudanophilia via at least one possible mechanism involving enhanced vascular permeability.

Characterization of pulsed-dye laser-mediated vasodilatation in a rabbit femoral artery model of vasoconstriction

Vasoconstriction is a clinical problem associated with invasive vascular procedures, microvascular reconstruction and subarachnoid hemorrhage. We sought to characterize the ability of pulsed-dye laser irradiation to reverse and prevent vasoconstriction in an anesthetized rabbit model of surgically and pharmacologically induced vasoconstriction. Five groups of experiments were performed to study the effect of pulsed-dye laser irradiation delivered through a 320 microns core ball-tip fiber into the femoral artery. The studies demonstrated that pulsed-dye irradiation can reproducibly cause vascular dilatation. The zone of vasodilatation propagated equally proximal and distal to the site of irradiation within the vessel. When saline was infused into the vessel to replace flowing blood during delivery of laser irradiation, no significant vasodilatation occurred. After laser irradiation reversed surgical and pharmacologic vasoconstriction, the vessel was resistant to further pharmacologic vasoconstriction. This resistance to pharmacologic vasoconstriction did not occur if the vessel was pharmacologically predilated before delivery of laser irradiation. Pathologic analysis of the vessels revealed endothelial damage and mild to moderate medial necrosis, most significant at the site of energy delivery. These studies provide characterization of pulsed-dye laser-mediated vasodilatation in an in vivo model. Delivery of pulsed-dye laser energy has potential clinical application and warrants further investigation.

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.

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)

Vascular reactivity during the progression of atherosclerotic plaque. A study in Watanabe heritable hyperlipidemic rabbits

The effects of varying degrees of atherosclerotic plaque on vascular responsiveness in aortas of Watanabe heritable hyperlipidemic (WHHL) rabbits and New Zealand White (normal cholesterolemic) rabbits were studied. Ring segments from the aortic arch and thoracic aorta were mounted in organ chambers for isometric tension recording and measurement of endothelium-derived relaxing factor. WHHL rabbits were divided into three groups according to age: group 1, 3-5 months; group 2, 6-9 months; and group 3, 12-14 months. Atherosclerotic changes (expressed as a percent of total surface area) in the aortic arches in groups 1, 2, and 3 were 11 +/- 3% (mild), 28 +/- 6% (moderate), and 54 +/- 8% (severe) respectively; only occasional plaques were present in the thoracic aorta in all groups. Maximal contractions elicited with phenylephrine progressively decreased with increasing degrees of atherosclerotic plaque. Contractions evoked by histamine were augmented in all groups of WHHL rabbits when compared with controls, whereas those to serotonin were augmented only in vessels with mild atherosclerosis. As the severity of the intimal lesions increased, endothelium-dependent relaxations to acetylcholine, ATP, and calcium ionophore A23187 progressively decreased. Endothelium-independent relaxation to nitroglycerin was virtually complete in all segments. However, vessels with severe atherosclerosis were less sensitive to this agent as illustrated by a significant increase in the ED50 value. Scanning electron microscopy revealed a predominant loss of endothelial cells in the central regions of fibrous plaques. Thus, in WHHL rabbits, hypercholesterolemia and atherosclerosis result in an increased responsiveness of vascular smooth muscle to histamine and serotonin. Endothelium-mediated relaxation of vascular smooth muscle is reduced with the progression of atherosclerosis primarily due to a loss of endothelial cells.

Recovery of heart tissue following focal injury induced by dietary restriction of potassium

Sixty-four Sprague-Dawley rats (initially weighing 200-225 grams) were divided into three groups. Group 1, the experimental group, was fed a potassium depleted diet for 42 days, followed by a potassium repleted diet for up to an additional 14 days. Group 2, the dietary control group, received a potassium deficient diet, but was continuously supplemented by drinking water containing potassium chloride 150 meq/L. Group 3, the control group remained on normal rat chow and tap water during the entire investigation. Quantitative morphometric analysis was used to assess the percent of myocardium occupied by lesion. These data were analyzed by an analysis of variance (ANOVA) for repeated measures, comparing the three groups with one another; a second analysis compared the myocardial lesions of the dietary experimental group during the potassium depletion and repletion periods. At the end of the dietary depletion period (day 42) focal areas of cardiac myocyte necrosis and mononuclear infiltrate were found in the experimental group. Morphometric assessment on day 42 revealed a volume fraction (Vv) of 8.61 (+/- 4.41)%, which was significantly greater (p = 0.0018), as compared with both control groups. Lesion area significantly regressed in two and one half days after potassium was supplemented in the dietary experimental group to 0.58 (+/- 0.34)% Vv (p = 0.0005). Six days after potassium was replaced in the diet, there was no significant difference between the experimental and control groups, and only a limited connective tissue scar was noted in the experimental group. The mechanism of the rapid regression of lesions and the production of only limited connective tissue scar is suggested but requires further elucidation.

Postmortem viability and early changes in organ culture of human and rabbit aortic endothelial cells

In order to understand the role of the postmortem interval (PMI) on endothelial cell changes both in human and rabbit aortas, we have examined the ultrastructural cytomorphologic alterations of these cells. Human aorta (HA) and rabbit aorta (RA) were maintained in calcium-free, glucose-supplemented Hank's balanced salt solution (HBSS). Rabbit endothelial cells (REC) on the aorta (organ culture) assayed morphologically survive for at least 12 h in culture solution. The predominant morphological change in the RA was the formation of multiple subendothelial vacuoles (SEV). These vacuoles may form as the results of increased permeability of endothelial cells to ions and fluid or cell contraction. Cell to cell connection remained intact. Individual and dispersed endothelial cells were observed 8 h after removal from the animal when incubated in calcium-free HBSS. These necrotic endothelial cells were scattered among viable endothelial cells. Human aortic endothelial cells were also well preserved in the same media for periods of 6-8 h postmortem. Increased extracellular calcium (1.3 mM) in the incubation media caused accelerated cell death. These findings suggest that aortic endothelial cells can be preserved for longer periods of postmortem time than would be expected and that the use of calcium-free HBSS media supplemented with glucose improves endothelial cell viability in vitro.

Measurement of ATP synthesis and flocculent matrix densities in mitochondria as a function of 'in vitro' ischemia in the heart and liver of rats

We intended to determine the levels of adenosine triphosphate (ATP) synthesis at the time when mitochondria ultrastructurally show flocculent densities in the matrix space. For this purpose, mitochondria were isolated from rat heart and rat liver after the tissues have been maintained under controlled ischemic conditions in vitro at 37 degrees C for intervals of 15, 30, 45, 60, 120, 180, and 240 (heart) min. The isolated mitochondria were tested for new ATP synthesis by luciferin/luciferase luminescence in the presence of substrate and adenosine 5'-diphosphate (ADP). The luminescence peaks were standardized and related to an external measure by measuring absorbance of ATP at 259 nm where the extinction coefficient is 15,400. Mitochondrial yield was monitored by measuring succinate dehydrogenase activity in the first homogenate and in the final mitochondrial pellet. Alternatively, cytochrome oxidase activity was used and the protein in the mitochondrial pellet was also determined. We found that the yield of mitochondria was above 53-54% in both liver and heart at 2 h of ischemia. Longer intervals were accompanied by lower yields. The ability to synthesize new ATP declined at different time intervals in ischemia of the heart compared to the liver. After 30 min ischemia, the synthesis in heart mitochondria is 18% of control, while the synthesis of liver mitochondria reaches 16% of control after 45 min of in vitro ischemia. Flocculent densities in heart mitochondria appeared at 45 min ischemia in vitro and in vivo, and at 60 min in liver mitochondria. We conclude that the decline of ATP synthesis is a significant early change in mitochondria and antedates the appearance of flocculent densities.

ATP hydrolysis by ischemic mitochondria

Cellular ATP levels are determined by the rates of ATP production and ATP hydrolysis. Both phenomena are affected by ischemia. Mitochondrial enzymes are damaged, inhibiting this organelle's ability to make ATP. Mitochondria are also uncoupled by ischemia and have the ability to hydrolyze ATP. We designed a series of experiments to determine whether decreased production or increased hydrolysis of ATP was the primary effect of mitochondrial damage. Rat hearts were subjected to 45 min of warm ischemia in order to induce irreversible cell damage. ATP or ADP was injected into cuvettes containing mitochondria isolated from normal myocardium or myocardium damaged by ischemia. Luciferin-luciferase, which fluoresces in the presence of ATP, was also added to the tubes as an indicator of ATP levels. Mixtures of uncoupled and coupled mitochondria were made and compared with the mitochondria damaged by ischemia. The results showed that mitochondria damaged by prolonged ischemia hydrolyze ATP more rapidly than normal mitochondria; however, normal mitochondria can easily compensate for increased ATP hydrolysis when in mixture with equal amounts of uncoupled mitochondria. These data suggests that the low cellular levels of ATP following irreversible ischemia are primarily due to decreased ATP synthesis and not to increased hydrolysis.

The role of the lymphatics in aiding regression of hypokalemic lesions in rat cardiac muscle

This study describes the role of lymphatics in the removal of macrophages from inflammatory lesions in the heart of hypokalemic rats and rats recovering from hypokalemia. The inflammatory lesions are characterized by focal cardiomyocyte necrosis, edema, and mononuclear infiltrate. The vascular and lymphatic capillaries are maintained along with the basement membrane of the necrotic cardiomyocyte. Through prior investigation, it was revealed that refeeding potassium led to a rapid reduction in lesion area. The purpose of the current investigation was to establish the role of the lymphatics as a means of reducing the lesion area by removal of the cellular infiltrate and edema. Using a limited potassium diet, hypokalemic rats were sacrificed via perfusion fixation during the hypokalemic and the potassium re-supplementation periods. Heart tissue was examined by light and electron microscopy. During the hypokalemic period, phagocytic mononuclear cells were found engulfing necrotic cardiac muscle cells. With refeeding of potassium, these phagocytic cells appeared to be diminished in number, a reduction that coincided with a decrease in the lesion size. Lymphatic channels were dilated and full of mononuclear cells. These channels were differentiated from the vascular capillaries by standard morphological criteria. In conclusion, the lymphatics play an important role in the healing process by reducing the lesion size through the removal of phagocytic cells and the uptake of proteinaceous material.

The effect of arterial pressure alterations during halothane anesthesia on residual flow and infarct size with transient regional ischemia of the dog

The present study was designed to determine if infarct size under halothane anesthesia could be reduced by increasing the pressure gradient across the collateral vascular bed, thereby increasing flow within the occluded vascular bed. Forty-nine mongrel dogs were anesthetized with halothane under identical physiologic conditions with the exception of systemic arterial blood pressure. The control group of 18 animals anesthetized with halothane was compared to two experimental groups. In one group of 15 dogs, the mean systemic pressure was raised 25% above control with phenylephrine (BP25). In the second group of 15 dogs, systemic pressure was raised 50% above control (BP50). Adjacent marginal branches of the left circumflex coronary artery were ligated for 90 minutes followed by 90 minutes of reflow. The area of the occluded vascular bed was similar in all groups, but the area of infarction as a percentage of the occluded vascular bed was reduced from 47.7 +/- 4.7% to 25.4 +/- 4.3% in the BP25 group (P < or = .05 v control) and to 33.1 +/- 5.0% in the BP50 group. Flow measurements using microspheres showed a larger zone of ischemic tissue receiving adequate residual flow in the BP25 and BP50 groups compared to the control. It is concluded that infarct size during halothane anesthesia in the dog can be reduced by increasing systemic blood pressure with phenylephrine.

Immature renal tissue in colonic wall of patient with caudal regression syndrome

We report an incidental microscopic finding of ectopic renal tissue in a newborn with multiple congenital anomalies. The ectopic renal tissue was located in the wall of the distal blind end of the colon. The tissue was composed of undifferentiated renal blastema with primitive and well-formed glomeruli and tubules. The potential for malignant transformation of this lesion into extrarenal Wilms' tumor is not known.

Blood and tissue concentrations of tricyclic antidepressant drugs in post mortem cases: literature survey and a study of forty deaths

Blood, urine, heart, liver, and psoas muscle concentrations of tricyclic antidepressant (TCA) drugs and their N-desmethyl metabolites were determined in forty medical examiner cases. The cases were evaluated for the role played by the TCA drugs in the cause of death and compared to a literature survey of previously reported cases. The incidence of the various individual TCA drugs as a factor and the significance of the disposition of the drugs and their metabolites is included. Comparing TCA drug concentrations in the heart and skeletal muscle and considering the differences in perfusion to these organs, TCA drugs and metabolites showed an affinity for the cardiac over the skeletal muscle. The case results were correlated with experimental studies to suggest the relationships of blood concentrations with toxicity.

A method for the determination of therapeutic and toxic concentrations of tricyclic antidepressant drugs in post mortem fluids and tissues

A sensitive and reliable procedure is presented for the measurement of the common tricyclic antidepressant (TCA) drugs in a variety of biological specimens at therapeutic as well as toxic concentrations. The method employs GC/NPD and a column packed with 3% OV-17 on Chromosorb W-HP. The pH of specimen extraction was optimized at 8.6, and 1-chlorobutane:ethyl ether (3:1) was found to be an efficient solvent for the primary extraction. Recoveries for all TCA drugs were at least 50% for each specimen. Linearity of extraction was observed over a range of therapeutic and toxic concentrations with a correlation coefficient greater than 0.99.

Pathologists' assistant training programs: a report

This report describes the training of pathologists' assistants in three training programs: at Duke University, at Quinnipiac College associated with Yale University, and at the University of Maryland School of Medicine. The role of this new health profession is described as well as the job situation, experience, and current status of accreditation.

To answer questions. A review of an autopsy service

Autopsies are important in the quality control of medical practice, in research, and in teaching. We have attempted to realize more of the service, teaching, and research potential from doing autopsies. The key of all efforts is the involvement of the senior staff. This involvement should be made possible by supporting such a person by a qualified team that consists of the mortuary service, pathologist's assistants, and highly trained and qualified residents. Such a staff person can direct his or her attention toward improving communication with clinicians, answering open questions in-depth, encouraging collaborative clinicopathological projects, developing new approaches to the performance of autopsies, such as the immediate autopsy, and using special laboratory modalities, such as electron microscopy and immunofluorescence. Computer storage of autopsy data and retrieval for special studies seem to make autopsy data available and usable. It is most important that autopsies be performed, that they be done well, and that their findings be carefully evaluated using all available scientific tools and, finally, that the results are adequately communicated.

A rapid method of cryofixation of tissues in situ for ultracryomicrotomy

A device is described for the rapid freezing of tissue in situ by a punch biopsy approach using a specially designed cryogun with a highly thermal conductive specimen holder. The cryogun consists of a sampling device using a double, spring-loaded gun mechanism and a system of cryochambers. Ultrathin freeze-dried sections cut from samples obtained with this cryogun are relatively free of artifacts and have few ice crystals. Organelles are seen by natural contrast when cryosections of approximately 1000 A are observed with a transmission electron microscope or in the transmission mode of a scanning electron microscope. The construction of the cryogun is described along with a method of obtaining improved, ultrafast cryofixation of tissue specimens. The reliability of obtaining x-ray microanalysis measurements of diffusible ions where movement within cell compartments has been retained is discussed.

Long-term culture of human aortas. Development of atherosclerotic-like plaques in serum-supplemented medium

Segments of human thoracic aorta were maintained in long-term explant culture for 18 weeks in serum-supplemented medium. The aortas were grossly normal in appearance, and random samples fixed for light microscopy prior to culture revealed a normal morphology. The intima contained no more than five layers of smooth muscle cells. After 7 days in culture, the intima was noticeably thicker than the uncultured segments. The increased thickness was due to proliferating smooth muscle cells and production of extracellular material. After several months in culture, extracellular material consisting of collagen and flocculent material was present in areas resembling atherosclerotic fibrous plaques. A peripheral growth, which formed around the explant, was composed of fibroblastlike cells and added to the overall thickness of the intima. However, aortic segment maintained for up to 2 months in serum-free culture medium showed no cellular proliferation. This study demonstrates that changes resembling early stages of atherosclerosis occur in human aortas maintained in explant culture using routine culture procedures.

The subcellular pathology of shock in trauma patients: studies using the immediate autopsy

In summary, our immediate autopsy program provides a new tool for investigating the pathophysiologic effects of shock and trauma at the cellular and subcellular levels. By minimizing the time delay between death and tissue sampling with this technique, we have demonstrated the feasibility of validly applying the refinements of electron microscopy, histochemistry and analytical biochemistry to human tissue. Qualitative, semi-quantitative and quantitative data with these techniques have been integrated with clinical, physiologic and chemical studies on these patients during life. Cell injury produces an altered steady state of metabolism within the cell, evidence of which is seen in altered ultrastructure. If the injury is too severe, the cell will pass the "point-of-no-return," at which time the changes in the cell are no longer compatible with life and the cell dies and undergoes necrosis. Although the initiating injury and the patterns of the altered steady state may vary, once the cell has passed the "point-of-no-return," the patterns of cell injury regardless of the initial insult, are similar. We believe that the cellular patterns seen in patients dying from shock and trauma are remarkably similar to those produced by hypoxic tissue injury in experimental systems. Tissue from control patients in whom ischemic injury due to episodes of hypotension did not occur show good morphologic preservation with normal mitochondria and other cell organelles. Tissue from patients who have experienced acute shock consisting of a period of hypotensive ischemia show changes in the mitochondria and ER compatible with the experimental picture of hypoxia: i.e., dilated ER, with loss of ribosomes, swelling of mitochondria and the appearance of flocculent densities in the mitochondria. Tissues taken from the patients who had experienced repeated episodes of shock, whom we designated as those in "chronic shock," showed changes paralleling the acute changes, but also showed much evidence of autophagocytosis as a) the cells attempted to achieve a lower metabolic requirement in order to survive, and b) they attempted to "clean-up" and remove altered and damaged organelles and debris from previous bouts with sublethal ischemic injury. We hope that the increased knowledge of tissue and cellular injury obtained by the immediate autopsy will provide a means of integration, hypothesis formation and testing of the vast knowledge of cell biology and pathology, and the opportunity for developing in the human the potential for testing new hypotheses in model systems resulting in immediate and innovative feedback for the patient in terms of diagnosis, functional monitoring and treatment.

Energy dispersive x-ray microanalysis of mitochondrial deposits in sideroblastic anemia

Energy dispersive x-ray microanalysis was used to analyze mitochondrial and lysosomal iron-containing deposits in sideroblastic anemia. Although it has been previously known that these deposits contain iron by inference from Prussian blue staining, the possible presence of other cations as well as the nature of the anions present has not been identified. The results show that the mitochondrial deposits in erythroid cells have peaks for iron and phosphorus indicating that they do not represent calcifications which commonly occur following injury and that the principal anion may be phosphorus. Studies of hemosiderin and ferritin aggregates in lysosomes of macrophages in the same bone marrow samples again reveal similar peaks for iron and phosphorus. The results also indicate the probable similarity of mitochondrial and macrophage deposists although ferritin itself was never identified in the mitochondrial deposits. The results illustrate the potential of this method for diagnostic and investigative pathology.

The use and application of autopsy in research

The only limit to the use and application of the autopsy in research is the imagination of the investigator. As pathologists, it would appear that we have really neglected this powerful tool in recent decades and have undersold the potentiality of this method. As we hope to have made evident by the foregoing discussion, the field of research utilizing autopsy tissues is truly as broad as medicine itself, and if developed properly, becomes an indispensable part of the fabric of on-going research in areas of carcinogenesis, environmental disease, atherosclerosis, and aging.

Studies on the pathogenesis of ischemic cell injury. XI. P/O ratio and acceptor control

Acceptor control index, P/O ratio and inner membrane permeability were examined in isolated mitochondria following periods of renal ischemia for 15, 30, 60, 120, and 240 min. It was noted that the P/O ratio remained unchanged until 1-2 h after the onset of ischemia. A similar change was noted in the contraction rate of isolated ischemic mitochondria after swelling in KCl and addition of ATP+Mg2+. Both changes are probably indications of a basic membrane alteration which correlates with the occurrence of irreversibility of cell injury. In contrast, the swelling rate in KCl and the acceptor control index are altered almost simultaneously with the onset of ischemia. Therefore, acceptor control index and the rate of swelling are affected prior to the point of irreversible cell injury. They are not, therefore, good as indicators of irreversible changes in the inner membrane of mitochondria leading to the "point-of-no-return."

Studies on the pathogenesis of ischemic cell injury. VI. Accumulation of calcium by isolated mitochondria of ischemic rat kidney cortex

Mitochondria isolated from rat kidney subject to in vitro ischemia at various time intervals demonstrated a continuous decline of the ability to accumulate calcium following a high initial stable phase of accumulation of calcium which is dependent both on ATP and respiration. This decline occurs during the reversible phase of cell injury and appears to be a sensitive indicator of membrane changes in a binding and/or transport protein or of other membrane permeability characteristics. The morphology of mitochondrial densities related to calcium accumulation in mitochondria varied. Any form of calcium accumulation, resulted in marked swelling of mitochondria. Control renal mitochondria in sucrose were highly condensed. Partially inhibited calcium accumulation in the presence of phosphate was also associated with numerous small spheric or punctate deposits in close relationship to the inner membrane. Uninhibited calcium accumulation resulted in the formation of needle-like structures radiating from such inner membrane associated sites.

Studies on the pathogenesis of ischemic cell injury. VII. Proton gradient and respiration of renal tissue cubes, renal mitochondrial and submitochondrial particles following ischemic cell injury

Electron transport in tissue cubes, isolated mitochondria and submitochondria particles were examined as a function of ischemic time. It was found that electron transport remains active in all systems beyond the 2 hour ischemic time interval. The NADH stimulated respiration, however, declined after 2 hours of ischemia in ASU (Ammonia-Sephadex-Urea) particles followed by respiration with matrix-located dehydrogenases tested by substrates such as glutamate, alpha-ketoglutarate and pyruvate plus malate. Succinate dependent respiration remains active at control levels. In contrast proton gradient reveals changes in two phases: Phase A is characterized by gradually increasing gradient without valinomycin and by a rapidly declining gradient with valinomycin in the medium. Phase B is characterized by a declining proton gradient with or without valinomycin. It is suggested that the alteration of the proton gradient between 1 and 2 hours ischemia is an important factor contributing to irreversible cell injury.

Studies on the pathogenesis of ischemic cell injury. V. Morphologic changes of the pars convoluta (P1 and P2) of the proximal tubule of rat kidney made ischemic in vitro

In summary, we have described the time course of changes of mitochondria following ischemia of the kidney proximal tubule. The sequence of morphological changes of matrix as well as inner membrane corresponds well with certain functional or physical parameters such as swelling, respiration, substrate metabolism, acceptor control and P/O ratio. This indicates that morphological parameters can be utilized to predict the functional alterations of mitochondria following ischemia in cells. The significant mitochondrial changes are early loss of granules (15-30 min) and condensation (15 min), swelling (30 min), appearance of fluffy densities (30 min) and flocculent densities (after 60 min), degeneration of cristal structure (240 min) and disintegration of mitochondria as structural units (24 h).

Recent studies on the pathophysiology of ischemic cell injury

We can summarize the results of our studies as follows (Fig. 15). The critical cellular factors involved in the loss of reversibility following ischemia appear to be the mechanisms involved in the membrane function of energy transduction. Irreversibility appears to correlate with an irrepairable defect in energy transduction. This could involve both the mitochondrial energy transduction functions and those in the plasma membrane. The mechanisms involved in this transition are not presently clear but they are associated with increased leakiness or permeability of these membranes accompanied by changes in lipid content, alterations in membrane proteins, and presumably in lipid-protein interactions. There are two prominent theories to explain energy transduction. These are the "proton pump" hypothesis of Mitchell (1972) and the "paired moving charge" hypothesis of Blondin and Green (1975). Both of these hypotheses require integrated function of membrane components, i.e., lipid and protein. The hypothesis of Blondin and Green, however, can work even with discontinuous membrane sheets because it involves the concept of ribbons of protein embedded in the protein-lipid membrane matrix. The characteristic finding of our studies following ischemic injury, namely, the continuous electron flow well into the irreversible phase while the energy transduction is impaired, could be explained by both hypotheses. What do these observations have to say about theories of energy conservation? We have observed that the vectorial nature of the proton separation is stopped. Charge separation may not occur at this time across the membrane since proton gradient and possible membrane potential are abolished. Electron transport, however, continues indicating the generation of protons. Since the decline of P/O ratio, decline of proton gradient and the cellular "point-of-no-return" coincide, these observations point toward the important membrane defects acquired at that particular time. The "paired moving charge" model which involves moving ions encapsulated in endogenous ionophores such as lecithin and maintenance of magnesium is favpred by the observation that phosphatidyl choline and phosphatidyl ethanolamine are lost in correlation with irreversibility. Furthermore, the decrease in magnesium content of cells is closely associated with the loss of viability following ischemia. The "paired moving charge" hypothesis has the attractive feature in that it involves antagonistic effects of calcium and magnesium. During reflow, calcium may inhibit magnesium mediated transport of inorganic phosphate by lecithin. Also, according to this theory fatty acids or their cyclic anions which act as uncouplers may foster the loss of phosphorylation capacity.

Studies on the subcellular pathophysiology of ischemia

The loss of ability to synthesize adenosine triphosphate (ATP) by mitochondria in ischemic cells even in a favorable medium correlates with the loss of cell viability. The early lesion at the molecular level needs further investigation but appears to involve an increased permeability of the mitochondrial membrane possibly promoting proton leak and obviating oxidative phosphorylation. The nature of this leak could involve changes in phospholipid-protein interactions, especially since the early release of free fatty acids and changes in phospholipid composition occur.

GM3 gangliosidosis: a novel human sphingolipodystrophy

A male infant of nonconsanguinous Jewish parents had clinical features of pseudo-Hurler's syndrome. A maternal uncle with similar features had previously died at 21/2 months of age. Following death at 3 1/2 months of age, analysis of the patient's brain and liver revealed increased amounts of ganglioside GM3, a virtual absence of higher ganglioside homologues (GM3, GM1, GD1a, and GT1) and a deficiency of the biosynthetic enzyme, UDP-Gal NAc:GM3 N-acetylgalactosaminyl-transferase. Since the biochemical findings denote a novel state of ganglioside deficiency, clinical findings emphasizing points of distinction from other causes of pseudo-Hurler's syndrome are presented.

Aging changes in the human aortic valve in relation to dystrophic calcification

To elucidate the pathogenesis of aging changes and their relation to age associated calcification, a morphological study of 27 human aortic valves was carried out. Nine valves were obtained from immediate autopsies and 18 valves from routine autopsies done within four hours after death. Calcium deposition was present deep in the zona fibrosa along a zone of lipid accumulation. Fibrocytes in the zona fibrosa showed predominant age associated changes, i.e., a massive accumulation of residual bodies in the cytoplasm probably derived from autophagic vacuoles. Light microscopic lipid accumulation corresponded with both intracellular accumulation of electron dense spherules and membranous vesicles derived from degenerate fibrocytes. Calcium deposition in various stages, including needle shaped hydroxyapatite crystals, was seen in close association with these cellular degradation products rather than collagen or elastic fibers. Dystrophic calcification in the aortic valve appears to result from cellular aging and death followed by petrification of cellular degradation products, which may progress to calcific aortic stenosis.

Effects of shock on the pancreatic acinar cell. Cellular and subcellular effects in humans

Pancreatic tissues from 22 patients with a wide variety of types of shock were obtained within minutes of somatic death for light and electron microscopy and for cytochemical studies. By light microscopy, it was difficult to ascertain any differences between the shock groups; however, electron microscopy disclosed subcellular alterations that could be correlated well with the type, severity, and duration of shock. Mild cases of shock or shock of short duration showed mild cell damage, while extreme cases of hemorrhagic or septic shock showed cell death and necrosis. No morphological evidence for lysosomal initiation of damage was seen, but it is clear that the pancreas can undergo severe cell injury during shock that could result in release of further damaging enzymes, most probably from zymogen granules rather than from lysosomes.

The application of electron microscopy and cellular biochemistry to the autopsy. Observations on cellular changes in human shock

A method based on the utilization of electron microscopy, morphometric analysis, tissue culture, and biochemical analysis in the study of human autopsies is described. In this method rapid sampling immediately following somatic death is conducted in order to make meaningful the application of such techniques. In addition to describing the procedure, we present some new findings relating to cellular changes associated with shock. As in cellular pathobiology, it is of utmost importance that ultrastructural changes be correlated with alterations in chemistry and function.

The relationship of intracellular pathways of iron metabolism to cellular iron overload and the iron storage diseases. Cell sap and cytocavitary network pathways in relation to lysosomal storage and turnover of iron macromolecules

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