Showing papers in "American Journal of Pathology in 1980"

Arterial foam cells with distinctive immunomorphologic and histochemical features of macrophages.

Abstract: A variable population of fat-filled "foam" cells in diet-induced experimental arterial intimal plaques of rabbits and monkeys were analyzed for several features characteristic of macrophages. These included: 1) surface binding and phagocytosis of antibody-coated or complement-coated erythrocytes to detect specific surface receptors; 2) cytochemical tests and ultrastructural features to evaluate cell function and structure; and 3) rapid adherence to glass, a feature of macrophage activity, to isolate and identify a homogeneous population of fat-filled foam cells from excised and disrupted arterial lesions. Mixed populations of cells grown in culture from explants of lesions were also analyzed and lipid-filled cells were studied in histologic sections of adjacent lesions. Eighty to ninety percent of the easily dislodged glass-adherent cells from lesions had surface receptors for the Fc portion of immunoglobulin G and for the third component of complement. Coated red blood cells were readily phagocytized, but noncoated cells were not. Acid lipase activity was demonstrated in the Fc-receptor-positive cells. These cells were also devoid of ultrastructural features of smooth muscle. Among the cells growing or migrating out of explants, a population of large round foam cells possessed all of the macrophage features found in the glass-adherent cells from lesions and lacked ultrastructural characteristics of smooth muscle. Fusiform lipid vacuolated cells also grew out of the explants but did not exhibit surface receptors, failed to phagocytize coated or noncoated erythrocytes and did not stain for acid lipase activity; these cells showed distinctive morphologic features of smooth muscle. In histologic sections of nearby lesions foam cells that showed macrophage characteristics, ie, acid lipase activity and the presence of lysozymelike antigen, lacked ultrastructural smooth muscle features. Smooth muscle cells in lesion sections often contained lipid but demonstrated no lysozyme or acid lipase activity. The occurrence of a population of cells with several functional and structural features of macrophages among the lipid-laden cells of experimental diet-induced arterial lesions suggests that some foam cells may be derived from monocytes. An alternative explanation, that metabolically altered autochthonous arterial wall cells assume one or more characteristics of mononuclear phagocytes is less likely, since some of the markers used in these experiments are unrelated. Both explanations deserve further careful study.

Chronic cryptococcal meningitis: a new experimental model in rabbits.

Abstract: This paper describes the salient features of a new model for chronic cryptococcal meningitis in cortisone-treated rabbits. Normal rabbits soon recovered after intracisternal inoculation of Cryptococcus neoformans, but cortisone-treated animals developed chronic progressive meningitis that was fatal in 2-12 weeks. Incidence and severity of infection was related to cortisone dose, not to inoculum size. The number of mononuclear cells that migrated into the subarachnoid spaces and cerebrospinal fluid of infected rabbits was strikingly reduced by cortisone treatment. Rabbits with cryptococcal meningitis were febrile; their high body temperature did not confer resistance to this infection. Cortisone-treated rabbits provide a new and expedient laboratory model for cryptococcal disease. Potential applications include study of the pathogenesis of cryptococcosis, investigation of the immunobiology of the CNS in chronic meningitis, and in vivo evaluation of newer anticryptococcal treatment regimens.

Silent corticotropic adenomas of the human pituitary gland: a histologic, immunocytologic, and ultrastructural study.

Abstract: Among 300 surgically removed pituitary adenomas, 17 tumors containing immunoreactive 1-39 adrenocorticotropin (ACTH) and/or 19-39 ACTH, beta-lipotropin, and alpha-endorphin but unassociated with clinical signs of Cushing's disease have been detected. These neoplasms were divided into basophilic adenomas with strong periodic acid-Schiff (PAS) and lead-hematoxylin positivity and chromophobic tumors with moderate or no PAS and lead-hematoxylin positivity. The former were densely granulated tumors with a fine structure strikingly similar to that of functioning corticotropic cell adenomas. The latter were sparsely granulated with varying ultrastructural patterns. The marked morphologic diversity suggests that these adenomas, despite their similar immunocytologic characteristics, represent more than one entity. Clinically, the most common finding was a rapidly progressing visual defect. An unusually high incidence of infarction (5 cases) and recurrence (5 cases) was noted, underlining the importance of correct morphologic diagnosis and careful follow-up.

Immunoperoxidase localization of keratin in human neoplasms: a preliminary survey.

Abstract: The distribution of intracellular keratin was studied in a variety of human tumors using a previously described immunoperoxidase technique employing antikeratin antibodies Squamous cell carcinomas, transitional cell tumors, and mesotheliomas exhibited strong reactivity with antikeratin antibodies Mammary adenocarcinomas were either negative or weakly positive In the lung, an organ which can give rise to several morphologically distinct forms of carcinoma, only the squamous cell type stained strongly for keratin; undifferentiated lung carcinomas were negative, and adenocarcinomas were either negative or weakly positive Colonic, renal, and prostatic adenocarcinomas were negative Sarcomas, lymphomas, and neural tumors were uniformly negative The analysis of intracellular keratin by the immunoperoxidase technique appears helpful in establishing the epithelial nature of primary or metastatic poorly differentiated neoplasms

Histogenesis of alcoholic fibrosis and cirrhosis in the baboon.

Abstract: Sequential liver specimens of 18 baboons exposed for up to 6 years to alcohol on a nutritionally adequate diet, as well as those of pair-fed controls, were examined by light microscopy. Whereas control animals failed to develop pathologic changes, in all baboons exposed, ethanol produced initial steatosis and subsequently fibrosis. Emphasis was on the pattern of the fiber accumulations as related to lesions of the hepatocytes. Segmented neutrophilic leukocytes were rarely observed, and the picture of frank alcoholic hepatitis was absent, but diffusely increased mononuclear sinusoidal cells and interstitial clusters of such cells with PAS-positive macrophages were abundant. Fibrosis proceeding to septum formation was associated mainly with large-droplet steatosis. Septum formation was initiated by excess layers of reticulin around steatotic hepatocytes or, more frequently, by linking of fiber accumulations around the clusters of mononuclear cells, in both instances with subsequent deposition of collagen fibers. Both processes were prominent in the centrolobular zone, creating a perivenous net-like fibrosis, but septum formation also started within the lobular parenchyma and eventually linked with the barely altered portal tracts. Fifteen alcohol-fed baboons developed septums, with diffuse septal fibrosis in 5; 4 proceeded to septal cirrhosis and 1 each to micronodular and to mixed micromacronodular cirrhosis. Cirrhosis in the baboons thus develops without the conspicuous polymorphonuclear inflammation characteristic of human alcoholic hepatitis. These observations indicate a pathway to cirrhosis over creeping fibrosis that might play a role also in man, instead of (or supplementing) the one proceeding over alcoholic hepatitis.

Hypoxia-induced structural changes in the media and adventitia of the rat hilar pulmonary artery and their regression.

Abstract: Chronic hypobaric hypoxia induces structural features characteristic of pulmonary hypertension, but little is known of their reversal. In the present study, rats have been exposed to hypobaric hypoxia for 10 days and subsequently allowed to recover in room air for 3, 14, 28, or 70 days. With the use of 1-mu sections and electron-microscopic and point-counting techniques, the regression of the medial and adventitial changes in the rat hilar intrapulmonary artery has been followed. In the media, 10-day hypoxia causes more than a doubling in thickness due to 1) hypertrophy of smooth muscle cells, particularly of rough sarcoplasmic reticulum and Golgi apparatus; 2) an increase in extracellular connective tissue, microfibrils, collagen fibers, and elastin, and 3) edemalike fluid. In addition, the elestic laminas are doubled in thickness, and myofilamentous processes of the hypertrophied smooth muscle cells contact them. After just 3 days' recovery, some cells have already returned to normal diameter, although medial thickening is unchanged. By Day 14 and at Days 28 and 70 of recovery, medial thickness and cell diameter are within the normal range, and by recovery Day 70, there is a significant increase in the relative areal proportion of extracellular collagen fibers and a decrease in elastin (P less than 0.001). Hypoxia also produces a more than twofold increase in adventitial thickness. Hypertrophy of fibroblasts and an increase in their number contribute to the thickening, as does as increase in collagen fibers. During 3-70 days of recovery, thickness is gradually reduced to normal levels, although it is still significantly above normal at Days 3, 14, and 28. The increases in thickness at these times are due mainly to the accumulation of collagen fibers, which are still apparent after 70 days of recovery. Thus, hypoxia causes a doubling in thickness of the medial and adventitial coats of the hilar muscular pulmonary artery, which with recovery regain near normal thickness but whose structure is altered. The increase in collagen fibers contributes to contracture and reduced distensibility in these vessels, which is apparent in arteriograms as narrowed lumen diameter.

Lysosomal alterations in hypoxic and reoxygenated hearts. I. Ultrastructural and cytochemical changes.

Abstract: Rabbit hearts perfused under hypoxic conditions underwent progressive subcellular damage, which becomes irreversible by one hour. During the first 20 minutes of perfusion, minor dilation of mitochondria and condensation of nuclear chromatin were the only salient features of cell injury. By 40 minutes moderate mitochondrial swelling was evident in hypoxic myocytes. Moreover, an increase in degenerating mitochondria and autophagic vacuoles was apparent. Reperfusion after either 20 or 40 minutes of hypoxia restored contractility, and injured myocytes underwent a cellular repair process that involved a dramatic increase in lysosomal autoplagy. One hour of hypoxia yielded irreversibly injured myocytes. Upon reoxygenation, some of these cells displayed typical changes of necrosis, but others apparently underwent an abortive repair process involving the formation of large, probably nonfunctional lysosomes. These observations suggest that lysosomal autophagy is important in the efforts at repair that cardiac cells initiate during and after hypoxia.

Cardiac disease induced by chronic adriamycin administration in dogs and an evaluation of vitamin E and selenium as cardioprotectants.

Abstract: Chronic adriamycin (ADR) intoxication was produced in three groups of beagle dogs by weekly intravenous injections (1 mg/kg body weight) for 20 weeks (cumulative dose 400 mg/sq m). Group A (6 dogs) received ADR only; Group B (6 dogs) were given ADR and weekly doses of vitamin E (17 mg/kg body weight) as alpha-tocopherol acetate; and Group C (6 dogs) received ADR and weekly doses of vitamin E as did Group B and selenium (0.06 mg/kg body weight as selenite). Each of the 18 dogs developed ADR-induced cardiomyopathy (CMY), and death occurred in 11 dogs during Weeks 17-20. Mortality was lowest in Group B (2 of 6), but no differences between groups were seen either in survival time of the dogs that died or in severity of CMY. Cardiomyopathy was more severe in dogs that died than in survivors. Congestive heart failure with transudation was present in 4 of 11 dogs that died. Cardiac histopathology was characterized by vacuolar degeneration of myocytes. Myocardial damage was most severe in the left ventricle and the ventricular septum, intermediate in the right ventricle and the left atrium, and least in the right atrium. Ultrastructural study showed that an early alteration in damaged myocytes was distention of sarcoplasmic reticulum to form sarcoplasmic vacuoles. Occasional damaged fibers had myofibrillar lysis and focal proliferation of sarcoplasmic reticulum. This study demonstrates that the dog offers a suitable model for studies of chronic ADR cardiotoxicity in man. The lack of cardioprotection from vitamin E and selenium supplementation fails to support the proposed role of lipoperoxidative damage in the development of chronic ADR-induced CMY.

Effects of epidermal growth factor on lung maturation in fetal lambs.

Abstract: Summary Injection of epidermal growth factor (EGF) into 24-day rabbit fetuses (5 pg, im or ip) induced accelerated maturation of the lung. On sacrifice at day 27, there was greater distensibility and stability on deflation associated with the appearance of a complement of type I1 cells approaching that of the rabbit at term. EGF treatment had no demonstrable effect on body weight or lung weight in this group of animals. Saline-injected control fetuses were not affected significantly. Speculation EGF is capable not only of promoting epithelial cell growth but also differentiation in the fetal rabbit lung. It may be an important hormone in the maturation of the lung and capable of protecting the prematurely delivered fetus against the development of hyaline membrane disease. EGF is a biologically active polypeptide first described in 1962 by Cohen (6), who observed that the daily injection of an extract of male mouse submaxillary gland into immature mice resulted in precocious tooth eruption and eye opening. Subsequent analysis of the salivary gland extract revealed that the biologically active component was a heat-stable, nondialyzable, single polypeptide chain of 53 amino acid residues with a molecular weight of 6045 daltons, as determined by amino acid composition (21). The biologic effects of EGF have been shown to be primarily those of generalized epithelial growth and keratinization. These effects of mouse-derived EGF (mEGF) have been demonstrated not only in the mouse and rat, but also in other species such as cultured chick embryo skin (7), human fibroblasts (8), and both chick and human embryo cornea (18). Recently, it has been demonstrated that EGF is also present in the human and that human EGF, when tested in organ culture systems, appeared to act in a manner identical to that of mEGF (19). In 1975. it was proposed that if EGF is a normal fetal growth hormone, it mig& aiso be capable of stimulating pulkonary e~ithelial cell growth. It was shown that the constant infusion of

Susceptibility of the mammary gland to carcinogenesis. II. Pregnancy interruption as a risk factor in tumor incidence.

Abstract: In the rat, pregnancy and lactation prior to carcinogen administration protect the mammary gland from developing carcinomas and benign lesions. In this study, the influence of pregnancy interruption versus full pregnancy and pregnancy plus lactation on the incidence of carcinomas and benign lesions was studied in the mammary glands of rats treated with 7,12-dimethylbenz(a)anthracene (DMBA). Fifty-nine Sprague-Dawley rats were separated into 5 groups: I) rats that had had one pregnancy and one lactation; II) rats that had had one pregnancy without lactation; III) rats that had had pregnancy interrupted at the 12th day of gestation; IV) age-matched virgin rats as a control Group I; and V) age-matched virgin rats as a control for groups II and III. The 5 groups received a single intragastric dose of DMBA (10 mg/100 g body weight), with the exception of 2 animals per group, which were killed 1 hour after an intraperitoneal injection of 2.5 mu Ci 3H-thymidine/g body weight. The number of labeled nuclei per 100 cells (DNA labeling index, LI) was counted in terminal end buds (TEBs), terminal ducts (TDs), and alveolar buds (ABs) of the glands. The number of structures and the DNA-LI were correlated with the incidence of tumors at 22 weeks after DMBA. Pregnancy, with or without lactation, resulted in elimination of TEBs and reduction in the DNA-LI of TDs and ABs. These groups did not develop carcinomas. After the interruption of pregnancy the mammary gland contained numerous TEBs, with a high DNA-LI; 77% of these animals developed carcinomas, and all of them developed benign lesions. Therefore, while pregnancy and lactation protected the mammary gland from developing carcinomas and benign lesions by induction of full differentiation, pregnancy interruption did not elicit sufficient differentiation in the gland to be protective, and these animals were at the same risk as virgin animals treated with the carcinogen.

Acute respiratory bronchiolitis: an ultrastructural and autoradiographic study of epithelial cell injury and renewal in Rhesus monkeys exposed to ozone

Abstract: The pathogenesis of acute respiratory bronchiolitis was examined in rhesus monkeys exposed to 0.8 ppm ozone fpr 4--50 hours. Epithelial injury and renewal was qualitatively and quantitatively characterized by correlated techniques of scanning and transmission electron microscopy as well as by light-microscopic autoradiography following labeling with tritiated thymidine. Extensive degeneration and necrosis of Type 1 epithelial cells occurred on the respiratory bronchiolar wall during the initial 4--12 hours of exposure. Increased numbers of labeled epithelial cells were present in this region after 18 hours of exposure, and the highest labeling index (18% was measured after 50 hours of exposure. Most (67--80%) of the labeled cells and all the mitotic epithelial cells (22) observed ultrastructurally were cuboidal bronchiolar epithelial cells. Of the labeled epithelial cells, 20--33% were Type 2 epithelial cells. After 50 hours of exposure the respiratory bronchiolar epithelium was hyperplastic. The predominant inflammatory cell in respiratory bronchiolar exudate was the alveolar macrophage. Monkeys that were exposed for 50 hours and allowed to recover in unozonized air for 7 days had incomplete resolution of respiratory bronchiolar epithelial hyperplasia. The results indicate that Type 1 epithelial cells lining respiratory bronchioles are the cell type most sensitive to injury and that both cuboidal bronchiolar epithelial cells and Type 2 epithelial cells function as stem cells in epithelial renewal.

Lactoferrin deficiency as a consequence of a lack of specific granules in neutrophils from a patient with recurrent infections. Detection by immunoperoxidase staining for lactoferrin and cytochemical electron microscopy.

Abstract: Neutrophils from a boy suffering from recurrent infections were found to be totally deficient in specific granules when studied by electron microscopy. In contrast, myeloperoxidase-containing azurophil granules were increased in number. This deficiency of specific granules could be detected at the light-microscopic level using an immunocytochemical technique to demonstrate the absence of lactoferrin. Neutrophils also exhibited abnormal nuclear segmentation, nuclear clefts, an abnormally weak cytochemical reaction for alkaline phosphatase, and an increased number of mitochondria and ribosomes. Some granulocytic precursors were abnormal, and many of these cells were phagocytosed by macrophages in the bone marrow. Despite these multiple abnormalities and the history of severe pyogenic infection, the in vitro bactericidal capacity of the neutrophils was within normal limits, and normal degranulation of azurophil granules occurred following phagocytosis. The precise mechanism by which the deficiency of specific granules in this patient led to an enhanced in vivo susceptibility to infection therefore remains obscure. However, attention is drawn to the fact that in three previously described cases of specific granule deficiency a history of recurrent infections was present.

The significance of variations in the distribution of copper in liver disease.

Abstract: Biopsy and autopsy specimens of liver from patients with Wilson's disease in various stages, chronic cholestatic conditions (including primary biliary cirrhosis, extrahepatic biliary obstruction, sclerosing cholangitis, and biliary atresia), chronic active hepatitis, and Indian childhood cirrhosis, as well as normal neonates, were examined by means of histochemical techniques for copper and copper-associated protein The intracellular localization of copper and the lobular distribution of the metal and its associated protein differed in these conditions Periportal hepatocytes containing granules (lysosomes) that were reactive for copper and for copper-associated protein were characteristic of cholestasis and neonatal liver However, in cholestasis extralysosomal copper was often present in the hepatocellular cytoplasm In contrast, in Wilson's disease, despite very high concentrations of copper in the early stages, the metal was diffuse in the cytoplasm, and the histochemical reactions for granular copper and its associated protein were usually negative Therefore, a failure to stain for copper does not exclude the diagnosis of Wilson's disease In the late stages of Wilson's disease staining varied in different nodules In Indian childhood cirrhosis copper was present throughout the parenchyma, with periportal predominance Differences in the distribution of copper and the cellular changes associated with its deposition suggest that different pathogenetic mechanisms and possibly different intracellular targets are susceptible to the toxic effects of the metal For diagnosis, staining for copper and for copper-associated protein may assist in the differentiation of primary biliary cirrhosis from chronic active hepatitis

Lysis of infected myofibers by coxsackievirus B-3-immune T lymphocytes.

Abstract: Spleen cells from male adult BALB/c mice given intraperitoneal injections of purified coxsackievirus B-3 were examined for the ability to lyse syngeneic neonatal myofibers in culture. Cytotoxicity against infected and uninfected targets was measured with the use of an in vitro 51Cr release assay. Immune spleen cells obtained 4--7 days after infection were cytotoxic for viral-infected myofibers. Peak reactivity was observed 5 days after infection. At this time immune spleen cells showed significantly less reactivity against uninfected myofibers. Cytotoxicity against infected targets was mediated by T lymphocytes, since reactivity was abolished by treatment with anti-thy 1.2 and complement. Treatment with anti-Ig and complement caused no loss of activity. Reciprocal assays performed with BALB/c and CBA cells showed that maximal cytotoxicity occurred against infected syngeneic myofibers, providing further evidence that viral-specific effector cells were T lymphocytes. In addition, hyperimmune rabbit anti-coxsackievirus B-3 antiserum could not block immune spleen cell lysis of infected targets, suggesting that coxsackievirus-infected myofibers expressed surface membrane antigens not recognized by specific neutralizing antibody.

Pulmonary injury induced by C3a and C5a anaphylatoxins.

Abstract: Homogeneous anaphylatoxins C3a (human or porcine), C5a (porcine), and the porcine classic anaphylatoxin, a mixture of C5a and C5a des Arg, isolated from complement-activated serum, were shown to induce acute pulmonary injury in the guinea pig following intrabonchial instillation. The gross physiologic response to these factors is characterized by respiratory distress with rapid, shallow breathing. Administration of 8--17 micrograms/kg of porcine classic anaphylatoxin proved lethal in 50% of the animals treated. The acute response (less than 20 minutes after instillation) of pulmonary tissue to insult by the anaphylatoxins is characterized by constriction of the smooth muscle walls in both bronchioles and pulmonary arteries and by focal atelectasis. Aggregates of platelets and leukocytes in pulmonary vessels and in other organs such as the chambers of the heart were commonly observed after intrabronchial administration of the anaphylatoxins. Although C3a was never lethal in guinea pigs even when doses as high as 500 micrograms/kg were administered by the intrabronchial route, this anaphylatoxin did induce the same pattern of acute pulmonary injury as C5a. In vitro experiments employing guinea pig platelets indicated that these cells aggregate in the presence of 10(-10) M porcine C5a but are not affected by C3a (human or porcine) even at levels up to 10(-6) M. Hence, platelet aggregation as observed in vivo may be directly affected by C5a, but in the case of C3a, secondary mediators must be involved. Anaphylatoxin preparations were also shown to induce contraction of guinea pig lung strips in vitro: this effect was not inhibited by antihistamines at concentrations that blocked contraction to exogenous histamine. The in vivo response to anaphylatoxin could be blocked with high doses of the antihistamine chlorpheniramine but not by corresponding doses of diphenhydramine.

The evolution of vascular changes in the spontaneously hypertensive rat.

Abstract: A longitudinal study on the development of vascular lesions was carried out in the spontaneously hypertensive rat (SHR) of the Aoki-Okamoto strain The aorta and intrarenal arterial vessels were examined at different ages, from 5 to 48 weeks, by light and electron microscopy Endothelial permeability to injected horseradish peroxidase (HRP) was evaluated in 20-week-old animals Morphologic differences between vessels of SHRs and age-matched normotensive controls (Wistar-Kyoto strain) were first noted at 10 weeks of age and became more pronounced with time Vascular pathology involved both intima and media Medial thickening was seen in both aorta and peripheral arteries and, in the latter, was associated with decreased luminal diameters These medial changes may contribute to the maintenance of the elevated blood pressure Intimal lesions affected predominantly the aorta and were characterized by an expansion of the subendothelial space with deposition of acid mucopolysaccharides There was increased accumulation of tracer HRP in the expanded subendothelium, which suggested enhanced permeability and/or retention of the tracer In animal species susceptible to atherosclerosis, these intimal changes could serve as the structural basis for the higher propensity for atheromatous lesions in hypertensive individuals In the SHR, despite stabilization of systolic blood pressure at about 20 weeks of age, both intimal and medial lesions continue to progress and become more extensive and severe; this suggests that not only the severity of hypertension but also its duration are significant determinants of the degree of vascular damage

The surface-connected canalicular system of blood platelets--a fenestrated membrane system.

Abstract: Recent reports have suggested that channels of the surface-connected or open canalicular system (OCS) in discoid blood platelets represent a reservoir of membrane that can be evaginated following activation and shape change and contribute to an increased ratio of surface area to volume. The present study has used electron cytochemistry and freeze-fracture to examine the organization of the OCS in unaltered platelets. Results of the investigation indicate that channels of the OCS are seldom if ever single tubular invaginations of the surface membrane. Each channel joins with other canaliculi of the OCS to form an anastomosing network of fenestrated conduits spreading throughout the cytoplasm from one side of the platelet to the other. The multiple connections of the interlocked channels to different sites on the platelet surface, their association in a continuous labyrinth, and participation with elements of the dense tubular system to form membrane complexes suggest that the OCS would have to be torn apart or undergo radical rearrangement before it could be evaginated and contribute to an increased surface area on activated cells.

A study of atherosclerosis regression in Macaca mulatta: III. Chemical changes in arteries from animals with atherosclerosis induced for 19 months and regressed for 48 months at plasma cholesterol concentrations of 300 or 200 mg/dl.

Abstract: The influence of two levels of plasma cholesterol concentration on the long-term regression of atherosclerotic plaques in rhesus monkeys (Macaca mulatta) was studied. Forty-eight young adult male rhesus monkeys were fed an atherogenic diet for 19 months, then diets designed to maintain plasma cholesterol concentrations at 280-320 mg/dl (actual 316 +/- 10 mg/dl; mean +/- SEM) of 180-220 mg/dl (actual 204 +/- 4 mg/dl). Twelve animals were killed after 19 months to evaluate the atherosclerosis produced. The remaining 36 monkeys were studied after 48 months of atherosclerosis regression. Significantly greater amounts of accumulated nonesterififed and esterified cholesterol were lost from the arteries of monkeys that underwent regression at about 200 mg/dl, in comparison with 300 mg/dl. Regression at both plasma cholesterol concentrations resulted in increased collagen and decreased elastin content in the thoracic aorta but not in the other arteries studied. After regression at 300 mg/dl there was no change (83%) in the frequency of calcification of the thoracic aorta, while at 200 mg/dl the frequency of calcification was reduced to 50%. When compared with monkeys whose athersclerotic lesions were produced in an identical manner but were regressed for only 24 months, after 48 months had increased cholesterol concenrations in the thoracic aorta and carotid artery but not the abdominal aorta of iliaco-femoral artery, regardless of the plasma cholesterol concentration. The lipid composition of the regressed plaque suggested a change in plaque lipid toward the character of extracellular deposits described physically as crystalline in nature. The physical state was influenced by the length of the regression period and the plasma cholesterol concentration during regeression. In the thoracic aorta, principally as a result of changes in elastin content, the collagen-to-elastin ratio increased between 24 and 48 months of regression. It is proposed that the differences in removal of cholesterol from the thoracic and abdominal aorta after 24 and 48 months of regression in animals at 300 mg/dl may be influenced by the rearrangement of connective tissue. On the basis of the lipid and mineral content of uncomplicated atherosclerotic plaques after 4 yers of regression, it appears that the plasma cholesterol concentration during the regression period is a signigicant factor influencing the extent of plaque regression as well as the potential for further progression.

Fine structural lesions and hormonal alterations in thyroid glands of perinatal rats exposed in utero and by the milk to polychlorinated biphenyls.

Abstract: Polychlorinated biphenyls (PCB) produced ultrastructural lesions of thyroid follicular cells and a reduction in serum levels of thyroid hormones in neonatal (0, 7, 14, and 21 days of age) Osborne-Mendel rats exposed to 50 or 500 ppm PCB in utero and by the milk Litter size was decreased significantly in rats fed 500 ppm PCB Body weights at 21 days of age were reduced in rats exposed to 50 and 500 ppm PCB The ultrastructural lesions in follicular cells were dose- and age-dependent but were less extensive than in adult rats of the same strain At all ages the lesions in thyroid follicular cells were characterized by increased development of rough endoplasmic reticulum and vacuolization of mitochondria There was an increase of colloid droplets and lysosomes in the older age groups (14 and 21 days) but little evidence for colloid droplet-lysosome interaction necessary for the secretion of thyroid hormones Shortening of microvilli, with the formation of club-shaped or branching forms, was observed only in 21-day-old rat pups These ultrastructural alterations in follicular cells exposed to PCB were associated with a significant reduction in serum thyroxine in the rats at birth and at 7, 14, and 21 days of age Serum triiodothyronine was reduced significantly in 7- and 14-day-old rat pups The ultrastructural alterations in follicular cells appeared to contribute to the significant lowering of serum thyroid hormone levels in 14- and 21-day-old rats exposed to PCB These findings suggest that alterations in thyroid structure and function may be important in the pathogenesis of certain metabolic disorders associated with PCB intoxication

Nodular glomerulopathy associated with nonamyloidotic kappa light chain deposits and excess immunoglobulin light chain synthesis.

Abstract: A nodular glomerulopathy characterized by mesangial deposits of monoclonal kappa light chains was detected by immunofluorescence in a renal biopsy from a patient with proteinuria and hypertension. These nodules lacked the tinctorial and morphologic features of amyloid. Ultrastructurally, the nodules contained electron-dense granular deposits as well as fibrils in parallel arrangement. The fibrils measured 110-140 A in diameter. They were consistent in size with amyloid fibrils. However, they differed in lacking the randomly oriented network of typical amyloid fibrils and more closely resembled fibrils intrinsic to mesangial matrix. The patient had no bone marrow or X-ray evidence of myeloma and no evidence of free monoclonal light chains in serum or concentrated urines. Biosynthetic studies of the patient's bone marrow cells demonstrated unbalanced immunoglobulin synthesis with excess production of monoclonal kappa light chains. These observations suggest that the observed glomerulopathy results from direct deposition of monoclonal light chains. Deposits with kappa light chain determinants have been found in 7 other patients with similar nodular glomerulopathies, 4 of whom had diagnosed clinical myeloma. The lesion of nonamyloidotic nodular glomerulopathy previously described in 19 patients, nor examined by immunopathologic techniques or not shown to contain light chain determinants, may have a similar pathogenesis.

Ultrastructural findings in lung biopsy material from children with congenital heart defects.

Abstract: The ultrastructural features of pulmonary arteries are described in lung biopsy material from 6 children with congenital heart defects. Right ventricular hypertrophy was found in all 6 children and increased pulmonary artery pressure in all but one. The presence of muscle in smaller and more peripheral arteries than expected for the age of the child was detected in all cases. Ultrastructural examination of the peripheral arteries revealed, for the first time, in the nonmuscular regions of human arterial walls, pericytes and intermediate cells (previously shown to be precursor smooth-muscle cells); in addition, new arterial muscle was found in the normally nonmuscular region. In the 4 cases where medial thickness of the normally muscular arteries was increased, the smooth-muscle cells were hypertrophied and the extracellular connective tissue increased. In all cases, junctions between endothelial cells and smooth-muscle cells, intermediate cells, or pericytes were found. These changes are similar to those described in the rat with hypoxia-induced pulmonary hypertension. In addition, in 2 of the 6 cases, bundles of nerve axons in Schwann cell sheaths were found in adventitial layer of small, intraacinar muscular arteries (not previously demonstrated ultrastructurally at this site in the human lung); varicosities with agranular and granular vesicles, probably adrenergic, were also identified.

A differential effect of C5a and C5a des Arg in the induction of pulmonary inflammation.

Abstract: Earlier studies have shown that C5 fragments induce an inflammatory reaction when instilled into the rabbit lung. Because C5a is rapidly converted to C5a des Arg in vivo, experiments were performed to determine which fragment was most effective in producing pulmonary inflammation in this animal model. C5a des Arg consistently produced marked inflammation. This was characterized by neutrophil accumulation, edema, hemorrhage, fibrin formation, and damage to alveolar epithelium. The time course of the inflammatory reaction initiated by C5a des Arg showed pulmonary vascular sequestration of neutrophils with no intra-alveolar migration at 30 minutes after injection. By 2 hours, interstitial and alveolar neutrophils were numerous, with the accumulation of neutrophils in the alveoli increasing to a maximum at 6 hours. At 24 and 48 hours, the predominant cells were mononuclear (macrophages). By 120 hours, the lesions were resolving. In contrast, at all doses examined, a similar instillation of C5a induced either no inflammation or a milder, more focal response than C5a des Arg. This inability of C5a to initiate inflammation was not apparently due to the generation of inhibitors, since mixtures of C5a and C5a des Arg were phlogistic. A prolonged, intrapulmonary infusion of C5a (20 minutes), in contrast to a bolus instillation (1 minute), did initiate an inflammatory response, which may reflect the conversion of the C5a to C5a des Arg in the lung. This study points out the inflammatory potential of products of complement activation, particularly of the C5 fragment C5a des Arg, when applied to the airway side of the lungs. This inflammatory response raises the possibility that cleavage of intrapulmonary C5 may play an important role in the initiation of pulmonary inflammation.

The relation of experimental arthritis to the distribution of streptococcal cell wall fragments.

Abstract: The intraperitoneal injection of peptidoglycan-carbohydrate fragments from Group A streptococci produces a chronic, polyarticular, erosive synovitis in rats. The cell wall material accumulates rapidly in the liver, spleen, and lymph nodes, where it causes little injury. At the same time, selective localization and persistence of the material in the synovial and periarticular tissues occurs. Its presence in the joint is associated with acute and recurrent inflammation with focal synotivitis, pannus formation, joint destruction, and ankylosis. Cell wall fragments become localized in the synovial and periarticular tissues at a time when there are leukocytes in the bloodstream, which appear to contain the material. During this early phase vascular lesions appear in the synovium and in periarticular tissues with collections of fibrin, neutrophils, macrophages, and cell wall fragments near the venules and capillaries. Recurrent episodes of inflammation and joint injury, associated with persistent cell wall antigen within macrophages, were observed over a period of 90 days.

The connective tissue component of the caprine arthritis-encephalitis syndrome.

Abstract: The gross and microscopic connective tissue lesions in 12 goats with caprine arthritis-encephalitis (CAE) are described, including those from which a virus (CAEV) was isolated. Lesions were most often associated with synovial-lined structures including joints, tendon sheaths, and bursae, and were typified by synovial cell proliferations, subsynovial mononuclear cell infiltration, the presence of fibrin, fibrinous concretions, necrosis, and mineralization. Extrasynovial lesions were located in kidneys, vessels, and brain. The inflammatory infiltrates in these organs were predominantly mononuclear. Amyloid was also found in liver, spleen, and kidney. Microbiologic techniques failed to demonstrate any bacteria, mycoplasma, or chlamydia in the lesions.

A pathogenetic study of the early connective tissue lesions of viral caprine arthritis-encephalitis.

Abstract: Experiments were designed to correlate morphologic lesions with the presence of caprine arthritis-encephalitis virus (CAEV). Twenty-one cesarean-derived goat kids were infected with 10(6) to 10(7) TCID50 of virus, killed sequentially, and examined for viral antigens by immunofluorescence, viral infectivity by isolation and titration, and morphologic changes by light microscopy. Fluorescent viral antigens were detected from 1 to 10 days postinoculation (DPI) and only in synovial cells. Virus was reisolated from several joints and from brain 0.5 to 79 DPI. Increases in synovial fluid cell counts were noted by 1 DPI, and morphologic changes in synovial membranes were present from 3 to 45 DPI. Joint lesions progressed from mild synovial cell hyperplasia and perivascular mononuclear cell infiltration to severe synovial cell hyperplasia and mononuclear cell infiltration with villous hypertrophy. Lesions elsewhere were mild, consisting only of perivascular mononuclear cell infiltrates. Eleven cesarean-derived control goats were negative for viral antigens, virus, and morphologic lesions.

Membranous glomerulopathy associated with hepatitis B core antigen immune complexes in children.

Abstract: Direct immunofluorescence, immunoelectron microscopy, and special immunohistochemical procedures including guinea pig complement fixation, differential elution, and in situ antigen binding were employed in an immunomorphologic analysis of kidney biopsy specimens from 98 children with clinically diagnosed nephrotic syndrome and/or glomerulonephritis (GN) Glomerular deposits of hepatitis B virus (HBV) antigens, immunoglobulins, and complement were detected in specimens from 24 children, all seropositive for hepatitis B surface antigen (HBsAg) and antibody to hepatitis B core antigen (HBcAg) Of these, 21 cases were diagnosed as membranous glomerulopathy (MGN), 1 as membranoproliferative GN, and 2 as diffuse mesangial proliferative GN HBaAg was identified as the only HBV antigen in about a third of the cases of MGN, whereas in another third it was accompanied by HBsAg HBsAg was the only HBV antigenic component detected in the glomerular deposits in the remaining third of the cases of this GN form The results of this study indicate that apart from, or in addition to, HBsAg immune complexes, HBcAg immune complexes may also participate in the pathogenesis of a significant number of MGN cases in children subclinically infected with HBV A possibility that these complexes include nonparticulate, presumably low-molecular-weight HBaAg components and that they are found in an environment of antibody-excess is discussed