Vascular damage in acute experimental leptospirosis of the guinea-pig

The pathogenesis of the haemorrhagic diathesis in experimental leptospirosis of the guinea-pig was investigated in the lung, diaphragm and kidney. The vascular damage was found to be focal and mainly capillary. Swollen endothelium with dilated endoplasmic reticulum, enlarged mitochondriae and open junctions seemed to be the initial lesions and endothelial necrosis the final picture in all tissues. The lung capillaries showed endothelial and epithelial blebs and desquamation with many myelin figures. Capillary thrombosis was observed in the pulmonary microcirculation, probably acting as an aggravating factor and being partly responsible for the particularly impressive lung haemorrhages. The peritubular renal capillaries as well as open junctions and gaps due to necrosis also had enlarged fenestrae which were permeable to colloidal carbon particles. The paucity of micro-organisms in the vicinity of the lesions is in accordance with the toxic genesis postulated for the vascular damage in leptospirosis. It is suggested that the vascular lesions induced by leptospirosis begin with increased permeability prior to endothelial necrosis.     

Rationale for the histological spectrum of tuberculosis. A basis for classification

There is need to re-appraise the cellular response to Mycobacterium tuberculosis. Histological analysis of 54 untreated patients with established disease demonstrated a continuous spectrum of tissue responses in which six groups correlated with evidence of resistance to bacterial multiplication. A predominance of cases in the two middle groups (82%) signified an immunological equilibrium in middle grade resistant patients that is absent in related diseases such as leprosy and cutaneous leishmaniasis. The dominant feature was necrosis, which increased progressively across the spectrum. Its form varied from minimal fibrinoid change, through fine eosinophilic necrosis, to basophilic necrosis characterized by neutrophil karyorrhexis, and finally to an almost acellular lesion with many bacilli. Cytological differentiation of the granuloma was of subsidiary significance, mature epithelioid cells being found only in high resistant cases. No correlation was found for the number of lymphocytes. This classification is thought to be an accurate reflection of the immune state in relation to antigenic load. It raises a hitherto unconsidered possibility that "caseation", a loosely applied macroscopic term, may embrace immunologically distinct states. The classification of multiple lesions was consistent. Histology offers a promising basis for further immunopathological investigation.     

Drug related vasculitis. Clinicopathologic correlations in 30 patients.

Drug related vasculitis has variously been described as necrotizing hypersensitivity or allergic angiitis or microscopic panarteritis nodosa. We reviewed tissue sections from 30 patients with validated drug hypersensitivity and vasculitis in order to precisely define this entity. No evidence of necrotizing vascular lesions or of fibrinoid associated with necrosis was found. The vascular lesions in all 30 patients involved small arteries, arterioles, capillaries, and venules. The inflammatory infiltrate consisted primarily of mononuclear cells and prominent numbers of eosinophils and was present in all three layers of the involved vessel walls. Clinically the patients developed either localized or systemic vasculitis, which could not be predicted on the basis of the associated drug. The findings of a skin rash, fever, or eosinophilia and the development of symptoms consistent with a hypersensitivity reaction while medication was being taken were all suggestive of the diagnosis of drug related vasculitis.     

Inflammatory reaction in experimental hepatic amebiasis. An ultrastructural study.

One of the hallmarks of tissue necrosis produced by the human protozoan parasite Entamoeba histolytica, the causative agent of human amebiasis, appeared to be the lack of inflammatory reaction to the invading trophozoites. Recent evidence suggests, however, that inflammatory cells do appear during early stages of amebic destructive lesions and that they contribute to the establishment of foci of tissue necrosis in intestinal and liver lesions. The present analysis of the fine-structural changes that take place during early stages of amebic liver abscesses induced in hamsters after the intraportal inoculation of axenic amebas has shown that large numbers of polymorphonuclear leukocytes (PMNs) are recruited around invading amebas. These leukocytes lyse as a consequence of contact-mediated damage induced by the trophozoites. Amebas were also capable of ingesting apparently intact PMNs. Macrophages and eosinophils were also recruited at the foci of inflammation. At all times examined, trophozoites of Entamoeba histolytica survived in spite of being in close contact with PMNs or degranulating eosinophils. The ultrastructural observations have also shown the lack of direct contact between amebas and liver parenchymal cells during the initial stages of the focal liver necrosis induced by the parasite, therefore supporting the view that hepatic damage may be effected indirectly through lysis of inflammatory cells. The results also provide a basis for the understanding of the induction of experimental protective immunity against invasive amebiasis, a process which seems to be mostly dependent on cellular mechanisms.     

Morphologic Variations in Periventricular Leukomalacia

Periventricular leukomalacia (PVL) usually is manifested as discrete foci of coagulation necrosis of the deep periventricular white matter in the human neonatal brain. During the examination of the brains of 116 infants utilizing an oil red O technic on gelatin-embedded frozen sections, 25 cases of PVL were found with typical foci of coagultion necrosis. Three morphologic varieties of the lesion could be demonstrated. In the first type, rather than being restricted to the periventricular zone, the discrete necrotic foci extended throughout the entire zone of cerebral white matter, even out to just beneath the cortex. The subcortical lesions appeared of short duration, whereas older lesions were always present nearer the ventricle. The second type of lesion presented as linear, some-what serpentine zones of coagulation necrosis radiating into the cerebral white matter. A third type of lesion consisted of a variegated irregular coagulation necrosis which was poorly delineated from more normal tissue. Diffuse pallor of the white matter, the nature of which is still not clear, was associted with the more severe lesions. Although the pathogenesis of PVL is unknown, it is suggested that these new varieties of PVL beyond the discrete periventricular foci of necrosis would be more apt to result in a diffuse loss of white matter and hence mental retardation if the child should survive.     

Multiple benign stromal cell tumours of the small bowel.

A rare case of multiple small intestinal stromal cell tumours is described in a 79 year old woman who presented with melaena and anaemia. At surgery, about 40 lesions were noted on the serosal surface of the small intestine, the largest of these tumours being located in the mid-jejunum. This lesion showed central necrosis and haemorrhage with a sinus opening into the jejunal lumen. Histological examination of this jejunal tumour showed epithelioid and spindle shaped cells. A smaller biopsied tumour was a pure spindle cell lesion. Both lesions fitted the criteria for benign stromal cell tumours. Although skenoid fibres were identified, the immunophenotype was characteristically heterogeneous. Multiple benign small intestinal tumours can raise the spectre of metastases when seen at surgery, although their presence in this case does not seem to indicate this.     

Identification of group 1 coronavirus antigen in multisystemic granulomatous lesions in ferrets (Mustela putorius furo)

Tissues from nine ferrets with granulomatous lesions similar to those seen in feline infectious peritonitis were examined histopathologically and immunohistochemically. Four main types of lesions were observed: diffuse granulomatous inflammation on serosal surfaces; granulomas with areas of necrosis; granulomas without necrosis; and granulomas with neutrophils. Other less commonly seen lesions were granulomatous necrotizing vasculitis and endogenous lipid pneumonia. FCV3-70 monoclonal antibody produced immunolabelling of group 1 coronavirus antigen in tissue samples from eight animals, the antigen being present in the cytoplasm of macrophages in the different types of granulomatous lesions.     

Increased expression of tumor necrosis factor-alpha in diabetic macrovasculopathy.

Large vessel disease, a common feature of diabetes mellitus, appears to run an aggressive course, but its cellular and molecular aspects remain partially elucidated. Although in common atherosclerosis and especially in other forms of accelerated vasculopathy, immunoinflammatory mechanisms participate in the disease process, it is unclear whether this is present in diabetic vasculopathy. We hypothesized that diabetic macrovasculopathy, compared with classical atherosclerosis, is associated with increased immunoinflammatory features and matrix accumulation. In this study, vessel segments obtained after lower-limb amputation for advanced atherosclerotic disease, from type 2 diabetic patients (n = 20; 68.9+/-10.9 years) and nondiabetic patients (n = 16; 67.1+/-14.6 years) were analyzed. Histological characteristics (extent of intimal proliferation, cellularity, and fibrosis) were semiquantitatively graded in the two lesion types. Using immunohistochemistry, the presence of T cells and macrophages, accumulation of fibronectin, and expression of tumor necrosis factor-alpha was also assessed. Histological features of these advanced atherosclerotic lesions were similar in the two lesions examined. By immunohistochemistry, a similar pattern of T-cell and macrophage infiltration and fibronectin accumulation was observed. Nevertheless, increased expression of tumor necrosis factor-alpha was observed in diabetic lesions (13/19 patients had positive staining), whereas only 2 of 16 lesions from nondiabetic patients had positive staining (p < 0.003), with an odds ratio of 15.17 (confidence interval 2.12-139.5). These data suggest that increased expression of tumor necrosis factor-alpha observed in the diabetic lesions may reflect an enhanced inflammatory activity associated with the development of vascular lesions in type 2 diabetic patients.     

Allylamine Cardiotoxicity: II. Histopathology and Histochemistry

The progression of cardiac lesions induced in the rat by allylamine administration (0.1% in drinking water) was studied histopathologically and histochemically. Early changes (4-8 days) consisted of piecemeal acute apical and subendocardial myocardial necrosis with morphologic features of coagulation necrosis and myocytolysis. These early lesions progressed and coalesced; resolution of the subendocardial necrosis was associated with remarkably proliferative fibroblastic tissus. Late lesions (21 days to 3 months) consisted of extensive dense fibrous tissue with adjacent continuing focal necrosis and organization. Although vascular alterations were not present during the early course of injury, after 21 days an exuberant proliferation of cells, predominantly within the intima of intramyocardial smaller arteries and not associated with total occlusion or thrombosis, became evident. Other late lesions included rare intraventricular mural thrombi and cartilagenous metaplasia of trabeculae carnae. Early histochemical alterations (3 days) included focal myocardial cell “calcification,” demonstrated by the alizarin red S stain, and increased monoamine oxidase (MAO) staining in apical subendocardium and periarterial myocytes. As necrosis continued and fibrosis developed (7-21 days) MAO dramatically increased in pericicatricial and periarterial cells. Biochemical measurement of myocardial MAO showed an initial drop in activity, followed by a steady rise to high activity (21 days), especially toward a Type “B” MAO substrate. Although there are many similarities between allylamine-induced myocardial necrosis and ischemic or catecholamine-induced myocardial damage, other unusual findings—especially the early histochemical and chemical MAO alterations and the proliferative late vascular and cicatricial lesions—suggest that the primary pathophysiologic effect of allylamine, mediated through the MAO system, is on the medial smooth muscle of intramyocardial arteries.     

Foreign serum-induced pancreatitis in mice. I. A new model of acute pancreatitis.

Within a few hours after one injection of fresh human serum by the intraperitoneal route only, mice developed pancreatic acinar cell necrosis and inflammation, fat necrosis, elevated serum amylase and a shocklike state. The extent of these lesions and mortalities were roughly dose dependent and were not noticeably modified by either different fasting cycles or pilocarpine. Acinar cell changes and necrosis usually developed first in subserosal acini. The earliest ultrastructural change detected was nonspecific swelling of cytoplasmic compartments which was reversible but also preceded the cytoplasmic degradation that developed in cells undergoing necrosis. Notably, zymogen granule dissolution neither preceded nor accompanied this swelling, but developed pari passu with cell degradation. Occasionally, intact granules were found in necrotic cells. Serum was cytotoxic for isolated acinar cells in vitro, even in the presence of soybean trypsin inhibitor. These results (1) indicate that the injury mechanism in vivo is directly initiated through contact of serum with acinar cell surfaces and is independent of zymogen secretions and trypsin activation, and (2) suggest that a rapid disturbance in cell membrane permeability results, the magnitude of which being the primary determinant of cell death. Pancreatic toxicity of human serum was abolished by aging, heating, ethylenediaminetetraacetic acid, heparin, zymosan, cobra venom factor, and absorptions with mouse red blood cells, against which fresh, unabsorbed serum was hemolytic. Pancreatic toxicity in vitro and, to a much lesser extent, in vivo was reconstituted by combining the red blood cell-absorbed serum with either heated serum, or with IgM-enriched, but not IgG serum fractions. Fresh cord serum was virtually nontoxic and could substitute for absorbed serum in such reconstitutions. These results indicate that the injury mechanism involves at least two serum components. By both circumstance and analogy, other results and a review of other examples of foreign sera toxicity suggest that they are components of a complement-dependent, cytotoxic heterophile antibody system. The relevance of this odd phenomenon is that it offers a simple model of acute pancreatitis, contributes to the debunking of traditional notions of the pivotal role of zymogens in the initiation of acute pancreatitis, and hints at a potential pathogenetic connection between pancreatitis and products of immune or related reactions.     

Caseous necrosis in cutaneous leishmaniasis.

A case of late stage cutaneous leishmaniasis with focal caseous necrosis is reported. The patient, a 30 year old Tunisian man, presented with idiopathic bone marrow aplasia. Microscopically, minimal changes were observed in the epidermis: slight hyperkeratosis and moderate acanthosis. Lesions predominated in the dermis. Epithelioid granulomas were found in the lower dermis. Some of these lesions were clearly surrounded by a ring of lymphocytes and were rarely confluent. A peculiar histological feature was the presence of focal acidophilic and slightly granular necrosis at the centre of some the tuberculoid lesions. Focal fibrinoid necrosis was found in the upper dermis, outside granulomas. A mild to moderate infiltrate of histiocytes, lymphocytes and plasma cells, with scanty neutrophils, was observed mainly in the upper dermis. No intracellular or extracellular Leishman-Donovan bodies were observed. Acid fast mycobacteria, however, were not detected. Leishmaniasis was diagnosed on culture of skin biopsy specimens. The presence of caseous necrosis could lead to diagnostic confusion and result in an erroneous diagnosis of, for example, tuberculosis, syphilis, acne agminata, and sarcoidosis with fibrinoid necrosis. This is especially the case when parasites are scanty or absent.     

The pathogenesis of small arterial lesions in nephrectomized rats by the administration of renin.

Intraperitoneal injection of purified hog renal renin produced a marked and sustained elevation of arterial pressure and lesions of the "fibrinoid necrosis" type in the small arteries and arterioles of the pancreas, heart and mesentery, but not of the brain, in bilaterally nephrectomized rats. Both the elevation of arterial pressure and the production of arterial lesions were completely prevented by pretreatment with oral SQ14225. Plasma renin clearance in bilaterally nephrectomized rats was markedly slower than that in sham-nephrectomized rats. Pre-treatment with oral SQ14225 did not affect renin clearance. It is suggested that sustained high blood pressure due to the sustained high plasma renin concentration in bilaterally nephrectomized rat was responsible for the production by renin of lesions of the fibrinoid necrosis type in the arteries.     

The development of Lewisite vapour induced lesions in the domestic, white pig.

Studies performed in the past in our laboratory have detailed the development of sulphur mustard lesions in the domestic, white pig using small glass chambers to achieve saturated vapour exposure under occluded conditions. We have now used this experimental model to produce cutaneous lesions for detailed histopathological studies following challenge with lewisite. Histological examination of resulting lesions have revealed that although the overall pattern of lesion development is similar to that seen following mustard challenge, the time-course of cellular events is very much compressed. The epidermis showed focal basal cell vacuolation with associated acute inflammation as early as one hour postexposure. Coagulative necrosis of the epidermis and papillary dermis was complete by 24 hours and followed the appearance of multiple coalescent blisters between six and 12 hours post-exposure. At 48 hours, the lesions were full thickness burns with necrosis extending into the deep subcutaneous connective and adipose tissues. The study of lesions beyond 24 hours revealed early epithelial regeneration at the wound edge. The overall spontaneous healing rate of these biologically severe lesions was significantly faster than comparable sulphur mustard injuries and probably reflected a lack of alkylation of DNA and RNA.     

Immunoreactive copper-zinc superoxide dismutase in damaged human myocardium.

The myocardium in 50 autopsy cases was studied using immunostaining for copper-zinc superoxide dismutase (CuZn-SOD) and standard histochemical procedures. Mucinous degeneration observed in 42 cases showed moderately enhanced expression of immunoreactive CuZn-SOD in lesions which were stained strongly by periodic acid-Schiff but negative with Heidenhain iron-hematoxylin (HIH), von Kossa and luxol fast blue (LFB) stains, whereas coagulation necrosis in 4 cases revealed almost identical immunostaining for CuZn-SOD and HIH to that of contraction band necrosis, i.e. strongly positive HIH staining but negative immunostaining. Basophilic alteration of the myocardial cells in sections fixed with 4% formalin in 2% calcium acetate was seen in 29 cases, being identified frequently in isolated cells as well as in several foci varying considerably in size. This type of alteration demonstrated significantly enhanced expression of immunoreactive CuZn-SOD and was strongly positive with von Kossa and LFB stains. The present study indicates that the myocardium can be affected by free radicals produced in any organ of the body, and that subsequently, insoluble phospholipids react with calcium ions in the fixative and accumulate in the basophilic sarcoplasm.     

The induction of renal papillary necrosis in Gunn rats by analgesics and analgesic mixtures.

Homozygous members of the mutant Gunn strain of Wistar rats genetically lack the enzyme uridine diphosphate glucuronyl transferase. "High" and "low" dose gavage feeding for 18-34 days of an analgesic mixture containing aspirin, phenacetin and caffeine (APC) confirmed the previously reported susceptibility of these animals to analgesic induced renal papillary necrosis. Heterozygotes do not share the gross enzyme deficiency of homozygotes and, when treated with APC under identical conditions, failed to develop renal papillary necrosis. Groups of homozygotes were dosed by gavage with aspirin, phenacetin and paracetamol for 4 weeks. Renal papillary necrosis was produced by all 3 drugs, the lowest frequency of lesions occurring with phenacetin. It is postulated that the enzyme deficiency of homozygous Gunn rats influences the metabolism of analgesics to favour the excretion of nephrotoxic metabolites. The renal papillary necrosis appearing in these experiments is essentially an acute lesion, differing both in natural history and morphology from the renal papillary necrosis of analgesic nephropathy, suggesting that the pathogeneses of the experimental and human lesions differ.     

Arterial wall lesions after pulmonary embolism, especially ruptures and aneurysms.

During an histological study of pulmonary thromboembolism, arterial wall splits, many associated with saccular microaneurysms, were observed in association with emboli or their fibrous residue. Other aneurysmal lesions, non-inflammatory focal medial necrosis, and medial scars were also seen in a few cases. The nature of the arterial rents indicates that they arose by mechanical splitting after acute stretching of the artery at the time of embolic impaction. Saccular aneurysms then developed in some. Impaction could also have caused the foci of medial necrosis while the medial scars could represent healed former necrosis of rupture. Though the observed incidence of lesions was relatively low, this seems to be due to their small sizes and the sampling inherent in conventional histological analysis. It is concluded that arterial splits are probably a common effect of pulmonary embolism and often give rise to small aneurysms.     

Population dynamics of arterial smooth muscle cells. V. Cell proliferation and cell death during initial 3 months in atherosclerotic lesions induced in swine by hypercholesterolemic diet and intimal trauma.

The sine qua non of the lesion of atherosclerosis in man and experimental animals is excessive focal accumulation of modified smooth muscle cells in the intima of arteries. In advanced stages extensive necrosis with accumulation of lipid-rich debris is a prominent feature. In swine fed hypercholesterolemic (HC) diets focal atherosclerotic lesions are produced, but they progress slowly and do not develop frank necrosis until they have been on HC diet for many months or even years. The atherosclerotic process can be greatly accelerated by traumatizing the arterial intima with a ballon-catheter in addition to feeding the HC diet. Within a few months thick atherosclerotic lesions with extensive necrosis and calcification can be produced. In regard to arterial cell population dynamics, we showed in the first part of the current study that under the specified experimental conditions, lesions produced in young swine by balloon-catheter trauma and HC diet have at least four features in common with lesions produced in young swine by HC diet alone. (1) Multiple cells are involved in the initiation of the lesions (i.e., they are not monoclonal in origin). (2) The cells do not divide in a completely random fashion. (3) The division pattern is consistent with polyclonal origin with considerable heterogeneity as regards growth rate. (4) Most and perhaps all lesion cells were in the dividing population during the periods that were studied. The differences observed between development of lesions produced by HC diet alone and those produced by HC diet plus ballon-catheter intimal trauma were quantitative and not qualitative, i.e., the lesions produced by the latter procedure had a greater rate of cell multiplication and proceeded more rapidly to the necrotic stage than did those produced by HC diet alone.In the second part of the current study, we have devised a method for calculating cell deaths in the atherosclerotic lesions produced by HC diet plus intimal trauma. In the period 60–97 days on HC diet which was studied we found that circa 40% of the lesion cells died during the perireplicative and/or perimitotic period of the cell cycle. The high cell death rate was offset in part by a high cell birth rate. As indicated by tritiated thymidine (³HTdR) labeling indices, approximately four times as many cells were synthesizing DNA at the time of observation as in the adjacent normal appearing media. Obviously the rate of growth of the atherosclerotic lesions that were studied was determined by the balance between excessive cell birth and death rates.     

Histological studies of surgically resected hepatocellular carcinoma following combined radiotherapy and hyperthermia.

Four cases of hepatocellular carcinoma (HCC) were surgically resected following combined radiotherapy (RT) and hyperthermia (HT). Complete necrosis of the tumor without viable tumor cell was found in one case and extensive tumor necrosis was observed in the other three cases; the percentage of necrosis in the specimens were 40%, 70%, and 80%, respectively. Histologic assessment showed mainly coagulative necrosis in the tumor with focal liquefactive necrosis. Cystic dilatation of sinusoids was observed in both tumor and nontumorous normal liver tissue. Other changes in normal liver tissue were unremarkable except for infiltration of inflammatory cells, fatty change, and proliferation of the bile ducts which can usually be seen beyond the area where any space occupying lesions are present. It is concluded that combined radiotherapy and hyperthermia can significantly induce coagulative necrosis of hepatocellular carcinoma with nonsignificant minimal histologic changes in adjacent nontumorous liver tissue.     

Ceroid granulomas in the female genital system.

Three cases of ceroid granulomas of the female genital system are presented, involving the cervix in two and lesions in the ovaries and bowel serosa in the other. Ceroid granulomas are unusual and interesting lesions formed when suitable substrates accumulate within macrophages to such an extent that a relative lack of biological antioxidants results and auto-oxidation and conversion to ceroid is favoured. This may occur in the setting of haemorrhage and necrosis, whether from tumour necrosis or associated with endometriosis. Other sources of lipids and lipoproteins include bile, meconium and vernix caseosa.     

Transmissible ileal hyperplasia of hamsters. I. Histogenesis and immunocytochemistry.

Transmissible ileal hyperplasia (TIH) was experimentally induced in weanling hamsters, and the development of lesions was characterized. Ileal lesions developed in two phases: a hyperplastic phase which was detected by Day 10 and an inflammatory phase which began by Day 20. Hyperplasia began as focal lengthening of villi with expansion of crypt-type epithelium onto villus walls. Diffuse hyperplasia of distal ileum developed; dilated, tortuous crypts penetrated subjacent supporting tissues; but metastases were not seen. Inflammation began in association with focal or segmental necrosis of crypt epithelium, and crypt abscesses developed. Severe pyogranulomatous inflammation of the ileal wall, focal peritonitis, mesenteric lymphadenitis, and portal hepatitis were common in advanced lesions. Development of ileal lesions was closely correlated with accumulation of particulate antigen, detectable by immunofluorescence, in the cytoplasm of mucosal epithelial cells. Antigen was also detected in ileal granulomas, mesenteric lymph nodes, and liver. There was simultaneous development of serum antibody specific for intracytoplasmic antigen. These studies comfirm that mucosal hyperplasia is the primary lesion in TIH.