Necrotic Debris In Thyroid Aspirates: A Feature of Follicular Carcinoma of the Thyroid

Fine needle aspirates from 44 follicular thyroid tumours (30 adenomas, 14 carcinomas) have been studied. All aspirates contained neoplastic cells in follicular and trabecular arrangements. The individual tumour cells showed varying degrees of anisonucleosis and nuclear pleomorphism. Colloid was scanty or absent from all smears. Granular or filamentous necrotic material was observed in both biopsies and smears from one moderately and two poorly differentiated follicular carcinomas, but in none of the adenomas. This suggests that necrotic debris may be a feature of follicular carcinoma of the thyroid.     

The role of macrophages in the early resistance to mouse hepatitus virus infection in nude mice.

Nude mice which had received intraperitoneal injection of silica simultaneously with infection of mouse hepatitis virus, NuU strain, died of severe necrotic hepatitis within 2 weeks postinfection, whereas those having received no silica survived for 3 weeks or more after challenge. Silica given day 4 postinoculation had no effect. The virus titers of the liver and spleen at day 4 as well as serum interferon levels at day 2 were much higher in silica-treated mice than those without silica treatment. At day 2 or 3 postinoculation, silica-treated mice were found to have a considerable number of necrotic foci in the liver with some neutrophil and lymphocyte infiltration, and viral antigen was present in the cytoplasm of some hepatocytes around necrotic foci. In contrast, those without silica treatment showed only some necrotic foci with some lymphocyte infiltration. Viral antigen was detected only in a few littoral cells but not in hepatocytes. The role of macrophages in the resistance at early stage of inection in nude mice is discussed.     

Enterohepatitis in Mongolian gerbils (Meriones unguiculatus) inoculated perorally with Tyzzer's organism (Bacillus piliformis)

Enterohepatitis was produced in Mongolian gerbils by intragastric inoculation with Tyzzer's organism from natural infection of a gerbil. Death occurred in 50 to 60% animals 5 to 7 days postinoculation (p.i.). On day 3 p.i., when a few necrotic foci appeared in the liver, a large amount of bacterial antigen was present within ileocecal enterocytes and reticuloendothelial cells of the Peyer's patches. Neutrophil and monocyte infiltration was found in the lamina propria. On day 5 or 6 p.i. there was severe necrotizing and hemorrhagic ileotyphlocolitis. Bacterial antigen was abundant within not only enterocytes, but also smooth muscle cells of the ileum and jejunum as well as reticular cells of the mesenteric lymph nodes. On day 7 p.i. the intestinal lesions subsided in the presence of fewer bacteria, while necrotizing hepatitis became well developed. The results indicated that Mongolian gerbils were highly susceptible to the oral route of infection with the Tyzzer's organism.     

Expression of CD15 in tumours of the nervous system

Summary The expression of the CD15 epitope was investigated by immunohistochemistry, western blotting and immuno-thin-layer chromatography on a large series of human nervous system tumours and ethylnitrosourea-induced rat gliomas. Our results show that CD15 is expressed as a glycoprotein- or glycolipid-associated epitope in normal human and rat brain. In contrast, immunoreactivity for CD15 was absent in tumour cells of experimental rat gliomas. In human tumours we found a more complex expression pattern. While intra- and perivascular granulocytes as well as macrophages in necrotic areas of anaplastic tumours were always strongly CD15-positive, immunoreactive tumour cells were detectable only in a fraction of low-grade gliomas. Anaplastic gliomas and glioblastomas consistently did not express the epitope on their tumour cells. In addition to individual low-grade gliomas, we found CD15-positive cases among metastatic carcinomas, craniopharyngeomas, meningiomas, germinomas and malignant melanomas. Our results suggest that immunohistochemistry for CD15 is potentially useful in diagnostic neuropathology as a marker for granulocytes in paraffin sections, as a supplementary tool for the histopathological grading of gliomas, and as an aid for differentiation between anaplastic glioma cells and non-neoplastic glia. Furthermore, it can be speculated that the lack of CD15 expression on anaplastic glioma cells may potentially be responsible for some of their characteristics-such as altered cellular interaction and loss of contact inhibition.     

Hyperplasia of elastic tissue in hepatic schistosomal fibrosis.

Elastic tissue hyperplasia, revealed by means of histological, immunocytochemical and ultra-structural methods, appeared as a prominent change in surgical liver biopsies taken from 61 patients with schistosomal periportal and septal fibrosis. Such hyperplasia was absent in experimental murine schistosomiasis, including mice with "pipe-stem" fibrosis. Displaced connective tissue cells in periportal areas, such as smooth muscle cells, more frequently observed in human material, could be the site of excessive elastin synthesis, and could explain the differences observed in human and experimental materials. Elastic tissue, sometimes represented by its microfibrillar components, also appeared to be more condensed in areas of matrix (collagen) degradation, suggesting a participation of this tissue in the remodelling of the extracellular matrix. By its rectratile properties elastic tissue hyperplasia in hepatic schistosomiasis can cause vascular narrowing and thus play a role in the pathogenesis of portal hypertension.     

Levels of selected growth factors in viable and necrotic regions of xenografted HCT-8 human colon tumours

Xenografted tumours were produced in nude mice by injection of HCT-8 human colon tumour cells. At average volumes of about 750 mm³, animals were injected with fast green vital dye, and 20 min later, tumours were excised and dissected into viable (stained) and necrotic portions (unstained). Viable and necrotic regions were then examined for cell yields, colony forming efficiencies, and levels of basic fibroblast growth factor (FGF-2), transforming growth factors-β₁ and -α (TGF-β₁, TGF-α), platelet derived growth factor (PDGF), and vascular endothelial growth factor (VEGF) using enzyme-linked immunoassay (ELISA) procedures. Levels in the viable and necrotic regions were compared to levels in unseparated tumours. The average extent of necrosis in HCT-8 tumours of this size was 64%. The data for cell yields, colony forming efficiencies FGF-2, VEGF, TGF-β₁ and TGF-α indicated that values determined in the unseparated tumours could be understood on the basis of the weighted average between viable and necrotic tissue, with the higher values occurring in the viable tissue. Low levels of FGF-2 and VEGF were found in the necrotic portions of the tumour while no measurable levels of TGF-β₁ and TGF-α could be determined. PDGF levels were, however, equivalent in both the viable and necrotic regions indicating that necrotic tissue could be an important reservoir for this growth factor.     

Apoptosis of phagocytes as one of the probable mechanisms of the pathogenetic action of Yersinia pestis "mouse" toxin

Apoptosis was evaluated by characteristic morphological changes of cells in preparations stained with histological dyes and in live preparations, as well as by DNA degradation, colorimetrically detected with the use of the diphenylamine reagent. "Mouse toxin" (MT) was found to have a pronounced apoptogenic action with respect to the phagocytic cells of mice, but not guinea pigs. Macrophages were affected by this action stronger than neutrophils, and in both cases this effect was dose dependent. As the dose of MT decreased to 0.01 microg/ml, the proportion of cells dying as the result of apoptosis increased, the necrotic type of damage was almost absent. On the contrary, as MT concentration rose to 1.0 microg/ml and over, the proportion of phagocytes dying due to necrosis increased with a decrease in the number of cells in which the process of apoptosis started. The results of the study are indicative of the fact that the mechanisms programming the death of cells under the action of MT on macrophages and neutrophils took part in the process, which, in its turn, determined their role in the pathogenesis of plague.     

An outbreak of "wet tail" in hamsters due to Tyzzer's organism (author's transl)

In a colony of Golden hamsters, many animals were found to show signs of "wet tail", and spontaneous deaths occurred during two months. With this outbreak of wet tail and death, etiologic and pathologic studies were made on 11 cases supplied from the colony. Gross pathologic examination disclosed hemorrhagic enteritis in 10 and necrotic foci in the liver in 5 out of 10 cases examined. A number of bacilli morphologically suggestive of Tyzzer's organisms were detected on smears of cut surfaces of the affected intestines and livers. After inoculation with homogenate of the intestines from the moribund cases into hamsters by oral route, the same clinical manifestations as observed in spontaneous cases were reproduced, and the inoculated animals died in 10 to 14 days with numerous Tyzzer's organisms in their intestines and livers. When apparently healthy hamsters were introduced into contaminated cages with soiled bedding which were allowed to stand at room temperature for about 2 months, most of them developed signs of wet tail and died in 5 to 19 days having liver necrosis characteristic of Tyzzer's disease.     

The thermal activity of the rabbit brain during the interaction of "animal hypnosis" and of the hunger dominant]

The character of interaction between two dominant foci (motivation hunger dominant and "animal hypnosis") which had been formed in the rabbit brain was ambiguous: the foci could either function simultaneously or compete. In the first case, summation food reactions were observed when the hunger dominant was tested during a hypnotic episode against the background of deep and continuous hypnotic state. Brain thermal activity was asymmetric the temperature being higher in the parieto-occipital areas of the left hemisphere. If the hypnosis inhibited the hunger dominant, summation reactions were absent and the brain temperature was higher in the parieto-occipital areas of the right hemisphere. In cases when despite the repeated immobilization sessions the hunger dominant prevented from induction of hypnosis, the left-hemisphere thermal dominance persisted against the background of general brain cooling.     

Mechanisms for virus-induced liver disease: tumor necrosis factor-mediated pathology independent of natural killer and T cells during murine cytomegalovirus infection.

The contribution of endogenous NK cells and cytokines to virus-induced liver pathology was evaluated during murine cytomegalovirus infections of mice. In immunocompetent C57BL/6 mice, the virus induced a self-limited liver disease characterized by hepatitis, with focal inflammation, and large grossly visible subcapsular necrotic foci. The inflammatory foci were most numerous and contained the greatest number of cells 3 days after infection; they colocalized with areas of viral antigen expression. The largest number of necrotic foci was found 2 days after infection. Overall hepatic damage, assessed as increased expression of liver enzymes in serum, accompanied the development of inflammatory and necrotic foci. Experiments with neutralizing antibodies demonstrated that although virus-induced tumor necrosis factor (TNF) can have antiviral effects, it also mediated significant liver pathology. TNF was required for development of hepatic necrotic foci and increased levels of liver enzymes in serum but not for increased numbers of inflammatory foci. The necrotic foci and liver enzyme indications of pathology occurred independently of NK and T cells, because mice rendered NK-cell deficient by treatment with antibodies, T- and B-cell-deficient Rag-/- mice, and NK- and T-cell-deficient E26 mice all manifested both parameters of disease. Development of necrotic foci and maximally increased levels of liver enzymes in serum also were TNF dependent in NK-cell-deficient mice. Moreover, in the immunodeficient E26 mice, virus-induced liver disease was progressive, with eventual death of the host, and neutralization of TNF significantly increased longevity. These results establish conditions separating hepatitis from significant liver damage and demonstrate a cytokine-mediated component to viral pathogenesis.     

Fine needle aspiration (FNA)-induced necrosis of tumours of the thyroid

Two cases of necrosis of thyroid oxyphilic tumours following FNA are reported. the first patient received surgery 4 weeks after FNA and histological examination revealed an encapsulated and totally necrotic tumour 2 cm in diameter. In the second patient surgery was performed after 25 days. Histological examination showed a 0.7 cm diameter tumour consisting mainly of fibrous tissue with residual oxyphilic tumour cells only in a small peripheral rim. In both patients no capsular or vascular invasion and no blood vessel thrombosis were present. A review of the literature revealed that oxyphilic tumours are susceptible to post-FNA necrosis, which might be due to the compromised vascular supply after FNA in conjunction with the intrinsic energy deficiency of oncocytic tumour cells.     

Morphopathological findings in dog's acute toxoplasmosis

Toxoplasmosis was clinically diagnosed in two dogs of 4 and respectively 18 months. A seven-day treatment remained inefficient and the animals died. Autopsy revealed a global inflammation of the lung, with necrotic lesions of bronchial lymph nodes and acute hyperplastic reaction of the spleen. Histologically, there were identified a diffuse, serofibrinous inflammation of the lung with necrotic foci, fibrinoleucocytic and necrotic exudate of bronchial and portal lymph nodes, small necrotic or fibrinonecrotic foci of the liver and spleen, lymphoglial foci and edema at the base of the cerebellum. In myocardium, as well as in the above mentioned organs, toxoplamas are free or accumulated in cysts. Inoculation of infected lung material into mice and newborn dogs gave positive results.     

Ultrastructure of cardiocyte degeneration and myocardial calcification in the dystrophic hamster

The myocardium of the Bio 14.6 cardiomyopathic hamster was examined with the electron microscope to identify cellular and organelle changes during the acute lesioning stage, a period typified by concomitant cardiocyte destruction and calcium elevation. Most cardiocytes retained their normal histologic and ultrastructural features, but scattered foci of altered and necrotic cells were observed in association with degenerative calcifying lesions. Prenecrotic alterations of myocytes included cellular edema; varying degrees of distension of sarcoplasmic reticulum and T-tubules; contraction bands and other myofibrillar abnormalities; mitochondrial clustering and hyperplasia; a wide spectrum of mitochondrial changes such as altered sizes, shapes, and cristal patterns, and increases in the number and size of osmiophilic matrix inclusions. Morphologic features consistent with substantial calcium excess were not observed in most altered but prenecrotic cells. Instead, calcium deposition within extruded mitochondria and upon degenerating organelle debris was observed only after cardiocyte disruption. Some calcifying cell remnants were phagocytized by macrophages, whereas large calcified plaques and other deposits remained in the interstitium. Mitochondrial calcification in vascular smooth muscle cells and fibroblasts was evident in highly calcified lesions. These observations suggest that most of the morphologically identifiable calcium deposition present in this cardiomyopathy results from secondary calcification subsequent to sarcolemmal disruption.     

Induction of chick embryo feather malformations by an influenza C virus

The effect of influenza C virus, strain JJ/50, on the development of chicken embryos infected at 10 or 12 days was documented by microscopic techniques, as well as by gross observations of embryos or chicks at hatching. The infected, newly hatched chicks displayed marked abnormalities in their feathering. Such abnormalities were observed neither in mock-infected embryos nor in embryos injected with virus which had been previously treated with specific influenza C virus antibody. At a microscopic level, the abnormalities apparently are a result of hypertrophy and/or hyperplasia of the developing barb and barbule cells. Further, the additional development of integumental necrotic foci was correlated with the development of relatively high viral titers (greater than 256) as measured by hemagglutination (HA). Embryos infected after 12 instead of 10 days incubation showed normal feathering at hatching. Infection at 12 days, however, was correlated with the development of relatively low viral titers (HA = 4) and limited degeneration of the respiratory epithelium. The relationship of teratogenic effects to the site of viral replication in rapidly differentiating tissue is discussed.     

In vivo labelling with halogenated pyrimidines of squamous cell carcinomas and adjacent non-involved mucosa of head and neck region

The frequency and distribution of labelled cells were studied immunohistochemically in 37 squamous cell carcinomas (SCC) of head and neck after in vivo infusion of IdUrd and BrdUrd. Tumours were classified according to their labelling patterns. Low and moderate grade SCC consisted of tumour islands separated by interstitial tissue. In some tumours labelled cells only appeared near the basal layer while in others proliferative cells were evenly distributed within the neoplastic island. In anaplastic carcinomas labelled cells were distributed either randomly or around blood vessels (cord structures). While the basal layer in adjacent normal epithelium contained very few labelled cells (LI = 1.6 ± 0.2%), the LI of basal cells in tumour islands were much higher than the average LI of the tumour (47.2 ± 2.8% and 23.8 ± 1.6%, respectively). In patients who had received cytotoxic therapy up to two months before the biopsy, the LI in the basal layer of normal epithelium was 19.0 ± 3.5%. In sequential biopsies obtained 1–2 weeks after the infusion of IdUrd and BrdUrd some labelled tumour cells were found in necrotic foci and in pearl structures. Additionally, in six tumours, we found areas of cells labelled with IdUrd alone, even though the IdUrd infusion had been followed by a BrdUrd infusion 1 h later. This is in agreement with the phenomenon of intermittent tumour blood flow described earlier in experimental tumours.     

Cell kinetics of hypoxic cells in a murine tumour in vivo: flow cytometric determination of the radiation-induced blockage of cell cycle progression

Cells from the small cell population of viable cells in the large necrotic centre of murine M8013 tumours were investigated with respect to their cell kinetics. Flow cytometry (FCM) of this part of subcutaneously transplanted tumours revealed the presence of tumour cells with G1, S and G2 + M phase DNA-contents. These severely hypoxic cells could have stopped cell cycle progression due to the nutritional deprivation, irrespective of their position within the cell cycle. Labelling methods, used to disclose the cell kinetics of this cell population, are hampered by the absence of a transport system in these large necrotic areas. Therefore, FCM was used to monitor radiation-induced changes in the cell cycle distribution. From this investigation it was concluded that hypoxic cells in the necrotic centre of the M8013 tumour progress through the cell cycle. As well as a cell population with a cell cycle time (Tc) of approximately 84 hr, a subpopulation with a Tc of approximately 21 hr occurred.     

"Vulnerable plaques"--ticking of the time bomb

Atherosclerosis and its sequelae are one of the leading causes of morbidity and mortality, especially in the developed nations. Over the years, treatment protocols have changed with the changing understanding of the disease process. Inflammatory mechanisms have emerged as key players in the formation of the atherosclerotic plaque. For the majority of its life span, the plaque develops silently and only some exhibit overt clinical manifestations. The purpose of this review is to examine the inherent properties of some of these "vulnerable" or symptomatic plaques. Rupture of the plaque is related to the thickness of the fibrous cap overlying the necrotic lipid core. A thin cap is more likely to lead to rupture. Multiple factors broadly grouped as the "determinants of vulnerability" are responsible for directly or indirectly influencing the plaque dynamics. Apoptosis is considered an important underlying mechanism that contributes to plaque instability. Inflammatory reactions within the plaque trigger apoptosis by cell-cell contact and intra cellular death signaling. Once started, the apoptotic process affects all of the components that make up the plaque, including vascular smooth muscle cells, endothelial cells, and macrophages. Extensive research has identified many of the key cellular and molecular regulators that play a part in apoptosis within the atherosclerotic lesion. This information will help us to gain a better understanding of the underlying mechanisms at the cellular and molecular level and enable us to formulate better therapeutic strategies to combat this disease.     

Effect of strain-specific hypersensitive resistance on spatial patterns of virus spread

Spatial patterns of spread were compared between strains of Bean yellow mosaic virus (BYMV) that differ in causing systemic necrotic (hypersensitive) or non‐necrotic symptoms in narrow‐leafed lupin (Lupinus angustifolius). Both types of BYMV were spread naturally by aphids from adjacent infected pasture into a large lupin block (‘natural spread site’), or from clover plants introduced as virus sources into two field experiments with lupin. Cumulative spatial data for plants with disease symptoms from a range of times in the growing period were assessed using Spatial Analysis by Distance IndicEs (SADIE). At the‘natural spread site’, with non‐necrotic BYMV, the extent of clustering of plants with symptoms increased gradually over time, while with necrotic BYMV there was less clustering and no increase over time. In both experiments, for the type of BYMV that was introduced into a plot, there was a gradual increase in clustering, but with this being greater with non‐necrotic BYMV. In the second experiment, there was also significant clustering of plants with symptoms of non‐necrotic BYMV in plots without introduced non‐necrotic foci but not for necrotic BYMV in plots without introduced necrotic foci. When clustering data for plants with newly recorded symptoms was tested for spatial association between successive assessment dates, association was positive for both BYMV types though stronger for the non‐necrotic type, declining as the temporal lag increased. Generally, association was strongest for assessments 2–3 wk apart, corresponding approximately to the period for BYMV to move systemically in plants and for obvious symptoms to appear in shoot tips. Contour maps for local association between dates showed that the strongest spatial associations were from coincidence of infection gaps rather than infection patches. The combination of information from clustering and association analysis showed that spread of non‐necrotic BYMV is less diffuse, with considerably more localised infection surrounding the infection sources. This work demonstrates how spatial virus spread can be diminished when hypersensitive (necrotic) resistance is deployed, and the limitations associated with employing hypersensitivity that is strain specific.     

The use of clostridial spores for cancer treatment

Hypoxic/necrotic regions, absent in normal tissues, can be exploited to target tumours in cancer therapy using nonpathogenic strains of the bacterial genus Clostridium. Following administration of Clostridium spores to tumour-bearing organisms, these spores can only germinate within the hypoxic/necrotic regions of solid tumours, proving their exquisite selectivity. Low oxygen tension is a common feature of solid tumours, which may arise from the unique physiological environment, generated to a large extent by the abnormal tumour vasculature, and provides as such a niche for anaerobic bacteria. Some clostridia tested clearly showed innate oncolytic activity, but they could not completely eradicate the tumour. Recombinant clostridia producing prodrug-converting enzymes or cytokines resulted in the production of such proteins solely within the tumour, and where applicable, could convert the prodrug in a toxic compound. Moreover, in some cases, tumour eradication or tumour control could be observed. This review brings an overview of the relative successes and failures of the Clostridium-directed tumour therapy with both wild-type strains and strains producing proteins useful in antitumour therapy.