[Analysis of the TNF receptor in KYM cells by affinity cross-linking]

We investigated the identity of the TNF receptor on the KYM cell membrane by cross-linking 125I-TNF and the presumed receptor site with DSS, and subjecting the TNF-receptor complex to electrophoresis. Four specific bands were observed at 145 K, 50 K, 35 K, and 17 K, and those at 50 K, 35 K and 17 K being consistent with trimers, dimers and monomers of TNF, respectively. The 145 K band disappeared after addition of excess unlabelled TNF or anti-human recombinant TNF monoclonal antibody (IV3-E), which quenched the cytotoxic activity of TNF and inhibited the TNF binding to the receptor. The molecular weight of native TNF as estimated by gel filtration was 45 K and this observation showed that native TNF existed only as the TNF trimer. These results confirmed that 95K, i.e., the difference between 145 K and 50 K, is the molecular size of the TNF receptor.

Epithelioid sarcoma and isolated necrobiotic granuloma: a comparative immunocytochemical study

Epithelioid sarcoma (ES) occasionally may be confused, both clinically and histologically, with isolated necrobiotic granulomas (ING), leading to misdiagnosis and potential mismanagement of these conditions. We studied 11 cases of ES and 11 of ING (6 examples of deep granuloma annulare and 5 of rheumatoid nodule) immunohistochemically, in an attempt to determine whether they could be diagnostically separated by such means. Monoclonal antibodies to cytokeratin polypeptides (CK), epithelial membrane antigen (EMA), and leukocyte common antigen (LCA) were applied to formalin-fixed, paraffin-embedded sections in each case, using the avidin-biotin-peroxidase complex technique. All ES cases stained positively for CK, and 6 expressed EMA, while examples of ING were non-reactive for these antigens. Conversely, the large epithelioid histiocytic cells in cases of ING were immunoreactive with anti-LCA, whereas no case of ES displayed this determinant in tumor cells. In the latter lesions, reactive peritumoral inflammatory cells were LCA-positive, but were readily distinguished from neoplastic cells on morphological grounds, as well as by their negativity with anti-CK and anti-EMA. Based on these data, it is concluded that immunohistologic stains for epithelial and hematopoietic antigens are valuable in the conclusive diagnostic separation of epithelioid sarcoma and necrobiotic granulomas.

Characterization of a novel gelatin-binding 21 kDa protein secreted by cultured adherent cells

A novel gelatin-binding 21 kDa protein was identified in the culture medium of fibroblastic and sarcoma cells by affinity chromatography on gelatin-Sepharose. Its affinity for gelatin was lower than that of the other gelatin-binding proteins, fibronectin and the 70 kDa protein, as judged by stepwise elution by urea and arginine. The protein bound also to spermine and to some extent to heparin but not to staphylococcal protein A, bovine serum albumin, concanavalin A or plain Sepharose 4B. In gel filtration chromatography the protein eluted in fractions differing from those of fibronectin and the Mr 70,000 protein and retained its ability to bind to gelatin-Sepharose, indicating that the binding was not mediated by the two other gelatin-binding proteins. It contains intrachain disulfide bridges, as judged by analysis under nonreducing and reducing conditions. The protein is composed of two major subtypes with pI values of 5.85-6.10 and 6.55-6.75. It was sensitive to trypsin but not to collagenase or thrombin. Antiserum was raised in rabbits against the gelatin-binding proteins isolated from serum-free conditioned fibroblast culture medium. The antiserum reacted with fibronectin, the Mr 70,000 protein and the Mr 21,000 protein in immunoprecipitation experiments. Absorption of the antiserum with human plasma fibronectin did not decrease its reactivity with the Mr 70,000 and 21,000 proteins. However, absorption with the Mr 70,000 protein abolished also the reactivity against the Mr 21,000 protein, suggesting immunological cross-reactivity. The protein was synthesized independently from the Mr 70,000 protein, as shown by pulse-chase labeling experiments of cells. The production of the Mr 21,000 protein in cultured cells was enhanced by transforming growth factor-beta.

Clear cell sarcoma of the kidney. An immunohistochemical study

Three cases of clear cell sarcoma of the kidney (CCSK) and 5 cases of Wilms' tumor were investigated immunohistochemically to examine the expression of tissue-specific intermediate filaments (cytokeratin, vimentin, and desmin) and myoglobin. In CCSK, tumor cells were negative for cytokeratin, except for occasional tubular structures, and vimentin was demonstrated in only one case. In Wilms' tumor, epithelial components were positive for cytokeratin and stromal cells were positive for vimentin, while no staining was found in blastemal cells for either. Both desmin and myoglobin were negative in all tumor cells except for skeletal muscle cells in Wilms' tumor. In the current study, some neoplastic cells in CCSK were revealed to be of mesenchymal nature, but blastemal cells in Wilms' tumor were not.

Ultrastructural study of a clear cell sarcoma suggesting schwannian differentiation

A clear cell sarcoma that developed on the left back of a 19-year-old Japanese female was studied ultrastructurally. The findings included basal laminae, desmosomelike junctions, cytoplasmic interdigitations, lamellar bodies, and immature melanosomes. These findings suggest schwannian differentiation of this tumor, since they are not usual features of malignant melanoma except for melanosomes. Therefore this tumor seems to be more akin to malignant schwannoma than to malignant melanoma.

Extraction of cells from paraffin-embedded tissue sections for single-cell DNA cytophotometry

A simple technique is presented for the isolation of cells from paraffin-embedded tissues for Feulgen DNA cytophotometric investigations. Tissue fragments from paraffin blocks were deparaffinized in xylene, rehydrated and refixed in a formalin solution and incubated in a solution of 0.5 pepsin in 0.25% hydrochloric acid. After filtration through a 70 micron mesh and centrifugation, the cells were smeared upon a glass slide. Comparison between the results obtained with freshly prepared imprints and with pepsin-extracted cells of the same tumor showed that the extraction technique does not influence the Feulgen reaction or the DNA distribution pattern. Investigations carried out on bladder and embryonal carcinomas have demonstrated that the method permits an analysis of histologically or histochemically identified tumor cells within individual tissue areas.

Mesoblastic nephroma contains fibronectin but lacks laminin

Non-metastatic mesoblastic nephromas from four young children were shown to contain fibronectin but not laminin using an immunoperoxidase staining procedure. In contrast, one metastasising spindle celled sarcomatous tumour from a neonate was laminin positive. During embryogenesis primitive nephrogenic mesenchyme contains only fibronectin and no laminin; metanephric blastema (permanent kidney) is positive for laminin. The staining for fibronectin and laminin may help to ascertain the histogenesis of different types of renal tumour.

Usefulness of basement membrane markers in tumoural pathology

The distribution of basement membrane (BM) markers, type IV collagen, laminin (LM), heparan sulphate proteoglycan (HSP) and fibronectin (FN) has been studied by indirect immunofluorescence using specific antibodies, in tumoural pathology. The disrupted pattern of BM by these markers in severe dysplastic lesions of the breasts, the bronchi and uterine cervix provides evidence for malignancy. In invasive carcinomas, there is generally a loss of these BM components, with FN persisting in the stroma. The loss of these markers in BM is concomitant and superimposable in double staining studies. In embryonic tumours, the presence of BM markers is related to a mesenchymal differentiation of malignant cells with pericellular FN and/or maturation towards organoid structures with BM. In sarcomas, there is a loss of the pericellular BM staining around most transformed muscular and Schwann cells and adipocytes. The persistence of this labelling in some well-differentiated areas can help to diagnose the nature of the sarcoma. The persistence of intercellular filaments of FN corresponds to the mesenchymal and/or sarcomatous nature of undifferentiated anaplastic proliferations.

Differentiation between metaplastic carcinomas and sarcomas of the human female breast by fibronectin

The distribution pattern of fibronectin in metaplastic carcinomas, stromal sarcomas, malignant cystosarcoma phyllodes tumours and histiocytic type lymphomas of the human female breast has been studied using the indirect immunoperoxidase technique on formalin fixed paraffin embedded tissue. Fibronectin was demonstrated as intensely stained strands between tumour cells forming an irregular network in metaplastic carcinomas and lymphomas. Stromal sarcomas and the malignant stromal component of the phyllodes tumours exhibited, in contrast, a uniform staining throughout tumour cells and stroma which was weaker than in adjacent normal-looking connective tissue. We suggest that the intense staining reaction of metaplastic carcinomas is due to the scirrhous reaction generally associated with invasive human breast carcinomas. The advantage of using fibronectin as a diagnostic tool in the differentiation of carcinoma/lymphoma versus sarcoma is the fact that the antigen is a stromal marker and its staining intensity is not influenced by the morphology or degree of differentiation of non-mesenchymal tumours.

Analysis of hyaluronic acid in the diagnosis of malignant mesothelioma

Using a modified papain digestion cetylpyridinium salt precipitation method, glycosaminoglycans were isolated from 21 mesotheliomas, 34 primary lung carcinomas, 12 carcinomas of other sites, and 7 soft tissue sarcomas. Qualitatively, hyaluronic acid (HA) was present in 20 of 21 mesotheliomas, about half of the primary lung adenocarcinomas, and all of the soft tissue sarcomas. On the average, HA constituted 45% of the total glycosaminoglycans in the mesotheliomas and 28% of the total in the lung cancers. Quantitatively, mesotheliomas contained statistically greater amounts (mean value, 0.74 mg/g) of HA than primary lung adenocarcinomas (mean value, 0.08 mg/g), but were not statistically different from soft tissue sarcomas (mean value, 2.01 mg/g) or primary ovarian serous neoplasms (mean value, 0.92 mg/g). The study concludes that, contrary to previous reports, HA is neither the sole nor the predominant glycosaminoglycan in most mesotheliomas, but, given the proper clinical and histologic setting, the finding of sufficiently high levels (greater than 0.4 mg/g dry tissue extract) supports the diagnosis of mesothelioma when the alternative diagnosis is primary adenocarcinoma of lung.

Detection of an interferon antagonist, sarcolectin, in human sarcomas and muscles

In a variety of human sarcomas we detected the presence of a sarcolectin which reversed an established antiviral protection induced by interferon (IFN). For the same protein concentration, this biological activity was significantly increased when compared to that of normal muscles. All the biological characteristics were comparable to those of a sarcolectin found in hamster tissues; namely the capacity to agglutinate cells and its inhibition by specific sugars, migration in sodium dodecyl sulfate gel, and pepsin, heat and sodium dodecyl sulfate stability. Except for its anti-IFN function and cell agglutinating activity, the biological significances of this sarcolectin is presently poorly understood.

Estrogen and progesterone receptors in head and neck cancer

The existence of hormone receptors on or within neoplastic tissue has potential diagnostic, therapeutic, and prognostic importance. It was the purpose of this study to measure estrogen and progesterone receptors in a large group of patients with head and neck cancer to determine their frequency. Sixty-five patients with head and neck tumors underwent a total of 75 estrogen and 50 progesterone receptor assays. In this group, 87.7% were squamous cell carcinoma. In the estrogen receptor assays, 89.3% (67/75) were negative, 8% (6/75) were borderline, and only 2.7% (2/75) were positive. In the progesterone receptor assays, 78% (39/50) were negative, 22% (11/50) were borderline, and there were no positive results. There were no changes in assays of tissue removed at biopsy v tissue removed during surgery. There was no impact with chemotherapy. In conclusion, head and neck cancers do not appear to possess estrogen or progesterone receptors and can be considered to be hormonally independent.

Cytoplasmic estrogen and progesterone receptor content of uterine sarcomas

Analyses of cytoplasmic estrogen receptor and progesterone receptor were performed on tumor specimens from 32 patients with uterine sarcomas. While the median and maximal quantitative levels of binding were lower than those observed in endometrial carcinomas, examples of estrogen receptor- and progesterone receptor-positive as well as estrogen receptor- and progesterone receptor-negative tumors were observed in all histologic categories of sarcomas. The presence of significant levels of estrogen receptor binding correlated (p less than 0.05) with the presence of progesterone receptor. The receptor binding status did not correlate with the histologic type of sarcoma, clinical stage, primary or metastatic tumor, presence of extrauterine metastases, age, previous exogenous estrogen therapy, mitotic count, or overall differentiation or nuclear differentiation of the sarcoma. The overall and nuclear differentiation of the carcinomatous elements of homologous mixed müllerian tumors did not correlate with receptor status. The presence of significant levels of estrogen receptor did demonstrate a trend (p less than 0.10) favoring enhanced survival through short-term follow-up, but this trend was not demonstrated with survival beyond 36 months. Steroid receptor status did not otherwise affect prognosis or disease-free survival. No correlation between receptor content and response to hormonal therapy or chemotherapy was observed.

Clear-cell sarcoma of tendons and aponeuroses: a clinicopathologic study. Presentation of six additional cases with review of the literature

Clear-cell sarcoma of tendons and aponeuroses is a rare and slowly growing soft tissue sarcoma, affecting mainly young adults. During the last 15 years, approximately 60 cases have been reported in the literature. In this report, six additional cases followed in the Sarcoma Unit at The Royal Marsden Hospital are presented, representing approximately 1% of the total number of sarcomas treated in our unit between 1972 and 1982. A review of the literature has also been included.

DNA-Feulgen-cytophotometric analysis of single cells isolated from paraffin embedded tissue

This study describes a method for the isolation of cells from paraffin embedded tissues for DNA-Feulgen-cytophotometric measurements. The relevance of the method used is demonstrated by the analysis of the DNA-distribution pattern of cells isolated from an alveolar sarcoma of the soft tissues of a 10-year old girl. The comparison between freshly prepared imprint preparations and specimens after pepsin--extraction clearly shows, that the preparation mode used did not influence the relative DNA-content. The mean values of DNA/nuclei did not show a decrease even after prolonged pepsin treatment (90 minutes). Therefore this method permits access to stored histopathological material for retrospective DNA-Feulgen-Cytophotometric investigations.

Distribution of laminin, fibronectin, and interstitial collagen type III in soft tissue tumours

The distributions of laminin, fibronectin, and interstitial collagen type III have been investigated in a series of 60 soft tissue tumours by immunochemistry. Positive laminin staining was seen in sites predicted by the distribution of ultrastructurally visible basal lamina. Pericellular laminin was present in all benign tumours of Schwann cell and smooth muscle origin examined, in the two malignant Schwannomas examined, and in six of 13 leiomyosarcomas. It was also evident around nests of cells in an alveolar soft part sarcoma and around malignant endothelial cells in an angiosarcoma. In fibroblastic and fibrohistiocytic tumours it was found only in blood vessel walls. The results of laminin staining led to revision of the original histopathological diagnosis in seven of the 60 cases studied. Fibronectin was abundant in the stroma of most neoplasms, both benign and malignant. It was also found in a distribution parallel to that of laminin. In some tumours this was clearly distinguishable from the distribution of interstitial collagen. Intracellular fibronectin was shown consistently only in mast cell granules. Its demonstration in synovial cells, fibroblasts, and histiocytes was more variable. Interstitial collagen type II had the most irregular distribution of the three proteins. It was as plentiful in tumours of smooth muscle origin as in tumours of fibroblastic origin, but was scanty in fibrous histiocytomas. Its distribution appeared similar to that of laminin and fibronectin in leiomyomas, but differed from these two proteins in Schwann cell tumours and other neoplasms. In one leiomyosarcoma fibronectin, laminin, and type III collagen appeared to be lost concomitantly from tumour cell peripheries.

Keratin proteins and carcinoembryonic antigen in synovial sarcomas: an immunohistochemical study of 24 cases

Twenty-four synovial sarcomas were examined for the presence of keratin proteins by an indirect immunoperoxidase method with paraffin-embedded tissues. Keratin proteins were identified in 16 of 24 cases (67 per cent). Both the pseudoglandular and spindle cell areas of all eight of the biphasic synovial sarcomas and the spindle cells of eight of the 16 monophasic synovial sarcomas contained keratin proteins. In spindle cell areas, staining was observed in single cells and small cords and clusters of cells in the absence of cleft formation or other evidence of a pseudoglandular component. The predominant cytologic staining pattern in all cases was peripheral, with localization of staining to the cell membrane or adjacent areas, but diffuse and focal cytoplasmic staining patterns were also observed. No staining for keratin proteins was seen in 101 control cases, including 52 sarcomas of various types. Carcinoembryonic antigen was also identified in four of the 24 synovial sarcomas by an indirect immunoperoxidase technique. The identification of keratin proteins may be helpful in the pathologic diagnosis of synovial sarcoma, particularly the spindle cell monophasic variant.

Estradiol and progesterone receptors in two cases of endometrial stromal sarcoma

The presence of estradiol and progesterone receptors in endometrial stromal sarcoma (ESS) has not been studied previously. Two cases of ESS are reported in which high concentrations of these receptors were found in the tumor tissue. One of these patients had retained the reactivity to hormone treatment for several years. It is suggested that the steroid receptors should be analyzed in all cases of ESS to find tumors with a high receptor content. Hormone treatment of these patients should be part of the primary adjuvant therapy. In cases of a good response the therapy should be prolonged and continued for the rest of the patient's life.

Immunohistochemistry of central nervous system tumors. Its contributions to neurosurgical diagnosis

Immunofluorescence and immunoperoxidase (peroxidase-antiperoxidase, PAP) techniques for the demonstration of neural and non-neural cell markers are contributing greatly to increase the diagnostic accuracy of difficult tumors of the central nervous system. Well characterized nervous system markers include glial fibrillary acidic (GFA) protein, the three protein subunits of neurofilaments, neuron-specific enolase (NSE), myelin basic protein, and S-100 protein. The most important and reliable of these is GFA protein, which is widely in use for the immunohistochemical diagnosis of tumors of the glioma group. Its many practical applications are reviewed and illustrated. Other neural markers, in particular the specificity of NSE and S-100 protein, need to be critically evaluated. Problems related to the immunohistochemical diagnosis of central neuroepithelial tumors of putative neuroblastic origin remain complex and still need to be resolved. Non-neural markers, such as vimentin, desmin, cytokeratins, Factor VIII, alpha-fetoprotein, human chorionic gonadotropin, and immunoglobulins have well defined, although more restricted, applications in surgical neuropathology.

Better prognosis of many cancers in female: a phenomenon not explained by study of steroid receptors

Experimental evidence indicates that specific sex hormonal imbalance, deficiency, and excess may be causes of tumors or at least contribute in some way to their development. Clinical observations show that the prognoses of patients with various malignancies differ among males and females, and some cancers can be alleviated and partially controlled by altering the accustomed hormonal environment. Although beneficial effects usually are only temporary, there is no doubt that some cancers are hormone-dependent to a degree. A significant number of prostatic carcinoma in males and breast carcinoma in both sexes have been treated with various additive or ablative endocrine manipulations. The detection and quantitation of specific steroid binding proteins in hormone-sensitive tumors have enhanced our understanding of the mechanism of endocrinal therapy. Excluding carcinoma of the breast and of the sex organs (ovary and uterus in females, testis and prostate in males), many other solid tumors have been tested for the presence of estrogen and other steroid receptors. A fair number of solid cancers contains estrogen and progesterone receptors (ER, PR), even those from male patients. Thus, the better prognosis of females with sarcoma, melanoma, liver, colorectal and other cancers cannot simply be explained by the presence or absence of estrogen or progesterone receptors. This review attempts to summarize clinical reports of this interesting phenomenon, including therapeutic results with estrogenic, antiestrogenic, and other hormonal approaches.

Expression of intermediate filament proteins in thyroid gland and thyroid tumors

The presence of intermediate filament proteins of cytokeratin/prekeratin type and vimentin type was evaluated in non-neoplastic thyroid glands and in different types of thyroid neoplasms. Follicular epithelium of both normal and goitrous thyroids showed a strong reaction with anticytokeratin antibodies that widely cross-react with various simple epithelia. On the other hand, in normal thyroid, there were only occasionally (in one of 12 cases) solitary cells reacting with antibodies to epidermal prekeratin. In nodular goiters, such cells were often seen (eight of 18), especially among the lining cells of cysts, and in chronic thyroiditis in all (12 of 12) cases. Only the stromal cells and intraluminal macrophages reacted with antibodies to vimentin. Neoplastic cells of papillary carcinomas showed a positive staining reaction both with antibodies to cytokeratins and to epidermal prekeratin. Follicular carcinoma cells, although positive for cytokeratins, could generally not be stained with antibodies to epidermal prekeratin. Medullary carcinoma cells also showed cytokeratin positivity and, only occasionally, positivity for epidermal prekeratin. Anaplastic carcinomas were also reactive with antibodies to cytokeratin but, for the most part, were negative for epidermal prekeratin. Interestingly, some neoplastic cells of all types of thyroid carcinomas also appeared to contain vimentin, as shown with both polyclonal and monoclonal antivimentin antibodies. In contrast to carcinomas, the intermediate filaments of thyroid sarcomas and lymphomas were only of vimentin type. Furthermore, it was found that the papillary structures in benign goiters were only reactive with cytokeratin antibodies and lacked, in contrast to papillary carcinomas, epidermal prekeratin-like immunoreactivity. Hence, the analysis of intermediate filament proteins of thyroid tumors can be utilized to differentiate between papillary and follicular carcinomas and between benign and malignant papillary lesions as well as between anaplastic thyroid carcinomas and sarcomas or lymphomas.

Malignant granular cell tumor of the right sciatic nerve. Report of an autopsy case with electron microscopic, immunohistochemical, and enzyme histochemical studies

An autopsy case of a malignant granular cell tumor of the right sciatic nerve was reported. The surgically excised malignant granular cell tumor of a 43-year-old women showed a close relationship with the sciatic nerve, and postmortem examination disclosed extensive metastases. Electron microscopic observations of the material obtained at surgery revealed many diagnostic granules containing myelin figures, as well as basement membrane-like structures around some of the tumor cells. Electron microscopic acid phosphatase staining suggested that the granules could be of a lysosomal origin. Immunohistochemical investigation showed the presence of S-100 protein in the tumor cells, a finding which is believed to be specific for the nervous system. And, focally, the cytoplasmic processes accompanied by basement membrane mimicked Schwann cells. This evidence suggested the highly malignant nature of the malignant granular cell tumor of probable Schwann cell origin.

Immunohistochemical localization of epidermal and Mallory body cytokeratin in undifferentiated epithelial tumors. Comparison with ultrastructural features

Twenty-one anaplastic tumors were studied by light microscopy (LM), immunoperoxidase staining using anti-epidermal cytokeratin (ECK) and anti-Mallory body cytokeratin (MBCK) antibodies, and electron microscopy (EM), to determine whether an epithelial origin could be confirmed. The tumors were derived from lung, stomach, colon, breast, uterus, kidney, bladder, and mesothelium. By LM, the tumors consisted of either large and polygonal, spindle or small, round cells. With immunoperoxidase staining, 11 (52%) of the anaplastic tumors were positive for ECK, positivity being either absent or only weak in the main tumor mass, but marked in areas of infiltration and metastases. In contrast, all of the anaplastic tumors were positive for MBCK in the main tumor mass, infiltrating areas, and metastases. In the case of adenocarcinomas, staining was either web-like or diffuse throughout the cytoplasm with concentration occurring at the cell surface, whereas in mesotheliomas, the staining was either diffuse or showed focal perinuclear accentuation. Twelve of 13 anaplastic tumors examined by EM showed epithelial features (desmosomes, tonofilaments, lumina, and/or microvilli). As controls, 21 non-epithelial tumors (five melanomas, eight sarcomas, and eight lymphomas) showed no reactivity with either cytokeratin antibody. These studies show that the epithelial nature of undifferentiated and poorly differentiated tumors can be confirmed by immunohistochemistry using anti-cytokeratin antibodies.

Distinction of nephroblastomas from other childhood tumors using antibodies to intermediate filaments

Ten nephroblastomas were investigated by antibodies to intermediate filaments. In seven cases, which in light microscopy were characterized by the presence of blastema and tubules, immunofluorescence microscopy with IF-specific antibodies reveals expression of cytokeratin and vimentin in blastema cells, while tubules were only labelled by the cytokeratin antibodies. This result was independent of whether the conventional cytokeratin antibody or monoclonal antibodies specific for cytokeratin 18 were used. Stroma cells were vimentin-positive. In two cases nephroblastomas were undifferentiated and also lacked tubuli formation. In both these tumors blastema cells were vimentin-positive and cytokeratin-negative. Finally one case of clear cell sarcoma of the kidney could only be labelled by the vimentin antibody. Thus antibodies to intermediate filaments seem to be useful tools to distinguish nephroblastomas from neuroblastomas or rhabdomyosarcomas, especially in cases of metastasis.

Elevated levels of a 17-kilodalton nuclear protein in carcinomas

The presence of a 17-kilodalton nuclear protein with pI variants of 6.7-6.9 in solid human malignant tumors is reported. This protein was more prominent in the carcinomas sampled compared to the sarcomas studied. Small amounts were detectable in placenta, but not in adult human liver, suggesting that the protein may be the product of a gene involved in normal differentiation.