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Biomedical subjects

D W Henderson

Publications and source records attributed to D W Henderson.

At least 19 recordsLinked to original sources
PubMed1995

Loss of heterozygosity in asbestos-induced mutations in a human mesothelioma cell line.

The relationship between occupational or environmental exposure to asbestos and the development of mesothelioma, typically after prolonged latency, has been accepted as one of cause and effect. Most studies have concluded that asbestos is not mutagenic to mammalian cells in vitro. We have studied the potential of crocidolite asbestos to induce mutations in a stable mesothelioma cell line, using a mutation assay that measures mutation at the autosomal HLA-A locus and permits clonal growth of mutant cells. The mesothelioma cell line chosen is more akin to the in vivo target cells of asbestos than human peripheral blood lymphocytes used in previous studies. Exposure of mesothelioma cells in culture to both 200 micrograms/ml and 50 micrograms/ml crocidolite for 72 hr did not result in a statistically significant difference in the mutation frequency (MF) in the HLA-A assay when compared to the spontaneous MF in these cells. Mutations in the mesothelioma cells were classified according to their molecular basis. Notwithstanding the lack of statistically significant change in overall MF, molecular analysis of mutants obtained following exposure of mesothelioma cells to crocidolite demonstrated a statistically significant increase in the class of mutations arising from loss of heterozygosity (LOH) events involving the selection locus (HLA-A) and more distal loci. Mutations following exposure to 200 micrograms/ml and 50 micrograms/ml crocidolite showed a greater frequency of LOH than did spontaneous mutants (P < 0.01 and P < 0.001, respectively). These results correlate with those obtained in an earlier study using lymphocytes. The mesothelioma cell-based assay may be useful in detecting the mutagenicity of other asbestiform fibers and man-made fibers.

Asbestos, Crocidolite↗
PubMed1994

Neutralization of bovine papillomavirus by antibodies to L1 and L2 capsid proteins.

We have generated four mouse monoclonal antibodies (MAbs) to bovine papillomavirus virions that bound type-specific, adjacent, and conformationally dependent epitopes on the L1 major capsid protein. All four MAbs were neutralizing at ratios of 1 MAb molecule per 5 to 25 L1 molecules, but only three effectively blocked binding of the virus to the cell surface. Therefore, antibodies can prevent papillomavirus infection by at least two mechanisms: inhibition of cell surface receptor binding and a subsequent step in the infectious pathway. The neutralizing epitopes of the bovine papillomavirus L2 minor capsid protein were mapped to the N-terminal half of L2 by blocking the neutralizing activity of full-length L2 antiserum with bacterially expressed peptides of L2. In addition, rabbit antiserum raised against amino acids 45 to 173 of L2 had a neutralizing titer of 1,000, confirming that at least part of the N terminus of L2 is exposed on the virion surface.

Animals↗
PubMed1992

Cytopathology of malignant mesothelioma: a stepwise logistic regression analysis.

Twenty-four cytologic features, previously reported to be useful in the distinction of malignant mesothelioma, adenocarcinoma, and benign mesothelial proliferation in serous effusions were assessed. Forty-four cases of malignant mesotheliomas, 46 cases of metastatic adenocarcinomas, and 30 cases of benign mesothelial proliferations were examined for these parameters. When these cytologic features were subjected to a stepwise logistic regression analysis, five features were selected to distinguish malignant mesothelioma from adenocarcinoma. These were true papillary aggregates, multinucleation with atypia, cell-to-cell apposition, acinus-like structures, and balloon-like vacuolation, the latter two features being characteristic of adenocarcinoma. The four variables selected to distinguish malignant mesothelioma from benign mesothelial proliferations were nuclear pleomorphism, macronucleoli, cell-in-cell engulfment, and monolayer cell groups, the latter being a feature of benign proliferations. Using these selected variables, the logistic model correctly predicted 95.4% of cases of malignant mesothelioma versus 100% of adenocarcinoma and 100% of malignant mesotheliomas versus 90% of benign mesothelial proliferations. The results of regression analysis suggest that many of the previously described cytologic features are not important diagnostic discriminators.

Adenocarcinoma↗
PubMed1992

The concept of mesothelioma in situ: implications for diagnosis and histogenesis.

The concept of mesothelioma in situ is explored by a detailed examination of seven patients, subsequently proven to have pleural malignant mesothelioma, who initially had no evidence of gross tumor and for whom biopsy material was available at this early presentation. The tissue was assessed by routine microscopy, the immunoperoxidase technique for epithelial membrane antigen and silver staining for nucleolar organizer regions. Tiny lesions of the pleura that merged with or were adjacent to microscopically flat monolayered or folded mesothelium with cytological atypia were observed. The atypical cells reacted positively to epithelial membrane antigen, and the nucleolar organizer region counts were elevated. These observations are considered to support the possibility of the presence of mesothelioma in situ. These findings are discussed in the light of the proposed concept of mesothelioma in situ, its histogenesis, and its possible clinical relevance.

Adult↗
PubMed1989

Effect of pubertal development on estrogen receptor levels and stromal morphology in the guinea pig prostate.

Using an immunocytochemical assay (ERICA) with a monoclonal antibody (H222Sp gamma) to the human estrogen receptor, we have demonstrated a stromal localization of the estrogen receptor in the dorsolateral prostate of the guinea pig. Specific staining of estrogen receptor in the guinea pig prostate was confined to the nuclei of periacinar and interacinar stromal cells. In comparison with prepubertal tissues, estrogen receptor staining intensity was markedly reduced in postpubertal prostatic tissues. No immunoreactive estrogen receptor was detected in the acinar epithelial cells irrespective of the developmental stage of the guinea pig prostate. Electron microscopic examination of the guinea pig prostate showed that the stromal component consists predominantly of smooth muscle cells, which, during pubertal development, undergo marked cytological changes and increase in size. These changes in the prostatic stroma were associated with a greater than fivefold reduction in levels of cytosolic and nuclear estrogen receptor determined by either a radioligand binding assay or an enzyme immunoassay (EREIA) and expressed relative to soluble protein. Morphometric analysis of the prostatic stromal cell density (SCD: nuclei/mm2 interacinar stroma), which is inversely proportional to stromal cell size, indicated that the SCD decreased approximately threefold during pubertal development. Furthermore, cytosolic estrogen receptor levels in mechanically separated prostatic stromal fractions were found to vary concordantly with the SCD during pubertal development. To determine whether estrogen influences normal development of the guinea pig prostate, the effect of various hormonal manipulations on stromal development was examined. Castration of prepubertal animals prevented the threefold decrease in SCD that is characteristic of pubertal development. Treatment of prepubertal castrates with estradiol and 5 alpha-dihydrotestosterone (DHT) in combination over a period equivalent to the transpubertal growth phase resulted in a stromal cell density similar to that seen in prostatic sections from intact postpubertal animals. In contrast, treatment of prepubertal castrates with either estradiol or DHT alone resulted in a prostatic stromal cell density intermediate between that observed in intact prepubertal and postpubertal animals. These findings suggest that both estrogen and androgen are required for the normal development of the guinea pig prostatic stroma.

Animals↗
PubMed1989

Development and characterization of primary cultures of smooth muscle cells from the fibromuscular stroma of the guinea pig prostate.

Primary cultures of smooth muscle cells (SMCs) were obtained by a two-step enzymatic digestion of guinea pig prostatic stroma. Ultrastructural morphology and growth characteristics of these cells conformed to those reported for SMCs isolated from vascular and visceral tissue sources. Electron microscopic examination indicated that the cells assumed modified myofibroblastoid features in culture. Microfilaments with associated dense bodies were markedly depleted in cultured smooth muscle cells, in comparison with those of the parent tissue. Cultured cells also possessed increased content of rough endoplasmic reticulum indicating the increased secretory or protein-synthetic capacity of the cells. Immunoperoxidase staining for cytoskeletal markers using monoclonal antibodies to desmin and vimentin supported the ultrastructural observations, suggesting a decline in desmin-staining intermediate filaments during "modulation" to the myofibroblastoid form. Despite this depletion of smooth muscle-specific differentiation markers and reversion to more general mesenchymal properties, the cells retained the ability to contract on challenge with norepinephrine, and grew in the characteristic "hill and valley" pattern on attaining confluence. Inasmuch as the estrogen and androgen receptor expression of the parent stromal tissue is also retained, these primary cell cultures should provide a useful model to study regulation of prostatic development.

Androgens↗
PubMed1989

Freeze-fracture study of the intercellular junctions in bronchiolo-alveolar carcinoma (Clara cell type).

Two bronchiolo-alveolar carcinomas of Clara cell type have been studied by thin section and freeze-fracture techniques. Thin sections of the tumour cells showed junctional complexes (tight junctions and intermediate junctions) at the luminal aspect of the lateral cell membranes and desmosomes below them. Freeze-fracture replicas showed well-developed tight junctions with strands arranged in parallel or polygonal patterns. The junctions were continuous 'zonula occludens' type, usually three or more strands deep, with focal proliferation in some areas. The granules in the tumour cells tended to be larger than those of normal human Clara cells, although they were morphologically similar. There was no evidence of secretion of granules from the tumour cells. The relationships between tumour differentiation and growth pattern, and junctional development are discussed.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1989

Primitive neuroepithelial tumours of soft tissues and of bone: further ultrastructural and immunocytochemical clarification of 'Ewing's sarcoma', including freeze-fracture analysis.

The ultrastructural appearances of 7 primitive neuroepithelial tumours (PNETs) originating in soft tissues and bone are described. Three of the tumours represented primary soft tissue lesions, while locally recurrent tumour or pulmonary metastases were studied from the 4 skeletal tumours, all of which had been diagnosed previously as Ewing's sarcomas. Rosettes were present in one of the soft tissue lesions and although not seen in the primary skeletal neoplasms, they were identified by light microscopy (LM) in 2 of 3 pulmonary metastases, one of which had the morphology of a neuroepithelioma, with innumerable Homer Wright rosettes. Conventional TEM revealed cytoplasmic processes in all cases and rosettes in varying stages of development were also evident, but the appearances did not achieve the level of cellular organization seen in neuroblastoma: microtubules were few, while dense-core granules varied in number but were generally sparse and pleomorphic, resembling lysosomes. However, typical neurosecretory granules were found in one lung metastasis; the neoplastic cells comprising the same tumour also had epithelial markers in the form of well constructed desmosomes, while freeze-fracture analysis demonstrated elaborate tight junctions. In thin sections, junctions in the other tumours appeared rudimentary, but freeze-fracture of a further case revealed small collections of membrane particles suggesting extremely poorly developed desmosomes. Immunocytochemical study of 4 tumours (2 originating in soft tissue and 2 in bone) demonstrated weak to moderate immunostaining for neurone-specific enolase and with several monoclonal antibodies reactive with neuroblastomas, but there was no evidence of immunolabelling for tyrosine hydroxylase.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1988

Lymphohistiocytoid mesothelioma: a rare lymphomatoid variant of predominantly sarcomatoid mesothelioma.

Of 394 "definite" mesotheliomas entered in the Australian Mesothelioma Surveillance Program, three bore a striking resemblance to malignant lymphoma by conventional light microscopy, and each was misinterpreted at some stage as lymphoma. The lymphoma-like morphology was a combined result of intense lymphoplasmacytic infiltration and the histiocytoid appearances of the underlying neoplastic cell population. Immunocytochemical analysis demonstrated cytokeratins coexpressed with vimentin within the tumor cells, whereas immunoreactivity for leukocyte common antigen was confined to the smaller lymphoid cells. Electron microscopy of two cases revealed a polymorphous population of fibrohistiocytic cells resembling those typical of malignant fibrous histiocytoma, admixed with lymphocytes and plasma cells, but sporadic cells expressed mesothelial properties in the form of sinuous villiform processes, intracytoplasmic neolumina lined by microvilli, and intermediate filaments that were aggregated into tonofilament bundles in some cells. The ultrastructural appearances, the localization of the tumors to the pleura, with effusion, and absence of anterior mediastinal mass lesions facilitated exclusion of lymphocyte-rich thymoma. In addition, a history of prior occupational exposure to asbestos was elicited in each instance. There was no apparent response to radiotherapy or chemotherapy, and the patients died at 4, 5, and 8 months after presentation. Our observations suggest that immunocytochemical or ultrastructural evaluation is mandatory for accurate diagnosis of all pleura-based lymphomatoid lesions with a mixed large and small cell pattern.

Aged↗
PubMed1988

Freeze-fracture study of intercellular junctions in benign and malignant mesothelial cells in effusions and a comparison with those seen in pleural mesotheliomas (solid tumour).

This study involves an analysis by thin section and freeze-fracture techniques of the intercellular junctions of exfoliated benign and malignant mesothelial cells obtained from 4 cases, two benign and two malignant effusions. Pleural biopsies (solid tumours) of two further cases of confirmed epithelial malignant mesotheliomas were also studied to compare the organization, distribution and characteristics of the tight junctions, gap junctions and desmosomes observed between the three groups of cases. The results showed that both tight and gap junctions varied greatly in their organization in the exfoliated benign and malignant mesothelial cells. However they were often large and very well developed. In contrast, the tight and gap junctions in the solid tumours were considerably reduced both in their size and frequency, a feature which is well recognized in the literature as consistent with the neoplastic process. Our observation of florid tight and gap junctions in the exfoliated benign and malignant mesothelial cells, raises some important aspects of behaviour of neoplastic cells in effusion fluid. It is our opinion that cells in the fluid are exposed to microenvironmental influences which are quite distinct from those in a 'solid' tumour. We suggest that alteration in the binding sites of the extracellular matrix molecules, their influence on the cytoskeleton and the consequent effect on the development of tight and gap junctions are important factors which need further elucidation. The most significant feature of this study is however the demonstration of essential differences in the cell junctional characteristics between neoplastic mesothelial cells in body cavity fluids and those in tissues thus emphasizing the importance of environmental influences in the development of a neoplasm and its spread.

Adult↗
PubMed1987

Antigen expression during early human granulocyte development studied with immuno-electron microscopy.

Expression of the hapten fucosyl-N-acetyllactosamine was correlated with ultrastructural development in human granulocyte precursors using the monoclonal antibody FMC 10 with immunogold techniques. The antigen was detectable from the myeloblast/early neutrophilic promyelocyte stage onwards and was associated with striking development of the rough endoplasmic reticular system. In addition, low levels of labelling were seen on monocytes, eosinophils and some basophil precursors. Contraction and alignment of the cisternae of the rough endoplasmic reticulum during the promyelocyte stage of neutrophilic differentiation gave the appearance of a plasma cell. However, on closer examination it was apparent that true plasma cells did not react with this antibody.

Antibodies, Monoclonal↗
PubMed1986

A human retinoblastoma cell line expressing the common acute lymphoblastic leukemia antigen and displaying an unusual chromosome abnormality.

A new continuous cell line derived from an untreated human retinoblastoma has been established. This cell line, FMC-RB1 is strongly positive for common acute lymphoblastic leukemia antigen and shows a number of ring chromosomes and two marker chromosomes considered to be derivations of chromosome #17; the nonrandom chromosomal changes associated with retinoblastoma, particularly the loss of a chromosome #13 or the deletion of 13q14 was not observed. The establishment of the cell line initially required the presence of bone marrow stromal cells. Morphologically, this cell line grew as a suspension of small round cells in grape-like clusters with periodic "shedding" of single cells. FMC-RB1 could be cloned in soft agar, even in the absence of bone marrow stromal cells as "feeders", making it suitable for a variety of biological studies.

Antigens, Neoplasm↗
PubMed1986

Preparation of cytoplasmic bodies (cytospheres) from isolated hepatocytes and their biochemical properties.

The controlled centrifugation of isolated rat hepatocytes at 260 000 g results in the formation of membrane-bounded cell fragments that we have termed 'cytospheres'. A method is described for the isolation of these cytospheres. Cytospheres are spherical, have a mean diameter of 9.2 +/- 3.2 microns (SD) and a protein content of 225 +/- 12 mg/g wet wt. About 3% of the protein from the original isolated hepatocyte suspension is recoverable. Transmission electron microscopy (TEM) shows cytospheres to possess a trilaminar membrane, and a finely granular hyaloplasm generally devoid of organelles, filaments and microtubules. Freeze-fracture studies reveal a membrane structure typical of a plasma membrane. Ouabain and wheat germ agglutinin (WGA)-binding studies indicate that the original orientation of the plasma membrane is maintained throughout the formation of the cytospheres. The cytospheres have also been characterized biochemically. Cytospheres are enriched in the enzymes normally associated with the hyaloplasm, whereas the activities of enzymes localized in organelles are greatly diminished. Lipid analysis of the cytosphere membrane indicates that it is derived from the plasma membrane of the hepatocyte. Cytospheres are sensitive to changes in the osmolarity and ionic composition of their environment. Cytospheres should therefore prove a useful preparation for the study of hyaloplasm metabolism and of plasma membrane receptor and permeability properties.

Animals↗
PubMed1986

Cilia and ciliogenesis in endometrial adenocarcinomas. An ultrastructural analysis.

Cilia in neoplastic cells were observed by electron microscopy in specimens from five of six consecutive patients with endometrial adenocarcinoma. Most cilia showed a range of defects, from misalignment and displacement of individual doublets to the absence of up to three peripheral doublets, the pattern varying from 9+2 to 6+2; the central pair of microtubules also was frequently missing. Single peripheral microtubules and displacement of the dynein arms were also observed. The high proportion of cilial defects in neoplastic cells (72%) compared with those in normal endometrium (26%), together with a broader spectrum of cilial abnormalities, suggests that the neoplastic state increases the number and range of cilial lesions.

Adenocarcinoma↗