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Biomedical subjects

A L Robertson

Publications and source records attributed to A L Robertson.

At least 19 recordsLinked to original sources
PubMed1998

The Quilty lesion enigma: focal apoptosis/necrosis and lymphocyte subsets in human cardiac allografts.

Quilty lesions, as first described by Billingham in 1981, or 'Quilty Effect' (QE) are distinct endomyocardial mononuclear cell infiltrates that have been observed in human heart transplant recipients, as well as in experimental models of heart transplantation. In the present investigations, the pattern and extent of apoptosis (programmed cell death) and myocyte necrosis, as well as specific lymphocyte subsets in Quilty lesions was assessed. Endomyocardial biopsies obtained from 13 patients at 10-3362 days post-transplant were examined. Apoptosis, as identified by DNA nick end-labeling, was found in myocytes at the periphery of Quilty lesions in 11 of 13 cases (85%), and 'early' stages of myocyte necrosis, as demonstrated by specific staining with alpha light chain myosin monoclonal antibodies (mAb), was observed at the same sites in 10 of 13 cases (77%) of both Quilty type A and type B lesions. Apoptosis was not identified in the lymphocyte infiltrates of any of the lesions examined. Lymphocyte subsets were characterized using mAb for T cell receptor (CD3), for helper/inducer T cells (CD4), for cytotoxic/suppressor T cells (CD8) and for mature B cells (CD20). Immunostaining revealed separate clusters of T lymphocytes with less prevalent B cells within the Quilty lesions. CD4+ cells were found in larger numbers than CD8+ cells in all cases. Non-B, non-T large lymphocytes were occasionally present. Except for the extent of the cellular infiltrate, no major cytochemical lymphocyte distribution differences were found between Quilty type A and B lesions. Myocyte apoptosis and early necrosis at the periphery of Quilty lesions suggest that early myocyte injury occurring in B lesions may represent initial or 'abortive stages' of cardiac allograft rejection. Why these lesions do not progress to overt rejection indeed warrant further detailed studies.

Actin Cytoskeleton↗
PubMed1995

Viral genomes and arterial disease.

Recent studies suggest that the initial stages of human atherogenesis may be defined as inordinate inflammatory-proliferative responses of intimal arterial cells, interacting with circulating lymphocytes and monocyte/macrophages, to multiple focal stimuli. The latter include transmembrane signal transductions induced by cytokines and growth factors as well as by activated immune cells releasing vasoregulatory molecules affecting local transarterial lipoprotein transport and metabolism. The observed discriminating cell proliferation and characteristic focal eccentric intimal thickening of spontaneous atheroma may thus result from the phenotypic expression of transformed cell clones with selective proliferative advantages and yet unaffected by tissue immune responses. A suggested mechanism for such cell transformation is the partial expression of widely distributed herpesvirus genomes, resulting in the induction of clonal expansion and enhancement of selective cell growth in transfected host cells. Major obstacles for the unambiguous laboratory demonstration of a direct cause/effect relationship between herpes induced cellular transformation and early human atheroma are (1) potential loss of recognizable viral transforming sequences in the host cell genome by the "hit and run" mechanism originally proposed by Skinner in 1976 and (2) irreversible cytopathic effects induced by these viruses in experimentally infected human cells in vitro, preventing any long-term proliferative or metabolic studies. The observation that immortalized cultured rabbit arterial cells retain for many generations marked mitogenic activity and accelerated lipoprotein uptake after herpesvirus transfection suggested to us the possibility of developing a reproducible in vivo laboratory model in inbred rabbits. To that end, discrete intraarterial injections of fragments of HSV-1 or HSV-2 genomes were made via specially designed catheters in temporarily isolated arterial segments of Watanabe heritable hyperlipemic rabbits. While normolipemic heterozygous animals developed segmental, highly localized, proliferative intimal tumors, containing over 95% HHF35 (+) smooth muscle cells with RAM 11 (+) macrophages and platelets attached to the endothelial surface in 30-60 days, no lesions were found in placebo-injected controls. When hyperlipemic homozygous rabbits were similarly tested, they manifested at injected loci larger intimal lesions containing abundant lipid-laden macrophages and smooth muscle cells before typical rabbit fatty streaks developed elsewhere. These findings suggest that selective transfection with viral genome sequences may indeed induce specific growth promoters for intimal arterial smooth muscle cells and thus play an important role during the initial stages of atherogenesis.

Animals↗
PubMed1990

Vascular changes in the nasal submucosa of chronic cocaine addicts.

A detailed, correlative, histologic evaluation of postmortem changes in the nasal mucosa of chronic cocaine users has shown characteristic mucosal and arteriolar changes as well as typical perivascular and subepithelial alterations compatible with chronic inflammation. These findings confirm and extend recent reports on the effects of cocaine in the coronary circulation and heart muscle as well as provide a new diagnostic tool to the forensic pathologist who suspects that a decedent has been a long-term cocaine abuser.

Adult↗
PubMed1989

Human uterine leiomyoma cells: binding and growth responses to epidermal growth factor, platelet-derived growth factor, and insulin.

The specific binding of epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and insulin were measured in matching cultures of human leiomyoma and myometrial cells, along with the effects of these proteins on DNA and protein syntheses. Scatchard analyses of the binding data revealed that the EGF receptor sites/cell were significantly lower in leiomyoma than myometrial cultures. Two types of PDGF binding were observed when porcine PDGF was used, and one type was seen with human PDGF. By contrast to EGF, more PDGF receptor sites/cell were found in leiomyoma than myometrium but the receptor affinity was higher in the latter. Insulin binding was similar among the myometrial and leiomyoma cells. Protein synthesis was stimulated 3-fold by EGF, PDGF, or insulin in both cell types. DNA synthesis, was higher in myometrial than leiomyoma cells in the basal state and was stimulated by EGF, insulin, or PDGF. A synergistic stimulation (p less than 0.02) of DNA synthesis was observed in both myometrial and leiomyoma cells when EGF was added with insulin. The addition of PDGF with insulin caused only additive stimulation of DNA synthesis. However, the addition of EGF with PDGF caused a synergistic decrease (p less than 0.05) in DNA synthesis by myometrial but no leiomyoma cells. Cultures of human vascular smooth muscle cells obtained from umbilical veins gave results similar to those from myometrium. These findings single out the EGF receptor and EGF, or perhaps an EGF-like growth factor, and to a lesser degree PDGF, as potential regulators of uterine leiomyomata.

Adult↗
PubMed1988

Herpesviridae in the coronary arteries and aorta of young trauma victims.

The presence of herpes simplex virus (HSV) and cytomegalovirus (CMV) nucleic acid and/or antigen was demonstrated in the coronary arteries and thoracic aortas of young trauma victims by the in situ DNA hybridization and ABC immunoperoxidase methods, respectively. Epstein-Barr virus (EBV) nucleic acid and capsid antigen were not detected in the arteries sampled in this study. Of 8 subjects in which virus was detected in the coronary arteries, 6 were positive for HSV and 2 for CMV; of 7 cases positive in the thoracic aorta, 5 were identified as HSV and 2 as CMV. Viral DNA and/or antigen were found in occasional cells in the intact luminal surface and in focal clusters of spindle-shaped or "foamy" cells in the intimal layer. The histologic findings indicate that HSV and CMV are associated with areas showing early or advanced atheromatous changes in the coronary arteries and with lesion-free as well as lesion areas in the thoracic aorta. The virologic findings support the concept that herpes-viruses may potentially play a direct or indirect role in the pathogenesis of human atherosclerosis.

Adolescent↗
PubMed1988

T lymphocytes in aortic and coronary intimas. Their potential role in atherogenesis.

In order to investigate the role of mononuclear cells in infiltrates during the initial stages of atherogenesis, the authors have studied by immunohistochemical methods the aortas and coronary vessels of children and young adults (ages 15-34) dying of acute trauma. Eccentric intimal thickening often accompanied by intimal mononuclear cell infiltration was commonly observed in sections of the lower thoracic aorta. These changes were usually related to intercostal branching sites and thus greater in the dorsal (posterior) than on the ventral aspect of the aorta in 64 of 75 cases examined. In some of these samples the authors were able to demonstrate the presence of T lymphocytes and monocyte-macrophages (mono/macs) by the use of the monoclonal antibodies T11 and Leu-M5, respectively. Many of the T lymphocytes were T8-positive and thus of the cytotoxic/suppressor subtype. T4-positive cells of the inducer/helper subtype were seen occasionally. T cells of both T4 and T8 subsets and mono/macs were also demonstrated in areas of eccentric intimal thickening in coronary arteries and in raised coronary lesions. In both the aortas and the coronary lesions the T cells and mono/macs were often closely associated with one another. This finding is of interest in view of the well-known cell-regulatory and cytotoxic potential of these cells. Extrapolating from findings in non-human primates, the authors suggest a potential role for mononuclear cells in human atherogenesis.

Adolescent↗
PubMed1986

Bovine coronary artery endothelium: in vitro culture and production of plasminogen activator.

A new method for isolation and culture of endothelial cells from bovine coronary artery (BCoAEC) is presented. This method involves in situ perfusion and digestion of main coronary arteries with a collagenase solution. The isolated cells were cultured and maintained through many cell passages in Dulbecco's Modified Eagle's Medium supplemented with fetal bovine serum derived from either whole blood or plasma. Confirmation of these cells' endothelial origin was obtained by demonstration of typical morphologic and growth characteristics of endothelium, immunofluorescent staining with antibodies to von Willebrand factor (Factor VIII: vWF), and measurement of plasminogen activator (PA). In addition, production of PA was inhibited by enzymatically active thrombin as has been previously described with bovine aortic endothelial cells in culture.

Animals↗
PubMed1986

The demonstration of papilloma virus in cervical dysplasia and/or neoplasia.

Thirty-three random biopsy specimens of uterine cervix were studied by immunoperoxidase technique to evaluate the presence of HPV antigen in dysplastic and neoplastic cells. Four cases of mild dysplasia, nine cases of moderate to severe dysplasia, two cases of carcinoma in situ and one case of invasive carcinoma were associated with condylomatous lesions. Intranuclear dark-brown precipitates were observed in superficial and intermediate zones of the dysplastic epithelium. Positive reaction was seen in condylomatous epithelium associated with neoplasia. No nuclear precipitates were observed in carcinoma cells, but one noncondylomatous lesion with moderate dysplasia showed positive intranuclear staining. These preliminary findings suggest that papilloma viruses may play a role in the development of human cervical neoplasias.

Condylomata Acuminata↗
PubMed1986

Basic proteins in the human aortic intima: nonequilibrium two-dimensional electrophoretic analysis of tissue extracts.

The protein composition of atheroma-free human thoracic intima was compared with that containing fatty streaks or fibro-fatty lesions utilizing two-dimensional gel electrophoresis (2-DE) and silver staining. Intimal proteins extracted with 9 M urea were separated by nonequilibrium pH gradient electrophoresis (NEPHGE) followed by polyacrylamide gel electrophoresis (PAGE) in the second dimension. NEPHGE-PAGE of proteins extracted from atheroma-free intima revealed several major proteins: actin, tropomyosin-like proteins, proteins with relative molecular weight (Mr) of 250,000 (P250), two proteins with Mr about 15,000 (P15a, P15b), and many medium proteins such as a myosin heavy chain, two myosin light chains, and proteins P47, P44, P32, P27, P20a, P20b, P19a, P19b. Several additional proteins were observed in intimas with fatty streaks and fibro-fatty lesions. Most of them, such as albumin, transferrin, Apo A-I, alpha 1-antitrypsin, fibrinogen beta-chain, IgG, appear to originate from plasma. Differences in protein composition of intima with fibro-fatty streaks compared with adjacent lesion-free intima varied from case to case and need further study. NEPHGE-PAGE in combination with isoelectric focusing (ISO)-PAGE revealed more intimal proteins in atheroma-free and diseased aortas than either method alone, proteins which might be quantitated, isolated for binding studies, and further evaluated for their potential role in atherogenesis.

Actins↗
PubMed1986

Human aortic intima protein composition during initial stages of atherogenesis.

Protein extracted from 24 human aortic intimas (6-33 years old) with 9 M urea mixture, were studied after separation by two-dimensional gel electrophoresis (2-DE) and silver staining. The protein composition of normal intima in 4 cases, each without any gross changes in the thoracic aorta, displayed similarity. In each 2-DE protein pattern of these intimas about 150 polypeptide spots were detectable/mg of wet tissue. Major and medium polypeptides were described by relative molecular weight Mr in kilodaltons (kDa) and relative charge Cr. Major proteins found were actin (P44-18; Mr = 44 kDa; Cr = -18), tropomyosin-like proteins (P34-29, P35-28.5, P36-31) and two glycoproteins (G35-21, G35-23.5). Several new major and medium extracellular proteins were demonstrated in fibro-fatty lesions as well as in the lesion-free intimas adjacent to lesion in 3 cases. Many of these proteins appeared to originate from plasma: albumin, IgG, alpha 1-antitrypsin, transferrin, haptoglobin beta-chain, apo A-I, apo A-II, fibrinogen beta-chain, alpha 2-HS glycoprotein and alpha 1-antichymotrypsin. Visual comparison of intimal protein patterns from 17 different cases with varying degree of fatty streaks in the thoracic aorta, showed variability in 2 polypeptides P32-17.8 and P32-19.8 as well as 4 plasma proteins albumin, alpha 1-antitrypsin, transferrin and apo A-I. This study suggests that changes in protein composition may occur in the human aortic intima during the initial histological stages of atherogenesis providing potentially useful markers for their identification and pathophysiological evaluation.

Adolescent↗
PubMed1986

Human thymocytes bind to autologous and allogeneic thymic epithelial cells in vitro.

The thymus plays a critical role in the generation of immunocompetent T lymphocytes. In the thymus, lymphocytes are in close contact with epithelial cells, and this contact is necessary for T-cell maturation. Using cultured human thymic epithelial (TE) cells, we have found that human thymocytes bind to human TE cells in vitro. Thymocytes bound to both allogeneic and autologous TE cells and to the epidermoid carcinoma cell line A431 but did not bind to epidermal keratinocytes or to thymic fibroblasts. Thymocyte binding to TE cells was trypsin- and cytochalasin B-sensitive. Indirect immunofluorescence assays showed that both mature (T6-, T3+) and immature (T6+, T3-) thymocytes bound TE cells. In our system, TE-thymocyte binding was not inhibited by antibodies to class I or class II major histocompatibility antigens. In vitro binding of thymocytes to TE cells may represent a correlate of in vivo TE-thymocyte interactions and provides a model system for the study of human intrathymic T-lymphocyte maturation and activation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1985

Effect of aging on human aortic protein composition. I. One-dimensional polyacrylamide gel electrophoretic analysis of tissue extracts.

Proteins extracted from matching areas of homogenized intimas of 17 human aortas, from two age groups (15-34 and 35-82), were studied after separation by polyacrylamide gel electrophoresis, silver staining, and densitometric scanning. Several definite protein bands including 6 major and 16 minor bands were identified in 17 aortic intima samples grossly and microscopically lesion free. However, such electrophoretic patterns were found to differ in the two age groups studied. For instance, (1) the integrated densities (amounts) of protein bands 1, 6, 13, 16, and 19 which we interpreted as of mural vascular origin were significantly higher in the younger age group, whereas the amounts of bands 2, 7, 9, 11, and 21 suspected to be of plasma origin were found to be significantly higher in the older age group; (2) protein band No. 8 was found to be double in the younger age group vs a single line in the older age group, whereas band No. 12 was the opposite. These changes in protein composition appear to correlate closely with diffuse intimal thickening found histologically in older age group, and will be further studied to relate to those in atherosclerotic lesions.

Adolescent↗
PubMed1985

Effect of aging on human aortic protein composition. II. Two-dimensional polyacrylamide gel electrophoretic analysis.

Arterial intima proteins were extracted by 9 M urea from matching histologically atheroma-free areas of 27 human thoracic aortas of both sexes from younger (15-34) and older (35-82) age groups and studied after separation by high-resolution two-dimensional polyacrylamide gel electrophoresis. Seventeen specific protein groups on each gel were identified according to their relative charges and molecular weights and their distribution in the two age groups compared. Some plasma-derived proteins occurred rarely in young aortas while they were consistently found in those from older cases, i.e., protein group 4 (alpha 1-antichymotrypsin) 1/13 (8%) vs 12/14 (86%), group 7 (haptoglobin beta-chain) 1/13 (8%) vs 13/14 (93%) and groups 6 and 9 (IgG chains) 3/13 (23%) vs 9/14 (64%), respectively. Other plasma-derived proteins such as group 3 (albumin) and 5 (alpha 1-antitrypsin) were identified in all samples of both age groups but their expression in the aortic intima increased with age. Proteins which are typically found intracellularly such as those from groups 11 (actin), 12 (cytoskeleton proteins), and 13 (tropomyosin-like proteins) appeared in samples of intima of both age groups but were less apparent in older specimens. These studies suggest that the changes in aortic intima protein distribution in the absence of atherosclerosis closely correlate with histological changes such as intimal thickening often found with aging, providing new sensitive markers of vascular senescence.

Adolescent↗
PubMed1985

In vitro growth and phenotypic characterization of mesodermal-derived and epithelial components of normal and abnormal human thymus.

Long-term in vitro cultures of human thymic tissue were established and phenotypically characterized using monoclonal reagents that define distinct components of the human thymic microenvironment. The epithelial component of the thymus, defined by monoclonal antibodies TE-3, TE-4, BBTECS, and AE1 (anti-keratin) was isolated from the mesodermal component, defined by antibody TE-7, and maintained separately in long-term culture. The epithelial cells were subcultured repeatedly and recovered from storage in liquid nitrogen. The in vitro phenotype of the cultured cells was compared to that of cultured human epidermal cells. A subpopulation of cultured thymic epithelial cells along with a subpopulation of cultured epidermal cells expressed antigens (TE-8, TE-15) characteristic of late stages of keratinized epithelial cell differentiation. Thus, we have established a system whereby components of the human thymic microenvironment can be cultivated in vitro while maintaining the capacity to differentiate. This approach can be used to evaluate the role of components of the thymic microenvironment at various stages of differentiation on developing T lymphocytes. In addition, keratin-containing thymic epithelial cells were successfully cultured from thymuses obtained from patients with myasthenia gravis and thymoma. Cultivation of abnormal thymic epithelium will provide insight into aberrant T lymphocyte-thymic epithelial interaction.

Adolescent↗
PubMed1985

Expression of antigens by cultured epithelial cells: comparison of epidermis and thymic epithelium.

We have established long term in vitro cultures of human thymic epithelium and human epidermis free of contaminating fibroblasts. The cultured cells were examined using a panel of monoclonal antibodies which were raised against human thymic stroma and recognize tissue specific differentiation antigens of human epidermis and thymic epithelium. A subset of cultured epidermal cells (50%) and thymic epithelial cells (18%) expressed the TE-4 antigen characteristic of basal keratinocytes in skin and endocrine epithelium found in the subcapsular cortex and medulla of the thymus. Subpopulations of the cultured cells expressed the antigens detected by antibodies TE-8 and TE-15. In tissue sections antibodies TE-8 and TE-15 bound to the stratum granulosum and stratum corneum of skin and to the Hassall's bodies of thymus, and therefore recognize antigens characteristic of late stages of keratinized epithelial differentiation. In addition, a subset of thymic epithelial cells expressed the antigen detected by antibody TE-3 which is expressed by nonendocrine thymic epithelium found in the thymic cortex. Thus, in vitro cultures of both epidermal and thymic epithelial cells expressed the entire array of differentiation antigens detected by our panel of monoclonal antibodies. This approach can be used to evaluate the role of components of the thymic microenvironment at various stages of differentiation on developing T lymphocytes. In addition, the cultured epidermal cells can be used to evaluate epidermis as a site of extrathymic T cell maturation.

Adolescent↗