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Biomedical subjects

D M MacDonald

Publications and source records attributed to D M MacDonald.

At least 73 records · Page 4Linked to original sources
PubMed1990

Activation and inducer subset phenotype of the lymphocytic infiltrate around epidermally derived tumors.

An in situ analysis of the mononuclear cell infiltrate found in association with a range of benign, premalignant, and malignant epidermal tumors is described. The predominant cell phenotype was that of the recently described immunoregulatory helper/inducer T lymphocyte. A large number of lymphocytes expressed antigens associated with cellular activation, suggesting an ongoing immunologic response by the host against the tumor, although evidence of in situ proliferation of these cells was lacking. These findings suggest that the infiltrate found in association with cutaneous tumors does not represent passive accumulation of lymphocytes from the circulation but rather an active antitumor response.

Antibodies, Monoclonal↗
PubMed1990

Platelet activating factor-induced clinical and histopathologic responses in atopic skin and their modification by the platelet activating factor antagonist BN52063.

The clinical and histopathologic responses to intradermal platelet-activating factor (PAF-acether) in atopic subjects, without evidence of atopic dermatitis are documented. An immediate acute wheal and flare reaction was observed in all volunteers. Histopathologically, the reaction was characterized by a predominantly neutrophilic response, which was seen at 30 minutes and was maximal at 4 hours. Eosinophils were observed in the infiltrate as early as 30 minutes after injection, and were maximal by 12 hours. The specific PAF-acether antagonist BN52063 antagonized the acute flare response to intradermal PAF-acether but had little effect on cellular recruitment at the site of injection.

Adult↗
PubMed1990

Interferon-gamma activates co-ordinate transcription of HLA-DR, DQ, and DP genes in cultured keratinocytes and requires de novo protein synthesis.

The purpose of this study was to determine the effect of interferon-gamma on keratinocyte major histocompatibility complex class II gene transcription. Transformed human foreskin keratinocytes (SVK14 cells) were incubated with recombinant IFN-gamma in the presence or absence of the protein synthesis inhibitor cycloheximide. Total cellular RNA was extracted from the cells and Northern blot analysis carried out using cDNA probes for all the functional class II genes. We report that 1) there is co-ordinate activation of all the class-II genes; 2) the rate of transcription varies between gene loci after activation; and 3) de novo protein synthesis is required for IFN-gamma activation of class II transcription.

Cell Line, Transformed↗
PubMed1990

Profound digital collagen atrophy: a new cutaneous presentation of adrenal-dependent Cushing's syndrome.

A 59-year-old Caucasian housewife presented with a 2-year history of marked loss of tissue substance from the finger and toe pulps and the heel pads. There was no clinical evidence or history of urticaria or other inflammatory change. Investigations demonstrated a raised plasma cortisol secondary to a left adrenal adenoma. Skin biopsies showed abnormalities of dermal collagen, but no evidence of elastin destruction. This case presents an unusual variant of the cutaneous atrophy associated with Cushing's syndrome.

Atrophy↗
PubMed1990

T-cell inducer populations in cutaneous inflammation: a predominance of T helper-inducer lymphocytes (THi) in the infiltrate of inflammatory dermatoses.

The mononuclear infiltrate found in a variety of inflammatory dermatoses was characterized by a predominance of T helper-inducer lymphocytes (THi), CD4+/CD45RA-/CD45RO+, a population of cells responsible for maintaining and promoting immune reactions. Only small numbers of T-suppressor-inducer lymphocytes (TSi), CD4+/CD45RA+/CD45RO-, cells responsible for inducing CD8 suppressor-effector cells to 'down regulate' immune reactions, were seen. The predominance of CD4+ THi lymphocytes was common to all dermatoses studied and suggests a common final pathway in chronic cutaneous inflammation, irrespective of initial causative factors.

CD4-Positive T-Lymphocytes↗
PubMed1990

Alterations induced in normal human skin by in vivo interferon-gamma.

In a study of the direct effects of interferon-gamma (IFN-gamma) on normal human skin, healthy adult male volunteers received either 3 micrograms (n = 4) or 30 micrograms (n = 9) of recombinant IFN-gamma administered intradermally over 3 days. Biopsies were taken on day 6 and histopathological examination of fixed paraffin-embedded sections from sites which had received 30 micrograms IFN-gamma revealed a moderate perivascular lymphohistiocytic dermal infiltrate with mast cells. Immunophenotyping of 5 microns cryostat sections demonstrated that 3 micrograms IFN-gamma induced keratinocyte HLA-DR expression in the absence of any significant infiltrate. More intense keratinocyte HLA-DR expression was produced by 30 micrograms IFN-gamma in all specimens, with HLA-DP concurrently expressed in three biopsies. The ratio of CD4:CD8 cells within the infiltrate was approximately 3:1. CD1 + cells within the epidermis were markedly depleted by 30 micrograms IFN-gamma, while CD1-labelled cells were observed in the dermal perivascular infiltrate. Intradermal IFN-gamma induces similar immunopathological changes to those observed in many of the inflammatory dermatoses.

Adolescent↗
PubMed1990

Altered expression of major histocompatibility complex (MHC) antigens by epidermal tumours.

Alteration in the major histocompatibility complex (MHC) antigen expression by cutaneous tumours may enable them to escape host defence mechanisms and to invade surrounding tissue. Immunohistochemical studies in a wide range of epidermally derived tumours demonstrated expression by keratinocytes of the class II molecule HLA-DR in squamous cell carcinoma (SCC) (2 of 8 cases) and keratoacanthoma (KA) (2 of 7 cases). Additionally, HLA-DP and DQ were expressed by single cases of SCC and KA, although, unlike the widespread distribution of DR, DP and DQ, were only present on keratinocytes adjacent to the inflammatory infiltrate. Therefore, keratinocytes in cutaneous tumours, like carcinoma cells of the colon and breast, may express class II MHC antigens during tumour growth. Beta-2-microglobulin (B2M), an invariant MHC class I marker, was absent in all cases of basal cell carcinoma. Variable loss of B2M was observed in squamous cell carcinoma, Bowen's disease and actinic keratoses, suggesting reduced B2M expression by dysplastic cells. However, the variability in B2M staining both between and within diagnostic categories restricts it's immunodiagnostic usefulness.

Antigens, Neoplasm↗
PubMed1989

The effect of in vivo interferon-gamma on the distribution of LFA-1 and ICAM-1 in normal human skin.

Lymphocyte function associated antigen 1 (LFA-1) and its ligand intercellular adhesion molecule 1 (ICAM-1) are cell surface adhesion molecules important in many lymphocyte-mediated responses. Recent in vitro studies have demonstrated that the cytokine interferon-gamma (IFN-gamma) can induce ICAM-1 expression by keratinocytes, and that lymphocytes adhere to IFN-gamma treated keratinocytes. In view of the importance of keratinocyte/lymphocyte interactions in the pathogenesis of cutaneous disease, we have examined the effects of in vivo IFN-gamma on cutaneous expression of LFA-1 and ICAM-1. Fourteen volunteers received intradermal IFN-gamma (dose: 1 or 10 micrograms) daily for 3 d. Biopsy was obtained on day 6. Cryostat sections were stained by the peroxidase antiperoxidase technique employing murine monoclonal antibodies to CD11, CD18, and ICAM-1. IFN-gamma intensified ICAM-1 expression by dermal endothelial cells and induced keratinocyte expression of ICAM-1. Furthermore, after administration of 10 micrograms of IFN-gamma LFA-1 positive (LFA + ve) lymphocytes were observed along the basement membrane zone closely related to ICAM-1 + ve basal keratinocytes and also surrounding dermal endothelium. Exposure to IFN-gamma induced expression of both CD11a and CD18 antigens on epidermal Langerhans cells. These studies suggest that the distribution of adherence molecules expression within cutaneous tissue in vivo is modulated by IFN-gamma, and that these alterations may be important in interactions involving cutaneous immunocompetent cells.

Administration, Cutaneous↗
PubMed1989

Keratinocyte expression of OKM5 antigen in inflammatory cutaneous disease.

Keratinocyte expression of the monocyte/macrophage surface antigens defined by OKM1 and OKM5 antibodies (Ortho Diagnostics) was examined using the peroxidase anti-peroxidase immunohistochemical technique. A range of inflammatory cutaneous disorders were investigated, including lichen planus, psoriasis and atopic dermatitis. Positive suprabasal keratinocyte expression of OKM5 antigen was observed in all disorders, while keratinocyte staining with OKMI antibody was consistently negative. These results provide further evidence that keratinocytes may play an important role in cutaneous immune responses. Furthermore, they are consistent with the recent observation that HLA-DR positive keratinocytes may modulate cutaneous immunological reactions by inducing T-cell unresponsiveness.

Adult↗
PubMed1989

Human cutaneous mast cells--a study of fixative and staining reactions in normal skin.

Routinely used formal saline fixation reduces the number of demonstrable mast cells in human skin by up to 30% compared with paired specimens fixed in Carnoys medium. Using metachromatic (toluidene blue), orthochromatic (alcian blue/safranin), enzymatic (chloroacetate esterase reaction) and immunofluorescence (berberine and fluorescein conjugated avidin) staining techniques, mast cells were demonstrated and quantified. Alcian blue/safranin and fluorescein-conjugated avidin were both superior to the other staining methods used. We recommend the use of Carnoys medium fixed tissue stained with either alcian blue/safranin or conjugated avidin for optimal visualization and assessment of mast cells in human skin.

Acetates↗
PubMed1989

Identification of CD16/NKH-1+ natural killer cells and their relevance to cutaneous tumour immunity.

The presence of natural killer (NK) cells, as defined by reactivity with the monoclonal antibodies Leu 7, Leu 11 and Leu 19 was assessed in the inflammatory infiltrate around epidermal neoplasms and compared with findings in a range of inflammatory dermatoses. HNK-1+ (Leu 7) cells were present in a wide range of malignant, pre-malignant and inflammatory disorders. Cells positive for the more specific NK cell antigens CD16 (Leu 11)/NKH-1 (Leu 19) had a distribution mainly restricted to cases of squamous cell carcinoma (five of nine) and keratacanthoma (three of seven). The variability in distribution between the different antibodies suggests that the majority of cutaneous HNK-1+ cells are not NK cells, but represent cross-reacting T lymphocytes. The qualitatively distinct distribution of CD16+ and NKH-1+ cells around some cases of squamous cell carcinoma and keratoacanthoma is of interest but their absence from a number of such cases calls into question a specific effector role for natural killer cells in these squamoproliferative tumours.

Antigens, Differentiation↗
PubMed1988

Psychiatric services in general hospitals. Rational and irrational considerations.

The structure of a psychiatric service in an urban general hospital is complex. Varied intrainstitutional and extrainstitutional relationships create stress, which can lead to rational and irrational reactions, often in combination. Psychologic mechanisms that exist in individuals also occur as shared defense mechanisms in an institutional setting, serving to reduce anxiety and stress but often at the expense of accurate reality perception. Good communication can play a vital role in reducing reality distortions but is itself often blocked or impaired by the same defense mechanisms that led to the distortions. An awareness of how these mechanisms operate in an institutional setting can aid the psychiatric administrator in correcting distortions and maintaining good channels of communication.

Communication↗
PubMed1988

Cutaneous endometriosis: a histopathologic study.

A detailed examination of material from 10 cases of cutaneous endometriosis revealed a range of histopathologic features similar to those found within the uterine endometrium at each of the main phases of the menstrual cycle. However, there appeared to be a poor correlation between histologic appearance and menstrual stage. Recognition of these cyclic variations is important for the accurate diagnosis of cutaneous endometriomas.

Endometriosis↗