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Biomedical subjects

M H Allen

Publications and source records attributed to M H Allen.

84 records · Page 5Linked to original sources
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↗
PubMed1988

Localization of cutaneous antigens by the immunogold-silver staining technique.

Immunogold-silver staining (IGSS) was evaluated for the localization of cutaneous antigens in frozen and paraffin-embedded tissue, employing antibodies to a variety of intracellular, cell-surface and extracellular epitopes in an indirect immunogold reaction, followed by silver enhancement. The principal advantages of IGSS are the avoidance of toxic reagents and the production of a silver precipitate that is permanent, clearly visible and of sufficient contrast with the reaction products of alternative immunolocalizing techniques to be of value in double-labelling procedures. It seems to localize antigenic determinants well, but does not appear to be particularly sensitive, especially for the demonstration of antibodies to extracellular constituents. Limitations of IGSS include the propensity to non-specific staining, and the need to vary the duration of the development stage during silver enhancement.

Antigens↗
PubMed1986

Monoclonal antibody labeling of mononuclear cell surface antigens in formaldehyde-fixed paraffin-embedded cutaneous tissue.

The influence of the sequential stages of conventional formaldehyde fixation and paraffin embedding of cutaneous tissue on monoclonal antibody labeling of cell surface antigens is described. The effects of variation in fixation time, dehydration, clearing, wax embedding, and enzyme treatment of cutaneous sections were examined. By curtailing fixation time, using cold ethanol dehydration, and limited cold clearing with xylene, immunoreactivity of several important monoclonal antibodies was retained. Wax embedding could be achieved at 58 degrees C for 1 h or by using low-melting-point wax at 42 degrees C for 3 h. Thus was derived an optimal processing procedure which afforded good tissue morphology and allowed reliable reproducible labeling by monoclonal antibodies to cell surface antigens.

Antibodies, Monoclonal↗
PubMed1985

In situ quantification of T-lymphocyte subsets and Langerhans cells in the inflammatory infiltrate of atopic eczema.

Tissue from the acute, non-infected eruption of sixteen atopic eczema subjects was subjected to an indirect immunoperoxidase technique using monoclonal antibodies recognizing T-lymphocyte subsets, Langerhans cells and natural killer cells. Over half the cells infiltrating the dermis were T lymphocytes, including a large majority of helper T cells and relatively few suppressor T cells. Langerhans cells were present in significant proportions in the dermis and probably reflected increased antigen presentation within the affected skin. There was no evidence of increased natural killer cell presence. This study suggests that type IV hypersensitivity may be implicated in the aetiology of atopic eczema.

Adolescent↗
PubMed1984

An assessment of Langerhans cell quantification in tissue sections.

In this paper we look at the regional variation of Langerhans cell (LC) numbers in tissue sections between different sites in the same individual and identical sites in different individuals. We also looked at the reproducibility of identification of LC in tissue sections by their OKT6 reactivity. In this way we could assess the validity of comparative enumeration in random tissue sections. Stepped sections were obtained and stained by the OKT6 method. The slides were projected, the cells counted, and an image analysis system used to measure the length of basement membrane. In this way we could calculate the number of LC per millimeter of basement membrane. Our subjects were six age- and sex-matched volunteers. We found that the number of LC on the trunk was significantly lower than on any of the limbs. However, each individual had significant site variation of LC that was different for each one. This makes direct comparison of individual sections invalid and suggests that the most suitable control, when counting LC in lesional skin, is adjacent normal skin.

Adult↗
PubMed1984

Ultrastructural features of metastatic cutaneous carcinoid.

Tissue from the cutaneous metastases of bronchial carcinoid was examined. Fine argyrophil secretory granules were demonstrated in the cytoplasm of the abnormal cells which showed positive labelling with neuron-specific enolase. Ultrastructural studies revealed numerous electron-dense membrane bound neuro-secretory granules, 50-300 nm in diameter. Other characteristic features included inter-digitating pseudo pod-like processes (up to 2 mu in size) in the cytoplasmic membrane, perinuclear filaments, a well-defined Golgi zone and numerous large mitochondria.

Aged↗
PubMed1981

Routine early endoscopy in upper-gastrointestinal-tract bleeding: a randomized, controlled trial.

To determine whether routine early endoscopy is beneficial to patients with upper-gastrointestinal-tract bleeding that ceases during hospitalization, we randomly assigned 206 patients to routine endoscopy (100 patients) or no routine endoscopy (106). Patients in the latter group underwent endoscopy only if recurrent bleeding occurred during hospitalization or if x-ray films disclosed gastric ulcer or suggested neoplasia. All patients were initially treated with an empiric antacid regimen. When the two groups were compared (experimental versus control), there were no significant differences in overall hospital deaths (11 versus eight), recurrence of bleeding (33 versus 32), number of transfusions required to treat recurrent bleeding (mean +/- S.E.M., 7.4 +/- 1.2 versus 6.3 +/- 0.7 units), deaths after recurrent bleeding (eight versus five), or duration of hospital stay. During the 12 months after discharge, there were also no significant differences in frequency of readmission to the hospital, incidence of further gastrointestinal bleeding, number of hemorrhage-related deaths, or frequency of gastrointestinal surgery. We conclude that endoscopy should not be a routine procedure in patients with upper-gastrointestinal-tract bleeding that ceases during treatment.

Clinical Trials as Topic↗
PubMedDate not supplied

Isolation and partial characterization of a Paracoccidioides brasiliensis 58 kDa extracellular glycoprotein which is recognized by human immune sera.

A novel 58 kDa antigenic determinant of the fungus Paracoccidioides brasiliensis was identified by enzyme-linked immunosorbent assay using a panel of species-specific murine monoclonal antibodies (MAbs). Western immunoblot analysis, deglycosylation studies and isoelectric focusing indicated that this 58 kDa antigen is a glycoprotein, with a pI of approximately 5.2. The molecule was purified from P. brasiliensis culture filtrate and yeast cytoplasmic antigens by membrane ultrafiltration, liquid isoelectric focusing and gel filtration; N-terminal amino acid sequence data revealed no substantial homology with known proteins. The presence of the antigen in the cytoplasm of both yeast and mycelial forms of the fungus was demonstrated when these MAbs were used as markers in immunofluorescence, immunoperoxidase and immunoalkaline phosphatase techniques to label P. brasiliensis in cryostat sections. These MAbs also recognized the cytoplasm of P. brasiliensis yeast forms in paraffin-embedded pathological specimens from human cases. A preparation of the 58 kDa component from yeast cytoplasmic antigen was reacted by Western immunoblotting with 26 different serum samples from paracoccidioidomycosis patients, and 81% of them recognized it.

Adult↗
PubMedDate not supplied

In utero diagnosis of trichothiodystrophy by endoscopically-guided fetal eyebrow biopsy.

OBJECTIVE: To describe the prenatal diagnosis of trichothiodystrophy (TTD) through endoscopically-guided fetal eyebrow biopsy. MATERIALS AND METHODS: A 32-year-old patient, gravida 4, para 3, with a history of 2 previous infants affected with TTD was referred at 17(5)/(7) weeks for fetal hair biopsy. DNA repair studies had been normal in the previous children. Four 1-mm biopsies were obtained from the external aspect of the fetal eyebrows under direct endoscopic guidance. Fetal hair samples were assessed with polarized microscopy, electron microscopy, hematoxylin and eosin staining, and were also sent for analysis of sulfur content (cystine levels). RESULTS: The fetal eyebrows were the only adequate source of hair in the early second trimester. The biopsy samples yielded adequate material for all tests. Polarized microscopy showed characteristic banding patterns, but trichoschisis was not apparent. Cystine levels (19 micromol/l) in the biopsy sample were significantly lower than an age-matched (fresh spontaneous abortion) control (368 micromol/l). CONCLUSION: Prenatal diagnosis of TTD is possible in the second trimester through endoscopically-guided eyebrow biopsy. An adequate amount of hair is present in the eyebrows by then, and the disease is already manifest. Analysis of sulfur content of the hair samples is preferred over polarized or electron microscopy, as many classic microscopic findings of TTD may not be present in the early second trimester.

Adult↗