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Biomedical subjects

M H Allen

Publications and source records attributed to M H Allen.

At least 19 recordsLinked to original sources
PubMed1992

Occupancy of a C2-C2 type 'zinc-finger' protein domain by copper. Direct observation by electrospray ionization mass spectrometry.

The metal ion specificity of most 'zinc-finger' metal binding domains is unknown. The human estrogen receptor protein contains two different C2-C2 type 'zinc-finger' sequences within its DNA-binding domain (ERDBD). Copper inhibits the function of this protein by mechanisms which remain unclear. We have used electrospray ionization mass spectrometry to evaluate directly the 71-residue ERDBD (K180-M250) in the absence and presence of Cu(II) ions. The ERDBD showed a high affinity for Cu and was completely occupied with 4 Cu bound; each Cu ion was evidently bound to only two ligand residues (net loss of only 2 Da per bound Cu). The Cu binding stoichiometry was confirmed by atomic absorption. These results (i) provide the first direct physical evidence for the ability of the estrogen receptor DNA-binding domain to bind Cu and (ii) document a twofold difference in the Zn- and Cu-binding capacity. Differences in the ERDBD domain structure with bound Zn and Cu are predicted. Given the relative intracellular contents of Zn and Cu, our findings demonstrate the need to investigate further the Cu occupancy of this and other zinc-finger domains both in vitro and in vivo.

Copper↗
PubMed1992

HIV infection in women: presentations and protocols.

In the 11th year of the AIDS epidemic in the United States, it is clear that more and more women are becoming infected with HIV. Genital infections by other pathogens may be the first clue to the diagnosis. With progressive immunodeficiency, such infections may follow a protracted course or become recurrent, often requiring maintenance therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Electrospray-ionization mass spectrometry for the detection of discrete peptide/metal-ion complexes involving multiple cysteine (sulfur) ligands.

Conditions have been developed to characterize the reversible interaction of one or more Zn(II) ions with cysteine (sulfur) ligands on metal-binding peptides by electrospray-ionization (ES) mass spectrometry. A 71-residue peptide with two separate clusters of four cysteine residues was selected as a model to optimize both the solution and electrospray variables most likely to affect the detection of stable cysteine (sulfur) ligand/Zn interactions. By infusing peptide in water alone, stable electrospray and ion signals were produced in both the absence and presence of up to 100 microM zinc sulfate. In the absence of Zn(II), the calculated mass of the fully reduced peptide (8248.5 Da) was observed (8248.4 +/- 0.4 Da). In the presence of Zn(II), peptides with zero, one and two bound Zn atoms were detected; all three species were present in several different charge states. The overall charge envelope was typically unchanged in the presence of Zn; the charge-state optimum (10+) observed for this peptide was apparently unaffected by the presence of bound Zn. The interaction of Zn(II) ions with sulfur ligands in this peptide appeared to result in tetracoordinate covalent bonds.(ABSTRACT TRUNCATED AT 250 WORDS)

Cysteine↗
PubMed1992

Differences in the conformational state of a zinc-finger DNA-binding protein domain occupied by zinc and copper revealed by electrospray ionization mass spectrometry.

Transition metal ions are important in biological regulation partly because they can bind to and stabilize protein surface domain structures in specific conformations that are involved in key molecular recognition events. There are two C2-C2 type zinc-finger sequences within the highly conserved DNA-binding domain of the estrogen receptor protein (ERDBD). Electrospray ionization (ESI) mass spectrometry has been used to demonstrate that the metal-binding sites within the 71-residue ERDBD can bind either Zn (up to 2) or Cu (up to 4). Evidence for the induction and/or stabilization of a different conformational state with bound Cu is revealed by a characteristic shift in the ESI charge envelope. The 10+ charge state is most abundant for the fully reduced ERDBD apopeptide and the ERDBD-Zn holopeptide (bound Zn does not alter the charge envelope). In contrast, the 8+ charge state is typically the optimum charge state observed for the ERDBD-Cu holopeptide; indeed, the entire charge envelope is frame-shifted to lower charge states with bound Cu. Interpretation of the altered charge states is simplified because (i) a single type of metal-binding ligand (sulfur) is involved in the case of both Zn and Cu binding, and (ii) the two different metal cations are both divalent. Thus, it is likely that the dissimilar charge envelopes represent different peptide conformers, each of which is stabilized by a different type of bound metal ion.(ABSTRACT TRUNCATED AT 250 WORDS)

Copper↗
PubMed1992

Adhesion molecule expression in polymorphic light eruption.

Endothelial leukocyte adhesion molecule-1 (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) are cytokine-regulated cell-surface leukocyte adhesion molecules. We have investigated the in vivo kinetics and pattern of expression of these adhesion molecules in relation to tissue accumulation of leukocytes in the photodermatosis, polymorphic light eruption (PMLE), which is characterized by dense perivascular leukocytic infiltration. Immunohistology was performed on biopsies taken at varying time points from PMLE lesions induced in 11 subjects by suberythemal solar simulated irradiation. Vascular endothelial ELAM-1 expression was first observed at 5 h, maximal at 24 to 72 h, and remained elevated at 6 d. VCAM-1, minimally expressed in control skin, was induced above background levels on endothelium and some perivascular cells after 24 h and maintained at 6 d. Endothelial cell ICAM-1 expression was increased above control levels at 72 h and 6 d. Keratinocyte ICAM-1 expression, most marked overlying areas of dermal leukocytic infiltration, began at 5 h and was strong at 72 h and 6 d. In addition to lymphocytes, significant numbers of neutrophils but not eosinophils were detected in the dermal leukocytic infiltrate that appeared at 5 h and persisted at 6 d. The pattern of adhesion molecule expression that we have observed is similar to that seen in normal skin during a delayed hypersensitivity reaction. These observations support an immunologic basis for PMLE.

Biopsy↗
PubMed1992

Preferential adherence of T lymphocytes and neutrophils to psoriatic epidermis.

T lymphocytes and neutrophils accumulate in psoriatic epidermis. To determine whether the epidermis plays an active role in this process through the production of cellular adhesion factors, leucocyte adherence to lesional psoriasis was compared with normal skin in a modified frozen-section adhesion assay. Lymphocyte and neutrophil suspensions were prepared by standard Ficoll-Hypaque techniques from peripheral blood of normal volunteers and overlaid on to glutaraldehyde-fixed 8-microns cryostat sections of skin. Adhesion of phorbol ester-activated T lymphocytes to the epidermis was significantly greater in psoriasis compared with normal skin (P < 0.01). Adhesion was absent (a) at 7 degrees C, (b) in the presence of EDTA and (c) in the absence of lymphocyte activation. Immunostaining demonstrated that all adherent lymphocytes were CD3+ve (i.e. T cells). Likewise, neutrophils adhered more prominently to psoriatic epidermis. Adhesion was most prominent at the tips of dermal papillae, corresponding to areas of maximal intercellular adhesion molecule-1 (ICAM-1) expression. Both neutrophils and lymphocytes adhered to dermal papillary vascular endothelium. These studies provide functional data that psoriatic epidermal cells are actively involved in leucocyte adherence. The distribution of adhesion suggests that both ICAM-1-dependent and independent mechanisms are involved.

Adult↗
PubMed1992

Abnormal expression of epidermal growth factor receptor in cutaneous epithelial tumours.

Epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) are important keratinocyte mitogens. Their effects are mediated by a cell membrane receptor (EGFR), quantitative and qualitative abnormalities of which may be responsible for deranged keratinocyte proliferation and differentiation. We have therefore examined EGFR expression immunohistochemically in a variety of benign and malignant epithelial neoplasms using monoclonal antibodies to the extracellular and intracellular receptor domains. In benign tumours (virus wart, seborrhoeic keratosis, keratoacanthoma), there was an ordered pattern of EGFR expression. In malignant tumours (basal and squamous cell carcinoma), there was loss of membrane labelling and cytoplasmic accumulation of the receptor. In premalignant proliferations, there was loss of membrane receptor with either absent cytoplasmic EGFR (actinic keratosis) or cytoplasmic receptor accumulation (Bowen's disease). Evidence of truncated receptors was not found. We suggest that dysregulation of the EGFR may be important in the development of cutaneous epithelial malignancies but that grossly abnormal forms of the receptor do not occur.

Antibodies, Monoclonal↗
PubMed1991

Sequential and simultaneous processing abilities of high-functioning autistic and language-impaired children.

Investigated the Sequential and Simultaneous processing distinctions of high-functioning autistic children and children with a developmental receptive language disorder (DRLD). Twenty autistic subjects and 20 DRLD subjects were matched on age and gender, and compared to each other on their Sequential and Simultaneous processing abilities utilizing the K-ABC and selected subtests of the WISC-R. Results showed that both groups manifested a relative sequential processing deficit. However, the groups did not differ significantly on their overall sequential and simultaneous processing capabilities relative to their degree of language impairment. The application of the sequential and simultaneous processing model to the WISC-R provided consistent convergent and discriminant validation for the assessment of these processes with the WISC-R.

Aptitude↗
PubMed1991

The development of a reproducible immunocytochemical technique for demonstrating colocalized cutaneous antigens.

A number of double immunocytochemical labeling techniques are available that allow simultaneous identification of two antigens in one tissue section. Those most commonly used are (a) the acid elution method, which uses acid buffer to remove one set of antibodies, thus allowing a second set to be applied; (b) the use of noncross-reacting combinations of immunoglobulin subclass and subclass-specific antibodies; and (c) application of the diaminobenzidine (DAB) reaction product as an antibody-blocking reagent, preventing cross-reaction of one set of antibodies with those of a second labeling method. We assessed each technique, using a variety of immunoenzyme methods, for the ability to label antigens that are anatomically separate in one tissue section and those that are colocalized on the same cell surface. Acid elution methods increased antibody cross-reaction. The use of immunoglobulin subclass antibodies resulted in inferior staining. The DAB blocking method, using peroxidase antiperoxidase (DAB substrate) and alkaline phosphatase antialkaline phosphatase (APAAP) (fast red substrate) optimally labeled non colocalized antigens. The substitution of fast blue as the APAAP substrate proved optimal for colocalized antigens, producing brown and blue single-labeled and black double-labeled cells.

Antibodies, Monoclonal↗
PubMed1991

Endothelial leucocyte adhesion molecule-1 (ELAM-1) expression in cutaneous inflammation.

Endothelial leucocyte adhesion molecule-1 (ELAM-1) is a recently described endothelial surface glycoprotein which is inducible by interleukin 1 (IL-1), tumour necrosis factor-alpha (TNF-alpha) or bacterial lipopolysaccharide (LPS). Using an immunohistochemical technique and a monoclonal antibody (1.2B6) specific for ELAM-1 we have found marked vascular endothelial expression of ELAM-1 in many cutaneous inflammatory disorders, including allergic contact dermatitis, atopic dermatitis and psoriasis, and in dermal infiltrates associated with benign, premalignant and malignant keratinocyte proliferation. In normal skin, minimal levels of ELAM-1 expression were detected. In psoriasis, double-immunoenzyme staining studies revealed a close spatial relationship between ELAM-1 expression and neutrophil margination, suggesting a functional link. Recombinant human interferon-gamma (30 micrograms) injected intradermally in normal adult human volunteers did not substantially upregulate ELAM-1 in contrast to its marked effect on intercellular adhesion molecule-1 (ICAM-1) expression, indicating that this cytokine is probably not involved in ELAM-1 induction in vivo. These results indicate that ELAM-1 is widely induced in cutaneous inflammation with a time course of expression that is longer than that observed in vitro. As ELAM-1 acts as an adhesion ligand for neutrophils, and perhaps monocytes, the expression of this molecule in cutaneous lesions is likely to be an indication of the ability of vascular endothelium to recruit these cells from the circulation. Furthermore, the cytokine inducibility of ELAM-1 is indirect evidence for functional interactions between perivascular mononuclear cells, other resident cells and the blood vessel wall.

Antigens, CD↗
PubMed1991

Antigenic profile of human acrosyringium.

The demonstration of HLA-DR on human acrosyringium has led to the suggestion that eccrine epithelium, through its interaction with certain molecules, might play an active role in epidermal immune responses. An immunohistochemical study was undertaken to identify the antigenic profile of acrosyringium in normal skin and following the intradermal administration of a T-lymphocyte-derived cytokine, interferon gamma (IFN-gamma). Acrosyringium in normal skin, in contrast to interappendageal epidermis, was found to lack CD1a+ Langerhans cells. However, antigens CD36 (OKM5) and L1 (MAC387) were uniquely expressed by keratinocytes immediately adjacent to the distal portion of acrosyringium. Constitutive expression of each class II MHC antigen, namely HLA-DR, DP and DQ was observed on luminal acrosyringial cells. EMB11 antigen (CD68), a mononuclear cell determinant, was similarly expressed on acrosyringial epithelium in normal skin. Following intradermal administration of IFN-gamma, intercellular adhesion molecule-1 (ICAM-1) (CD54) was induced on acrosyringial epithelium and the expression of HLA-DR was intensified. A range of other markers including CD3, CD4, CD8, CD11a, CD11b and CD15 were not expressed by acrosyringium either in normal skin or after administration of IFN-gamma. Expression of antigens associated with cell-mediated immune mechanisms on acrosyringium is consistent with the hypothesis that it may have an immunological role in epidermal immune responses.

Adult↗
PubMed1991

Drug abuse and pregnancy: some questions on public policy, clinical management, and maternal and fetal rights.

An estimated 9202 drug-exposed infants were born in the United States in 1986 according to the National Center for Health Statistics; the number increased to 13,765 in 1988. These figures were substantially underreported, however, notes the 1990 report by the U.S. General Accounting Office (GAO) (1). It surveyed 10 hospitals, two each in Boston, Chicago, Los Angeles, New York, and San Antonio, accounting for 44,655 births, of which approximately 4000 resulted in drug-exposed infants in 1989. Maternal cocaine use was estimated to range from below 1 to 12 percent among the 10 hospitals. The GAO report concluded that the number of these infants born nationwide each year could be "very high," and that in these five cities the unavailability of drug treatment and lack of adequate prenatal care are contributing to the problem (1). Two health professionals and a health lawyer were invited to respond to some questions about the problems of cocaine and substance abuse by pregnant women and how maternity caregivers, health and social service agencies, law, and society are dealing with the issues.

Child Abuse↗
PubMed1991

Keratinocyte expression of CD36 antigen in benign and malignant epidermal cell-derived tumours.

Keratinocytes express the macrophage/monocyte antigen CD36 in a variety of inflammatory cutaneous diseases characterised by a T lymphocyte rich infiltrate. Since cell-mediated immune mechanisms also play a role in host responses to skin tumours, we investigated the presence of CD36 antigen on keratinocytes in a range of epidermal cell-derived benign and malignant tumours characterised by a peritumoural, dermal lymphocytic infiltrate. Frozen tissue sections of lesional tissue from a range of epidermally derived tumours were labelled with antibodies to CD1a, CD11b, CD36, and HLA-DR antigens. Benign and malignant squamoproliferative tumour cells exhibited a spectrum of CD36 expression, whereas those of basal cell origin were consistently CD36-. Suprabasal expression of CD36 was present in the normal perilesional epidermis of all tumours studied including basal cell carcinoma. Keratinocyte CD11b expression was not observed. The widespread presence of keratinocyte CD36 positivity in squamoproliferative, but not basal epidermal, tumours suggests its expression may be linked to the degree of keratinocyte differentiation. The stimulus for expression is unknown, but the fact that suprabasal perilesional epidermis expressed CD36 strongly in the absence of infiltrate suggests it may represent a non-specific response by keratinocytes to various stimuli.

Adult↗
PubMed1991

Ascertainment of maternal deaths in New York City.

Maternal deaths in New York City are defined as deaths from any cause in a woman while pregnant or within six months of pregnancy termination. Pilot studies seeking to improve maternal death ascertainment found that selected medical examiner reports contributed an additional 10.5 percent of the total maternal deaths, vital statistics review contributed 6.3 percent, linkage of death tapes of women of reproductive age to live birth and fetal death tapes contributed 1.0 percent. Medical examiner cases should be incorporated into surveillance data for accurate ascertainment of pregnancy associated deaths.

Adolescent↗
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

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↗