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Biomedical subjects

A P Kelly

Publications and source records attributed to A P Kelly.

At least 19 recordsLinked to original sources
PubMed2006

Elevated prolidase activity in keloids: correlation with type I collagen turnover.

BACKGROUND: Keloid pathogenesis involves an altered balance of extracellular matrix metabolism, mainly accumulation of type I collagen. This could be due to excessive synthesis or decreased degradation of matrix, or a combination of both processes. Prolidase, an imidodipeptide-cleaving cytosolic enzyme, plays an important role in the collagen catabolic process by recycling proline for collagen synthesis. Collagen accumulation in keloids is due to an imbalance in the steady state of collagen turnover. OBJECTIVES: To investigate prolidase activity and its role in the steady state of collagen turnover between normal skin and keloid tissue and their derived fibroblasts. METHODS: Ten sets of keloid and normal skin tissues and their derived fibroblasts were employed. Measurements were made of tissue prolidase activity, free proline level, and concentrations of the collagen synthesis product aminoterminal propeptide of type I procollagen (PINP) and the collagen degradative product carboxyterminal telopeptide of type I collagen (ICTP). Also, synthesis of collagens type I and III and matrix metalloproteinases 1 and 2 was investigated using Western blot analysis. RESULTS: Keloid tissues had a significant increase in prolidase activity, up to fourfold that in normal skin. The elevated prolidase activity was accompanied by an increase in tissue PINP and ICTP concentrations in keloid; in addition, the collagen turnover index (PINP/ICTP) was higher in keloids. CONCLUSIONS: The combination of elevated prolidase activity and associated higher collagen synthesis to degradation ratio in keloids suggests a possible metabolic process for the excessive accumulation of type I collagen in keloids.

Adolescent↗
PubMed2000

Dermatofibrosarcoma protuberans growing around plantar aponeurosis: excision by Mohs micrographic surgery.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a spindle cell malignancy that has a high local recurrence rate after excision with minimal or no immediate tissue margin assessment. DFSP is exceedingly rare on the palms and soles. OBJECTIVE: To report a case of a locally aggressive DFSP on the sole excised using Mohs micrographic surgery. METHODS: Case report and review of the literature. RESULTS: Mohs micrographic surgery unmasked tumor infiltration that extended around plantar aponeurosis and into underlying plantar muscle fascia. CONCLUSION: Mohs micrographic surgery should be considered the treatment of choice for DFSP, especially in acral locations. This technique allows the surgeon to trace out deep tumor extensions that may wrap around underlying tendon, a finding that may not be appreciated clinically.

Adult↗
PubMed1999

Accurate intracellular localization of HLA-DM requires correct spacing of a cytoplasmic YTPL targeting motif relative to the transmembrane domain.

HLA-DM is an MHC class II-related heterodimer that is targeted to lysosomal compartments by a tyrosine-based signal YTPL, present in the cytoplasmic tail of the beta chain. Similar signals in other proteins control transport to different intracellular locations and can be recognized at several sorting sites within the cell including the trans-Golgi network, the plasma membrane and the early or sorting endosome. Therefore, in addition to recognizing the basic tyrosine motif, the sorting machinery must be sensitive to additional features associated with these elements. Here we show that efficient trafficking of HLA-DM to lysosomal compartments is dependent upon the proximity of its tyrosine motif to the transmembrane domain. Constructs in which the spacing is altered are rapidly internalized but are expressed at the cell surface. We conclude that the spacing of the HLA-DMB-encoded tyrosine motif relative to the transmembrane domain is an important feature controlling DM sorting in endosomes.

Amino Acid Sequence↗
PubMed1999

Absence of MHC class II gene expression in a patient with a single amino acid substitution in the class II transactivator protein CIITA.

We investigated the underlying genetic defect in an immunodeficient patient who presented with recurrent bacterial infections in his late twenties and demonstrated a transcriptional defect in major histocompatibility complex (MHC) class II regulation. Transient heterokaryon analysis implicated functional loss of CIITA, the MHC class II transactivator protein, and in support of this MHC class II antigen expression was restored by stable transfection with the wild-type molecule. A single amino acid substitution, phenylalanine to serine, in the COOH-terminal portion of the CIITA sequence correlated with reduced transcription of both classical (HLA-DP, -DQ, and -DR) and nonclassical (HLA-DM and -DO) class II genes. The long survival of the patient, although remarkable, was not associated with partial CIITA function as evidenced by residual MHC class II expression. These data define at high resolution a region of CIITA that is essential for function in both professional and nonprofessional antigen presenting cells and which could potentially constitute a target for therapeutic intervention by novel factors with a propensity to downregulate MHC class II antigen expression.

Adult↗
PubMed1999

Treatment of pseudofolliculitis barbae with the diode laser.

Pseudofolliculitis barbae is a common skin disorder of the beard area that is characterized by the presence of inflammatory follicular papules due to terminal hair shafts re-entering the epidermis. Postinflammatory hyperpigmentation and scarring often occur with pseudofolliculitis barbae. Such skin changes can lead to cosmetic disfigurement and be of great concern to the patient. We report a case of pseudofolliculitis barbae and hirsutism with associated postinflammatory hyperpigmentation in an African-American woman who was effectively treated with the diode laser.

Adult↗
PubMed1998

Multiple signals regulate the intracellular trafficking of HLA-DM in B-lymphoblastoid cells.

Peptide loading by major histocompatibility complex (MHC) class II molecules occurs in the endocytic pathway and is critically dependent upon the function of the class II-related molecule human leucocyte antigen-DM (HLA-DM). We have previously shown that a tyrosine-based lysosomal targeting signal present in the cytoplasmic tail of DMB has the capacity to target HLA-DM to peptide-loading compartments in HeLa cells. Here we investigate the importance of this signal in directing HLA-DM to processing compartments in professional antigen-presenting cells. We reconstituted a DMB-negative B-lymphoblastoid cell line with native or targeting-deficient DMB and show that in the absence of its tyrosine signal, DMB-Y230A is as efficient as the wild-type molecule in inducing MHC class II SDS stable dimer formation; restoring expression of the conformation-dependent DR3 epitope 16:23; the removal of CLIP; and accessing lysosomal peptide-loading compartments. By transient transfection in HeLa cells we show that Ii is able to compensate for loss of DMB-encoded targeting information. These data imply that in cells expressing physiological levels of class II, Ii and DM, there is sufficient association with Ii to direct the majority of DM into the endocytic pathway. Thus MHC class II and HLA-DM may follow similar intracellular trafficking pathways on route to antigen-processing compartments.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1997

Aesthetic considerations in patients of color.

This article focuses on the aesthetic cutaneous considerations in analyzing and treating the aging face in patients of color. Initially some of the physiologic differences between dark and light pigmented skin are elucidated. Hair conditions that lead to aesthetic unacceptance are discussed as are facial enhancing cosmetic procedures, with special emphasis on people of color. Information on treatment of dandruff, xanthelasma, and melasma in people with dark skin is also presented.

Adult↗
PubMed1997

Generation of novel human MHC class II mutant B-cell lines by integrating YAC DNA into a cell line homozygously deleted for the MHC class II region.

The human B lymphoblastoid cell line (LCL) 721.174 sustains a large homozygous deletion in the major histocompatibility complex (MHC) class II region that results in an absence of DQ and DR molecules as well as a deficiency in the assembly and transport of class I molecules to the cell surface. The deleted genes include the transporters associated with antigen processing TAP1 and TAP2, DMA and DMB which are involved in editing class II bound peptides, and four genes whose roles in antigen processing are unclear; the low mass polypeptide genes LMP2 and LMP7, and DNA and DOB. To study this region we have integrated into 721.174 two overlapping yeast artificial chromosome (YAC) clones which cover the interval LMP2-DRA inclusive. Three clones (11.2A1.1, 4D1D10.1 and 4D1D10.2), containing complete copies of the transfected YAC, produced varying levels of mRNA from the LMP, TAP, DQ and DR genes and corresponding levels of LMP and TAP protein. Class I cell surface expression was restored in 11.2A1.1 and 4D1D10.1, as was DR expression in both 4D1D10 transfectants. These studies demonstrate the feasibility of introducing large groups of functional genes back into human lymphoblastoid cells sustaining deletions, with full restoration of biological function. The procedure could be exploited in order to restore all but one gene covered by the deletion, effectively producing a single gene defect. This could be used to introduce copies of genes engineered to contain mutations and to study cis regulatory elements at some distance from the chosen loci.

Amino Acid Sequence↗
PubMed1996

A sequential study of the bovine tuberculin reaction.

The sequential histopathological and immunocytochemical changes that characterize the tuberculin reaction were studied in 13 cattle experimentally sensitized to Mycobacterium bovis, and 14 cattle naturally infected with M. bovis. There were two distinct, temporally related patterns of morphological change that were similar for both groups of cattle. The first phase, between 6 hr and 24 hr after the intradermal injection of purified protein derivative (PPD), was characterized by a perivascular aggregation of WC1+ gamma delta T cells and neutrophils and the presence of leucocytoclastic vasculitis within the papillary dermis. The second phase of the reaction was characterized by increased numbers of infiltrating BoCD4+ cells, BoCD8+ cells and macrophages, as well as an increase in expression of the interleukin-2 (IL-2) receptor and the ACT2 antigen. Macrophages were the most numerous infiltrating leucocytes between 24 hr and 72 hr after the intradermal injection of PPD. At 72 hr, the reaction was characterized by intense perivascular cuffing with BoCD4+ cells, BoCD8+ cells and macrophages; gamma delta T cells and neutrophils were a minor component of the reaction and leucocytoclastic vasculitis was no longer observed. No B cells were detected in the dermis throughout the period of study. The increase in skin thickness was primarily because of inflammatory oedema that was contained within the area by a meshwork of fibrin deposited around the collagen bundles of the reticular dermis.

Animals↗
PubMed1995

Acne keloidalis nuchae: treatment with excision and second-intention healing.

BACKGROUND: Acne keloidalis nuchae (AKN) is a chronic inflammatory disorder of the posterior aspect of the neck and occipital region of the scalp. Despite numerous medical and surgical treatment modalities, few offer cure or a superior cosmetic result for patients with extensive disease. OBJECTIVE: Our purpose was to determine whether excision with second-intention healing is an effective therapeutic modality for AKN. METHODS: Excision of the involved area to the level of the muscle fascia or deep subcutaneous tissue was performed in six patients. Postoperative sites healed by second intention. RESULTS: Four of six patients had a horizontal elliptic excision of the involved area that included the posterior hairline, with good to excellent results. The other two, who received nonelliptic excision of affected scalp that spared the hairline, had slower wound healing and poor contraction. CONCLUSION: Best results were achieved in excision of AKN with second-intention healing when the excision was a horizontal ellipse of the posterior aspect of the scalp including the posterior hairline.

Acne Keloid↗
PubMed1994

Molecular genetic analysis of the pullulanase B gene of Bacillus acidopullulyticus.

A fragment from Bacillus acidopullulyticus strain 294-16 encoding a pullulanase activity has been cloned into Bacillus subtilis. The nucleotide sequence of the 3972 base pairs (bp) fragment has been determined and shown to include only one complete open reading frame (ORF) of 863 codons. The deduced amino acid sequence of this ORF, denoted pulB, shows homology to a number of amylolytic enzymes. Primary and secondary structure analysis indicates that the central region of the protein forms the catalytic domain in a characteristic (beta/alpha)8 barrel. Three carboxylic acid residues essential for catalysis were identified. Regions within the catalytic domain proposed to be involved in substrate binding have been identified by homology.

Amino Acid Sequence↗
PubMed1994

MRI of degenerative disease of the lumbar spine.

Low back pain (LBP) is one of the most common reasons that patients seek medical attention. Although acute LBP is generally a self-limiting condition, the estimated cost for this health care problem exceeds $8 billion annually. MR accurately depicts both the morphologic as well as biochemical sequelae of disc degeneration. Additionally, MR is superior in its ability to depict disease processes that can present in an indistinguishable fashion. Although multiple mechanisms have been proposed for the possible etiology of disc degeneration, it remains incompletely understood at this time. In addition to the unknown etiology of disc degeneration, the relationship between degenerative disc disease and LBP has not been firmly established. Substantial percentages of people without a history of LBP or sciatica have been shown to have abnormal imaging examinations. Mechanical compression of neural elements by disc herniation, as well as direct biochemical and inflammatory effects of the contents of the nucleus pulposus upon neural structures, have been proposed as possible sources of LBP. Due to the above, caution is urged before attributing a particular anatomic finding as the patient's source of low back pain.

Humans↗
PubMed1993

Alleles and haplotypes of the MHC-encoded ABC transporters TAP1 and TAP2.

TAP1 and TAP2 are two major histocompatibility complex (MHC) genes, located between HLA-DP and -DQ, whose products form a transporter molecule involved in endogenous antigen processing. Polymorphic residues have been described in both genes and, in this study, we have identified another polymorphic site within the adenosine triphosphate (ATP)-binding domain of TAP2. We have used the amplification refractory mutation system (ARMS) polymerase chain reaction (PCR) to characterize TAP1 and TAP2 alleles and haplotypes in a reference panel of 115 homozygous typing cell lines. Of four possible TAP1 alleles, we observed three, and of eight possible TAP2 alleles, we observed five. Among 88 (homozygous typing cells) (HTCs) homozygous at HLA-DR, -DQ and -DP, 80 were also homozygous at TAP1 and TAP2. Of 27 HTCs homozygous at HLA-DR and -DQ, but heterozygous at -DP, 14 were homozygous at TAP1 or TAP2 and 13 heterozygous, consistent with recombination taking place either side of the TAP loci. Of the fifteen possible combinations of TAP1 and TAP2 alleles, we observed eleven, each at a frequency similar to that predicted by individual allele frequencies. In this ethnically heterogenous panel there is no indication that particular combinations of TAP1 and TAP2 have been maintained together.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

A new human HLA class II-related locus, DM.

HLA class II molecules have a crucial role in the immune response to antigens. We have isolated two new class II-like complementary DNA sequences, RING6 and RING7, which map between the HLA-DNA and -DOB loci. They are novel members of the immunoglobulin gene family which may have diverged before the duplications that gave rise to the main class II loci. The RING6 and RING7 genes seem to encode alpha- and beta-chains of a previously undiscovered class II-related protein.

Amino Acid Sequence↗
PubMed1991

Human major histocompatibility complex class II-negative colon carcinoma cells present staphylococcal superantigens to cytotoxic T lymphocytes: evidence for a novel enterotoxin receptor.

The staphylococcal enterotoxins (SE) bind to major histocompatibility complex (MHC) class II molecules on target cells and activate T cells expressing particular T cell receptor V beta sequences. In this report we demonstrate that SE bind to the MHC class II- SW620, Colo320DM and WiDr human colon carcinoma cell lines and direct cytotoxic T lymphocytes (CTL) to mediate strong target cell killing. Flow cytometry analysis, immunoprecipitation and Northern blotting experiments failed to demonstrate any surface expression of HLA-DR, HLA-DP and HLA-DQ isotypes on the SW620 colon carcinoma cell line, whereas abundant expression of these isotypes was seen on Raji cells, SEB and SEC1 were efficiently presented at picomolar concentration by the MHC class II- colon carcinoma cells and MHC class II+ Raji cells, whereas SEA and SED were preferentially presented on the MHC class II+ Raji cells. An anti-HLA-DR monoclonal antibody inhibited SEB-induced CTL targeting to Raji, but did not influence the killing of SW620 cells. Our data suggests the existence of functionally active SE-binding structures on human colon carcinoma cells which are distinct from the conventional MHC class II molecules. The possibility that these putative new SE receptors play a role in the enterotoxin action of SE must be considered.

Antigens, Bacterial↗
PubMed1990

Acne keloidalis.

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Acne Keloid↗