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Biomedical subjects

J Leonard

Publications and source records attributed to J Leonard.

At least 73 records · Page 4Linked to original sources
PubMed1996

Sulphapyridine--a new agent for the treatment of ocular cicatricial pemphigoid.

AIMS: Ocular cicatricial pemphigoid (OCP) is a severe, potentially sight threatening systemic disease that sometimes requires systemic immunosuppression. This study assessed the clinical outcome of patients with OCP treated with sulphapyridine, a sulphonamide with an anti-inflammatory and immunosuppressive action but few side effects. METHODS: A prospective, single armed, unmasked clinical trial was undertaken at Moorfields Eye Hospital. Twenty consecutive patients with moderate or marked conjunctival inflammation due to OCP were treated with oral sulphapyridine 500 mg twice daily. The degree of ocular inflammation was assessed as nil, mild, moderate, marked, or severe. Success was defined as resolution to mild or less. Ocular limbitis, systemic features of the disease, and side effects of the drug were also monitored. RESULTS: Follow up was a mean of 12.3 (SD 4.0) months and ranged from 7 to 17 months. A successful reduction in inflammation was recorded in 22/39 eyes (56%) and 10/20 patients (50%). This improvement occurred within 1 month in 64% and in all by 2 months. Three patients developed allergy. Other side effects included nausea (n = 3), headache (n = 1), urinary hesitancy (n = 1), and mild lymphocytopenia (n = 1). These were dose dependent. Progression of cicatrisation was observed in 1/22 eyes. Success was less likely if there were systemic features of OCP or ocular limbitis. CONCLUSIONS: Sulphapyridine was clinically effective in 50% of patients with moderate marked inflammation and had few side effects. It is a good alternative to dapsone.

Administration, Oral↗
PubMed1996

Elements in the murine c-mos messenger RNA 5'-untranslated region repress translation of downstream coding sequences.

Murine c-mos transcripts isolated from testes have 5'-untranslated regions (5'UTRs) of approximately 300 nucleotides with a series of four overlapping open reading frames (ORFs) upstream of the AUG codon that initiates the Mos ORF. Ovarian c-mos transcripts have shorter 5'UTRs (70-80 nucleotides) and contain only 1-2 of the upstream ORFs (uORFs). To test whether these 5'UTRs affect translational efficiency, we have constructed plasmids for the expression of chimeric transcripts with a mos-derived 5'UTR fused to the Escherichia coli beta-galactosidase coding region. Translational efficiency has been evaluated by measuring beta-galactosidase activity NIH3T3 cells transiently transfected with these plasmids and with plasmids where various mutations have been introduced into the 5'UTR. We show that the 5'UTR characteristic of testis-specific c-mos mRNA strongly represses translation relative to the translation of transcripts that contain a 5'UTR derived from beta-globin mRNA, and this is mainly due to the four uORFs. Each of the four upstream AUG triplets can be recognized as a start site for translation, and no single uAUG dominates the repressive effect. The uORFs repress translation by a mechanism that is not affected by the amino acid sequence in the COOH-terminal region of the uORF-encoded peptides. The very short uORF (AUGUGA) present in ovary-specific transcripts does not repress translation. Staining of testis sections from transgenic mice carrying chimeric beta-galactosidase transgene constructs, which contain a mos 5'UTR with or without the uATGs, suggests that the uORFs can dramatically change the pattern of expression in spermatogenic cells.

Animals↗
PubMed1995

The homeodomain protein IPF-1/STF-1 is expressed in a subset of islet cells and promotes rat insulin 1 gene expression dependent on an intact E1 helix-loop-helix factor binding site.

The mouse homeodomain protein insulin promoter factor-1 (IPF-1) and the rat homologue somatostatin transactivating factor-1 (STF-1) are involved in early pancreatic development and have been implicated in the cell-specific regulation of insulin- and somatostatin-gene expression in mature islet beta- and delta-cells. The cell specificity of IPF-1/STF-1 expression in mature islets is, however, still unclear. Using antisera against recombinant IPF-1 and STF-1 in combination with antisera against islet hormones we find that all beta-cells in monolayers of newborn rat islet cells express STF-1, as do a fraction of the delta-cells. In adult rat and mouse pancreas we find a similar distribution. IPF-1/STF-1 expression was not detected in glucagon-producing alpha-cells. In islet cell tumour models we found that a glucagon/islet amyloid polypeptide (IAPP)-producing pluripotent rat islet cell line (NHI-6F-GLU) expresses STF-1 in all cells prior to insulin gene activation induced by in vivo culture. In contrast, a mouse alpha-cell line (alpha TC1) exclusively expressed IPF-1 in a small subset of insulin-producing cells while an insulin-negative subclone (alpha TC1.9) was negative for IPF-1. In transfection experiments using alpha TC1.9 cells STF-1 activated a rat insulin 1 reporter gene dependent not only on both STF-1-binding sites, but also on the E1-binding site for the helix-loop-helix factor IEF-1. However, the endogenous mouse insulin genes remained inactive in these cells. These results suggest that the insulin promoter acquires its very high, yet cell-specific, activity at least partly through the action of IPF-1/STF-1. This action is dependent on helix-loop-helix factors bound to the E1 element.

Animals↗
PubMed1995

An in vivo model for screening peptidomimetic inhibitors of gelatinase A.

Gelatinase A, a matrix metalloproteinase, is frequently associated with human solid tumors, and its secretion and activation in the tumor milieu is considered important in the process of angiogenesis, invasion, and metastasis. Consequently, metalloproteinase inhibitors may be of value in the therapy of cancer as well as other disease states involving tissue remodeling and release of biologically active peptide/protein by proteolytic cleavage. Here we describe the development of a rapid screening assay for in vivo activity of peptidomimetic inhibitors of gelatinase A that involves assessment of inhibition of an enzyme-substrate reaction in a circumscribed body compartment, the mouse pleural cavity. As examples of the utility of this assay, in vivo activity of the aryl sulfonamide, sulfamyl urea, morpholino and carboxylic acid functionality at the P3' position of a series of hydroxamic acid inhibitors was examined after administration both intraperitoneally (ip) (to approximate systemic administration) and orally. For up to 2 h after ip administration, all inhibitors tested showed marked activity (> 90% inhibition) at 17 mumol/kg (approximately 10 mg/kg). This activity declined in a dose-responsive manner to insignificant levels at 0.67 mumol/kg (approximately 0.4 mg/kg). Aryl sulfonamides showed significant inhibition (> 50%) for up to 7 h after administration. A higher dosage (136 mumol/kg, approximately 80 mg/kg) was required to reveal oral activity, which was observed only with morpholino compounds (> 50% inhibition). Thus, the model described may be of value in the identification of orally active gelatinase A inhibitors.

Administration, Oral↗
PubMed1995

Absence of gluten-specific T lymphocytes in the skin of patients with dermatitis herpetiformis.

Dermatitis Herpetiformis (DH) is an immunobullous skin disease with an associated gluten-sensitive enteropathy. Withdrawal of gluten from the diet leads to the resolution of both the skin lesions and the enteropathy. A T cell-mediated immune response to gluten has been implicated in the damage to the gut; the possible gluten specificity of the T cell infiltrate in DH skin lesions has not, however, been investigated. T cell lines (TCL) were therefore established from the skin lesions of eight patients with DH by culturing skin fragments for 11-17 days with a medium supplemented with 20 U/ml of IL-2. In three cases, gliadin (fraction of gluten toxic to the DH gut) and irradiated, autologous peripheral blood mononuclear cells were also added. The TCL were stained for CD3, CD4, CD8, TCR alpha beta and gamma delta expression by indirect immunofluorescence, and their proliferative responses to mitogens and gluten fraction III (a peptic-tryptic digest of gluten) investigated. Of the eight CD3+ TCL, four were predominantly CD4+ (82.1-98.8%), three predominantly CD8+ (92.6-98.6%) and one TCL contained both 87.6% CD4+ and 95.2% CD8+ T cells, a substantial proportion of which were presumably double-labelled CD4+, CD8+ T cells. All eight TCL, which were almost exclusively TCR alpha beta +, proliferated in response to PHA whilst six out of the eight were stimulated by Concanavalin A. None of the TCL proliferated to gluten fraction III alone; however, two TCL showed increased proliferation to the antigen in the presence of exogenous IL-2 or IL-4 (10 U/ml) compared to cytokine alone.(ABSTRACT TRUNCATED AT 250 WORDS)

CD3 Complex↗
PubMed1995

Efficacy of constant infusion of A-77003, an inhibitor of the human immunodeficiency virus type 1 (HIV-1) protease, in limiting acute HIV-1 infection in vitro.

A-77003, a human immunodeficiency virus type 1 (HIV-1) protease inhibitor, is effective for both acute and chronic infection in vitro and was evaluated clinically by continuous intravenous infusion administration. The minimum effective dose (the concentration required to completely inhibit viral replication) was determined in vitro in a population of uninfected (99%) and HIV-infected (1%) cells exposed to A-77003 by continuous infusion in hollow-fiber bioreactors. The production of infectious HIV and release of p24 antigen from infected cells were completely inhibited in cultures exposed to A-77003 at or above a concentration of 0.5 microM. Measurement of unintegrated HIV-1 DNA synthesis and flow cytometric analysis for cells expressing HIV p24 antigen demonstrated that the spread of HIV to uninfected cells was also blocked at 0.5 microM A-77003. Dose deescalation to 0.25 microM or removal of A-77003 resulted in the limited spread of the virus throughout the culture, the resumption of viral DNA synthesis, and release of p24. HIV produced after exposure to 0.5 microM A-77003 was noninfectious for a period of 72 h after the removal of the drug. Addition of 1 mg of alpha 1-acid glycoprotein per ml to this in vitro system completely ablated the anti-HIV effect of 0.5 microM A-77003. These data suggest that determination of the minimum effective dose under conditions which simulate human pharmacodynamic patterns may be useful in determining the initial dose and schedule for clinical trials. However, other factors, such as serum protein binding, may influence the selection of a therapeutic regimen.

Antiviral Agents↗
PubMed1995

Expression of murine STF-1, a putative insulin gene transcription factor, in beta cells of pancreas, duodenal epithelium and pancreatic exocrine and endocrine progenitors during ontogeny.

The XlHbox 8 homeodomain protein of Xenopus and STF-1, its mammalian homolog, are selectively expressed by beta cells of adult mouse pancreatic islets, where they are likely to regulate insulin expression. We sought to determine whether the expression of the homeobox protein/s during mouse embryonic development was specific to beta cells or, alternatively, whether XlHbox 8/STF-1 protein/s were initially expressed by multipotential precursors and only later became restricted to the insulin-containing cells. With two antibodies, we studied the localization of STF-1 during murine pancreatic development. In embryos, as in adults, STF-1 was expressed by most beta cells, by subsets of the other islet cell types and by mucosal epithelial cells of the duodenum. In addition, most epithelial cells of the pancreatic duct and exocrine cells of the pancreas transiently contained STF-1. We conclude that in mouse, STF-1 not only labels a domain of intestinal epithelial cells but also provides a spatial and temporal marker of endodermal commitment to a pancreatic and subsequently, to an endocrine beta cell fate. We propose a model of pancreatic cell development that suggests that exocrine and endocrine (alpha, beta, delta and PP) cells arise from a common precursor pool of STF-1+ cells and that progression towards a defined monospecific non-beta cell type is correlated with loss of STF-1 expression.

Animals↗
PubMed1995

Software development kit for electrophysiological signals processing.

A software development kit (SDK) for electrophysiological signal processing (hardware control, storage, and graphic visualization) is presented. Its architecture is described, and emphasis is made on the underlying technology. Results obtained in continuous EEG and Evoked Potential monitoring at Cuban Neuroscience Center are presented.

Electrodiagnosis↗
PubMed1994

Transcriptional regulation of the human insulin gene is dependent on the homeodomain protein STF1/IPF1 acting through the CT boxes.

Insulin gene transcription is a unique feature of the pancreatic beta cells and is increased in response to glucose. The recent cloning of insulin promoter factor 1 (IPF1) and somatostatin transcription factor 1 (STF1) unexpectedly revealed that these are mouse and rat homologues of the same protein mediating transactivation through binding of CT box-like elements in rat insulin 1 and somatostatin promoter/enhancer regions, respectively. By using oligonucleotides representing each of the three CT boxes of the human insulin (HI) gene enhancer and nuclear extracts from the mouse islet tumor cell lines beta TC3 and alpha TC1, we have identified a beta-cell-specific binding activity as reported for IPF1, which has maximal affinity toward the CT2 box. However, in pluripotent, HI-transfected rat islet tumor cells, NHI-6F, this binding activity is present prior to induction of (human) insulin gene transcription. Its migration is identical to that of in vitro translated STF1 in electrophoretic mobility-shift assays; it is specifically recognized by anti-STF1 antibodies and has an apparent molecular mass of 46 kDa. Mutation of the CT2 box decreases transcriptional activity of a HI reporter plasmid by approximately 65% in beta TC3 cells and blocks the glucose response in isolated newborn rat islet cells. Furthermore, cotransfection with STF1 cDNA into the glucagon-producing alpha TC1 cells increases the activity of the HI enhancer 4- to 5-fold, suggesting that STF1/IPF1 can confer on alpha TC1 cells the ability to transcribe the HI gene. We conclude that STF1/IPF1 is a necessary but not sufficient key regulator of insulin gene activity, possibly also involved in glucose-regulated transcription.

Animals↗
PubMed1994

An integration-defective U5 deletion mutant of human immunodeficiency virus type 1 reverts by eliminating additional long terminal repeat sequences.

Nonoverlapping deletions that eliminated the 5' (HIV-1US/603del), middle (HIV-1U5/206del), and 3' (HIV-1U5/604del) thirds of the U5 region of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) were studied for their effects on virus replication (transient transfection of HeLa cells) and infectivity (T-cell lines and peripheral blood mononuclear cells). All three mutants exhibited a wild-type phenotype in directing the production and release of virus particles from transfected HeLa cells. In infectivity assays, HIV-1U5/206del was usually indistinguishable from wild-type virus whereas HIV-1U%/603del was unable to infect human peripheral blood mononuclear cells or MT4 and CEM cells. Investigations of HIV-1U5/603del particles revealed a packaging defect resulting in a 10-fold reduction of encapsidated genomic RNA. The HIV-1U5/604del mutant either was noninfectious or exhibited delayed infection kinetics, depending on the cell type and multiplicity of infection. Quantitative competitive PCR indicated that HIV-1U5/604del synthesized normal amounts of viral DNA in newly infected cells. During the course of a long-term infectivity assay, a revertant of the HIV-1U5/604del mutant that displayed rapid infection kinetics emerged. Nucleotide sequence analysis indicated that the original 26-nucleotide deletion present in HIV-1U5/604del had been extended an additional 19 nucleotides in the revertant virus. Characterization of the HIV-1U5/604del mutant LTR in in vitro integration reactions revealed defective 3' processing and strand transfer activities that were partially restored when the revertant LTR substrate was used, suggesting that the reversion corrected a similar defect in the mutant virus.

Base Sequence↗
PubMed1994

Insulin expression in pancreatic islet cells relies on cooperative interactions between the helix loop helix factor E47 and the homeobox factor STF-1.

The development of endocrine cell types within the pancreas is thought to involve the progressive restriction of pluripotential stem cells, which gives rise to the four major cell types: insulin-, glucagon-, somatostatin-, and pancreatic polypeptide-expressing cells. The mechanism by which these peptide hormone genes are induced and then either maintained or repressed during development is unknown, but their coexpression in early precursor cells suggests the involvement of common regulatory factors. Here we show that the somatostatin transcription factor STF-1 is also a principal regulator of insulin expression in beta-cells of the pancreas. STF-1 stimulates the insulin gene by recognizing two well defined islet-specifying elements on the insulin promoter and by subsequently synergizing in trans with the juxtaposed helix-loop-helix protein E47. Within the STF-1 protein, an N-terminal trans-activation domain functions cooperatively with E47 to stimulate insulin transcription. As truncated STF-1 polypeptides lacking the N-terminal activation domain strongly inhibit insulin promoter activity in beta-islet cells, our results suggest that the specification of islet cell types during development may be in part determined by the expression of STF-1 relative to other islet cell factors.

Animals↗
PubMed1994

Hepatic ultrasound findings in the glycogen storage diseases.

Hepatic ultrasonography was performed on 70 patients with the hepatic glycogen storage diseases (GSDs) to assess parenchymal echogenicity. 27 patients had GSD-I, 24 had GSD-III and 19 had GSDs-VI/IX; ages varied from 0.6 to 35.7 years (median 11.7). 31 (44%) had normal or mild parenchymal changes, and 41% (11/27) of those with GSD-I, 25% (6/24) with GSD-III and 11% (2/19) with GSDs-VI/IX had marked changes. No relationships were found between the ultrasonographic appearances and other indices of metabolic control, including plasma triglycerides, total cholesterol or height standard deviation score. Seven adult patients (21-29 years) were found to have hepatic tumours: six with GSD-I and one with GSD-III. Those with GSD-I and tumours tended to have the more severe hepatic parenchymal changes. We conclude that ultrasonography may be useful in identifying patients with GSD-I at risk of hepatic tumour formation.

Adenoma↗
PubMed1994

Correlation of buccal mucosal transudate collected with a buccal swab and urine levels of cocaine.

In this preliminary study, the level of Benzoyl Ecgonine (BE), a metabolite of cocaine, was compared in urine and buccal mucosal transudate collected by a salt impregnated swab in volunteers admitted for cocaine use. The presence of BE (specificity) was verified by the SYVA EMIT method and the urine and transudate levels measured using the Sigma ELISA methods. Results were confirmed using Gas Chromatography/Mass Spectrometry. In all, 44 patients volunteered, and BE in urine or saliva confirmed that each volunteer had in fact used cocaine. The salt-impregnated swab permitted detection of cocaine or its derivative in 27 of the 44 cases. The paper discusses the possibility of using buccal mucosal transudate as collected by salt-impregnated buccal swab as a minimally-invasive measure of cocaine use. This method would allow positive confirmation by a witness that the sample came from a given patient.

Adult↗
PubMed1994

The cutaneous signs of eating disorders.

Anorexia nervosa and bulimia nervosa are common yet occult eating disorders which each affect between 1 and 2% of young adult women in the UK (1). Cutaneous signs may provide valuable clues allowing earlier diagnosis. Eating disorders may both imitate (Table I) and complicate other medical illnesses, resulting in unnecessary and expensive investigations. Organic diseases that may be complicated by eating disorders are Crohn's disease (2), diabetes mellitus (3, 4) and human immune deficiency virus disease (5). The concurrence of an additional eating disorder will destabilize the primary medical condition. In anorexia nervosa the mortality rate has been found to be between 15 and 18% (6, 7). Early diagnosis and treatment are essential to reduce the morbidity and mortality of these concealed conditions. This report describes a patient who exhibited excoriations and scars over the dorsum of her hands, leg ulceration and loss of teeth as cutaneous signs of an eating disorder.

Adult↗