Biomedical subjects
A Martin
Publications and source records attributed to A Martin.
A modification of the extended Hildebrand approach to predict the solubility of structurally related drugs in solvent mixtures.
A modification of the extended Hildebrand equation is proposed to estimate the solubility of an organic drug in solvent mixtures. The equation accurately reproduces the solubility of four sulphonamides in dioxane-water mixtures without requiring the heat of fusion of the solute. A single equation is obtained for predicting the solubility of related drugs using the solubilities of the drugs in the pure solvents, dioxane and water, and solute-solvent interaction terms consisting of the solubility parameter, delta 2, of the solute and the solubility parameter, delta 1, and basic partial solubility parameter, delta 1b, of the solvent mixture. By this procedure a single equation was obtained to estimate the solubilities of three xanthines in dioxane-water and another equation to obtain the solubilities of four sulphonamides. The equation obtained for sulphonamides is able to predict the experimental solubilities of two parent compounds, sulphasomidine and sulphathiazole, and the solubilities of a drug of different structure, p-hydroxybenzoic acid. This suggests that the intermolecular solute-solvent interaction of sulphonamides and p-hydroxybenzoic acid are similar. The results indicate that the solubility behaviour of drugs having different structures may be modelled using a common equation provided that they show similar solute-solvent interactions.
Functional studies of truncated soluble intercellular adhesion molecule 1 expressed in Escherichia coli.
We have expressed in Escherichia coli the two N-terminal immunoglobulin (Ig)-like domains of the intercellular adhesion molecule 1 (ICAM-1). The first 188 residues of ICAM-1 were expressed with an N-terminal methionine (MP188) or as a maltose-binding fusion protein which was cleaved with factor Xa (XP188). After refolding, both MP188 and XP188 were active in binding to the leukocyte integrin lymphocyte function-associated antigen 1, which has previously been shown to bind to the N-terminal Ig domain of ICAM-1. The major group of rhinoviruses and malaria-infected erythrocytes bind to distinct sites within the first Ig-like domain of ICAM-1. Both MP188 and XP188 bound to malaria-infected erythrocytes; however, only XP188 inhibited human rhinovirus plaque formation. A product (MdQ1P188) with the initiation methionine fused to residue 2, i.e., with glutamine 1 deleted, inhibited plaque formation. MdQ1P188 was able to induce a conformational change of the virus capsid as shown by conversion of 149S particles to 85S particles, whereas MP188 had no effect. These results show that functionally active fragments of ICAM-1 can be produced in E. coli, that glycosylation is not required for ligand binding, and that the N-terminal residue of ICAM-1 is proximal to or part of the human rhinovirus-binding site.
A mutation in the RNA polymerase of poliovirus type 1 contributes to attenuation in mice.
The attenuated Sabin strain of poliovirus type 1 (PV-1) differs from the neurovirulent PV-1 Mahoney strain by 55 nucleotide mutations. Only one of these mutations (A-480-->G, in the 5' noncoding (5' NC) region of the genome, is well characterized, and it confers a strong attenuating effect. We attempted to identify genetic attenuation determinants in the 3'-terminal part of the Sabin 1 genome including the 3D polymerase (3Dpol) gene and the 3' NC region. Previous studies suggested that some of the 11 mutations in this region of the Sabin 1 genome, and in particular a mutation in the polymerase gene (U-6203-->C, Tyr-73-->His), are involved to some extent in the attenuation of PV-1. We analyzed the attenuating effect in the mouse model by using the mouse-adapted PV-1/PV-2 chimeric strain v510 (a Mahoney strain carrying nine amino acids of the VP1 capsid protein from the Lansing strain of PV-2). Mutagenesis of locus 6203 was performed on the original v510 (U-6203-->C) and also on a hybrid v510/Sabin 1 (C-6203-->U) carrying the downstream 1,840 nucleotides of the Sabin 1 genome including the 3Dpol and 3' NC regions. Statistical analysis of disease incidence and time to disease onset in numerous mice inoculated with these strains strongly suggested that nucleotide C-6203 is involved in the attenuation of the Sabin 1 strain. Results also suggested that, among the mutations located in the 3Dpol and 3' NC regions, nucleotide C-6203 may be the principal or the only one to be involved in attenuation in this mouse model. We also found that the effect of C-6203 was weaker than that of nucleotide G-480; the two nucleotides acted independently and may have a cumulative effect on attenuation. The U-6203-->C substitution also appeared to contribute to the thermosensitivity of the Sabin 1 strain.
Rearrangements of c-myc and c-abl genes in tumour cells in Burkitt's lymphoma.
Rearrangements of oncogenes c-myc and c-abl were detected by non-radioactive hybridisation in a case of Burkitt's lymphoma/leukaemia. The surface phenotype of Burkitt's cells were positive for CD19, CD20, HLA-DR, CD14, CD33 and surface immunoglobulin markers. Although cytogenetic analysis was not performed, the c-myc and heavy immunoglobulin genes had the same 14.2 kilobase EcoRI molecular size fragment, suggesting a possible t(8;14) translocation which is a common marker of this malignancy. The c-abl oncogene was also rearranged in DNA digested BamHI and EcoRI. The physiopathological implications of the rearranged c-abl gene are unknown, this being the first case, as for as is known, of Burkitt's lymphoma/leukaemia with a rearranged c-abl gene.
Endogenous antigen presentation by autoantigen-transfected Epstein-Barr virus-lymphoblastoid cells. I. Generation of human thyroid peroxidase-reactive T cells and their T cell receptor repertoire.
To develop a model for endogenous thyroid autoantigen presentation, we transfected EBV-transformed B lymphoblastoid cell lines (EBV-LCL), established from patients with autoimmune thyroid disease and normal controls, with cDNA for the human thyroid autoantigen thyroid peroxidase (hTPO). hTPO-antigen presentation to patient peripheral blood T cells was demonstrated after stimulation in vitro for 7 d with irradiated hTPO-transfected or untransfected autologous EBV-LCL. Anti-hTPO-reactive T cells were subsequently cloned in the presence of irradiated, autologous hTPO-transfected EBV-LCL and IL-2.10 T cell-cloned lines exhibited specific hTPO-induced proliferation (stimulation indices of 2.1-7.9) towards autologous hTPO-transfected EBV-LCL, and were subjected to human T cell receptor (hTCR) V gene analysis, using the PCR for the detection of V alpha and V beta hTcR gene families. The results indicated a preferential use of hTCR V alpha 1 and/or V alpha 3 in 9 of the 10 lines. In contrast, hTCR V beta gene family use was more variable. These data demonstrate a model for the endogenous presentation of human thyroid peroxidase in the absence of other thyroid specific antigens. The high frequency of antigen-specific T cells obtained from PBMC using this technique will facilitate further studies at both the functional and hTCR V gene level.
Islet cell autoantigen 69 kD (ICA69). Molecular cloning and characterization of a novel diabetes-associated autoantigen.
We have identified a novel 69-kD peptide autoantigen (ICA69) associated with insulin-dependent diabetes mellitus (IDDM) by screening a human islet lambda gt11 cDNA expression library with cytoplasmic islet cell antibody positive sera from relatives of IDDM patients who progressed to the overt disease. The deduced open reading frame of the ICA69 cDNA predicts a 483-amino acid protein. ICA69 shows no nucleotide or amino acid sequence relation to any known sequence in GenBank, except for two short regions of similarity with BSA. The ICA69 cDNA probe hybridizes with a 2-kb mRNA in poly(A+) RNA from human pancreas, brain, heart, thyroid, and kidney, but not with skeletal muscle, placenta, spleen, or ovary. Expression of ICA69 was also detected in beta cells and cell lines, as well as in tumoral tissue of islet cell origin. The native ICA69 molecule migrates to 69 kD in SDS-PAGE as detected with specific antibodies. Serum samples from relatives of IDDM patients specifically reacted with affinity-purified recombinant ICA69 on Western blotting. The structural gene for ICA69 was designated ICA1. A homologue in the mouse, designated Ica-1 was mapped to the proximal end of chromosome 6 (within 6 cM of the Met protooncogene). ICA69 adds a novel autoantigen to the family of identified islet target molecules, and by the manner of its identification and characterization large amounts of antigen are available for development of quantitative, convenient predictive assays for autoantibodies and analysis of the role of this molecule in diabetes autoimmunity, as well as its physiologic function.
Neuropsychological performance, mood, and complaints of cognitive and motor difficulties in individuals infected with the human immunodeficiency virus.
Seventy-nine military medical beneficiaries infected with human immunodeficiency virus (HIV+) and 27 HIV-seronegative control subjects (HIV-) completed a neuropsychological evaluation and a semistructured interview inquiring about difficulties in function. More HIV+ than HIV- subjects reported difficulties. HIV+ subjects reporting difficulties were significantly more likely to be deficient on attention, response speed, motor function, and memory than those not reporting difficulties. Findings for early-stage HIV+ subjects were similar. HIV+ individuals who complained of difficulties reported depression and anxiety symptoms significantly more frequently than those who did not complain, but these symptoms were not related to neuropsychological performance. Complaints of difficulties by HIV+ individuals may reflect either actual neuropsychological deficiency or mood disturbance, but the effects of each appear to be independent.
Clinical management of lithium-induced polyuria.
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Preservation of functioning human thyroid organoids in the scid mouse: 1. System characterization.
We have characterized a system for preserving reconstituted human thyroid follicles in vivo by transplanting human thyrocytes into mice with severe combined immunodeficiency (scid mice). Human thyroid organoids were constructed from thyroid monolayer cells derived from both normal and abnormal thyroid tissue, and embedded within a basement membrane preparation which was then transferred sc to scid mice. As early as 4 weeks, and as late as 3 months post transplantation, histological examination of human thyroid organoids demonstrated widespread neofollicle formation and colloid accumulation which stained positive for human thyroglobulin (hTg). Although there were no changes in murine serum T4 levels; the transplanted thyroid epithelial cells secreted hTg into the scid mouse circulation (with an average level of 29 micrograms/L). In addition, hTg release was stimulated in vivo by ip administration of recombinant human TSH (0.1-1.0 IU/mouse) achieving greater than 20-fold increases in scid mouse serum hTg levels. In situ immunohistochemistry showed that thyroid organoids derived from patients with Graves' disease retained scattered lymphocytes in peripolesis with the thyroid epithelial cells; those lymphocytes were identified as human T cells of the memory (CD45RO +), rather than naive, type. These data demonstrate that functioning human thyroid organoids establish in scid mice and remain responsive to TSH stimulation. The system offers a unique opportunity to examine human thyroid-lymphocyte interaction within the confines of a predictable animal model.
Preservation of functioning human thyroid organoids in the scid mouse: II. Biased use of intrathyroidal T cell receptor V genes.
The severe combined immunodeficiency (scid) mouse, which lacks functional B cells and T cells, has proven a useful model for exploring the survival of transplanted human lymphocytes and thyrocytes. In order to further characterize T cell infiltrates in reconstituted sc human thyroid organoids, we examined for the presence of 18 human T cell receptor (hTcR) V alpha and 21 hTcR V beta gene families using polymerase chain reaction (PCR) analysis. Human TcR V gene activity was confirmed by Southern blot analysis of the PCR fragments from all but one of the thyroid organoids, confirming the continued survival of human T cells within the thyroid organoids. However, only 3.5 out of 18 V alpha and 5.9 out of 21 V beta gene families were detected in these human thyroid organoids indicating a marked bias in T cell survival. Sequencing of the V-D-J regions of the amplified TcR fragments showed that approximately 60% of the sequences were representative of clonally expanded T cells. Hence, these passenger T cells exhibited highly biased use of particular TcR V gene families similar to that observed previously in thyroid tissue and intrathyroidal T cell cultures. Furthermore, variations in the V-D-J regions of sequences from similar V gene families indicated that the V gene region was important in T cell selection rather than the CD3 region.
Responses of dwarf and normal chickens to feed restriction, Eimeria tenella infection, and sheep red blood cell antigen.
Relationships among stress responses, habituation to feed restriction, resistance to Eimeria tenella, and antibody response to SRBC were studied in dwarf and normal White Plymouth Rocks. Transfer of chicks at 22 days of age from starter to developer batteries resulted in an increase within 24 h of heterophil:lymphocyte (H:L) ratios of chicks of both genotypes. Restriction of feed intake from ad libitum (AL) to 60% of ad libitum reduced body weight and increased size of the crop-esophagus. As measured by H:L ratios, the effect of adapting to the 60% feed restriction dissipated between 12 and 16 days after initiation. Release of 60% restricted chicks to 80% of ad libitum also elicited a stress response as measured by H:L. These effects were noted in both dwarf and normal chicks. Time required for chicks on restriction to consume their daily allotment was curvilinear with a plateau occurring at a smaller value for dwarf than for normal chicks. Neither feeding regimen nor genotype had an effect on antibody response to SRBC. Resistance to E. tenella was greater in normal than dwarf chicks and greater for restricted than ad libitum chicks.
Antigen-specific T cell proliferation following coccidia infection.
Coccidia antigen-specific T lymphocyte proliferation induced by Eimeria acervulina was measured in chickens congenic at the major histocompatibility complex and in two unrelated lines. Sporozoites and merozoites induced high proliferation of lymphocytes following primary infection, with similar changes seen for splenic or peripheral blood lymphocytes. Highest antigen-specific proliferation after both primary and secondary infection was seen in Line 15I5, which contributed the background genome to the congenic lines. In general, merozoites elicited higher proliferation responses than sporozoites. Analyses of differences between uninfected and infected chickens showed that, at some points in the infection cycle, proliferation of lymphocytes was greater and at other times less for infected than uninfected chickens.
[Tissue diffusion of amoxicillin-clavulanic acid for antibiotic prophylaxis in colorectal surgery].
Tissue penetration of amoxicillin and clavulanic acid given for antibiotic prophylaxis was studied in 15 patients. On induction of anesthesia patients were given 2 g amoxicillin and 200 mg clavulanic acid. The same dose was given two hours later. At time of surgical incision amoxicillin and clavulanate levels were 15.9 +/- 7.7 micrograms/g and 2.23 +/- 2.69 micrograms/g in abdominal wall fat and 16.6 +/- 10.5 and 1.72 +/- 1.35 micrograms/g in epiploic fat, respectively. Similar levels were measured at time of closure of the abdomen. In colonic wall, amoxicillin et clavulanate levels were 22.7 +/- 13.4 micrograms/g and 2.65 +/- 2.35 micrograms/g. By comparison with blood levels, tissue penetration of both drugs was 20 to 30 p. cent into fatty tissues and 60 to 70 p. cent into colonic wall.
The NASCET-ACAS plaque project. North American Symptomatic Carotid Endarterectomy Trial. Asymptomatic Carotid Atherosclerosis Study.
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[Liver transplantation in Italy and the scarcity of donors: causative factors and ethical considerations].
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[Promotion of ethics in gastroenterology: joint meeting of the members of JSGE and OMGE].
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[Ivemark syndrome: 2 case reports].
Ivemark Syndrome is a multiple organ syndrome associated with splenic abnormalities, complex cardiac pathology and an abnormality of the abdominal viscera. The incidence in our department is 1/6000 deliveries and the teratogenic effect seems to occur between the 30th and 40th days of intrauterine life, but the cause is unknown. The principal warning signal is bradycardia. Prenatal diagnosis can be made by ultrasound. The prognosis depends on the degree of malformation of the heart.