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Biomedical subjects

D Witte

Publications and source records attributed to D Witte.

At least 37 records · Page 2Linked to original sources
PubMed1996

Turnover and distribution of intravenously administered mannose-terminated human acid beta-glucosidase in murine and human tissues.

Gaucher disease type 1, the most prevalent lysosomal storage disease, is caused by the defective activity of the lysosomal enzyme, acid beta-glucosidase, or glucocerebrosidase. Infusion of purified acid beta-glucosidase containing alpha-mannosyl-terminated oligosaccharides (alglucerase) is efficacious in reversing hematologic, hepatic, splenic, and bony disease manifestations. The murine tissue distribution and turnover of bolus injections of alglucerase was evaluated by enzymatic activity, quantitative cross-reacting immunologic material analyses, and immunofluorescence studies. Enzyme activity measurements detected distribution to liver, spleen, thymus, kidney, and bone marrow mononuclear cells, but not to lungs and brain. In kidney and thymus, the enzyme was transiently present. In liver and spleen, enzyme activity peaked at about 20 min postinjection followed by a biphasic decrease with t1/2 approximately 40-60 min and approximately 12-14 h. In bone marrow maximal enzyme activity was at 40-60 min with a disappearance t1/2 approximately 60 min. Quantitative cross-reacting immunologic material studies of liver and spleen showed delivery of enzyme with decreased catalytic rate constants whose degradation included denaturation and proteolytic components. By immunofluorescence the human enzyme was distributed primarily to reticuloendothelial cells of the liver and spleen. In autopsy material from a Gaucher disease type 2 patient treated with enzyme, immunohistochemical and activity studies showed distributions similar to those in mice. These studies indicate a complex delivery and intracellular degradation of acid beta-glucosidase with lower intrinsic activity than the administered therapeutic agent.

Animals↗
PubMed1996

ABT-431: the diacetyl prodrug of A-86929, a potent and selective dopamine D1 receptor agonist: in vitro characterization and effects in animal models of Parkinson's disease.

(-)-Trans 9,10-hydroxy-2-propyl-4,5,5a,6,7,11b-hexahydro-3-thia-5- azacyclopent-1-ena[c]phenanthrene hydrochloride (A-86929) is a potent and selective full agonist at the dopamine (DA) D1-like receptor. Judging by its binding affinities to the D1 and D2 classes of receptors, the compound is approximately 20-fold D1 receptor-selective, whereas relative potencies based on functional in vitro assays indicate that A-86929 is greater than 400-fold D1-selective. A-86929 has moderate to weak (Ki > 1 microM) affinity at other monoaminergic and peptidergic receptors, at ion channels and at monoamine uptake sites. The catechol of A-86929 was bis-acetylated to produce the prodrug, (-)-trans 9,10-acetoxy-2-propyl-4,5,5a,6,7,11-b-hexahydro-3-thia- 5-azacyclopent-1-ena[c]phenanthrene hydrochloride (ABT-431), which is more chemically stable yet is rapidly converted to the parent compound with a half-life of less than 1 min in plasma. Both A-86929 and ABT-431 produced contralateral rotation in rats bearing unilateral 6-hydroxydopamine lesions, with ED50 values of 0.24 mumol/kg s.c. and 0.54 mumol/kg s.c., respectively. A-86929 and ABT-431 improved behavioral disability scores and increased locomotor activity in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned marmoset model of Parkinson's disease in a dose-dependent manner (the minimum effective dose was 0.10 mumol/kg s.c.). When administered three times daily for 30 consecutive days to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned marmosets, A-86929 significantly improved disability scores throughout the duration of the study. Current Parkinson's disease therapy includes L-dopa, which stimulates both classes of DA receptors by virtue of its conversion to DA in vivo, and direct-acting D2-selective agonists. Stimulation of the D2 receptor, which is associated with all current DA agonist-based therapies, may contribute to their dose-limiting side effects. An agent such as A-86929 (or its prodrug ABT-431), which selectively stimulates the D1 receptor, may represent a novel mechanism for Parkinson's disease therapy with the potential for an improved side-effect profile and, consequently, improved patient compliance.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1996

Immunohistological characteristics of T cell infiltrates in different forms of childhood onset chronic arthritis.

OBJECTIVE: To characterize synovial T cell infiltrate, in terms of CD4/CD8 ratio and level of activation of T cells, in juvenile rheumatoid arthritis (JRA) and juvenile spondyloarthropathy(JSpA), to correlate these findings with clinical outcomes of the different forms of disease, and to compare them with findings in adult RA synovium. METHODS: We studied synovial tissue specimens from 22 individuals with childhood onset of chronic arthritis (12 polyarticular JRA, 5 pauciarticular JRA, 5 JSpA) and 4 with adult RA. Specimens were selected from an initial bank from 40 patients on the basis of significant inflammation on hematoxylin and eosin and CD3 and CD68 monoclonal antibody staining (T cells and macrophages, respectively). Indirect immunohistochemistry was used with monoclonal antibodies to CD3, CD4, CD8, and interleukin 2 receptor alpha to determine CD4/CD8 ratios and the levels of activation within the T cell subsets. The distribution of gamma delta T cells was also studied. RESULTS: Two patterns of T cell infiltration were seen. The majority of patients had lymphocytic aggregates associated with diffuse infiltrates; a few tissue specimens had diffuse infiltrates without aggregates. The CD4/CD8 ratio was significantly lower in pauciarticular course JRA than polyarticular JRA (p < 0.01) and RA (p < 0.05). Similarly patients with JSpA had a significantly lower CD4/CD8 ratio than patients with polyarticular JRA (P < 0.05). The level of T cell activation (CD3+IL-2R+) was significantly higher in pauciarticular compared with both polyarticular JRA (P < 0.01) and RA (p < 0.05). In general, higher levels of activation of CD8 cells than CD4 cells were seen, particularly in the pauciarticular JRA and JSpA groups. gamma delta T cells were prominent in 2 patients. CONCLUSION: Demonstrated differences in T cell subset distribution between types of childhood chronic arthritis at a histopathological level may reflect different pathogenic mechanisms.

Adolescent↗
PubMed1994

Functional dichotomy of neutral and acidic sphingomyelinases in tumor necrosis factor signaling.

Ceramide produced by sphingomyelinases (SMases) has been recognized as an important second messenger in growth factor receptor signaling. Tumor necrosis factor (TNF), through binding to the 55 kDa TNF receptor (TNF-R55), rapidly activates two distinct types of SMase, a membrane-associated neutral (N-)SMase, and an endosomal acidic (A)-SMase. N-SMase and A-SMase are activated independently by different cytoplasmic domains of TNF-R55. Each type of SMase specifically couples to select pathways of TNF signaling. Ceramide generated by N-SMase directs the activation of proline-directed serine/threonine protein kinase(s) and phospholipase A2. In contrast, A-SMase triggers the activation of NF-kappa B. No apparent crosstalk was detected between N-SMase and A-SMase pathways, indicating that ceramide action depends on the topology of its production. These results suggest that N-SMase and A-SMase control important yet dissociable and nonoverlapping pathways of TNF receptor signal transduction.

Animals↗
PubMed1994

Ossification of the Achilles tendon: imaging abnormalities in 12 patients.

Ossification of the Achilles tendon is a rare clinical entity that is characterized by the presence of an ossific mass contained within the fibrocartilaginous substance of the tendon. Because the radiographic features of this condition have not been documented entirely and the magnetic resonance (MR) imaging findings have not been determined, a review of 16 affected tendons in 12 patients was performed in an attempt to characterize the imaging abnormalities associated with this process. MR imaging was performed in three Achilles tendons which demonstrated thickening of the tendons at the level of the ossifications and a lack of intratendinous signal abnormalities compatible with acute tendinitis. Signal intensity similar to that of bone marrow was present in the ossifications.

Achilles Tendon↗
PubMed1994

Expression of the neural intermediate filament proteins peripherin and neurofilament-66/alpha-internexin in neuroblastoma.

BACKGROUND: Peripherin and neurofilament (NF)-66/alpha-internexin are recently characterized, neuron-specific intermediate filament proteins that are expressed in the developing peripheral nervous system. Peripherin, in particular, is highly enriched in neuronal derivatives of the neural crest. We speculated that these intermediate filament proteins would be expressed in neuroblastoma (NB), a neural crest-derived tumor with many neuronal features. EXPERIMENTAL DESIGN: By use of antibodies specific to peripherin and NF-66/alpha-internexin, we detected these proteins on Western blots of NB tissue extracts and in paraffin sections of NBs. RESULTS: Western blotting indicated that NB tumor extracts contained immunoreactive proteins that co-migrated with rat peripherin and human NF-66/alpha-internexin from normal tissues, thus establishing the specificity of the antibodies for these proteins in tumors. The antibody specific for peripherin labeled all NBs, including immature NBs, composite ganglioneuroblastomas and ganglioneuromas. In contrast, the NF-66/alpha-internexin antibody labeled only 50% of NBs, and only weakly labeled most ganglioneuroblastomas and ganglioneuromas. Neither antibody labeled other small blue cell tumors such as lymphomas, rhabdomyosarcomas, Wilms' tumors, and Ewing sarcomas. CONCLUSIONS: The specificity of the peripherin labeling of NB and the ability of the peripherin antibody to label the entire spectrum of NBs, including ganglioneuroblastomas and ganglioneuromas, indicate that this intermediate filament protein has potential as a diagnostic marker for these related neural crest neoplasms.

Animals↗
PubMed1992

The relationship of human papillomaviruses to anorectal neoplasia.

This review begins with an overview of the anatomy of the anal canal, which is followed by a discussion of human papillomavirus (HPV) infections in the anogenital tract. The organization of the HPV genome and the function of the encoded proteins is discussed in relation to the oncogenic potential of these viruses. Particularly stressed are interactions with known tumor suppressor genes. Then the interaction of HPV with the host cells and some growth factors is reviewed. An important consideration is the synergy between this virus and other known carcinogenic factors. These include smoking, immunologic status, and other factors. Finally, the pathologic features of anal warts and malignant lesions are summarized with respect to their histologic findings and expression of viral subtypes.

Anus Neoplasms↗
PubMed1991

Cholecystokinin antagonists: (R)-tryptophan-based hybrid antagonists of high affinity and selectivity for CCK-A receptors.

The intriguing structural similarities of glutamic acid based cholecystokinin (CCK) antagonists (A-64718 and A-65186) and the benzodiazepine CCK antagonist MK-329 (L-364,718) have been reported. Efforts to include the weak CCK antagonist benzotript into this construct utilizing a similar approach have resulted in a novel series of benzotript-based hybrid antagonists N alpha-(3'-quinolylcarbonyl)-(R)-tryptophan di-n-pentylamide (9, A-67396), N alpha-(4',8'-dihydroxy-2'-quinolylcarbonyl)-(R)-tryptophan di-n-pentylamide (23, A-70276), and N alpha-(3'-quinolylcarbonyl)-(R)-5'-hydroxytryptophan di-n-pentylamide (36, A-71134) which possess respectively binding affinities of 23, 21, and 11 nM for the pancreatic CCK-A receptor and which inhibit CCK8-induced amylase secretion. Compound 9 possesses a selectivity of greater than 500-fold for the pancreatic CCK-A receptor over the CCK-B receptor.

Animals↗
PubMed1989

Molecular differential pathology of rhabdomyosarcoma.

Tumors of the soft tissues are classified histogenetically according to their phenotypic resemblance to normal adult tissue. Here we describe molecular approaches that make it possible to distinguish between one class of these tumors, rhabdomyosarcoma, and other small-, round-cell tumors. We show that the ascertainment of specific genotypic changes can be used to distinguish further between the embryonal and alveolar subtypes of rhabdomyosarcoma. We tested our model in two ways: first, in a retrospective analysis of diagnostically problematic cases of undifferentiated, small-cell tumors and, second, in a blind study of pediatric tumors. Rhabdomyosarcoma was correctly identified in all cases using this strategy alone. The underlying simplicity of the strategy used to define rhabdomyosarcoma subtypes with molecular markers suggests a model by which tumors can be unequivocally identified, which may apply equally well to other human solid tumors.

Adolescent↗
PubMed1989

Evidence for a complex regulatory array in the first intron of the human adenosine deaminase gene.

Adenosine deaminase (ADA) is expressed ubiquitously by diverse mammalian cells and tissues but at levels that vary according to tissue and species. In humans, the thymus exhibits levels of the enzyme up to 100-fold higher than most other tissues. Using transgenic mice, we identified human ADA gene regulatory domains. Up to 3.7 kb of 5'-flanking and first exon DNA from the human ADA gene failed to promote the expression of a chloramphenicol acetyl transferase (CAT) reporter gene in an efficient, reproducible, or tissue-appropriate manner in transgenic mice. However, when 12.8 kb of DNA from the first intron of the human ADA gene was placed 3' of CAT-coding and -processing sequences, transgenic mice reproducibly expressed CAT activity in most tissues, with profoundly high levels in the thymus. DNase I hypersensitivity studies demonstrated that among transgenic mouse tissues, human thymus, and a variety of human cell lines, a region of the intron 4-10 kb downstream of the first exon exhibited an array of hypersensitive sites that varied according to tissue and cell type. Deletion of this region from the gene construction eliminated high-level expression in transgenic mice. In transfection-transient expression assays, the 12.8-kb intron fragment exhibited enhancer activity in several cell types. A 1.3-kb fragment encompassing two of the hypersensitive sites exhibited some of these activities. The results of these studies suggest that the diverse pattern of human ADA gene expression is determined, in part, by a cluster of cis-regulatory elements contained within its large first intron.

Adenosine Deaminase↗
PubMed1989

Distinct requirements for activation at CCK-A and CCK-B/gastrin receptors: studies with a C-terminal hydrazide analogue of cholecystokinin tetrapeptide (30-33).

We describe here the properties of tert-butyloxycarbonyl-Trp-Leu-Asp-Phe-NHNH2 (A-57696), a C-terminal hydrazide analogue of tert-butyloxycarbonyl-CCK4 (Boc-Trp-Met-Asp-Phe-NH2), at four cholecystokinin (CCK) receptor-bearing tissues, the guinea pig pancreas and gall bladder (Type A), guinea pig cortex (Type B), and NCI-H345 cells, a human small cell lung cancer cell line that expresses CCK-B/gastrin receptors. Using 125I-Bolton-Hunter-cholecystokinin octapeptide (26-33) (125I-Bolton-Hunter-CCK8) as the radioligand, A-57696 was found to be selective for cortical CCK-B receptors (IC50 = 25 nM), compared with pancreatic CCK-A receptors (IC50 = 15 microM). A-57696 behaved as a competitive antagonist in reversing CCK8-stimulated pancreatic amylase secretion and phosphoinositide breakdown. By Schild analysis, its Kd was determined to be 4.7 and 6.8 microM in amylase and phosphoinositide assays, respectively. A-57696 (100 microM) did not elicit gall bladder contraction, and it inhibited contractions induced by CCK8. The Kd of A-57696 at gall bladder CCK-A receptors was 19 microM. In contrast, A-57696 behaved as a partial agonist (80% of maximal CCK8 response) in stimulating calcium mobilization at CCK-B/gastrin receptors on NCI-H345 cells. A-57696 and CCK8 inhibited each other in calcium mobilization experiments utilizing the fluorescent dye Indo-1. Stimulatory actions of CCK8 and A-57696 were reversed by the CCK-B-selective (R)-L-365,260 (100 nM), whereas at the same concentration, the CCK-A-selective (S)-L-365,260 was ineffective. Binding studies using 125I-Bolton-Hunter-CCK8 and 125I-gastrin indicated that binding sites labeled by these two ligands displayed similar affinities for CCK8, desulfated CCK8, gastrin, A-57696, and both enantiomers of L-365,260. A-57696 represents a new class of CCK-A peptide antagonist at guinea pig pancreas a new class of CCK-A peptide antagonist at guinea pig pancreas and gall bladder. Its contrasting functional activities at guinea pig CCK-A and CCK-B/gastrin receptors in a human tumor cell demonstrate that, in addition to the previously described differences in binding specificity for selective agonists and antagonists, CCK-A receptors and CCK-B/gastrin receptors have different requirements for activation.

Amino Acid Sequence↗
PubMed1985

Autoimmune anti-androgen-receptor antibodies in human serum.

Circulating autoantibodies to human and rat androgen receptors are present at high titers in the blood sera of some patients with prostate diseases. The antibodies from some serum samples were associated with a purified IgG fraction and interacted with the 3.8S cytosolic androgen-receptor complexes of rat ventral prostate to form 9- to 12S units. Other serum samples, however, formed 14- to 19S units, suggesting that other immunoglobulins might be involved. In the presence of an anti-human immunoglobulin as a second antibody, the androgen-receptor-antibody complexes could be immunoprecipitated. The antibodies interacted with the nuclear and the cytosolic androgen-receptor complexes, either the DNA-binding or the nonbinding form, but not with receptors for estradiol, progestin, or dexamethasone from a variety of sources. Human testosterone/estradiol-binding globulin, rat epididymal androgen-binding protein, or rat prostate alpha-protein (a nonreceptor steroid-binding protein) also did not interact with the antibodies to form immunoprecipitates. About 37% of male and 3% of female serum samples screened had significant antibody titer. The chance of finding serum with a high titer is much better in males older than 66 years than in the younger males or females at all ages. The presence of the high-titer antibodies may make it possible to prepare monoclonal antibodies to androgen receptors without purification of the receptors for immunization.

Age Factors↗
PubMed1984

The use of a hydroxylapatite-filter steroid receptor assay method in the study of the modulation of androgen receptor interaction.

Receptors for androgen, estrogen, and glucocorticoid can be assayed by hydroxylapatite adsorption of the radioactive steroid-receptor complex and washing of the adducts on membrane filters mounted on a multiple filter holder. The method is economical, very rapid and sensitive. This new receptor assay method was used to study the modulation of androgen receptor of rat ventral prostate by metal ions, thiols, and ligand structure. The interaction of androgen with the naked receptor is inhibited by 10 microM ZnCl2, CdSO4, or CuSO4 but this inhibition is competed by androgen and is reversed by DTT. The androgen-receptor complex is less sensitive to divalent metal ions but Zn2+, at 3 mM, appears to alter the conformation of the receptor and promote the release of androgen. Certain phenanthrene derivatives exhibited striking structural specificities in their ability to compete with radioactive androgen for binding to the prostate receptor. The results suggest that the receptor has binding preference toward individual ring structure in the steroid.

Animals↗
PubMed1983

Time of appearance and tissue distribution of a cell surface antigen in early chick development.

The distribution of the antigen defined by monoclonal antibody 224-1A6-A1 in the early chick embryo was studied. The antigen is unequivocally present in the rudimentary neural tube as early as the 12 somite stage (approximately 40 h of incubation). The antigen appears on some but not all derivatives of the ectoderm and mesoderm, but appears to be absent on endodermal derivatives. Monoclonal antibody 224-1A6-A1 therefore serves as a marker for early events in the developmental sequence leading toward the formation of the nervous system.

Animals↗