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D Bronson

Publications and source records attributed to D Bronson.

At least 19 recordsLinked to original sources
PubMed2001

Mechanical testing of a single rod versus a double rod in a long-segment animal model.

This study involved the mechanical testing of single-rod segmental hook fixation and double-rod segmental hook fixation in a long-segment animal model. The goals were first to compare the flexibility of a single-rod scoliosis construct with that of a double-rod construct when tested in torsion, and second, to determine the effect of not using instrumentation with every vertebral segment for the single rod. Another study found that the single-rod construct was as stiff in torsion as the standard double-rod construct in a model of 10 vertebral segments. The amount of neutral zone (NZ) rotation was tested in five calf spines using an MTS (Material Testing System) machine. Five constructs were tested and included 1) a single rod with hooks at every level except the apex; 2) a single rod with two fewer hooks; 3) a single rod with four fewer hooks; 4) a double-rod construct; and 5) no instrumentation. The amount of NZ rotation between vertebral segments was measured over 12, 10, 8, 6, 4, and 2 vertebral segments. An analysis of variance with all constructs showed that the instrumented spines had significantly less movement than did the uninstrumented spine. Statistical comparison using analysis of variance of constructs (constructs 1 to 4) showed that over 12 vertebral segments (T4-L3), all single-rod constructs (constructs 1 to 3) allowed more NZ rotation than did the standard double-rod construct. This testing indicated that over 12 vertebral segments the single rod allowed more NZ rotation than a double-rod construct.

Animals↗
PubMed1999

Molecular characterization of a third member of the guanylyl cyclase-activating protein subfamily.

The mammalian retina contains at least two guanylyl cyclases (GC1 and GC2) and two guanylyl cyclase-activating proteins (GCAP1 and GCAP2). Here we present evidence of the presence of a new photoreceptor-specific GCAP, termed GCAP3, which is closely related to GCAP1. The sequence similarity of GCAP3 with GCAP1 and GCAP2 is 57 and 49%, respectively. Recombinant GCAP3 and GCAP2 stimulate GC1 and GC2 in low [Ca2+]free and inhibit GCs when [Ca2+]free is elevated, unlike GCAP1, which only stimulates GC1. GCAP3 is encoded by a distinct gene present in other mammalian species but could not be detected by genomic Southern blotting in rodents, amphibians, and lower vertebrates. The intron/exon arrangement of the GCAP3 gene is identical to that of the other GCAP genes. While the GCAP1 and GCAP2 genes are arranged in a tail-to-tail array on chromosome 6p in human, the GCAP3 gene is located on 3q13.1, suggesting an ancestral gene duplication/translocation event. The identification of multiple Ca2+-binding proteins that interact with GC is suggestive of complex regulatory mechanisms for photoreceptor GC.

Amino Acid Sequence↗
PubMed1998

Guanylate-cyclase-inhibitory protein is a frog retinal Ca2+-binding protein related to mammalian guanylate-cyclase-activating proteins.

Two guanylate-cyclase-activating proteins (GCAP) encoded by a tail-to-tail gene array have been characterized in the mammalian retina. Using frog retina as a model, we obtained evidence for the presence of a photoreceptor Ca2+-binding protein closely related to GCAP. This protein (206 amino acids) does not stimulate guanylate cyclase (GC) in low [Ca2+], but inhibits GC in high [Ca2+], and is therefore termed guanylate-cyclase-inhibitory protein (GCIP). Sequence analysis indicates that GCIP and GCAP1 and GCAP2 have diverged substantially, but conserved domains present in all vertebrate GCAP are present in GCIP. Moreover, partial characterization of the GCIP gene showed that the positions of two introns in the GCIP gene are identical to positions of corresponding introns of the mammalian GCAP gene array. As to the major differences between GCIP and GCAP, the fourth EF hand Ca2+-binding motif of GCIP is disabled for Ca2+ binding, and GCIP does not stimulate GC. Monoclonal and polyclonal antibodies raised against recombinant GCIP identified high levels of GCIP in the inner segments, somata and synaptic terminals of frog cone photoreceptors. The results suggest that GCIP is a Ca2+-binding protein of the GCAP/recoverin subfamily. Its localization in frog cones closely resembles that of GC in mammalian cones. GCIP inhibits GC at high free [Ca2+], competing with GCAP1 and GCAP2 for GC regulatory sites.

Amino Acid Sequence↗
PubMed1997

Repeat expansion detection analysis of (CAG)n tracts in tumor cell lines, testicular tumors, and testicular cancer families.

The mutational expansion of triplet repeat microsatellite sequences underlies the transmission of a number of heritable neurological disorders. However, this form of microsatellite instability has not previously been observed in association with malignant disease. Because trinucleotide expansions can dramatically alter gene expression and protein function, we hypothesized that they might occur in neoplastic cells as a mechanism through which to alter cancer genes. Accordingly, we used the repeat expansion detection technique to determine whether (CAG)n triplet repeat expansions were present in DNA from malignant cells. No expansions were observed in a survey of 20 tumor cell lines derived from neoplasms of the breast, ovary, cervix, endometrium, lung, colon, placenta, or hematopoietic system. However, we did observe expanded (CAG)n tracts in DNA from 5 of 11 testicular tumor cell lines and in 1 of 11 sporadic testicular tumors. Examination of the corresponding normal DNA, when available, revealed that some of the expansions were germline in nature. To assess the possibility that (CAG)n expansions underlie some cases of inherited testicular cancer, we also analyzed germline DNA from members of five kindreds predisposed to this malignancy. An increase in (CAG)n tract size was observed in all five families and was particularly striking in one large pedigree in which expansions were observed in three of four affected siblings. These observations raise the possibility that the germline transmission of expanded (CAG)n tracts may play a role in testicular tumorigenesis.

Adenine↗
PubMed1995

Loss of heterozygosity of tumor suppressor genes in testis cancer.

Little is known of the molecular changes that occur in germ cell tumors (GCT) of the testis. We studied three GCT cell lines and 44 tumors for loss of heterozygosity (LOH) of the tumor suppressor genes APC, MCC, DCC, RB, TP53, and WT-1. We observed that LOH occurred in 55% (21 of 38) of informative cases at DCC, in 28% (10 of 36) of informative cases at APC, in 23% (6 of 26) at MCC, in 30% (13 of 43) at RB, and in 27% (6 of 22) at WT-1. The LOH level in these tumors using anonymous primers mapping to the short and long arms of chromosome 19, which is cytogenetically normal in GCT, revealed LOH of 11 and 5%, respectively. We also observed a LOH of 22% in the TP53 gene, despite the fact that mutations in TP53 do not occur in testis cancer. Since a high frequency of LOH at DCC (18q21.3) occurs equally at all histological subsets in GCT, we conclude that the loss of the function of this gene is an early event in testicular GCTs. However, the observed LOH levels at APC/MCC (5q21), RB (13q14), and WT-1 (11p13) could represent a functional loss of the corresponding tumor suppressor gene in some GCTs or reflect the loss of sequences in the same general chromosome region but involving a different tumor suppressor locus. Therefore, detailed mapping of these chromosomes is required to define the precise locations of maximal LOH in testis cancer.

Base Sequence↗
PubMed1991

Blistering diseases. Diagnostic help for primary care physicians.

At presentation, the differential diagnosis of bullous disease may seem difficult. However, the diagnosis may be clarified by considering such factors as Nikolsky's sign, age of the patient at onset, and pattern and distribution of blisters. Careful review of family, recreational, occupational, and drug histories may also help to identify the cause.

Adult↗
PubMed1985

A human embryonal-yolk sac carcinoma model system in athymic mice.

Two new human cell lines (1411H and 1411HRQmet) have been established from a patient with metastatic testicular cancer whose primary and metastatic histology included seminoma, teratoma, embryonal carcinoma (EC), and yolk sac tumor (YST). In vitro, the cells have been maintained for more than 70 passages, produce alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG), and have a human karyotype. When 2 X 10(7) cells of either line are inoculated into athymic mice, 87.5% of the animals (21/24) develop tumors. Initially 80% to 90% of the mass is EC, whereas the central portion is YST. After 90 to 390 days in vivo, the tumors achieve a large volume (2.13 +/- 0.97 cm3), become cystic, and undergo histologic change. The peripheral rim of the mass remains EC, but the central 80% to 90% becomes YST. The sera of tumor-bearing mice were positive for hCG and AFP in 11% and 38% of animals, respectively. Tumor cyst fluid was positive for hCG and AFP in 87% and 59% of animals, with mean values of 108 mIU/ml and 2,478 ng/ml, respectively. Tumor cyst fluid also contained placental alkaline phosphatase and human fibronectin. These two cell lines are useful for studies on the interrelationship of EC and YST and the differentiation of human germ cell cancer.

Adolescent↗
PubMed1985

Cytoskeletal calmodulin-dependent protein kinase. Characterization, solubilization, and purification from rat brain.

Brain calmodulin-dependent protein kinase was isolated as the major cytoskeletal component of the post-synaptosomal fraction, accounting for about 50% of the total protein. The alpha- and beta-subunits of the enzyme were present in a ratio of about 6:1. The cytoskeletal preparation was also distinguished by the regular presence of tubulin and actin in approximately equimolar amounts to the beta-subunit. Electron microscopic morphology suggested that the enzyme formed a hierarchy of cytoskeletal complexes with an average diameter of 85 nm. These results indicate that cytoskeletal calmodulin-dependent protein kinase may have a structural as well as a catalytic role in neurons. The cytoskeletal enzyme could be solubilized in 8 M urea, displaying similar properties to its cytosolic counterpart. The postsynaptosomal cytoskeleton provides a simplified and well-defined model for the study of the protein-protein interactions involving calmodulin-dependent protein kinase.

Animals↗
PubMed1985

Evidence for an association between calmodulin and membrane patches containing gonadotropin-releasing hormone--receptor complexes in cultured gonadotropes.

participation of calmodulin, clathrin, and actin in receptor mediated endocytosis of gonadotropin-releasing hormone (GnRH) was studied in an in vitro system of dispersed pituitary cells with a triple staining procedure. Cells were incubated in D-Lys6-Pro9-Des10-GnRH-biotin and stained with avidin-peroxidase-diaminobenzidine. Calmodulin, clathrin, and actin as well as luteinizing hormone were identified by indirect immunofluorescence with FITC- and rhodamine-labeled second antibody. The results indicate a close spatial association of calmodulin, but not of clathrin and actin, with GnRH-containing plasma membrane patches.

Actins↗
PubMed1984

Evaluation of AFP glycosylation heterogeneity in cancer patients with AFP-producing tumors.

It has been postulated that analysis of alpha-fetoprotein (AFP) glycosylation heterogeneity in cancer patients whose AFP levels are elevated (e.g., non-seminomatous germ cell tumors, ovarian germ cell tumors and primary hepatocellular carcinoma) might provide useful clinical information. We undertook a study to determine whether scrutiny of AFP glycosylation heterogeneity in patients with non-seminomatous germ cell tumors would provide information useful in diagnosis, staging, prognosis, or monitoring for recurrence of disease following therapy. While an analysis of AFP glycosylation heterogeneity using Concanavalin A lectin chromatography did not provide useful information in regard to staging or prognosis, it does supply unique information useful in discriminating between benign liver dysfunction (e.g. alcoholic hepatitis, chemotherapy-related liver damage) and that due to nonsemininomatous germ cell tumors. It was also concluded that an analysis of Concanavalin A binding patterns is not sufficient to discriminate between recurrent non-seminomatous germ cell tumor and primary hepatocellular carcinoma in patients with elevated serum AFP.

Adult↗
PubMed1984

Ca2+-calmodulin-dependent protein kinase in neuronal nuclei.

Ca2+-calmodulin-dependent protein kinase represents a major enzyme activity in neuronal nuclei. Most of the protein kinase activity is associated with the nuclear matrix but it can phosphorylate a broad range of substrates which derive from different nuclear compartments. Notable among these substrates is a Mr = 50,000 component of the nuclear matrix and a high mobility group chromatin protein which behaves like HMG17. The high level of activity, age- and tissue-specificity, and sensitivity to low concentrations of calmodulin suggest a role for this Ca2+-calmodulin-dependent protein kinase in regulating neuronal function at the level of the nucleus.

Age Factors↗
PubMed1984

Specificity of a phosphatase for phospholipid, Ca2+-dependent protein kinase-phosphorylated histone H1 resides in the catalytic subunit.

A protein phosphatase from liver which acts preferentially on histone phosphorylated with phospholipid, Ca2+-dependent protein kinase has been purified and the intrinsic specificity determined to reside in the catalytic subunit of the enzyme complex. Comparison with a preparation of pork heart protein phosphatase suggests that this specificity may be a general property of a class of protein phosphatases. Protein kinase C-phosphorylated histone H1 represents an improved substrate for phosphatase detection providing a five to tenfold greater sensitivity than other substrates including cAMP-dependent protein kinase phosphorylated H1.

Animals↗
PubMed1983

Histones H3 and H4 inhibit protein kinase C specifically.

The lysine-rich histone H1 is a preferred substrate for the Ca2+-phospholipid-dependent protein kinase (protein kinase C). Histones H3 and H4 are poor substrates but potent inhibitors of the enzyme. The inhibitory effect of H3 and H4 seems to result mainly from a decreased sensitivity of protein kinase C to stimulation by phosphatidylserine (PS). These observations suggest that site-specific phosphorylation of one histone type can be regulated by other histones.

Animals↗
PubMed1983

A specific phosphoprotein phosphatase acts on histone H1 phosphorylated by protein kinase C.

A phosphohistone phosphatase from rat liver cytosol acts specifically on histone H1 that is phosphorylated with the Ca2+-phospholipid-dependent protein kinase (protein kinase C). The apparent Km for 32P-labeled H1 is 1 microM; other histones or cytosolic proteins phosphorylated with protein kinase C or with cyclic AMP-dependent protein kinase are poor substrates for the phosphatase. The enzyme has been partially purified by gel-permeation chromatography and by utilizing a high-performance liquid chromatography ion-exchange column. The physical properties of this enzyme include a Stokes radius of 5.0 nm, a sedimentation coefficient (s20,w) of 7.0 S, and a Mr of 150,000. The detection of protein kinase as well as the specific phosphohistone phosphatase in purified rat liver nuclei suggests a physiologic role for a histone H1 phosphorylation-dephosphorylation cycle mediated by protein kinase C and the corresponding phosphohistone phosphatase.

Animals↗
PubMed1983

Erythropoietin production by a human testicular germ cell line.

An established human testis germ cell line (1411-H) was found to produce significant amounts of erythropoietin (Ep), the primary regulator of erythropoiesis. Media conditioned by the 1411-H cells stimulated erythropoiesis both in vivo and in vitro. This activity was neutralized by anti-Ep. This continuous cell line provides a unique model for the study of the mechanisms of control of Ep biogenesis.

Cell Line↗
PubMed1983

Lupus vulgaris.

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Female↗
PubMed1982

Formation and identification of cytoskeletal components from liver cytosolic precursors.

Liver cytosol forms a macroscopic fibrillary network in the presence of low concentrations of MgCl2. This process represents the generation of 3- to 11-nm filaments from soluble precursors, involving selectively at least 12 major polypeptides. Similar polypeptides are enriched in the detergent-insoluble fraction from hepatocytes, suggesting that they may be important constituents of the native cytoskeleton. AcA 34 gel-permeation chromatography resolves the cytosol into three independently "polymerizing" peaks: A, B, and C. The formation of filaments follows biphasic kinetics in peaks B and C, whereas peak A lacks the slow phase. Filament formation in all three systems is inhibited by 1-15 mM inorganic phosphate, 10 mM NaF, or 10 mM sodium molybdate. The polymerization of peak C only is inhibited by 0.2-2 mM ATP. CaCl2 (1-100 microM) has no apparent regulatory effect. Two-dimensional polypeptide analysis and peptide mapping show that actin is a major component of peak C, while peaks A and B contain prominent polypeptides that may be related to intermediate filament subunits. In addition, all three systems contain two or three high molecular weight (greater than 170,000) polypeptides that may participate in modulating and extending the filament network. The filaments from peaks A and B are soluble in 8 M urea and reform on removal of the urea in the presence of 5 mM MgCl2. The polypeptide composition remains constant through three such cycles.

Actins↗