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D K Johnson

Publications and source records attributed to D K Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Smile esthetics after orthodontic treatment with and without extraction of four first premolars.

Standardized frontal photographs were taken of the face during smiling for 60 retention patients; 20 from each of three different private orthodontic practices. Thirty patients had been treated with extraction of four first premolars, and 30 with full edgewise appliances but no extractions. Smile esthetics were judged by a panel of 10 laypersons. There were no significant differences in the mean esthetic score of extraction and nonextraction patients. The only variable that strongly predicted the esthetics of extraction patients was the office in which they were treated, indicating that there may be a significant difference among practitioners in the esthetic outcome of four premolar extraction treatment. Variables related to the "buccal corridor" or other measures of the relationship between the width of the dentition and the width of the mouth during a smile showed no relationship to extraction esthetics. The results indicate that there is no predictable relationship between the extraction of premolars and the esthetics of the smile.

Adolescent↗
PubMed1995

Deficiency of the beta 3 subunit of the type A gamma-aminobutyric acid receptor causes cleft palate in mice.

In addition to its function in the nervous system, gamma-aminobutyric acid (GABA) has been implicated in mouse craniofacial development by the results of both teratological, and genetic studies. We previously reported that disruption of the cleft palate 1 (cp1) locus, closely linked to the pink-eyed dilution (p) locus on mouse chromosome 7, causes a 95% penetrant, recessive, neonatally-lethal cleft palate (CP) in mice homozygous for the p(4THO-II) deletion. We proposed that the beta 3 subunit gene (Gabrb3) of the GABAA receptor might be a candidate for cp1 (ref. 4); our earlier studies had localized cp1 to an interval beginning distal to the gene for the GABAA receptor alpha 5 subunit (Gabra5) and ending within the Gabrb3 coding region. To test the hypothesis that deletion of Gabrb3, and not another gene in the interval, causes CP, we performed an experiment to rescue the CP phenotype by introducing a Gabrb3 transgene into p(4THO-II) homozygotes. We now show that such transgenic mice are phenotypically normal, indicating that Gabrb3 is indeed the cp1 locus.

Animals↗
PubMed1995

Complementation analyses for 45 mutations encompassing the pink-eyed dilution (p) locus of the mouse.

The homozygous and heterozygous phenotypes are described and characterized for 45 new pink-eyed dilution (p) locus mutations, most of them radiation-induced, that affect survival at various stages of mouse development. Cytogenetically detectable aberrations were found in three of the new p mutations (large deletion, inversion, translocation), with band 7C involved in each case. The complementation map developed from the study of 810 types of compound heterozygotes identifies five functional units: jls and jlm (two distinct juvenile-fitness functions, the latter associated with neuromuscular defects), pl-1 and pl-2 (associated with early-postimplantation and preimplantation death, respectively), and nl [neonatal lethality associated with cleft palate (the frequency of rare "escapers" from this defect varied with the genotype)]. Orientation of these units relative to genetic markers is as follows: centromere, Gas-2, pl-1, jls, jlm p, nl (equatable to cp 1 = Gabrb3); pl-2 probably resides in the c-deletion complex. pl-1 does not mask preimplantation lethals between Gas2 and p; and no genes affecting survival are located between p and cp1. The alleles specifying mottling or darker pigment (generically, pm and px, respectively) probably do not represent deletions of p-coding sequences but could be small rearrangements involving proximal regulatory elements.

Animals↗
PubMed1995

Molecular analysis of 36 mutations at the mouse pink-eyed dilution (p) locus.

Thirty-six radiation- or chemically induced homozygous-lethal mutations at the p locus in mouse chromosome 7 have been analyzed at 17 loci defined by molecular probes to determine the types of lesions, numbers of p-region markers deleted or rearranged, regions of overlap of deletion mutations, and genetic distances between loci. A linear deletion map of the [Myod1, Ldh3]-[Snrpn, Znf127] region has been constructed from the molecular analyses of the p-locus deletions. The utility of these deletions as tools for the isolation and characterization of the genes specifying the neurological, reproductive, and developmental phenotypes genetically mapped to this region will grow as more detailed molecular analyses continue.

Animals↗
PubMed1995

Redistribution of GPIb/IX and GPIIb/IIIa during spreading of discoid platelets.

The purpose of the present study was to prelabel mobile receptors on discoid platelets with specific ligands identifiable in the electron microscope and follow their redistribution during spreading. Platelets were incubated in suspension with cytochalasin E (CE) to preserve discoid form, chilled and mounted on cold formvar grids or glass slide fragments to inhibit receptor movement, covered with cold bovine or ristocetin-activated human plasmas as sources of vWF to bind GPIb/IX, fibrinogen-coated gold particles (Fgn/Au) to couple GPIIb/IIIa, or both probes simultaneously, washed to remove CE and rewarmed to 37 degrees C for intervals up to 30 min to stimulate spreading. After brief fixation grids and glass fragments were incubated with anti-vWF antibody and, subsequently, staphylococcal protein A coupled to 5 nm and 10 nm gold particles to detect vWF multimers. Virtually all of the CE-treated chilled platelets retained their discoid shape. Half of the discs (53.3%) bound Fgn/Au, and all bound vWF. Receptors for both ligands were randomly dispersed on discoid cells from edge to edge. During rewarming discoid platelets expanded into spread forms. Fgn/Au-GPIIb/IIIa complexes moved into caps over cell centres and into residual channels of the open canalicular system (OCS). vWF bound to GPIb/IX moved with the cell membrane as the surface expanded during spreading. Discoid platelets prelabelled with both ligands demonstrated similar findings. During rewarming Fgn/Au-GPIIb/IIIa complexes moved to cell centres and into OCS channels. vWF multimers bound to GPIb/IX moved apart from each other toward peripheral margins of the spread cells. Thus, surface activation resulting in conversion of discoid platelets to spread forms does not cause clearance of GPIb/IX receptors to cell centres and channels of the OCS in the manner that GPIIb/IIIa receptors coupled to Fgn/Au are simultaneously translocated and concentrated in OCS channels.

Blood Platelets↗
PubMed1993

Concordance between isolated cleft palate in mice and alterations within a region including the gene encoding the beta 3 subunit of the type A gamma-aminobutyric acid receptor.

Genetic and molecular analyses of a number of radiation-induced deletion mutations of the pink-eyed dilution (p) locus in mouse chromosome 7 have identified a specific interval on the genetic map associated with a neonatally lethal mutation that results in cleft palate. This interval, closely linked and distal to p, and bracketed by the genes encoding the alpha 5 and beta 3 subunits of the type A gamma-aminobutyric acid receptor (Gabra5 and Gabrb3, respectively), contains a gene(s) (cp1; cleft palate 1) necessary for normal palate development. The cp1 interval extends from the distal breakpoint of the prenatally lethal p83FBFo deletion to the Gabrb3 locus. Among 20 p deletions tested, there was complete concordance between alterations at the Gabrb3 transcription unit and inability to complement the cleft-palate defect. These mapping data, along with previously described in vivo and in vitro teratological effects of gamma-aminobutyric acid or its agonists on palate development, suggest the possibility that a particular type A gamma-aminobutyric acid receptor that includes the beta 3 subunit may be necessary for normal palate development. The placement of the cp1 gene within a defined segment of the larger D15S12h (p)-D15S9h-1 interval in the mouse suggests that the highly homologous region of the human genome, 15q11-q13, be evaluated for a role(s) in human fetal facial development.

Animals↗
PubMed1993

Improved detection of hepatic lesions using MoAb B72.3 and a modified 111In labelling technique in patients with recurrent colon cancer.

In this study, the clinical usefulness of 111In-SCN-Bz-diethylenetriaminepentaacetic acid (DTPA) monoclonal antibody (MoAb) B72.3 in patients with recurrent colorectal carcinoma was evaluated. In previous studies with radiolabelled MoAb B72.3, metastatic liver lesions in patients with colon cancer appeared as areas of either increased (hot lesions) or decreased (cold lesions) activity, and extrahepatic lesions appeared as areas of increased activity. Eleven patients were enrolled in this study, and 12 MoAb imaging study results were correlated with computed tomography/magnetic resonance imaging findings. The improved detection rates (number of hot lesions) in MoAb imaging were 48% (14/29) for hepatic metastases and 60% (6/10) for extrahepatic metastases. This represents a significant improvement in the rate of detection of metastatic disease of the liver in patients with recurrent colon cancer when compared to the rate in previous reports. Seventeen clinically unsuspected hepatic and extrahepatic areas of increased uptake were also identified on MoAb studies, and two of these areas were confirmed as metastatic disease at surgery. The rate of detection of extrahepatic metastases with 111In-SCN-Bz-DTPA MoAb B72.3 was also compared and found to be equal to the detection rates with other radiolabelled immunoconjugates. No major adverse side effects were noted during the administration of the MoAb. Four of nine patients tested had a positive anti-mouse antibody (HAMA) response 3 months after injection. These preliminary data indicate that this 111In-labelled immunoconjugate of MoAb B72.3 demonstrates an improvement in hepatic lesion detection rate than did previously reported preparations in patients with recurrent colon cancer.

Adult↗
PubMed1993

Yeast DNA recombination and repair proteins Rad1 and Rad10 constitute a complex in vivo mediated by localized hydrophobic domains.

The Saccharomyces cerevisiae Rad1 and Rad10 proteins are required for damage-specific incision during nucleotide excision repair and also for certain mitotic recombination events between repeated sequences. Previously we have demonstrated that Rad1 and Rad10 form a specific complex in vitro. Using the 'two-hybrid' genetic assay system we now report that Rad1 and Rad10 proteins are subunits of a specific complex in the cell nucleus. The Rad10-binding domain of Rad1 protein maps to a localized region between amino acids 809-997. The Rad1-binding domain of Rad10 protein maps between amino acids 90-210. These domains are evolutionarily conserved and are hydrophobic in character. Although significant homology exists between Rad10 and the human-DNA-repair protein Ercc1 in this region, we were unable to detect any interaction between Ercc1 and Rad1 proteins. We conclude that Rad1 and Rad10 operate in DNA repair and mitotic recombination as a constitutive complex.

Base Sequence↗
PubMed1993

Local intimal-medial uptakes of 125I-albumin, 125I-LDL, and parenteral Evans blue dye protein complex along the aortas of normocholesterolemic minipigs as predictors of subsequent hypercholesterolemic atherogenesis.

This report describes the normalized intimal-medial uptakes [uptake (M, mg.cm-2) divided serum concentration (c0, mg.cm-3)] of 125I-albumin, 125I-low-density lipoprotein (LDL), and in vivo Evans blue dye (EBD)-albumin complex as functions of pressure (P), time (t), molecular species (i), and location (z) along a ventral longitudinal z axis of the normal, intact, aortic endothelial surface in adult normocholesterolemic Sinclair Research Farm (SRF) minipigs and compares these uptake (M/c0) measurements with atherogenesis in hypercholesterolemic cohorts. Uptakes of porcine serum 125I-albumin (n = 21) and 125I-LDL (n = 10) were measured in freshly excised, metabolically supported aortas using a recently developed organ-support system. In vivo intimal-medial EBD uptake vs z data were measured photometrically on opened descending aortas from another group (n = 6) of normocholesterolemic, adult, SRF minipigs 18 hours after the intravenous administration of EBD. For comparison purposes, the corresponding incidence of atherosclerotic lesions along the aortic z axis was calculated using topographic data from hypercholesterolemic minipig cohorts (n = 39). The results showed that uptakes varied greatly with t, z, and macromolecule (i) but not with P. More specifically, the value of M/c0 at any location (z) rose with t, was insensitive to P, decreased with macromolecular (i) size, and varied with z in a pattern that "peaked" in the upstream region, decreased to a nadir in the downstream region, and then rose again as it approached the abdominal celiac orifice. The spatially z-averaged uptake rates for the three different labeled serum proteins were 0.31 x 10(-3) cm.h-1 for 125I-albumin, 0.42 x 10(-3) cm.h-1 for EBD-albumin, and 0.04 x 10(-3) cm.h-1 for 125I-LDL. Nondimensionalized analysis of the individual sets of uptake data indicated that the overall uptake relationship [M(t,P,z,i)/c(io), cm] could be characterized empirically by the simple product of two separate functions: one, a "scaling function" [m(z,i)], that described the uptake magnitude for a given i and z and appeared to be independent of t or P; the other, a "shape function" [s(t,P)], that described the shapes of the uptake vs t and P relationships and appeared to be independent of z or i. The "scaling function" [m(z,i)] vs z contour appeared to correlate well with the corresponding atherosclerotic lesion incidence vs z contour from the group of hypercholesterolemic minipig cohorts. Assuming passive transport, it was shown ("Appendix") that m(z,i) can be interpreted physically in terms of an endothelial diffusive permeability coefficient (P,cm.s-1).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Lesion-by-lesion comparison of computerized tomography and indium-111-labeled monoclonal antibody C110 radioimmunoscintigraphy in colorectal carcinoma: a multicenter trial.

C110 is an anti-carcinoembryonic antigen murine IgG1 monoclonal antibody. Indium-111-labeled C110 radioimmunoscintigraphy (RIS) in colorectal cancer was studied in 51 presurgical patients at four institutions. Planar and SPECT images were obtained at least twice between 48 and 96 hr after injection of 5 mCi/5 mg of 111In-C110. Fifty-one patients had 87 biopsy-proven lesions at surgery (57 hepatic, 30 extra-hepatic). Thirty-three patients (64.7%) had positive radionuclide scans, while 32 (62.8%) had positive CT scans (p = NS). While CT was better at overall lesion detection (62.1% versus 56%, p < 0.05), radionuclide scans were better than CT for extra-hepatic disease (60% versus 46.7%, p < 0.01). Hepatic metastases (52.6%) were visualized by Mab scans to selectively concentrate radioactivity. Uptake in draining lymph nodes was a significant limitation, making evaluation of these sites difficult. Indium-111-C110 shows selective uptake in metastatic colorectal cancer, including more than half of all hepatic lesions evaluated.

Adult↗
PubMed1991

Preclinical assessments of 90Y-labeled C110 anti-carcinoembryonic antigen immunotoxin: a therapeutic immunoconjugate for human colon cancer.

We have synthesized 90Y-labeled immunotoxin (IT) containing ricin A chain and C110 anti-carcinoembryonic antigen monoclonal antibody (MAb) to produce a therapeutic immunoconjugate for human colon cancer. The C110 IT was labeled with 90Y via a benzylisothiocyanate derivative of diethylenetriaminepentaacetic acid. The efficiency of 90Y labeling was consistently 90 to 98%, with a specific activity of about 1 microCi/microgram. In in vitro stability studies, more than 80% of 90Y remained bound to the C110 IT for up to 5 days after incubation. The percentage of binding of 90Y-labeled C110 IT to carcinoembryonic antigen-coated microbeads was 86%, indicating good retention of the initial immunoreactivity of the C110 MAb. In in vitro protein synthesis inhibition assays, 90Y-labeled C110 IT was approximately 3.7-fold more toxic to the LS174T human colon carcinoma cell line than unmodified C110 IT and 1380-fold more toxic than 90Y-labeled C110 MAb. Biodistribution studies of 90Y-labeled C110 IT in LS174T tumor-bearing mice showed that, at 24 h following i.p. injection, high accumulation of radioactivity was seen in the i.p. tumor and liver and, thereafter, high accumulation in these tissues remained almost unchanged until up to 168 h, with percentage of injected dose/g ranging from 15 to 18% in the tumor and 10 to 15% in the liver. The radioactivity in the spleen and bone gradually increased with time and reached their highest levels (approximately 8% of injected dose/g) at 168 h. Estimation of absorbed radiation doses to the tissues showed that i.p. tumor would have received an approximately 1.5 to 7 times higher radiation dose than normal organs. In in vivo therapeutic trials, 90Y-labeled C110 IT provided survival prolongation of LS174T tumor-bearing mice superior to that with either unmodified C110 IT or 90Y-labeled C110 MAb (4 less than 0.01; Mann-Whitney U test). These results indicate that 90Y-labeled C110 anti-carcinoembryonic antigen IT may be a potent therapeutic immunoconjugate for human colon cancer and that it may have direct relevance for i.p. treatment of peritoneal carcinomatosis from colon cancers.

Animals↗
PubMed1991

Detection of hepatic metastases from colorectal carcinoma using indium-111 (111In) labeled monoclonal antibody (mAb): MSKCC experience with mAb 111In-C110.

Sixteen patients with colorectal carcinoma and a rising serum carcinoembryonic antigen (CEA) level and no evidence of extra-abdominal disease were administered 5 mg of an anti-CEA monoclonal antibody (mAb), C110, labeled with approx. 5 mCi of 111In. All patients subsequently underwent exploratory laparotomy, and samples of tumor and normal tissue were obtained. Hepatic lesions (confirmed by histopathology) were visualized as areas of increased radiotracer uptake in 13 of 16 patients. Single photon emission computed tomography (SPECT) considerably aided detection, being positive in two patients with normal planar images. Ten of the 16 patients had positive x-ray computed tomographic (CT) images. The radioimmunodiagnostic study was falsely negative in 3 of 16 patients with subsequently proven hepatic disease, in one of whom CT was also normal. The antibody study was positive in 80% of lesions, thus being, in this small series, significantly more sensitive (P less than 0.01) than CT. 111In-C110 is a promising monoclonal antibody for the detection of hepatic metastases from colorectal carcinoma; this is the first study to show consistently greater concentration of 111In-labeled antibody in hepatic lesions than in surrounding normal hepatic parenchyma.

Adult↗
PubMed1991

Reverse genetics in the mouse and its application to the study of deafness.

Genetic variants of the laboratory mouse can serve as useful models for hereditary deafness syndromes in humans. Recessive mutations at the shaker-1 (sh-1) and whirler (wi) loci, in chromosomes 7 and 4, respectively, both result in circling behavior and a deafness syndrome. In sh-1 homozygotes this deafness is associated with neurophysiological abnormalities that may be accompanied by structural abnormalities of the inner ear. Radiation-induced deletion mutations are being used in a strategy of reverse genetics to identify the genes defined by these mutations. Genetic analyses have refined the position of sh-1 to a chromosomal interval between break points of deletions involving the closely linked albino (c) locus. A cDNA encoding olfactory marker protein (OMP) and the anonymous locus D7OR1 have also been mapped to this interval. These clones contribute to the physical map of the sh-1 region and could be important for accessing the sh-1 gene itself. Similarly, we have identified a radiation-induced deletion of the brown (b) locus that covers the wi locus and two that do not. Thus, the wi locus has been located within a chromosome 4 interval defined by structural rearrangements, which should likewise aid in identifying closely linked molecular clones.

Animals↗
PubMed1990

Pharmacokinetics in patients of an anti-carcinoembryonic antigen antibody radiolabeled with indium-111 using a novel diethylenetriamine pentaacetic acid chelator.

The pharmacokinetics of the C110 anti-carcinoembryonic antigen antibody radiolabeled with 111In via a novel benzylisothiocyanate derivative of diethylenetriamine pentaacetic acid have been determined in 12 patients. The chelator was attached to the protein via a thiourea bond and in such a way that all 5 carboxymethyl arms were presumably able to participate in chelation. Patients with known or suspected colorectal carcinoma received between 5 and 20 mg of the IgG antibody labeled with 5 mCi of 111In. Individual organ radioactivity levels were quantitated, and serum and urine samples were analyzed, principally by size exclusion high-performance liquid chromatography (HPLC). Total urinary excretion averaged 0.18% of the injected dose/h with large patient to patient variation. At early times postadministration (less than 8 h) the predominant radiolabeled species in urine was free diethylenetriamine pentaacetic acid most probably administered as a small radiocontaminant in the injectate. Thereafter, radioactivity in urine was primarily present as a low molecular weight catabolic product. Analysis of serum by size exclusion HPLC occasionally showed 3 radioactivity peaks, 2 of which are due to circulating immune complexes and labeled antibody. The third peak is of low molecular weight and is due to one or more products of antibody catabolism. Transchelation of 111In to circulating transferrin was observed but at modest levels. Quantitation of organ radioactivity showed that 18 +/- 4 (SD)% of the injected dose was in the liver at 1 day postadministration and 1.4 +/- 1.1 and 1.2 +/- 0.9% was in the spleen and in both kidneys, respectively, at this time. The mean half-life for clearance of total injected radioactivity was fitted to a single exponential and was found to be 34 h (SD, 14 h; N = 13) and that for antibody alone, assessed by size exclusion HPLC analysis of serum samples, was calculated to be 22 h (SD, 8 h; N = 10). Neither of these values nor organ radioactivity levels were affected by antibody-loading dose.

Adult↗
PubMed1990

An optimized antibody-chelator conjugate for imaging of carcinoembryonic antigen with indium-111.

A monoclonal antibody to carcinoembryonic antigen showing minimal cross-reactivity with blood cells and normal tissues was derivatized with benzylisothiocyanate derivatives of EDTA and DTPA. Seven chelators per immunoglobulin could be incorporated without loss of immunoreactivity. The resulting conjugates, labeled with indium-111, showed low liver uptake in animals. A cold kit, comprising the DTPA conjugate at a molarity of antibody bound chelator exceeding 1 x 10(-4) M, gave radiochemical yields of indium labeled antibody of greater than or equal to 95% and was stable for 1 yr.

Animals↗
PubMed1990

Rhabdomyosarcoma-associated locus and MYOD1 are syntenic but separate loci on the short arm of human chromosome 11.

The MYOD1 locus is preferentially expressed in skeletal muscle and at higher levels in its related neoplasm, rhabdomyosarcoma. We have combined physical mapping of the human locus with meiotic and physical mapping in the mouse, together with synteny homologies between the two species, to compare the physical relationship between MYOD1 and the genetically ascertained human rhabdomyosarcoma-associated locus. We have determined that the myogenic differentiation gene is tightly linked to the structural gene for the M (muscle) subunit of lactate dehydrogenase in band p15.4 on human chromosome 11 and close to the p and Ldh-1 loci in the homologous region of mouse chromosome 7. Because the rhabdomyosarcoma locus maps to 11p15.5, MYOD1 is very unlikely to be the primary site of alteration in these tumors. Further, these analyses identify two syntenic clusters of muscle-associated genes on the short arm of human chromosome 11, one in the region of rhabdomyosarcoma locus that includes IGF2 and TH and the second the tightly linked MYOD1 and LDHA loci, which have been evolutionarily conserved in homologous regions of both the mouse and the rat genomes.

Alleles↗
PubMed1989

Molecular cloning and mapping of the ecotropic leukemia provirus Emv-23 provides molecular access to the albino-deletion complex in mouse chromosome 7.

Genetic analysis of radiation-induced deletion mutations involving the chromosome 7 albino (c) locus has expanded the functional map of this 6 to 11-cM region of the mouse genome. To generate one of many points of molecular access necessary for intensifying the analysis of the genes and phenotypes associated with this particular complex of deletions, we have cloned an endogenous ecotropic leukemia provirus (Emv-23), known to be closely linked to c, along with its flanking chromosome 7 sequences. A unique-sequence probe (23.3), derived from a region immediately 5' to the proviral integration site, was found to map less than 0.5 cM from c in a standard backcross analysis. Southern blot analysis of DNAs from animals carrying homozygous or overlapping albino deletions demonstrated that the 23.3 probe was deleted in several relatively small c-region deletions. The deletion mapping of the 23.3 probe places the Emv-23 locus between c and Mod-2, just proximal to a region important for male fertility and juvenile fitness. Mapping of this locus also provides a refinement of the genetic/deletion map for several mutations within this deletion complex.

Albinism↗