Search PubMed⌕ Search

Biomedical subjects

K R Miller

Publications and source records attributed to K R Miller.

At least 19 recordsLinked to original sources
PubMed2001

Patient with trisomy 6 mosaicism.

Trisomy 6 and trisomy 6 mosaicism were found in chorionic villi cell culture and short term incubation in a prenatal diagnosis at 12 weeks of gestation in a pregnancy with a growth retarded fetus showing nuchal translucency. The child was born in the 25th gestational week with a number of malformations including heart defects, deep-set ears, cleft right hand, cutaneous syndactylies, and overlapping toes of irregular shape and length. Trisomy 6 was not found in peripheral blood lymphocytes but was confirmed in umbilical cord fibroblasts. Currently, at the age of 2-3/4 years, the development of the child is relatively normal despite considerable growth delay. At the age of two years, she developed a papular erythema clinically suggestive of epidermal nevi. Cytogenetic analysis of fibroblast cultures derived from skin from a right hand finger and the inguinal area confirmed the presence of a trisomy 6 mosaicism. This is the first observation of a liveborn with trisomy 6 mosaicism.

Child, Preschool↗
PubMed2001

Linguistic diversity in deaf defendants and due process rights.

Historically, ensuring the due process rights of deaf defendants has been a problematic issue in the criminal justice system (McAlister, 1994; Smith, 1994; Vernon & Coley, 1978; Vernon & Greenburg, 1996; Vernon & Miller, in press; Vernon & Raifman, 1997; Whalen, 1981; Wood, 1984). Inadequate communication can radically affect a deaf defendant's interactions in the courtroom. Pursuant to the concepts of fairness enshrined in the U.S. Constitution and the specific statutory language contained in federal and state laws, the courts must provide equal access for deaf defendants (Berko, 1992; Gallie & Smith, 2000; McCoy, 1992; Simon, 1994; Vernon & Raifman, 1997). It is the responsibility of the court to ensure that the appropriate accommodation is provided in the language most readily understood by the defendant.When adjudicating a deaf criminal defendant, courts must make certain that the defendant has equal access to various due process activities, such as assisting counsel in the development of a defense, deciding whether to testify, deciding which plea to enter, understanding the charges, understanding one's position as defendant, and comprehending the role of the defense and prosecuting attorneys, and judge (Berko, 1994; King, 1990; Simon, 1994; Smith, 1994; Vernon & Coley, 1978; Vernon & Miller, in press; Vernon, Raifman, & Greenberg, 1996).However, complex linguistic issues that impinge on adjudicative competence are present in some deaf defendants (Vernon & Miller, in press; Vernon & Raifman, 1997). Adjudicative competence refers to an individual's ability to adequately comprehend and participate in legal proceedings and due process activities. When diverse language use is an issue, a deaf defendant's ability to participate in proceedings can be established by the court using the modern test of adjudicative competence (Dusky v. U.S., 1960). This test examines a defendant's state of mind at the time of trial rather than at the time of the offense in terms of these factors: a defendant's capacity to participate, reasonable understanding of the proceedings, and level of cognitive functioning, irrespective of any mental disorder. This article will outline linguistic barriers to due process for deaf defendants.

Journal Article↗
PubMed2001

Access to sign language interpreters in the criminal justice system.

Historically, the provision of sign language interpreters to deaf suspects, defendants, and offenders has been a problematic issue in the criminal justice system. Inconsistency in the provision of interpreter services results largely from the ignorance of criminal justice professionals regarding deaf people's communication needs and accommodation options. Through analysis of 22 post-Americans with Disabilities Act cases and a survey of 46 professional sign language interpreters working in criminal justice settings, the present study considered access issues concerning sign language interpreters in law enforcement, courtrooms, and correctional settings. Recommendations to increase the accessibility of interpreting services include providing ongoing awareness training to criminal justice personnel, developing training programs for deaf legal advocates, and continuing access studies.

Criminal Law↗
PubMed1999

The lack of binding of methyl-n-amyl ketone (MAK) to rat liver DNA as demonstrated by direct binding measurements, and 32P-postlabeling techniques.

It has been reported that 14C-labeled methyl-n-amyl ketone (MAK, 2-heptanone) is able to bind spontaneously, in vitro, to isolated rat liver DNA to the extent of 400 pmol/mg DNA; and that 14C-MAK, when given by gavage to female Fischer 344 rats, resulted in HPLC chromatograms of isolated, hydrolyzed liver DNA in which some radiolabel was not associated with the four normal DNA bases dA, dT, dC, and dG. The present studies were undertaken to re-examine the hypothesis that MAK is able to bind to rat liver DNA. In the in vitro study, liver nuclear DNA was incubated with [2-14C]-labeled MAK (25 mCi/mmol) in the absence, or in the presence of rat liver microsomes, precipitated, washed free of unbound MAK, and counted by scintillation spectrometry. No binding to DNA by MAK was detectable. In the in vivo study, groups of five female F344 rats were exposed by inhalation to 0, 80, 400, or 1000 ppm MAK for 6 h/day for 10 days. DNA was purified from the liver nuclei of the 0 and 1000 ppm dosed animals, and 32P-postlabeling techniques were used to assay for adducts. No DNA adducts were detected using these techniques. It was concluded that MAK lacks the ability to bind to rat liver DNA in vitro and in vivo.

Animals↗
PubMed1999

The bacterial SecY/E translocation complex forms channel-like structures similar to those of the eukaryotic Sec61p complex.

The SecYEG complex is a major component of the protein translocation apparatus in the cytoplasmic membrane of bacteria. We have purified a translocationally active complex of the two subunits, SecY and SecE, from Bacillus subtilis. As demonstrated by electron microscopy, SecY/E forms ring structures in detergent solution and in intact lipid bilayers, often with a quasi-pentagonal appearance in projection. The particles represent oligomeric assemblies of the SecY/E complex and are similar to those formed by the eukaryotic Sec61p complex. We propose that these SecY/E rings represent protein-conducting channels and that the two essential membrane components SecY and SecE are sufficient for their formation.

Bacillus subtilis↗
PubMed1999

Clinical significance of postlaser indocyanine green angiographic hot spots in age-related macular degeneration.

OBJECTIVE: To report the natural history and clinical significance of indocyanine green (ICG) angiographic hot spots in age-related macular degeneration (ARMD) after laser photocoagulation. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Two hundred thirty consecutive patients with exudative ARMD who underwent krypton laser treatment between March 1993 and December 1996. INTERVENTION: Krypton laser photocoagulation was performed on all patients. Digital videoangiograms, including both fluorescein angiography and ICG angiography, were obtained at 2 weeks, 4 weeks, 6 weeks, and 3 months postlaser treatment on each patient and repeated if clinical changes were noted. MAIN OUTCOME MEASURES: Detection by ICG of hyperfluorescent spots (hot spots) within the hypofluorescent laser-treated area. RESULTS: Forty patients (18%) developed ICG hot spots 2 weeks after laser treatment. The hot spots disappeared spontaneously without recurrent choroidal neovascular (CNV) membrane in 31 patients (78%). Recurrent CNV was discovered at the hot spot in four patients and away from the hot spot in five patients. CONCLUSION: The postlaser ICG angiographic hot spot is not rare. These spots tend to disappear spontaneously and do not necessarily represent a recurrent CNV. The presence of a hot spot on ICG angiography is not an indication for immediate laser retreatment.

Aged↗
PubMed1998

The multisubunit IkappaB kinase complex shows random sequential kinetics and is activated by the C-terminal domain of IkappaB alpha.

The multisubunit IkappaB kinase (IKK) catalyzes the signal-inducible phosphorylation of N-terminal serines of IkappaB. This phosphorylation is the key step in regulating the subsequent ubiquitination and proteolysis of IkappaB, which then releases NF-kappaB to promote gene transcription. As measured by 33P incorporation into a GST-IkappaB alpha fusion protein, varying both the concentration of GST-IkappaB alpha and [gamma-33P]ATP resulted in a kinetic pattern consistent with a random, sequential binding mechanism. Values of 55 nM and 7 microM were obtained for the dissociation constants of GST-IkappaB alpha and ATP, respectively. The value of alpha, a factor by which binding of one substrate changes the dissociation constant for the other substrate, was determined to be 0.11. This indicates that the two substrates bind in a cooperative fashion. Peptides corresponding to either amino acids 26-42 (N-terminal peptide) or amino acids 279-303 (C-terminal peptide) of IkappaB alpha inhibited the IKK-catalyzed phosphorylation of GST-IkappaB alpha; the C-terminal peptide, unexpectedly, was more potent. The inhibition by the C-terminal peptide was competitive with respect to GST-IkappaB alpha and mixed with respect to ATP, which verified the sequential binding mechanism. The C-terminal peptide was also a substrate for the enzyme, and a dissociation constant of 2.9-6.2 microM was obtained. Additionally, the N-terminal peptide was a substrate (Km = 140 microM). Competitive inhibition of the IKK-catalyzed phosphorylation of the C-terminal peptide by the N-terminal peptide indicated that the peptides are phosphorylated by the same active site. Surprisingly, the presence of the C-terminal peptide greatly accelerated the rate of phosphorylation of the N-terminal peptide as represented by a 160-fold increase in the apparent second-order rate constant (kcat/Km). These results are consistent with an allosteric site present within IKK that recognizes the C terminus of IkappaB alpha and activates the enzyme. This previously unobserved interaction with the C terminus may represent an important mechanism by which the enzyme recognizes and phosphorylates IkappaB.

Amino Acid Sequence↗
PubMed1997

L-arginine and superoxide dismutase prevent or reverse cerebral hypoperfusion after fluid-percussion traumatic brain injury.

To determine whether treatment with L-arginine or superoxide dismutase (SOD) would prove effective in reducing cerebral hypoperfusion after traumatic brain injury (TBI), we measured cerebral blood flow (CBF) using laser Doppler flowmetry (LDF) in rats treated before or after moderate (2.2 atm) fluid-percussion (FP) TBI. Rats were anesthetized with isoflurane and prepared for midline FP TBI and then for LDF by thinning the calvaria using an air-cooled drill. Rats were then randomly assigned to receive sham injury, sham injury plus L-arginine (100 mg/kg, 5 min after sham TBI), TBI plus 0.9% NaCl, TBI plus L-arginine (100 mg/kg, 5 min post-TBI), TBI plus SOD (24,000 U/kg pre-TBI + 1600 units/kg/min for 15 min after TBI), or TBI plus SOD and L-arginine. A second group of rats received TBI plus saline, L-, or D-arginine (100 mg/kg, 5 min after-TBI). After treatment and TBI or sham injury, CBF was measured continuously using LDF for 2 h and CBF was expressed as a percent of the preinjury baseline for 2 h after TBI. Rats treated with saline or D-arginine exhibited significant reductions in CBF that persisted throughout the monitoring period. Rats treated with L-arginine alone or in combination with SOD exhibited no decreases in CBF after TBI. CBF in the SOD-treated group decreased significantly within 15 min after TBI but returned to baseline levels by 45 min after TBI. These studies indicate that L-arginine but not D-arginine administered after TBI prevents posttraumatic hypoperfusion and that pretreatment with SOD will restore CBF after a brief period of hypoperfusion.

Animals↗
PubMed1997

Influence of vesicle surface composition on the interfacial binding of lecithin:cholesterol acyltransferase and apolipoprotein A-I.

Interfacial binding affinities and capacities of lecithin:cholesterol acyltransferase (LCAT) and apolipoprotein A-I (apoA-I) for surfaces of different phosphatidylcholine (PC) composition, cholesterol content, and apolipoprotein content were measured with a vesicle model system. Native polyacrylamide gel electrophoresis was used to separate free protein from vesicle-bound protein. ApoA-I was isolated from human plasma and radiolabeled with iodine, whereas radiolabeled LCAT was purified from the media of Chinese hamster ovary cells that were transfected with human LCAT cDNA and incubated in the presence of [35S] cysteine and methionine. Bound and free radiolabeled LCAT and apoA-I were quantified by phosphorimage analysis. ApoA-I binding was not influenced by cholesterol content (14 mole%) but was influenced by the PC fatty acyl composition of the vesicle. PC species containing long chain, polyunsaturated fatty acids (PUFA) in the sn-2 position resulted in increased binding affinity (Kd = 75-177 nM) but reduced capacity (0.1-0.3 apoA-I/ 1000 PC) in comparison to sn-1 palmitoyl, sn-2 oleoyl PC (POPC, 750 nM and 1.4 apoA-I/1000 PC). LCAT binding affinity to POPC (2190 nM) was stronger in the presence of cholesterol (530 nM), and LCAT binding capacity was reduced (2.63 and 0.6 molecules LCAT/1000 PC, respectively). In comparison to POPC, LCAT binding affinity to sn-1 palmitoyl, sn-2 arachidonyl PC was stronger (611 nM) and binding capacity was reduced (0.7 LCAT/1000 PC). LCAT binding affinity and capacity to sn-1 palmitoyl, sn-2 eicosapentaneoyl PC (2041 nM, and 2.5 LCAT/1000 PC) were similar to those observed for POPC. We conclude that vesicle surface PC fatty acyl composition and cholesterol content significantly influence LCAT and apoA-I interfacial binding and therefore may alter LCAT enzymatic activity.

Animals↗
PubMed1996

Oligomeric rings of the Sec61p complex induced by ligands required for protein translocation.

The heterotrimeric Sec61p complex is a major component of the protein-conducting channel of the endoplasmic reticulum (ER) membrane, associating with either ribosomes or the Sec62/63 complex to perform co- and posttranslational transport, respectively. We show by electron microscopy that purified mammalian and yeast Sec61p complexes in detergent form cylindrical oligomers with a diameter of approximately 85 A and a central pore of approximately 20 A. Each oligomer contains 3-4 heterotrimers. Similar ring structures are seen in reconstituted proteoliposomes and native membranes. Oligomer formation by the reconstituted Sec61p complex is stimulated by its association with ribosomes or the Sec62/63p complex. We propose that these cylindrical oligomers represent protein-conducting channels of the ER, formed by ligands specific for co- and posttranslational transport.

Animals↗
PubMed1996

Glycosylation structure and enzyme activity of lecithin:cholesterol acyltransferase from human plasma, HepG2 cells, and baculoviral and Chinese hamster ovary cell expression systems.

The glycosylation state of lecithin:cholesterol acyltransferase (LCAT) may be important in determining its enzymatic activity. We compared glycosylation structure, enzyme kinetics, and phosphatidylcholine (PC) acyl specificity of human LCAT from four sources: human plasma (pLCAT), media from HepG2 cells (HepG2 LCAT), media from SF21 cells infected with a recombinant baculovirus (bLCAT) and media from stably transfected Chinese hamster ovary (CHO) cells (CHO LCAT). bLCAT was underglycosylated (molecular weight approximately 50 kDa) and resistant to digestion by N-glycanase F, endoglycosidase F, and neuraminidase. CHO and HepG2 LCAT were overglycosylated (approximately 68 kDa and approximately 70-75 kDa) compared to pLCAT (approximately 65 kDa). CHO LCAT, like pLCAT, was sensitive to N-glycanase F and neuraminidase but not to endoglycosidase F. HepG2 LCAT demonstrated resistance to N-glycanase F and endoglycosidase F. Apparent Km values for all four enzymes were similar (1.4-9.2 microM cholesterol) for recombinant high density lipoproteins (rHDL) containing sn-1 16:0, sn-2 18:1 PC (POPC). Apparent Vmax values (nmol cholesteryl ester formed/h per micrograms) were 52.6 for pLCAT, 48.6 for CHO LCAT, 15.3 for bLCAT, and 8.3 for HepG2 LCAT. Changes in PC acyl specificity in the presence and absence of cholesterol were characterized by comparing the ratio of LCAT activity on rHDL containing sn-1 16:0, sn-2 20:4 PC (PAPC) or POPC (PAPC/POPC activity ratio). The ratios for pLCAT, bLCAT, CHO LCAT, and HepG2 LCAT activity were 0.63, 0.49, 0.56, and 0.51 with cholesterol and 0.34, 0.29, 0.36, and 0.99 without cholesterol, respectively. We conclude that LCAT source influences glycosylation structure, which affects the apparent Vmax for cholesteryl ester formation with only minor changes in apparent Km or acyl substrate specificity.

Amidohydrolases↗
PubMed1994

Activation of protein kinase C by phorbol esters disrupts the tegument of Schistosoma mansoni.

The tegument of the human parasite Schistosoma mansoni is critical for parasite survival within the mammalian host. The role of protein kinase C (PKC), a major effector molecule in the phosphoinositide pathway, in maintaining the structural organization of this syncytial layer was examined in adult worms. Phorbol 12-myristate, 13-acetate (PMA) and phorbol 12,13-dibutyrate (PDB), phorbol esters that activate PKC, induced formation of surface vesicles as determined by light and scanning electron microscopy. Similar results were seen with sn-2-dioctanoyl-glycerol, a synthetic analogue of diacylglycerol. No effect was seen in parasites incubated with 4-alpha-phorbol ester or alpha isomers of PMA or PDB, compounds that do not activate PKC. Vesicle formation was reversible in parasites treated with sn-2-dioctanoyl-glycerol but not with phorbol esters. The tegument of male worms was more sensitive to the effect of phorbol esters than females. Transmission electron microscopy revealed vacuolization of the tegument. These data suggest that signal transduction pathways may have a critical role in the maintenance of the structural integrity of the tegument of parasitic helminths.

Animals↗
PubMed1993

Ligand-protein electrostatic interactions govern the specificity of retinol- and fatty acid-binding proteins.

Cellular retinol-binding protein II (CRBP-II) and intestinal fatty acid-binding protein (I-FABP) are both expressed in small intestinal enterocytes and exhibit 31% sequence identity. I-FABP binds a single molecule of long-chain fatty acid and forms an ion-pair electrostatic interaction between the cationic side chain of arginine-106 and the anionic fatty acid carboxyl group. In contrast, CRBP-II binds all-trans-retinol or -retinal and contains a glutamine residue in the corresponding position, residue 109. We have characterized and compared the interactions of fatty acids and retinoids with I-FABP, CRBP-II, and two reciprocal mutant proteins. The mutants were designated CRBP-II(Q109R), where glutamine-109 was replaced by arginine, and I-FABP(R106Q), where arginine-106 was replaced by glutamine. As monitored by titration calorimetry and carbon-13 NMR spectroscopy, the fatty acid-binding properties of CRBP-II(Q109R) were found to be essentially identical to those of wild-type I-FABP. Both proteins bound 1 molecule of fatty acid with identical affinities (Kd = 0.2 microM). The enthalpic contribution to the total free energy of binding was large for both proteins: 66% and 87%, respectively. In addition, the carboxyl groups of fatty acids bound to both proteins were solvent-inaccessible. There was little or no change in the ionization state of the bound fatty acid over a wide pH range, as monitored by the chemical shift of the fatty acid carboxyl 13C resonance. Furthermore, the binding of fatty acid to both proteins was accompanied by a selective perturbation of the guanidino 13C resonance of a single arginine residue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Effects of excitotoxin exposure on metabolic rate of primary hippocampal cultures: application of silicon microphysiometry to neurobiology.

Increasing evidence implicates glutamate receptor over-stimulation in the neurotoxicity associated with a host of metabolic insults, including seizures and hypoxia-ischemia. To begin to understand more completely the role of energy metabolism in the mechanism of neuron death following excitatory amino acid exposure, we investigated the effects of kainic acid exposure on metabolic rate in cultured hippocampal cells using a recently developed silicon microphysiometer. The device gives a continual real-time measure of metabolism in relatively small numbers of cells, as assessed by efflux of protons generated at least in part by ATP hydrolysis and lactic acid production. In the first half of this report, we characterize the feasibility of using this device for measuring cellular metabolism in hippocampal cultures. Metabolic rate in both astrocytes and neurons was readily detectable, with a high signal-to-noise ratio. The rate was proportional to the number of cells and was sensitive to metabolic enhancement or depression. We then utilized this device to study metabolic responses to the excitotoxin kainic acid. We observed a receptor-mediated, dose-dependent increase in metabolic rate upon stimulation by kainic acid, with an EC50 of approximately 100 microM. Exposure to toxic levels of kainic acid for 10 min produced an initial elevation (for 2 hr) in metabolic rate and then a gradual decline in metabolism over the next 8 hr that preceded a measurable loss of cell viability. This study further delineates a time window for the onset of kainic acid-induced damage. The results clearly show the feasibility of using silicon microphysiometry for assessing metabolism of brain cultures and for exploring the relationship between metabolism and synaptic activation.

Animals↗
PubMed1989

Studies on asparagine-linked protein glycosylation in differentiating skeletal muscle cells.

The embryonic development of skeletal muscle proceeds by the adherence and fusion of myoblast cells to form multinucleated myotubes. In the present study, enzymes in the dolichol pathway for asparagine-linked glycoprotein synthesis and oligosaccharide chain composition were characterized in myoblasts and myotubes derived from the C2 (mouse) muscle cell line. The N-acetylglucosaminyltransferase responsible for chain initiation and the mannosyl- and glucosyltransferases for Dol-P-Man and Dol-P-Glc synthesis were characterized with respect to substrate, cation, and detergent dependence. Time course studies in the absence and presence of exogenous Dol-P revealed that myoblasts had a two- to threefold higher capacity than myotubes for Dol-sugar synthesis. Pulse-chase experiments following the elongation of the Dol-oligosaccharide by intact cells showed myoblasts to label oligosaccharide intermediates approximately fourfold greater than myotubes; myotubes, however, were more efficient than myoblasts for converting the intermediates to the glucosylated Dol-tetradecasaccharide. Oligosaccharide chains isolated from sarcolemma glycopeptides were analyzed by Con A, WGA, and QAE chromatography. There were no differences between myoblast and myotube oligosaccharides with respect to the proportion of tri-tetraantennary complex, biantennary complex, and high mannose chains. Hybrid chains were not detected. The major high mannose chain contained nine mannose residues. Sialyltransferase activity was identical. The results suggest that higher levels of Dol-P and protein acceptor contribute to the greater degree of protein glycosylation in myoblast vs myotube muscle cells.

Animals↗
PubMed1989

Localization of light-harvesting complex II to the occluded surfaces of photosynthetic membranes.

The photosynthetic membranes of green plants are organized into stacked regions interconnected by nonstacked regions that have been shown to be biochemically and structurally distinct. Because the stacking process occludes the surfaces of appressed membranes, it has been impossible to conduct structural or biochemical studies of the outer surfaces of the photosynthetic membrane in regions of membrane stacking. Although stacking is mediated at this surface, it has not been possible to determine whether membrane components implicated in the stacking process, including a major light-harvesting complex (LHC-II), are in fact exposed at the membrane surface. We have been able to expose this surface for study in the electron microscope and directly label it with antibodies to determine protein exposure. The appearance of the newly exposed outer stacked surface highlights the extreme lateral heterogeneity of the photosynthetic membrane. The surface is smooth in contrast to the neighboring nonstacked surface that is covered with distinct particles. Although some investigators have suggested the existence of a cytochrome b6/f-rich boundary region between stacked and nonstacked membranes, our results provide no structural support for this concept. To explore the biochemical nature of the occluded membrane surface, we have used an mAb against the amino terminal region of the LHC-II. This mAb clearly labels the newly exposed outer stacked surface but does not label the inner surface or the outer nonstacked surface. These experimental results confirm the presence of the amino terminal region of this complex at the outer surface of the membrane in stacked regions, and also show that this complex is largely absent from nonstacked membranes.

Antibodies, Monoclonal↗