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Biomedical subjects

R D Coleman

Publications and source records attributed to R D Coleman.

At least 19 recordsLinked to original sources
PubMed1999

Unexpected ratio of allozyme expression in diploid and triploid individuals of the clonal hybrid fish Phoxinus eos-neogaeus.

Phoxinus eos-neogaeus, a North American freshwater fish, was formed by hybridization between P. neogaeus and P. eos. Individuals of P. eos-neogaeus express one allozyme of P. eos and one allozyme of P. neogaeus for enzymes for which the parental allozymes are distinctive. We performed densitometry on phosphoglucomutase (PGM) and one glucose-6-phosphate isomerase locus (GPI-A) separated by cellulose acetate electrophoresis to determine if the parental species' allozymes are expressed in proportion to the number of genomes present in diploid and triploid individuals, and if these enzymes are regulated separately in different tissues. In diploids, activity of the P. eos allozyme was greater than the P. neogaeus allozyme in eye, liver, and muscle but not in heart (one sample t-test, P = 0.05) for PGM. The activity of the P. eos GPI-A allozyme was significantly greater than the P. neogaeus allozyme in heart, eye and muscle but not in liver (one sample t-test, P = 0.05). The expected ratio of eos:neogaeus expression in triploid P. eos-neogaeus x eos individuals is 2:1. For PGM, the observed ratio of eos:neogaeus expression was not significantly different from 2:1 in all four tissues. The P. eos allozyme for GPI was expressed less than expected in all four tissues (one-sample t-test, P = 0.05). Thus, greater than expected expression of the P. eos allozyme was not observed in triploid individuals as it was in the diploids. These data show that PGM and GPI are regulated separately, and that regulation differs by tissue, and in fish of distinct ploidy levels. J. Exp. Zool. 284:663-674, 1999.

Animals↗
PubMed1999

Neuropsychological deficits associated with antiphospholipid antibodies.

Neurologic events associated with antiphospholipid antibodies (aPAs) include transient ischemic attack, stroke, and vascular dementia in individuals much younger than is typically observed with these disorders. The present study evaluated 27 non-elderly adults with aPAs but without concurrent disease processes or history of neurologic event and 27 age- and education-matched controls. MANOVA (p <.01) indicated group differences in executive functioning, verbal learning and memory, and visuospatial ability. In contrast, gross attentional processes and fine motor skills appeared unaffected by the <?Pub Caret>syndrome. Moreover, the frequency of impaired neuropsychologic performance was greater among individuals with aPAs than among controls (p <.01). The presence of cognitive deficits in otherwise asymptomatic patients with aPAs indicates a preclinical phase of neurologic involvement and may prove to be the most sensitive markers of the syndrome.

Antibodies, Antiphospholipid↗
PubMed1998

Effects of coaching on malingered motor function profiles.

Measures of motor functioning were evaluated to assess a nonphysiological performance pattern initially revealed in a sample of litigating patients with postconcussive syndrome (grip strength < finger tapping < grooved pegs). The opposite pattern is observed in patients with traumatic brain injury, whose performance follows a gradient of increasing impairment corresponding to the sensory-motor complexity of these tasks. Naive and coached malingerers performed worse on all three motor tests relative to controls (N = 92); however, the presence of nonphysiologic configurations showed poor predictive accuracy among malingerers and controls. Exploratory analyses suggested that IQ may mediate the ability to dissimulate successfully. Although worthy of additional study, the use of pattern analysis in evaluation of malingered motor functioning has not been proven reliable or valid.

Adolescent↗
PubMed1998

Effects of coaching on detection of malingering on the California Verbal Learning Test.

The diagnostic accuracy of California Verbal Learning Test (CVLT) indices to detect malingered head injury was examined using a simulation paradigm that included naive malingerers, malingerers provided with information about head injury, and normal controls (N = 90). The application of diagnostic cutoff scores for Recognition Discriminability and Recognition Hits derived from populations of individuals with bona fide head injury and individuals suspected of malingering (Millis et al., 1995) proved highly sensitive and modestly specific in detecting feigned head injury among both simulation groups. Results of analyses of variance and logistic regression support previous findings that malingerers overestimate memory impairment associated with mild head injury; however, they indicate that exposure to a simple instructional set may render insensitive many indices of malingering. In contrast, indices based on more subtle principles of learning theory hold promise in the detection of malingering, even in the presence of an instructional set.

Adolescent↗
PubMed1993

Fungal degradation of organophosphorus insecticides.

Organophosphorous insecticides are used extensively in agriculture. As a group, they are easily degraded by bacteria in the environment. However, a number of them have half-lives of several months. Little is known about their biodegradation by fungi. We showed that Phanerochaete chrysosporium mineralized chlorpyrifos, fonofos, and terbufos (27.5, 12.2, and 26.6%, respectively) during an 18-d incubation in nutrient nitrogen-limited cultures. Results demonstrated that the chlorinated pyridinyl ring of chlorpyrifos and the phenyl ring of fonofos undergo cleavage during biodegradation by the fungus. The usefulness of P. chrysosporium for bioremediation is discussed.

Basidiomycota↗
PubMed1990

Determination of cysteine on low-density lipoproteins using the fluorescent probe, 5-iodoacetamidofluoresceine.

Using the fluorescent sulfhydryl probe, 5-iodoacetamidofluoresceine, to label the free sulfhydryl of low-density lipoprotein, the positions of two cysteine residues in apolipoprotein B were located. The tryptic peptides containing the fluorescent probe were isolated by high-performance liquid chromatography systems and sequenced by automatic techniques. The free cysteine residues of apolipoprotein B-100 on low-density lipoprotein are located at positions 3734 and 4190, either or both of which can potentially form a disulfide linkage with apolipoprotein(a) in lipoprotein(a).

Amino Acid Sequence↗
PubMed1990

Analysis of the carbohydrate composition of glycoproteins by high-performance liquid chromatography.

A procedure for rapid and sensitive analysis of carbohydrate in glycoproteins is described. After methanolysis and benzoylation of the monosaccharides and carbohydrates of a glycoprotein, the derivatized sugars were analyzed by reverse-phase high-performance chromatography using a Vydac C18 stationary phase and a mobile phase composed of a water/acetonitrile gradient. The advantages of this procedure over previously described methods are (1) the simple binary solvent system which is used requires no buffering salts and (2) separate sets of peaks from individual sugars obviate the usual need to reacetylate sugar amino groups.

Carbohydrates↗
PubMed1987

Detection of pullulanase in polyacrylamide gels using pullulan-reactive red agar plates.

After electrophoresis, active pullulanase bands in acrylamide gels have been detected by overlaying and then incubating the gel on a replica gel containing 2.5% pullulan-reactive red conjugate and 2.1% agar. The enzyme activity is revealed as a clear band against a red background on the replica gel. The sensitivity of the replica plate is such that 0.0012 unit of Klebsiella aerogenes pullulanase can be detected easily. This procedure is effective in enzyme screening to distinguish pullulanase from other carbohydrases.

Agar↗
PubMed1987

Cloning of the debranching-enzyme gene from Thermoanaerobium brockii into Escherichia coli and Bacillus subtilis.

The gene for an enzyme with single or dual specificity on complex carbohydrates has been transferred from its native host (Thermoanaerobium brockii), a thermophilic anaerobe, into Escherichia coli and Bacillus subtilis. Most of the gene coding region is in a 2.2-kilobase PstI fragment that is common to the E. coli and B. subtilis chimeric vectors pCPC902 and pCPC903, respectively. Although the T. brockii debranching enzyme secreted from B. subtilis was unglycosylated and had less thermostability, more enzyme was secreted from B. subtilis (0.80 to 1.0 U/ml) than from T. brockii (0.23 U/ml). E. coli did not export any measurable enzyme. From the fermentation broth of B. subtilis containing pCPC903, three active species of the debranching enzyme were separated; two species are possibly protease digestion products of the larger protein (105,000 molecular weight). Whereas the enzyme can cleave all of the alpha-1----6 glucosidic linkages (and none of the alpha-1----4 bonds) in pullulan, it hydrolyzed mostly alpha-1----4 and very few of the alpha-1----6 linkages in starch. Upon hydrolysis of pullulan by the enzyme, only maltotriose was produced, while starch was digested to various-sized oligomers.

Bacillus subtilis↗
PubMed1983

Low-dose captopril titration in patients with moderate-to-severe hypertension treated with diuretics.

To study the value of low-dose captopril (6.25 and 12.5 mg) and a diuretic combination, the blood pressure and heart rate of 17 patients with moderate-to-severe hypertension were monitored for 6 hours (hospital) or 3 hours (office) after the single low-dose or larger (25, 50, 100 and 150 mg) captopril dosage. All patients had preserved renal function and were taking an oral diuretic (hydrochlorothiazide or furosemide) for at least 4 weeks. The supine and upright acute blood pressure lowering with 6.25 mg was not different from the larger captopril doses; none produced persistent or profound hypotension. There was no deterioration of renal function, new or persistent increase in proteinuria, neutropenia or agranulocytosis acutely or during 17 +/- 2 weeks of follow-up. Low-dose captopril (6.25 or 12.5 mg three times daily) normalized the supine blood pressure of 35% of these patients acutely. We suggest that in hypertensive patients already taking a diuretic, a lower starting dose of captopril than the recommended 25 mg three times daily may be desirable.

Adult↗
PubMed1980

Perception of images moving at saccadic velocities during saccades and during fixation.

During saccadic eye movements, images of external objects move rapidly across the retina. Small, unpredictable displacements imposed upon a target moving at saccadic velocity were detected with equal accuracy when (1) the retinal image velocity was caused by an eye movement, or (2) when the same velocity was produced during fixation (simulated saccadic conditions). The results provide no evidence of a specific non-visual suppression of vision during saccades, nor of any other compensatory modification of afferent visual inflow which might contribute to our sense of directional stability during saccades.

Eye Movements↗
PubMed1980

A double base change in alternate base pairs induced by ultraviolet irradiation in a glycine transfer RNA gene.

The glyUsuAGA mutation affects Escherichia coli tRNA Gl y GGG, changing it to an AGA missense suppressor tRNA. Sequence studies have shown that the mutation involves a double base subsitution at the first and third positions of the tRNA anticodon, the result being a change in the anticodon from CCC to UCU. A system has been developed to facilitate the detection of this novel mutation, and we have shown that ultraviolet irradiation and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) are effective in causing the double base change. A single observation of the mutation occurring spontaneously has been made also. The frequency of MNNG-induced glyUsuAGA mutations is compatible with their being caused by two separate mutagenic events. The frequency of UV-induced glyAGA mutations, however, strongly suggests that the occurrence of one base substitution strongly enhances the chance of finding the second substitution at the alternate position. In addition to the double change in the anticodon, the glyUsuAGA tRNA differs from tRNA Gl y GGG in that it bears a modification of the A adjacent to the 3' position of the anticodon. Most likely, this modified base is N-[9-(beta-D-ribofuranosyl)-purin-6-ylcarbamoyl] threonine.

Base Composition↗
PubMed1980

Renal tubular function in glycerol-induced acute renal failure.

The purpose of this study was to examine proximal and distal tubular function in rats with nonoliguric, myohemoglobinuric acute renal failure (ARF). ARF was induced with glycerol (50%, 10 ml/kg of body wt, i.m.), and renal function was studied 24 hours after glycerol or saline (controls) injection. Glycerol injection caused a 50 to 90% depression in GFR and a significant rise in blood urea nitrogen concentration. Animals with ARF exhibited glycosuria with normal blood sugar levels and a striking depression in tubular glucose reabsorption per milliliter of GFR. The capacity to reabsorb (mEq/liter GFR) was intact at normal blood bicarbonate levels, but was markedly depressed when blood bicarbonate was raised. The tubular maximum for para-aminohippurate (PAH) secretion and the renal extraction fraction of PAH were strikingly depressed in rats with ARF. Distal acidification as assessed by the urine-to-blood gradient of PCO2 (UB PCO2) was normal both during maximal alkalinization of the urine with bicarbonate (urine pH, approximately 7.8) or during neural phosphate infusion (urine pH, approximately 7.0). Net acid excretion per milliliter GFR and minimal urine pH (less than 5.5) following 3 days of ammonium chloride ingestion was similar in control and ARF animals. Potassium excretion was intact in maximal urinary osmolality were significantly altered in animals with ARF. Cortical and outer medullary Na-K-ATPase specific activities were significantly depressed in ARF rats. This occurred as a consequence of enzyme loss and not secondary to alterations in enzyme kinetics of absolute tubular sodium reabsorption. Light and electron microscopy showed diffuse proximal tubular damage, whereas glomeruli and distal tubules were intact. These data demonstrate that glycerol injection produces a diffuse proximal tubular transport defect associated with histologic and enzymatic alterations.

Acute Kidney Injury↗