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Biomedical subjects

C C Young

Publications and source records attributed to C C Young.

31 records · Page 2Linked to original sources
PubMed1994

Characterization of a new ion selective electrode for ionized magnesium in whole blood, plasma, serum, and aqueous samples.

Results from a novel ion selective electrode (ISE) for ionized magnesium (Mg2+) correlate well with atomic absorption spectroscopy on aqueous solutions containing from 0.1-3.0 mmol MgCl2/L. Day to day precision (coefficient of variation) of the electrode on protein-based controls is < 4%; aqueous-based controls < 6%. The new ISE is selective for Mg2+ with a selectivity constant for Ca2+ (KMgCa) of 8 x 10(-2). Adding pathophysiologic concentrations of Cd2+, Ca2+, Cu2+, Fe3+, K+, Na+, or Zn2+ to serum and aqueous solutions gave negligible to minimal changes in measured Mg2+. Ligand binding studies in aqueous solution indicate that pathophysiologic concentrations of different anions (e.g. heparin, lactate, bicarbonate, phosphate, acetate and sulfate) bind to Mg2+, effectively reducing its concentration in solution. Likewise, silicon (as either found in Vacuutainer tubes or as chlorosilane) failed to exert any significant effect on measured Mg2+. Addition of Intralipid (up to 500 mg/dL) gave negligible to minimal changes in Mg2+. Mg2+ measurements on whole blood, plasma, and serum for a given human subject's samples are virtually identical, at least within the reference range for Mg2+. Typically, Mg2+ is 71% of TMg, but varies from subject to subject; i.e. Mg2+ cannot be predicted from TMg. Clinical studies revealed that the Mg2+/TMg ratio could be remarkably consistent in sequential samples (e.g., throughout the course of coronary bypass surgery) taken from one patient, but that this ratio could differ dramatically from the ratio in sequential samples taken from another. Mg2+ is held within a narrow range (0.53-0.67 mmol/L) in normal, healthy subjects when compared to TMg (0.70-0.96 mmol/L).

Adult↗
PubMed1993

Polyvinylpyrrolidone-agarose gel electrophoresis purification of polymerase chain reaction-amplifiable DNA from soils.

This communication describes a modification of agarose gel electrophoresis to provide a rapid and simple method for the purification of polymerase chain reaction-amplifiable DNA from soil. This modification is to add polyvinylpyrrolidone to the agarose gel. The polyvinylpyrrolidone addition retards the electrophoretic mobility of denaturing phenolic compounds so that they do not comigrate with nucleic acids.

Journal Article↗
PubMed1992

A new method for the rapid determination of ionized Mg2+ in whole blood, serum and plasma.

A novel ion selective electrode (ISE) for ionized magnesium (IMg2+) in whole blood (WB), plasma (PL) and serum (S) has now been designed and characterized in normal human subjects, diseased and pregnant subjects. Using this ISE on various levels of aqueous Mg2+ solutions (0.1-3.0mM), mean Mg2+ values are within 94.6 and 99.2% of their targets. The linearity of the ISE (0.1-3.0mM) in aqueous solution and human PL and S ranges between 92.0 and 99.3%. The ISE is highly selective for IMg2+, yielding measurements in less than 2 min, and exhibiting no or negligible effects from physiologic concentrations of Ca2+,Na+,K+ or H+. Ligand binding studies indicate that pathophysiologic concentrations of most smaller molecular weight anions fail to interfere with IMg2+ measurements in aqueous solution, PL or S. Likewise, pathophysiologic concentrations of heavy metals or lipids do not interfere with measurements for IMg2+. Comparison of healthy, normal WB, PL and S IMg2+, using the ISE, with measurements of ultrafilterable Mg by atomic absorption spectroscopy (AAS) are excellent. The mean value for IMg2+ in normal WB, PL and S is 0.58-0.60mM (range = 0.53-0.67mM). Compared to total Mg (TMg) (0.75-0.96mM) and ICa2+ (1.10-1.30mM), IMg2+ is held in a narrow, tight range, representing 71% of TMg. Preliminary studies on plasma and serum IMg2+ during open heart surgery and term pregnancy demonstrate significant abnormalities in IMg2+ and % IMg2+. The new ISE for IMg2+ should prove invaluable and revolutionary in studies of Mg metabolism in both healthy and diseased states.

Adult↗
PubMed1991

Elongation factor Tu is methylated in response to nutrient deprivation in Escherichia coli.

It has been shown previously that starvation of a mid-logarithmic-phase culture of Escherichia coli B/r for an essential nutrient results in the methylation of a membrane-associated protein (P-43) (C. C. Young and R. W. Bernlohr, J. Bacteriol. 172:5147-5153, 1990). In this communication, the purification of P-43 and sequence analysis of cyanogen bromide-generated peptide fragments identified P-43 as elongation factor Tu (EF-Tu). This was confirmed by the ability of anti-EF-Tu antibody to precipitate P-43. We propose that the nutrient-dependent methylation of EF-Tu may be involved in the regulation of growth, possibly as a principal component of an unidentified signal transduction pathway in bacteria.

Amino Acid Sequence↗
PubMed1990

Nutrient-dependent methylation of a membrane-associated protein of Escherichia coli.

Starvation of a mid-log-phase culture of Escherichia coli B/r for nitrogen, phosphate, or carbon resulted in methylation of a membrane-associated protein of about 43,000 daltons (P-43) in the presence of chloramphenicol and [methyl-3H]methionine. The in vivo methylation reaction occurred with a doubling time of 2 to 5 min and was followed by a slower demethylation process. Addition of the missing nutrient to a starving culture immediately prevented further methylation of P-43. P-43 methylation is not related to the methylated chemotaxis proteins because P-43 is methylated in response to a different spectrum of nutrients and because P-43 is methylated on lysine residues. The characteristics of P-43 are similar to those of a methylated protein previously described in Bacillus subtilis and B. licheniformis (R. W. Bernlohr, A. L. Saha, C. C. Young, B. R. Toth, and K. J. Golden, J. Bacteriol. 170:4113-4118, 1988; K. J. Golden and R. W. Bernlohr, Mol. Gen. Genet. 220:1-7, 1989) and are consistent with the proposal that methylation of this protein functions in nutrient sensing.

Autoradiography↗
PubMed1989

The effect of surface and internal electrodes on the gait of children with cerebral palsy, spastic diplegic type.

The purpose of this study was to determine whether surface and internal fine-wire electromyography electrodes had an effect on gait. The subjects for the experiments were 38 children with the spastic diplegic type of cerebral palsy. The children were filmed using the high-speed cinematographic technique while they walked (a) with no electrodes (unencumbered), (b) with only surface electrodes, and (c) with internal electrodes. Single stance time, step length, cadence, and walking velocity were compared with analysis of variance and Bonferroni t tests. The results included a significant decrease in cadence (-6.3% of unencumbered walking; p less than 0.05) when comparing walking with surface electrodes with walking without any electrodes. The internal electrodes caused significant decreases from normal walking in the following parameters: step length for both the measured leg (-18.6%; p less than 0.005) and the nonmeasured leg (-18.0%; p less than 0.005), cadence (-7.9%; p less than 0.02), and walking velocity (-23.5%; p less than 0.005). Internal electrodes caused significant decreases as compared with surface electrodes in the step length for both the measured leg (15.7%; p less than 0.01) and the nonmeasured leg (15.6%; p less than 0.005) and walking velocity (19.7%; p less than 0.005). Single stance phase did not change significantly in any of the comparisons. It appears that the addition of the surface electrode apparatus does change the normal gait of a subject, causing a large decrease in cadence. The measurement of gait with internal electrodes causes further change in gait, resulting in large decreases in step length and walking velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Nutrient-stimulated methylation of a membrane protein in Bacillus licheniformis.

When nitrogen-starved vegetative cells of Bacillus licheniformis A5 were presented with a good nitrogen source in the presence of chloramphenicol and methyl-labeled methionine, a 40-kilodalton (kDa) protein was found to be reversibly methylated, with a half-life of approximately 10 to 15 min. The 40-kDa protein was strongly methylated in response to the addition of ammonia, glutamine, or sodium glutamate nitrogen sources that produce generation times of less than or equal to 90 min) but was very poorly methylated in the absence of a nitrogen source or in the presence of potassium glutamate or histidine (generation times of greater than 150 min). The methylated protein was found to be membrane associated, but the methylation reaction did not appear to be related to chemotaxis, because the spectrum of nutrients that promoted methylation was different from that which prompted a chemotactic response. In addition, the methyl residue on the 40-kDa protein was found to be alkali stable. Approximately 180 to 640 molecules of the methylated protein were found per cell. The characteristics of this methylated protein were consistent with the hypothesis that the reversible methylation of the protein functions in nutrient sensing to regulate growth, cell division, and the initiation of sporulation.

Ammonia↗
PubMed1982

Collection and Identification of Allelopathic Compounds from the Undisturbed Root System of Bigalta Limpograss (Hemarthria altissima).

Collection of allelopathic chemicals from the undisturbed plant root system is difficult because of their low concentrations and the high level of contaminants in growth media such as soil. A new approach for the continuous trapping of quantities of extracellular chemicals from donor plants is described. Bigalta limpograss (Hemarthria altissima), a tropical forage with allelopathic activities, was established in sand culture. Nutrient solution was circulated continuously through the root system and a column containing XAD-4 resin. Extracellular hydrophobic metabolites were selectively adsorbed by the resin, while inorganic nutrients were recycled to sustain plant growth. Columns were eluted with methanol and the eluate separated into neutral, acidic, and basic fractions. Bioassays of trapped root exudates using lettuce seed combined with paper and thin layer chromatography showed that the inhibitors were mainly phenolic compounds. The active neutral fraction was methylated and analyzed by gas chromatography-mass spectrometry. Twelve compounds were identified, with two additional compounds tentatively identified. 3-Hydroxyhydrocinnamic, benzoic, phenylacetic, and hydrocinnamic acids were the major rhizospheric compounds with known growth regulatory activities.Inasmuch as the root system was undisturbed and the recovery of exudates was highly efficient compared to conventional solvent extraction methods, this trapping system should be useful for a wide range of studies that relate to the chemistry of the rhizosphere.

Journal Article↗
PubMed1980

Preclinical and phase I studies of malonatoplatinum.

After preclinical toxicologic study in baboons, we are conducting a phase I trial of malonatoplatinum, starting with 3 mg/kg and now reaching 1 mg/kg. Toxicity, mainly hematologic, was mild and our study was mainly limited by poor solubility. Regressions, which have been rare in the advanced-tumor patients, have been observed in three patients considered as clinically resistant to cisdichlorodiammino-platinum (DDP). Malonatoplatinum pharmacokinetics appeared similar to those of DDP as far as total platinum is concerned.

Adolescent↗