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Biomedical subjects

D Ellis

Publications and source records attributed to D Ellis.

At least 253 records · Page 14Linked to original sources
PubMed1977

New approach to evaluation of proteinuric states.

We evaluated the use of immunonephelometric methods for measuring specific urinary proteins. Using a nephelometer to detect light scattering (angle, 31 degrees), we measured some proteins immunonephelometrically in serum and aliquots of 24-h urines from 50 apparently healthy children, ages 2-17 years. The mean urinary excretion rate (mg/24h) and the range of values was: for albumin 5.5 (range, 0-13.3), for transferrin 0.5 (0-1.9, for IgG 3.3 0-12), and for alpha 2-macroglobulin 0.6 (0-2.3). Direct comparison of the values for pathological urines with those for a reference population may offer more meaningful information concerning the integrity of the glomerular basement membrane than is provided by protein selectivity indices, and measuring a plasma protein such as albumin in urine may better define pathological proteinuria.

Adolescent↗
PubMed1976

Direct measurement of the intracellular pH of mammalian cardiac muscle.

1. The intracellular pH (pHi) of sheep heart Purkinje fibres and rat, ferret and guinea-pig ventricle has been measured using recessed-tip pH-sensitive micro-electrodes. 2. In the absence of CO2 the pHi was approximately 7-2 in all the preparations used. In 5% CO2 the mean pHi was 7-14 in rat and ferret ventricle and 7-02 in sheep Purkinje fibres. 3. The pHi response to an increase or a decrease in the CO2 level (at constant external pH) was biphasic with a large transient change followed by a partial recovery to a new sustained pHi. 4. The intracellular buffering capacity was 34-8 +/- 2-7 m-equiv H+/pH unit per l. (+/- S.E. of mean) in sheep Purkinje fibres, 76-6 +/- 13-6 in rat ventricle and approximately 69 in ferret ventricle. 5. The pHi of all the preparations tested indicated that H+ ions were not passively distributed across the cell membrane. There was also little or no pHi change produced by depolarization with high K solutions. 6. Short exposures to hypertonic solutions (100 mM sucrose or 50 mM-KCl) produced a decrease in pHi of approximately 0-1 pH units. 7. Acetazolamide slowed the pHi response to CO2 changes. 8. Restoration of the pHi after displacement by increasing the CO2 was not blocked by ouabain or SITS. 9. The relationship between pHi and cardiac contractility is discussed.

Acetazolamide↗
PubMed1973

Induction kinetics of the L-arabinose operon of Escherichia coli.

After addition of l-arabinose to growing Escherichia coli, the l-ribulokinase (EC 2.7.1.16) and l-arabinose isomerase (EC 5.3.1.4) first appear at about 0.7 and 1.4 min, respectively. These times are consistent with the distances of the genes from the ribonucleic acid polymerase initiation site in the operon. The kinetics of appearance of these enzymes as well as those of beta-galactosidase (EC 3.2.1.23) in the same strain are consistent with a peptide elongation rate of no less than 14 amino acids per second. A measurement of the average peptide elongation rate made by measuring the kinetics of radioactive amino acid appearance in completed polypeptides yielded a rate of about 12 amino acids per s. Convenient assays of the arabinose isomerase and ribulokinase are also given.

Arabinose↗