A continuous monitoring spectrophotometric method for the measurement of angiotensin-converting enzyme in human serum

A continuous monitoring spectrophotometric method for the measurement of angiotensin-converting enzyme in human serum is described. It is based on the hydrolysis of furylacrylylphenylalanylglycylglycine and applied to an IL Multistat III centrifugal analyser. The method offers better precision and freedom from interference than a fluorimetric assay we have previously described.

The presence and orientation of ecto-5'-nucleotidase in rat liver lysosomes

Purified rat liver lysosomes contained 5'-nucleotidase activity which was 92 +/- 2% [4]latent. This latency was lost in response to a permeant sugar at a similar rate to that of the lysosomal marker enzyme beta-N-acetylglucosaminidase indicating that the 5'-nucleotidase was genuinely located in the lysosome and not a plasma membrane contaminant. Lysosomal 5'-nucleotidase exhibited the following properties characteristic of ecto-5'-nucleotidase inhibition by specific polyclonal antibodies: binding to a monoclonal antibody; inhibition by 1 mmol/1 alpha beta-methylene ADP; immunoreactive subunits of 70 and 38 kDa. Lysosomes in addition contained immunoreactive species of intermediate molecular mass.

A kinetic fluorimetric assay for the measurement of angiotensin-converting enzyme in human serum

The development and assay performance of a direct kinetic fluorimetric assay for angiotensin-converting enzyme is described. It is based on the substrate developed by Carmel et al. (Clin Chim Acta 1979; 93: 215-20), and applied to a microcentrifugal analyser with fluorescence optics. The method is sufficiently sensitive and precise to detect both normal and pathological activities; the method is linear up to at least three times the upper limit of the reference range. The method correlates well with an established method. Because of interference, the method is unsuitable for use with icteric or haemolysed samples.

Evidence for interference by ascorbate in the measurement of cerebrospinal fluid glucose by a kinetic glucose oxidase/peroxidase procedure

Glucose in the cerebrospinal fluid (CSF) of neonates, as measured with a kinetic glucose oxidase/peroxidase procedure, was sometimes very low. When these samples were stored at 4 degrees C and subsequently re-analyzed, or if the samples were analyzed at any time after receipt by using a glucose dehydrogenase assay, the values were much higher. We found that the discrepancies in the values were caused by a lag phase in the kinetic method, during which no color developed. Because the lag phase exceeds the time over which the reaction is monitored in the kinetic procedure, this leads to the erroneously low values. The interference could be reproduced experimentally by adding ascorbic acid to CSF or plasma samples, or removed by adding ascorbate oxidase to CSF samples. Plasma glucose, as estimated by the kinetic glucose oxidase method, showed no such interference.

Evidence for interference by ascorbate in the measurement of cerebrospinal fluid glucose by a kinetic glucose oxidase/peroxidase procedure

Glucose in the cerebrospinal fluid (CSF) of neonates, as measured with a kinetic glucose oxidase/peroxidase procedure, was sometimes very low. When these samples were stored at 4 degrees C and subsequently re-analyzed, or if the samples were analyzed at any time after receipt by using a glucose dehydrogenase assay, the values were much higher. We found that the discrepancies in the values were caused by a lag phase in the kinetic method, during which no color developed. Because the lag phase exceeds the time over which the reaction is monitored in the kinetic procedure, this leads to the erroneously low values. The interference could be reproduced experimentally by adding ascorbic acid to CSF or plasma samples, or removed by adding ascorbate oxidase to CSF samples. Plasma glucose, as estimated by the kinetic glucose oxidase method, showed no such interference.

Sugar transport in rat liver lysosomes. Direct demonstration by using labelled sugars

Purified rat liver lysosomes ('tritosomes') were prepared from rats injected with Triton WR-1339. 2. The water space of tritosomes, measured by using [3H]water and [14C]sucrose, was 2.15 +/- 0.72 microliter/mg of protein (mean +/- S.E.M., n = 12). 3. Tritosomes, when compared with a crude preparation of normal lysosomes by an indirect method of study, showed sugar specificity but decreased stereospecificity of sugar uptake. 4. At 125 mM the relative rates of net uptake of D-[14C]ribose, D-[14C]- or D-[3H]glucose and 2-deoxy-D-[3H]glucose were the same as that inferred from the indirect study. 5. The entry of D-[3H]glucose into tritosomes showed concentration-dependence suggestive of saturation, with a Km of 48 +/- 18 mM (4). 6. D- and L-glucose, D-ribose, 2-deoxy-D-glucose and D-mannose competed with D-[14C]glucose or D-[14C]ribose for uptake. 7. Cytochalasin B inhibited D-[3H]glucose uptake. 8. Uptake of 1 mM-L-[14C]glucose was slower than for 1 mM-D-[14C]glucose. 9. It is concluded that a facilitated-diffusion transport system is present in purified rat liver lysosomes.

Volunteer program to assist the elderly to remain in home settings

A community-based volunteer program was organized to improve the quality of life for elderly individuals in the community. Each elderly client referred for the program from welfare and home health agencies, or from family and friends, was matched with a volunteer who visited regularly. The volunteers also assisted with transportation, sitting, home maintenance, and meal preparation when these services were not available. The goals of the program were to improve the quality of life of elderly in the community, to assist the clients to remain in their home setting despite physical limitations, to encourage positive attitudes toward the elderly by the volunteers, and to increase the community's awareness of the older person's needs. The program also included educational seminars on gerontology for volunteers and community members.