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Biomedical subjects

G Prenna

Publications and source records attributed to G Prenna.

8 recordsLinked to original sources
PubMed1978

Low temperature microspectrofluorometry: design of a 'cold chamber'.

Low temperature microspectrofluorometry allows an improvement of spectral resolution and an increase of fluorescence intensity. Suppression of fluorescence fading, or at least a marked reduction, is also obtained. A cooling chamber for microspectrofluorometric measurement is described which allows the cooling, under a microscope, of a biological sample down to liquid nitrogen temperature. Objectives with numerical apertures better than 1.0 and a magnification power up to 100X can be used. Low temperature measurements on a histological sample are presented and discussed.

Bacillus cereus↗
PubMed1977

Cytofluorometric quantification of the activity and reaction kinetics of acid phosphatase.

This paper describes how fluorogenic substrates derived from naphthol AS can be used for the microscopic demonstration and cytofluorometric quantification of the activity and reaction kinetics of acid phosphatase in single living cells. A special study has been made of acid naphthol AS-BI phosphatase. However, the method can be extended to other hydrolytic enzymes. The method is sensitive and accurate because: quantification of very low enzyme activity is possible; the reaction kinetics can be evaluated with a good degree of precision inasmuch as the initial reaction velocity is derived over short times; there is an absence of distributional error; and the errors due to extra-cellular diffusion of the hydrolysed substrate, to photodecomposition, and to autofluorescence can be contained within very narrow limits. The procedures for determining enzyme activity and reaction kinetics, and the instrumental characteristics and devices required for carrying out these measurements, are described. Some possible applications are indicated.

Acid Phosphatase↗
PubMed1975

An electronic device for the automatic correction of fluorescence emission spectra.

An electronic device is described for the automatic correction of fluorescence emission spectra obtained by digital microspectrofluorometry based on multichannel scaling and single photon detection as described previously. This device consists of: (a) an arithmetic unit for the correction of the spectral values and for the curve integration processes; (b) a circuit that operates directly on data in the memory of the multi-channel analyser by subtracting from then a pre-established value corresponding to the background; and (c) an averaging unit for calculating a mean for the spectral value.

Electronics↗