On Estimating the Constants of the `Multi-Hit' Curve Using a Medium Speed Digital Computer

Tyler, Sylvanus A.; Dipert, Merlin H.

doi:10.1088/0031-9155/7/2/306

Cited by 20 publications

(10 citation statements)

References 3 publications

(6 reference statements)

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“…Both curves can be described by the expression, where S is the fraction of cells surviving an inactivating dose D , and k and n are positive constants. The least square estimates [9] and standard errors of kl and n, for curve 1 are 0.047 +0-001 (ergs mrn-*)-' and 2.9 k 0-4, respectively. Corresponding estimates, k, and n,, for curve 2 are 0.0139~0.0002 and 1.6kO-2 respectively.…”

Section: Experimental and Discussionmentioning

confidence: 91%

“…Thus, the increase in surviving fraction due to reactivating light of duration t is attributed to repair of first, primarily cells with single events, then cells with two events, etc., until the sum of these cells accounts for the increase in survival. This is expressed in symbolic form by equation (9). when y is a constant such that, 0 d y < 1, under the restriction…”

Section: The Sequential Reactivation Modelmentioning

confidence: 99%

“…Secondly, we can postulate that damage causing lethality in the non-photoreactivable sector is not capable of reversal by photoreactivation and is mechanistically different from damage in the photoreactivable sector, which is all reversible. The number of reactivable events (L) was computed for each surviving fraction using equations (9) and (1 I), and the mean number was determined for each photoreactivation time. Under the first postulate, Pi@) in equation (4) was set equal to 1.…”

Section: ~( D )mentioning

confidence: 99%

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A Sequential Repair Model of Photoreactivation in Bacteria*

Davies

Tyler

Webb

1970

Photochem & Photobiology

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Abstract— Kinetics of photoreactivation were studied in E. coli WP2 hcr‐, a strain deficient in dark repair. Cells in aqueous suspension were subjected to u.v.‐irradiation, then exposed to photoreactivating light for different periods. Survival curves, with samples at a minimum of six u.v. doses, were obtained at several periods of photoreactivation ranging from zero to maximum. The surviving fractions do not conform to a dose‐reduction model, but instead, they fit a ‘sequential repair’ model that assumes as a limiting condition that the number of active enzyme molecules is small. The model used assumed: (1) a single enzyme molecule is active at any one time; and (2) inactivating events are nullified consecutively around the DNA molecule. The mathematics of the model are derived and presented. Photoreactivation is attributed to the action of two processes. (1) A photochemical process, that is rate limiting below 1000 ergs mnr‐2 sec‐1, was measured at a photoreactivating irradiance of 60 ergs mm‐2 sec‐1. This has a rate constant of 5 × 10‐5‘events’ erg‐1 mm2. (2) A dark process, measured at photoreactivating irradiances of 4000 and 6000 ergs mm‐2 sec‐1, has a rate constant of 2.2 ‘events’ min‐1.

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Section: Experimental and Discussionmentioning

confidence: 91%

Section: The Sequential Reactivation Modelmentioning

confidence: 99%

Section: ~( D )mentioning

confidence: 99%

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A Sequential Repair Model of Photoreactivation in Bacteria*

Davies

Tyler

Webb

1970

Photochem & Photobiology

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“…A lot of other models ranging from the inactivation of bacterial to mammalian cells describe the zero initial destruction rate with the same mathematical approach (Alper, Gillies, & Elkind, 1960;Bender & Gooch, 1962;Powers, 1962;Tyler & Dipert, 1962). Fig.…”

Section: Introductionmentioning

confidence: 99%

Impact of agglomeration on the quantitative assessment of Bacillus stearothermophilus heat inactivation

Mathys¹,

Heinz²,

Schwartz³

et al. 2007

Journal of Food Engineering

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“…Computers have been employed to fit best lines to inflected survival curves by Bender & Gooch (1962), Porter (1964) and Miller (1970) ;Tyler & Dipert (1962) developed a computer program which derived least squares estimates for the parameters of radiation resistance of bacterial suspensions. This program may be applied to heat resistance data.…”

mentioning

confidence: 99%

A Digital Computer Program for the Statistical Analysis of Heat Resistance Data Applied to Bacillus stearothermophilus Spores

Navani

Scholefield

Kibby

1970

Journal of Applied Bacteriology

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Summary. A digital computer program is described which fits log‐linear regression lines to survival curves and thermal destruction time lines and performs appropriate statistical tests. The use of the program is illustrated with heat resistance data from 4 strains of B. stearothermophilus spores at 8 time–temperature relationships. D, F, zD and Q10 values were calculated by the computer program. The heat resistance of the strains was in the order of B

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On Estimating the Constants of the `Multi-Hit' Curve Using a Medium Speed Digital Computer

Abstract: On Estimating the Constants of the ' Multi-Hit ' Curve Using a Medium Speed Digital Computer. j-By SYLVANCS !l . TYLER, &l.sC., and RfERLIN H. DIPERT, icI.sC.

Cited by 20 publications

References 3 publications

A Sequential Repair Model of Photoreactivation in Bacteria*

A Sequential Repair Model of Photoreactivation in Bacteria*

Impact of agglomeration on the quantitative assessment of Bacillus stearothermophilus heat inactivation

A Digital Computer Program for the Statistical Analysis of Heat Resistance Data Applied to Bacillus stearothermophilus Spores

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