Diurnal Rhythm in Endoplasmic Reticulum of Rat Liver: Electron Microscopic Study

Chedid, Antonio; Nair, Vivek V

doi:10.1126/science.175.4018.176

Cited by 88 publications

(24 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other semiquantitative estimates of the amount of RER and SER in different regions of rat liver reached different results (Ghedid and Nair, 1972): only in the midzonal area an increase of RER was observed at 22.00 hr, but in this area and in the central area a rhythmic increase in the amount of SER was observed at night. In this context it may be noted that hepatocytes even in the same area are not homogenous with respect to the amount of RER and SER, possibly in relation to the amount of glycogen (Müller et al, 1966).…”

Section: Catecholaminesmentioning

confidence: 88%

The rhythmic organization of Rodent Liver a review

Hardeland

Hohmann²,

Rensing

1973

Journal of Interdisciplinary Cycle Research

View full text Add to dashboard Cite

Section: Catecholaminesmentioning

confidence: 88%

The rhythmic organization of Rodent Liver a review

Hardeland

Hohmann²,

Rensing

1973

Journal of Interdisciplinary Cycle Research

View full text Add to dashboard Cite

“…A circadian rhythm in the hepatic drugmetabolizing enzyme activity of laboratory animals has been reported 2 17 Similarities between the oxidative drug-metabolizing enzymes and the adrenocorticosteroid hydroxylases suggest that adrenocorticosteroids may be natural substrates for hepatic drug-metabolizing enzymes. 10 In man, exogenous plasma cortisol halflife was shorter at 4 P.M. than at 8 A.M.; moreover, endogenous cortisol concentrations correlated inversely with exogenous plasma cortisol half-life.…”

Section: Min)mentioning

confidence: 96%

Temporal variations in acetaminophen and phenacetin half‐life in man

Shively

Vesell

1975

Clin Pharma and Therapeutics

View full text Add to dashboard Cite

Acetaminophen (APAP) and phenacetin mean plasma half-lives were approximately 15% longer in normal male volunteers at 6 A.M. than at 2 P.M. as determined after oral administration of each drug at 6 A.M. and 2 P.M. Concentrations of plasma 11-hydroxycorticoids (11-OHCS) in these volunteers were approximately 42% higher at 6 A.M. than at 2 P.M. The mean apparent volume of distribution (aVd) of APAP decreased by approximately 13% from 6 A.M. to 2 P.M., whereas the mean metabolic clearance rate (MCR) of APAP did not change significantly. Neither the mean aVd nor the mean MCR of phenacetin changed significantly from 6 A.M. to 2 P.M. Measurement of urinary metabolites showed no alteration in APAP glucuronidation in the 8-hr period following APAP administration at 6 A.M. or 2 P.M., but indicated that after phenacetin administration 10% more of the dose was oxidatively metabolized to APAP during a 24-hr period beginning at 2 P.M. than at 6 A.M. Within each subject, plasma acetaminophen or phenacetin half-life at 2 P.M. or 6 A.M. was highly reproducible, but large interindividual variations occurred in the extent of temporal variation during this period.

show abstract

“…The smooth endoplasmic reticulum (SER) shows a decline with age that correlates with the decline in the yield of liver microsomal protein [8]. Because the mixed-function oxidases (MFOS) exhibit a diurnal variation [10], the differences during aging have not been tested.…”

Section: Morphological Changes In Aging Livermentioning

confidence: 99%

Aging Liver

Anantharaju¹,

Feller²,

Chedid³

2002

Gerontology

158

View full text Add to dashboard Cite

Aging is characterized by a progressive decline of cellular functions. The aging liver appears to preserve its function relatively well. Aging is associated in human liver with morphological changes such as decrease in size attributable to decreased hepatic blood flow. Ultrastructural analysis of the human liver has revealed that the integrity of mitochondria and enzymatic activity remain mostly unchanged with aging. Reactive oxygen species (ROS) are involved in the aging process and result mainly from nonenzymatic processes in the liver. Endogenous free radicals are generated within mitochondria and suspected to cause severe injury to mitochondrial DNA. This damaged DNA accumulates with aging. In addition, polyunsaturated fatty acids, highly sensitive to ROS, decrease in liver mitochondria from human centenarians, a feature acquired during evolution as a protective mechanism to favor longevity. Diet is considered the main environmental factor having effect on lifespan. It has a major impact on aging liver, the central metabolic organ of the body. The ubiquitin proteolytic pathway in the liver serves to destroy many proteins, among them p21 which is encoded by abundant mRNA in senescent cells, can inhibit cell proliferation and favors DNA repair. Drug therapy in the elderly may be complicated by several factors such as decline in body weight, renal function, liver mass and hepatic blood flow, making adverse drug reactions more frequent. Hepatic drug metabolism is mainly mediated by the cytochrome P₄₅₀system and drug interactions in the elderly are likely related to the progressive decline of this system after the fifth decade of life and another decrease in individuals aged >70. Antihypertensive therapy in the elderly depends upon either hepatic or renal function and should be adjusted accordingly. Finally, telomerases are the biological clocks of replicative lifespan. Shortening of telomeric ends of chromosomes correlates with aging and decline in the replicative potential of the cell: replicative senescence. Telomere DNA of human somatic cells shortens during each cell division thus leading to a finite proliferation. Transfection of the telomerase reverse transcriptase gene results in elongation of telomeres and extension of lifespan. This also applies to humans. Replicative senescence in human cells evolved as a mechanism to protect them from continuous divisions leading to multiple mutations. Longer-lived species such as humans had to develop replicative senescence to ensure that they would have the increased protection that their longevity necessitates.

show abstract

Diurnal Rhythm in Endoplasmic Reticulum of Rat Liver: Electron Microscopic Study

Cited by 88 publications

References 28 publications

The rhythmic organization of Rodent Liver a review

The rhythmic organization of Rodent Liver a review

Temporal variations in acetaminophen and phenacetin half‐life in man

Aging Liver

Contact Info

Product

Resources

About