Syrian Hamster Liver Research Articles

Metabolism of zinc and copper in the neonate: Changes in the concentrations and contents of thionein-bound Zn and Cu with age in the livers of the newborn of various mammalian species

The livers of newborn rabbits, mice, Syrian and Chinese hamsters contain high cytoplasmic concentrations of metallothioneins. In the rabbit and mouse the hepatic concentrations of these metalloproteins are highest at, or immediately after birth and then decrease rapidly whereas, in the Syrian and Chinese hamster, maximum concentrations are not reached until 4 and 9 days post partum, respectively. In the human liver the metallothionein concentration appears to be maximal during gestation and is appreciably less in the newborn than the 33-week foetus. In addition to age-related variations in metal content, the metal composition of the hepatic metallothionein fraction also varies with species; that of the rabbit always contains Zn as principal bound metal, that of the mouse or the Chinese hamster usually contains Zn and Cu in ratios greater than unity, whilst that of the Syrian hamster, at least until 14 days post partum, contains more Cu than Zn. In all of these species, as in the human foetus and infant, however the Zn: Cu ratio in the metallothionein varies with age. Values for this ratio, as well as the concentrations of thionein-bound Zn and Cu, in the rodent species seem to be determined by the concentrations of these metals in the whole liver. It is suggested, therefore, that in foetal and newborn animals, thionein synthesis acts as a protective mechanism against excessive amounts of the essential, but potentially toxic Zn and Cu ions, possibly before the development of other control processes.

Persistence of methylated bases in ribonucleic acid of syrian golden hamster liver after administration of dimethylnitrosamine

1. Syrian golden hamster liver ribosomal RNA was isolated up to 96 h after administration of [14C]dimethylnitrosamine at 25 mg/kg or 2.5 mg/kg body weight. 2. The chemical alkyation products, 7-methylguanine, 3-methylcytosine, O6-methylguanosine and 1-methyladenosine, were measured after acidic or enzymic hydrolysis of the RNA to bases or mononucleosides followed by ion-exchange chromatography. 3. Between 7 and 96 h, the relative amounts of alkylation products did not change with time even though the absolute amounts fell by approx. 80% and 51% after the high and low doses respectively. 4. The results suggest that base specific excision repair does not exist for RNA alkylation products in this experimental system.

Excorporation Efficacy with Ca-DTPA of 241 Am and 252 Cf in the Skeleton, Liver, and Kidney of the Rat and Syrian and Chinese Hamsters Lack of Correlation with the Biological Half-Times

Distribution of intraperitoneally injected /sup 241/Am- and /sup 252/Cf-citrate in the skeleton, liver, and kidneys at 8 and 71 days after ip injection was investigated in rat and in Syrian and Chinese hamsters. The results confirmed that the most obvious difference of radionuclide metabolism among these animal species is the considerably shorter biological half-time in rat liver (several days) compared to that in livers of Syrian and Chinese hamsters (>100 days). Single injections of Ca-DTPA (diethylenetriaminepentaacetate) given 24 hr after radionuclides mobilized similar amounts of /sup 241/Am and /sup 252/Cf from the rat and Chinese hamster livers. In Syrian hamster liver, DTPA effectiveness was markedly lower. On a double logarithmic scale the dose--effect functions for the removal of /sup 252/Cf from liver were linear and, with regard to animal species, parallel to each other. In kidneys, DTPA efficacy increased in the order of rat, Syrian hamster, and Chinese hamster. After 12 Ca-DTPA doses (30 ..mu..moles/kg once weekly, starting 4 days after /sup 252/Cf) chelate efficacy was identical in skeleton of all animal species tested (50% of control removed). From liver and kidneys of Chinese hamster, 94 and 90% of the /sup 252/Cf activity in untreated animals could be mobilized, respectively,more » whereas DTPA effectiveness was considerably lower in liver and kidneys of rat and Syrian hamster. Thus, no relationship has been established between biological half-lives and availability to DTPA of radionuclides.« less

Polyadenylated RNA molecules and polyribosomes in tumours of chemical and viral origin.

The distribution of poly(A)-enriched mRNA in nuclei, mitochondira, free and membrane-bound polyribosomes from normal C3HA mouse and Syrian hamster livers and normal chicken fibroblasts has been compared with that in corresponding subcellular fractions in a transplantable, chemically induced MD hepatoma, non-virus-producer hamster and virus-producer chicken Rous sarcomas. It has been shown that the content of poly(A)-RNA is increased in all tumour fractions except in free polyribosomes. The distribution of different classes of polysomes i.e. free, membrane-bound and mitochondrial outer-membrane-associated polysomes in tumour cells was changed in comparison to that in normal cells. It is concluded that in tumours of chemical and viral origin, the observed changes in the two components of the protein-synthesizing apparatus occur simultaneously.

Metabolic conversion of benzo(a)pyrene by Syrian hamster liver microsomes and binding of metabolites to deoxyribonucleic acid.

Metabolic conversion of benzo(a)pyrene by Syrian hamster liver microsomes and binding of metabolites to deoxyribonucleic acid.

Re-evaluation of the quantity of DNA in cell nucleus of two animal species by microspectrophotometry and autoradiography.

Microspectrophotometric evaluation of the DNA content of cell nuclei and 3H-thymidine autoradiography were carried out on the cells from cerebellums, thymus, glandular stomach, liver, and kidney of embryonic, suckling, and adult Syrian hamsters and Buffalo rats. The results obtained from this study were as follows: 1) In both hamsters and rats, the cells with diploidDNA (2C) showed the main modal peak in various organs examined of embryonic to 6-month-old animals. 2) In liver tissues, tetraploid cells (4C) began to appear in the 3-day-old animals and increased gradually in number until 6 months old, 40% or more of the cells showing tetraploid value of DNA. 3) No cells with intermediate or extra DNA were found in tissues examined during the growth period of animals, and neither octaploid nor higher nuclei appeared even in liver tissues of the adults. 4) 3H-thymidine labeling index showed high percentages in organs of embryo to 1 day after birth. 5) 3H-thymidine labeling index rapidly declined 1 week after birth in all the organs except in the cells of glandular stomach. 6) There is a close correlation between labeling and mitotic indices and the distribution pattern of DNA value. From these data it would be supposed that the appearance of the cells with extra or intermediate DNA value is due to the existence of the cell in S-phase.

Multiple enzyme determinations in sera and livers of tumor bearing hamsters.

SummaryEnzyme activity changes of LDH, GOT, ICD, PHI, alkaline and acid phosphatase in the serum and livers of Syrian hamsters bearing adenovirus type 12 induced tumors have been studied. Five to six weeks post inoculation the serum values for LDH, GOT and ICD were 154%, 77% and 141% respectively above the means of the unin-oculated controls. PHI serum levels were slightly increased from the beginning until termination of the experiment 6 weeks post inoculation. The values during this period were 24%; (mean) higher than those of the uninoculated controls. Serum enzyme activities of adenovirus type 5 infected animals remained essentially unchanged, except for slightly decreased PHI levels. The enzyme content of GOT and ICD in the livers of adenovirus type 12 injected hamsters, which revealed no evidence of malignant cells by microscopic examination, were 3-4 times greater than controls. Variations in enzyme activities in the serum have been discussed in the light of the different sources of enzymes release...