ISSN:0004-945X    

DOI:10.1038/icb.1977.60

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

摘要:

SummaryMarsupial × eutherian cell hybrids would he very useful for studies of mammalian genetics and cell biology. A critical step in the formation of such hybrids is the fusion of cells to form heterokaryons. We have examined many different combinations of marsupial and eutherian cells for their ability to fuse, and we have found that nil combinations yielded heterokaryons, but with different frequencies, depending on the cell types used. Ranked in order of decreasing ability to fuse with eutherian cells, the marsupial cell types were; established lines, primary diploid fibroblasts and lymphocytes. In all fusion experiments there was a marked preference for the formation of homokaryons compared with heterokaryons. It was possible to control the numbers and types of heterokaryons formed by varying the input ratio of parental cells.

ISSN:0004-945X    

DOI:10.1038/icb.1977.61

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

摘要:

SummaryThree different type A influenza viruses have been isolated from pelagic birds nesting on islands of the Great Barrier Reef. One of these, isolated in 1972, was of subtype Hav6Nav5. The other two, which are described in this paper, were isolated in 1975 and belonged to subtypes Hav5Nav2 and Hav3Nav6. Of eight isolates of the latter virus, seven were recovered from cloacal swabs and only one from the trachea.

ISSN:0004-945X    

DOI:10.1038/icb.1977.62

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1977.63

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

摘要:

SummaryAedes(Finlaya)notoscriptus(Skuse), a mosquito which occupies a similar ecological niche toAedes (Stegomyia) aegypti(L), the urban vector of yellow fever virus, was screened as a possible vector of this disease. The results indicate that almost certainlyAe. notoscriptusis refractory to the virus and could not act as a vector if yellow fever were introduced to Australia.

ISSN:0004-945X    

DOI:10.1038/icb.1977.64

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

摘要:

SummaryThe presence of a variety of embryonic and foetal gene products in neoplasms is well documented. Two such products, i.e. carcinoembryonic antigen and alpha foetoprotein, are currently being used for clinical diagnosis and the assessment of prognosis. The purpose of this study has been to examine the possibility of the reactivation of a foetal gene associated with foetal liver in the Morris 5123C hepatoma and host liver after prolonged tumour bearing. The foetal gene for globin was chosen for study as production of foetal globin in cancer patients has been observed and the technique for quantitation of globin messenger RNA is available. The quantitation of globin mRNA permits the identification of a gene product which is not related to the tissue of origin of the tumor being studied and which is influenced by pre‐translational control mechanisms only. The influence of tumour bearing on foetal globin gene expression by the host liver is also reported. We report molecular hybridization studies of total nucleic acid extracts from foetal, 2‐day neonatal, adult and host liver and the Morris 5123C transplantable hepatoma with a complementary DNA copy of globin messenger RNA. The results indicate that there is no activation of the foetal globin gene in these tissues in spite of erythrocytosis in the host animal.

ISSN:0004-945X    

DOI:10.1038/icb.1977.65

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

摘要:

SummaryPharmacokinetic parameters which describe, distribution and elimination of sulfadimethoxine were determined in cats. Following intravenous administration of a single dose (55 inn/kg), disposition of the drug was described in terms of the hiexponential expression: Cp= Ae−αt+ Be−βt. Based on total (free and bound) sulfonamide levels in the plasma, pseudo‐distribution equilibrium was slowly attained and the half‐time of elimination (half‐life) was 10·16 h ± 2·50 (S.D. n = 6). Body clearance, which is the sum of all clearance processes, was 18·8 ± 4·6 ml kg−1h−1. Plasma protein binding, measured by equilibrium dialysis at sulfonamide concentration of 50 μg/ml, was extensive (87.5% ± 6·3. n = 10). Computer‐generated curves for an animal representative of the group, based on individual rate constants associated with the two‐compartment open model, showed that 12% and 5% of the dose were present in the central and peripheral compartments, respectively, 24 h after administering the drug. A satisfactory dosage regimen might consist of a priming dose (55 mg/kg) and maintenance dosage (27·5 mg/kg at 24 h dosage intervals). Predicted plasma sulfadimethoxine concentrations would oscillate between 125 and 25 μg/ml during the steady state. Influence of bacterial disease and febrile states on predicted levels remains to be verified experimentally.

ISSN:0004-945X    

DOI:10.1038/icb.1977.66

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

摘要:

SummaryThe recent identification and synthesis of the endecapeptide substance P has renewed interest in this naturally occurring compound. The original substance P of Euler and Gaddum was a mixture of biologically active substances, some of which were peptides. The peptide component was responsible for gut‐contracting, hypotensive and sialogogic properties attributed to substance P. For almost 40 years following its discovery, substance P resisted isolation and purification. Even the most highly active preparations were heterogeneous and there was a divergence of results from experiments using preparations which were partially purified by different techniques. Nevertheless, much of the early work on the distribution and pharmacology of crude substance P has been confirmed using the synthetic endecapeptide and has stimulated research towards the elucidation of a possible functional role for substance P. Most proposed functions have been highly speculative but, at present, evidence is accumulating in support of a physiological role for substance P as a neurotransmitter in sensory pathways.

ISSN:0004-945X    

DOI:10.1038/icb.1977.67

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1977.68

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY

摘要:

SummaryLong chain fatty acids were found to inhibit (Na++K+)– ATPase prepared from rat heart. Unsaturated and polyunsaturated fatty acids were more inhibitory than saturated fatty acids with myristic acid being the most inhibitory saturated fatty acid tested and linoleic the most inhibitory unsaturated fatty acid.As an example of fatty acid modification of the enzyme, inhibition of (Na++K+)–ATPase by oleate was examined. When compared to ouabain, inhibition of (Na++K+)– ATPase by oleate was found to be similar in that both were dependent on K+concentration, but, in contrast to the almost instantaneous inhibition by ouabain, oleate inhibition was a slow process requiring over 20 min incubation at 37° to produce maximum inhibition. Inhibition of rat heart (Na++ K+) –ATPase by oleate was found to be readily reversible by washout. In the presence of albumin an oleate/albumin molar ratio greater than 7·5 was required for inhibition to occur.The activity of rat heart (Na++K+)‐ATPase had a temperature optimum above 40° and a discontinuous Arrhenius' plot with a transition temperature of 25°. In the presence of oleate, however, the enzyme's optimum temperature decreased to below 40°, the activation energy of the reaction at temperatures below 25° was lowered from 24.7 kcal/mol to 12.6 kcal/mol and tire enzyme had a linear Arrhenius' plot.The possibility ofin vivoinhibition of cardiac (Na++K+)– ATPase under conditions of elevated fatty acids is discussed.

ISSN:0004-945X    

DOI:10.1038/icb.1977.69

出版商:Nature Publishing Group    

年代:1977

数据来源: WILEY