bluuebunny/crossref_metadata_2025_split huggingface dataset:
STEROID HORMONE METABOLISM IN RESPONSIVE TISSUES IN VITRO
Authors: Robel Paul 
Published: October 2009

ABSTRACT
Of the information available on steroid hormone metabolism in responsive tissues, only that relating hormone metabolism to physiological activity is reviewed, i. e. metabolite activity in isolated in vitro systems, binding of metabolites to target tissue receptors, specific steroid hormone metabolizing enzymes and relationship of hormone metabolism to target organ physiological state.
Further, evidence is presented in the androgen field, demonstrating 5α-reduced metabolites, formed inside the target cells, as active compounds. This has led to a consideration of testosterone as a »prehormone«. The possibility that similar events take place in tissues responding to progesterone is discussed.
Finally, the role of hormone metabolism in the regulation of hormone availability and/or renewal in target cells is discussed. In this context, reference is made to the potential role of plasma binding proteins and cytosol receptors.
SURVIVAL AND GONADOTROPHIN RESPONSIVENESS OF LUTEAL CELLS IN VITRO
Authors: Hansel William 
Published: October 2009

ABSTRACT
Simplified methods for incubating luteal tissues have been developed. Progesterone biosynthesis in washed, minced bovine luteal tissue is stimulated by added bovine LH. The response is linear in the range 2–200 ng added LH per ml of medium. The use of covariance analysis to correct for differences in time elapsing between mincing the tissue and the beginning of incubation reduces the standard error of the mean and results in marked improvement in the indices of precision. Progesterone biosynthesis in washed, minced bovine luteal tissues appears specific for LH; no other pituitary hormones give a response, and the response is completely negated by adding anti-bovine LH serum to the incubation medium. Prior treatment of cattle from which the incubated corpora lutea are obtained with various levels of human chorionic gonadotrophin, results in greatly increased luteal tissue weights. However, this tissue has a markedly reduced sensitivity to LH added in vitro. No conclusive evidence was found for a feedback inhibition of progesterone on its own synthesis in this system. The incubation system developed is sensitive enough to serve as a bioassay for LH in biological tissues and fluids. Preliminary data suggest that a simplified protein binding assay can be successfully used to measure the progestins synthesized by minced, washed bovine luteal tissue in response to added bovine LH.
MORPHOLOGICAL EVALUATION OF PERFUSED TISSUES
Authors: Panigel Maurice 
Published: October 2009

ABSTRACT
Morphological evaluation of perfused or preserved tissues can establish the extent of damage to the cellular architecture (vasculature, connective tissue, parenchymal cells) as a result of organ distress during the experimental procedure. Distress in perfused organs becomes evident by a rise of the vascular resistance to the perfusion flow and by an increase in the interstitial oedema which is easily detected and measured but is difficult to prevent in long term experiments.
There exists a hierarchy of preservability for the different tissues but the haemochorial human (or monkey) placental membrane is a unique structure for assessing morphological and functional integrity of the layers (trophoblast, villous stroma, endothelium) which separate the two different perfusion streams in the maternal and foetal blood channels.
In this review, emphasis has ben placed on two essential criteria to evaluate placental viability and functional capacity:

– the control of the efficiency of perfusion by radio-angiographic visualization of the diffusion of the perfusate in the isolated placental lobule.
– the histological and electron microscopical study of placental biopsies and post perfusion controls.
Similarly to the case in other tissues, light microscopy of the placenta only shows the gross alterations due to prolonged unsatisfactory survival conditions in vitro. Electron microscopy, however, provides a sensitive morphological test to detect early changes in the metabolic activity of the trophoblast and to control the integrity of the foetal capillary wall. Ultrastructural alterations, when they appear, are first seen at the cell borders and in the organelles (endoplasmic reticulum, mitochondria, lysosomes) of the syncytiotrophoblast layer. The endothelial cell lining of foetal capillaries usuallly remains intact during the first hours of a satisfactory perfusion with dilute blood but a swelling of the endothelium and abnormal endothelial cytoplasm projections in the capillary lumen may be observed when other perfusion fluids are used.
The physiological importance of the lysosome-like bodies found in the apical cytoplasm of the syncytiotrophoblast and the in vitro stability of the lysosomal membrane necessitate further investigations.
TECHNIQUES FOR THE COLLECTION OF LYMPH WITH SPECIAL REFERENCE TO THE TESTIS AND OVARY
Authors: Morris Bede , McIntosh G. H. 
Published: October 2009

ABSTRACT
This paper describes the general surgical procedures used for cannulating lymphatics and for collecting lymph from various tissues of the body. Special reference is made to the lymphatic drainage of the testis and ovary of the sheep and to the relationships of the lymphatics and blood capillaries in these organs to the hormone secreting cells. The formation of lymph in these organs is related to some of their physiological activities, and details of the biochemical composition of testicular and ovarian lymph are given. The role of the lymphatic system in hormone transport and the possible significance of the composition of the interstitial fluid in regulating the synthesis and secretion of hormones is discussed.
LIVER PERFUSION IN THE STUDY OF HORMONE EFFECTS ON THE IONIC CONTENT AND MEMBRANE POTENTIAL OF LIVER CELLS
Authors: Lambotte L. , Kestens P. J. 
Published: October 2009

ABSTRACT
Factors responsible for the success of canine liver perfusion are reviewed along with the description of the method used by the authors; emphasis is placed on the avoidance of anoxia, perfusion with blood by the hepatic artery and the portal vein, use of optimal values for haematocrit, pCO2 and temperature. The validity of this method of perfusion is established by biochemical tests but also by its ability to support the viability of livers before transplantation.
The monitoring of the perfusion is obtained with an on line digital computer gathering data from autoanalyzers, transducers (temperature, pressure) and from intracellular microelectrodes for the measurement of the membrane potential of the liver cell.
Various applications of this system to the study of ionic movements are described. Non-hormonal factors, such as temperature or pH changes modify the ion concentration and the membrane potential; some of the mechanisms involved are briefly discussed. Epinephrine injection produces by stimulation of the α receptor an hepatic potassium loss coupled with an equivalent sodium gain which are concomitant to a marked depolarization. These phenomena can be related to an increase in membrane permeability to the sodium ion. Comparisons are made between the stimulation of a and β adrenergic receptors. The effect of insulin on potassium uptake is studied during liver perfusion and in vivo in order to demonstrate antagonism between insulin on one hand and glucagon and cyclic AMP on the other hand.
In conclusion, liver perfusion offers some advantage over in vivo or other in vitro techniques but the method employed must maintain the liver in perfect functional condition. The measurement of membrane potential could be used to evaluate the viability of the perfused liver.
PERFUSION OF THE THYROID
Authors: Folkman Judah , Gimbrone Michael A. 
Published: October 2009

ABSTRACT
Thyroid glands maintained by isolated perfusion have been used for studies in metabolism, micro-circulation and tumour angiogenesis. Recent work is described.
Thyroid metabolism can be studied for brief periods of 4–5 hours, after which there is progressive parenchymal damage. Pulsatile flow, and anti-coagulated whole blood or platelet-rich plasma provide for optimum perfusion conditions at normothermic temperatures.
There is gradual degeneration of capillary endothelium in every isolated thyroid perfusion. For this reason, tumours implanted into these organs, fail to become vascularized. This failure of angiogenesis in the isolated perfused organ, has been demonstrated to stop tumour growth at 1 to 2 mm in diameter.
The isolated perfused thyroid gland has also been used to elucidate the role of platelets in nurturing capillary endothelium. Platelets appear to play an essential role in the prevention of endothelial degeneration and its sequelae under normothermic perfusion conditions.
PERFUSION OF OVARIES IN VITRO AND IN VIVO
Authors: Ahrén Kurt , Janson Per Olof , Selstam Gunnar 
Published: October 2009

ABSTRACT
This paper discusses in vivo and in vitro ovarian perfusion systems described so far in the literature. The interest is not focussed primarily on the results of these studies but rather on the advantages and disadvantages of the techniques and methods used. Another part of the paper summarizes the points which are most important, in our opinion, to take into consideration when developing an in vitro perfusion technique of the ovary. The last part of the paper gives a description of and some preliminary results from an in vitro perfusion system of the rabbit ovary which is under development in this laboratory.
EXTRACORPOREAL PERFUSION OF THE HUMAN FOETUS, PLACENTA AND FOETO-PLACENTAL UNIT
Authors: Lerner U. , Saxena B. N. , Diczfalusy E. 
Published: October 2009

ABSTRACT
A system is described for the extracorporeal perfusion of the human foeto-placental unit at midgestation. The same system is used for the perfusion of isolated midgestation foetuses and midgestation or term placentas.
Various gas mixtures were used for the oxygenation of the blood to be perfused, and the pH, pO2 and pCO2 values were monitored at frequent intervals in the perfused blood as well as in the various perfusates. Compared with the values reported for maternal arterial blood, oxygenation of the blood to be perfused with an air + CO2 mixture (23.1 % O2 + 3.5–3.7 % CO2) yielded a normal pH and almost normal pO2 and pCO2 values, whereas oxygenation with carbogen (93.7 % O2 + 6.3 % CO2) resulted in low pH, highly elevated pO2 and almost normal pCO2 values.
In all foetal, placental and foeto-placental perfusions conducted at 36°C, the use of blood oxygenated with the air + CO2 mixture resulted in significantly better pH, pO2 and pCO2 values of the perfusates than when blood oxygenated with carbogen was employed. However, the pH, pO2 and pCO2 values in the perfusates obtained in the former series of experiments were still outside the range of normal values reported in the literature.
HUMAN CHORIONIC SOMATOMAMMOTROPIN (HCS) PLASMA LEVELS IN NORMAL AND PATHOLOGICAL PREGNANCIES AND THEIR CORRELATION WITH THE PLACENTAL FUNCTION
Authors: Genazzani A. R. , Cocola F. , Neri P. , Fioretti P. 
Published: October 2009

ABSTRACT
The results of a study of HCS plasma levels and behaviour in normal and pathological pregnancies may be summarized as follows: a) HCS plasma levels gradually increase during normal pregnancy, reaching the highest values at the 38–39th week after the last menstrual period; in the last few days of pregnancy and just before labour a slight decrease is observed; b) in threatened abortion the behaviour of HCS plasma levels in successive assays clearly divides the cases ending in spontaneous abortion (low or decreasing levels) from those favourably resolved; c) in molar pregnancies the very low HCS plasma levels support the diagnosis; d) in Rhesus-isoimmunization the HCS plasma levels are near normal in all the cases in which the foetus is only slightly affected. On the contrary, very high levels were found in cases of foeto-placental hydrops and the rapid increase in HCS plasma levels in these cases seems to correlate with the appearance of hydropic conditions; e) in diabetic pregnancies, the HCS plasma levels are normal or slightly below normal; decreasing HCS values in subsequent assays preceded the intra-uterine foetal death (IUFD) in one case; two cases of juvenile diabetes treated with less than the required doses of insulin showed very high HCS values; f) in preeclamptic pregnancies the HCS levels are lower than normal and show no further increase after the 32–33rd week; several cases followed up for some weeks support this observation, and cases ending in IUFD or premature labour showed very low HCS levels; g) similarly, low HCS levels which failed to increase in subsequent assays are found in all the cases of foeto-placental dystrophy and multiple placental infarct; h) the cases of IUFD in uncomplicated pregnancies examined during the first 24 hours after the IUFD demonstrate normal or raised HCS levels in three cases where IUFD occurred before the 27th week, and below normal values in 7 out of 9 cases where IUFD occurred afterwards; i) higher than normal levels are demonstrated in twin pregnancies and pregnancies with large babies; j) a significant correlation between the foetal weight and the HCS levels is demonstrated if the plasma samples are collected at least five days before delivery; k) in prolonged pregnancy the observation of low HCS levels clearly indicates the presence of foetal post-maturity or chronic foetal distress; in fact, in uncomplicated prolonged pregnancies the HCS plasma levels are similar to those found in normal pregnancy at term.
All these data indicate the value of plasma HCS radioimmunoassay in an evaluation of the placental function and sustain the importance of its application during the whole pregnancy, and in the presence of any pathological condition of gestation.
METHODS FOR STUDYING PROTEIN-NUCLEIC ACID INTERACTION
Authors: Bourgeois Suzanne 
Published: October 2009

ABSTRACT
Attention is focused on the study of regulatory proteins, repressors or activators, which bind DNA to inhibit or stimulate transcription, respectively.
The best characterized examples of repressors and activators, isolated from bacteria or phages, are cited. Some general properties are pointed out, which appear to be common to all proteins binding DNA with great specificity and high affinity. The techniques available for their purification and fractionation are mentioned.
Sensitive methods for the study of protein-nucleic acid interaction involve the separation of the radioactively labelled nucleoprotein complex from the free labelled reactant. Different techniques that can be used are briefly outlined. The membrane filter technique, which is most sensitive, convenient and fast, is discussed in detail.
The membrane filter technique is illustrated by its use in the study of the E. coli lactose operon repressor-operator interaction. The binding constant for that interaction is Kd = 10−13m. The effects of a variety of parameters on the binding, as well as the mode of action of inducers and anti-inducers, are known. The rate constants for the repressor-operator association and dissociation have been measured. Repressors altered by mutations have been characterized. The membrane filter technique also provides an assay and a means to purify operator DNA.
The approach to similar studies in an animal cell system is briefly discussed.
MORPHOLOGICAL STUDIES OF TRANSCRIPTION
Authors: Miller O. L. , Bakken Aimée H. 
Published: October 2009

ABSTRACT
Preparative techniques are detailed for isolating nuclear contents of amphibian oocytes and HeLa cells for electron microscopy, and the ultrastructure of presumptive ribosomal RNA (rRNA) genes and other active chromosomal loci is described. The rRNA genes from the two cell types present strikingly similar structural configurations, both being fully loaded with RNA polymerases and exhibiting gradients of short to long nascent ribonucleoprotein (RNP) fibrils. Other chromosomal loci in the two cell types are strikingly different; those on lampbrush chromosomes of amphibian oocytes show closely-spaced polymerases and extremely long RNP fibrils, whereas those on HeLa genomes have widely-spaced polymerases and relatively short attached RNP fibrils.
STRUCTURAL AND FUNCTIONAL PROPERTIES OF THREE MAMMALIAN NUCLEAR DNA-DEPENDENT RNA POLYMERASES
Authors: Chambon P. , Gissinger F. , Kedinger C. , Mandel J. L. , Meilhac M. , Nuret P. 
Published: October 2009

ABSTRACT
Three DNA-dependent RNA polymerases AI, BI and BII were purified from calf thymus. These enzymes were characterized by their sensitivity to amanitin, their subunit pattern and their template specificities. Enzyme AI is resistant to amanitin, while B enzymes are inhibited by this poison. Each of these enzymes contains two subunits of high molecular weight: A1 (M.W. 197 000) and A2 (M.W. 126 000) for enzyme AI, Bl (M.W. 214 000) and B3 (M.W. 140 000) for enzyme BI, B2 (M.W. 180 000) and B3 for enzyme BII. In addition, each enzyme contains several subunits of lower molecular weight. Purification of B enzymes from rat liver showed the presence of two enzymes similar to calf thymus RNA polymerases BI and BII and suggested the existence of an additional B enzyme in rat liver. The number of RNA polymerase form B molecules was determined in a variety of animal tissues by binding of labelled amanitin. The values ranged from 1 × 104 to 6.5 × 104 molecules per haploid genome.
Studies with derivatives of rifamycin indicated that calf thymus B enzymes were able to recognize specific initiation sites on calf thymus DNA, which were different from those recognized by enzyme AI or E. coli RNA polymerase. These results favour the hypothesis that the multiplicity of animal RNA polymerases could play an active role in the control of transcription.
mRNA STABILITY AND CELLULAR DIFFERENTIATION
Authors: Kafatos Fotis C. 
Published: October 2009

ABSTRACT
The diversity of mRNA half-lives was investigated in a differentiated insect tissue, the silkmoth galea, which is specialized for production of a characteristic protein, the zymogen of the proteolytic enzyme, cocoonase. It appears that the differentiation-specific cocoonase mRNA is uniquely stable (half-life ca. 100 h). In addition, the non-specific mRNAs (average half-life ca. 2.5 h) show considerable variability in terms of stability. General methods are described for evaluating half-lives of mRNAs coding for distinguishable semipurified proteins. Some of the limitations of these procedures are also discussed.
The observations that mRNA half-lives are variable, and that the differentiation-specific mRNA is unusually stable, have numerous developmental implications. A key role is attributed to differential mRNA stability in a quantitative model of developmental regulation.
PROTEIN-RNA INTERACTIONS IN BACTERIAL RIBOSOMES
Authors: Garrett R. A. , Wittmann H. G. 
Published: October 2009

ABSTRACT
There are several ribosomal proteins which can bind specifically to the three ribosomal RNA's of E. coli. Some structural properties of these proteins and of the RNA are described together with the optimal conditions for binding. Evidence for conformational changes occurring in some proteins, and in the RNA's during binding, is also discussed.
The partial localisation of protein binding sites on the 16S and 5S RNA's, and for one protein on the 23S RNA has been attained recently. However, relatively little is known about the regions of the protein which interact with the RNA. Although the nature of the specificity of the protein-RNA interactions is not yet understood, some experimental approaches which are in progress to elucidate the basis of this specificity are mentioned together with a discussion of the structural factors which may be important.
THE TRANSLATION OF MESSENGER RNA INJECTED IN LIVING OOCYTES OF XENOPUS LAEVIS
Authors: Gurdon J. B. 
Published: October 2009

ABSTRACT
Messenger RNA (mRNA) can be injected in known quantities into oocytes of the frog Xenopus laevis. Haemoglobin mRNA from rabbit, mouse, or duck blood cells is accurately translated, and oocytes can translate messages from different cell-types of all vertebrate groups. Oocytes and eggs have a spare capacity to translate injected messages, even when supplied in excess, and these do not compete with the cells' own messages already in use. The cell component which restricts the translation of injected mRNA above a saturating amount appears not to be KCl-released ribosome factors or transfer RNA. A message-specific component may be responsible for the lower efficiency of translation of α than of β globin mRNA in oocytes. Injected haemoglobin mRNA appears to be translated less frequently in oocytes than in reticulocytes at the same temperature, but continues to be translated in oocytes at nearly the same rate for a period of up to nearly 2 weeks. The injection of mRNA into oocytes is especially valuable for studying the control of protein synthesis in living cells.
NON-RIBOSOMAL POLYPEPTIDE SYNTHESIS
Authors: Lipmann Fritz 
Published: October 2009

ABSTRACT
The biosynthesis of the cyclic decapeptide antibiotic, tyrocidine, was analyzed in particle-free supernatant fractions of RNase-treated homogenates of Bacillus brevis ATCC 8185. From the extracts, three complementary fractions with molecular weights of (1) 100 000, (2) 230 000, and (3) 440 000 were obtained. (1) activates and racemizes the initiating phenylalanine, (2) activates the three following amino acids, and (3) activates the last six amino acids by primary reaction with ATP to AMP-amino acid and secondary transfer to an enzyme-bound -SH. The enzymes alone fix amino acids but do not polymerize. The mixture, on sequential addition of amino acids + ATP, polymerizes first to enzyme-bound polypeptides, which after addition of all ten amino acids, cyclize. The enzymes (2) and (3) each contain one mole of 4'-phosphopantetheine which appears to act in transpeptidation. By mild autolysis and dodecyl sulphate gel electrophoresis, the polyenzymes may be split to subunits of 70 000 molecular weight, retaining only amino acid activation.
In recent attempts to analyze the biosynthesis of the thyrotropic release hormone, a tripeptide made in the hypothalamus, we have met with great difficulties due to the presence of potent peptidases in brain preparations.
PROTEIN SYNTHESIS IN MAMMARY GLAND
Authors: Gaye Pierre , Houdebine Louis , Pétrissant Guy , Denamur Robert 
Published: October 2009

ABSTRACT
The induction of the synthesis of milk proteins is accompanied by a very large increase in the number of polyribosomes in the cells of the mammary gland. The two classes of polyribosomes (free and membrane-bound) possess very different degrees of aggregation. The ratio of bound to free polyribosomes is very high in the normally lactating gland, or after stimulation by prolactin. On the other hand, it is low after inhibition of milk secretion by progesterone. The synthesis of milk proteins is almost exclusively the consequence of activity of bound polyribosomes and the rate of turnover of the RNA content of mRNP is also more rapid for free than for bound polyribosomes. mRNAs were prepared from bound polyribosomes by sucrose-gradient ultracentrifugation and by chromatography on poly U Sepharose. The fractions thus isolated were capable of directing the synthesis of casein αs, β and K in heterologous cell-free systems. Some of the mRNAs for αs casein contained a significant poly A sequence. The control of the synthesis of mammary proteins by initiation factors and tRNAs is discussed. The purification of 2 isoacceptors of Met tRNA has enabled us to show that the mammary initiator tRNA does not possess the sequence GTψC which is present in all other tRNAs.