Showing papers in "Nature in 1972"
TL;DR: Water photolysis is investigated by exploiting the fact that water is transparent to visible light and cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm.
Abstract: ALTHOUGH the possibility of water photolysis has been investigated by many workers, a useful method has only now been developed. Because water is transparent to visible light it cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm (ref. 1).
27,819 citations
TL;DR: It is suggested that large complex systems which are assembled (connected) at random may be expected to be stable up to a certain critical level of connectance, and then, as this increases, to suddenly become unstable.
Abstract: Gardner and Ashby1 have suggested that large complex systems which are assembled (connected) at random may be expected to be stable up to a certain critical level of connectance, and then, as this increases, to suddenly become unstable. Their conclusions were based on the trend of computer studies of systems with 4, 7 and 10 variables.
2,424 citations
TL;DR: H2-receptor antagonist, a new group of drugs, may help to unravel the physiology of histamine and gastrin.
Abstract: H2-receptor antagonist, a new group of drugs, may help to unravel the physiology of histamine and gastrin.
2,135 citations
TL;DR: Chemotaxis toward amino-acids results from the suppression of directional changes which occur spontaneously in isotropic solutions.
Abstract: Chemotaxis toward amino-acids results from the suppression of directional changes which occur spontaneously in isotropic solutions.
2,069 citations
TL;DR: In this article, an implosion system energized by a high energy laser was proposed to compress hydrogen to more than 10,000 times liquid density by an imploding system, which makes possible efficient thermonuclear burn of small pellets of heavy hydrogen isotopes, and makes feasible fusion power reactors using practical lasers.
Abstract: Hydrogen may be compressed to more than 10,000 times liquid density by an implosion system energized by a high energy laser. This scheme makes possible efficient thermonuclear burn of small pellets of heavy hydrogen isotopes, and makes feasible fusion power reactors using practical lasers.
1,550 citations
TL;DR: The observed concatemers of T7 DNA are consistent with replication schemes resulting in double-helical molecules with 3´ ended tails as discussed by the authors, and they can then join to form dimers which on further replication similarly form larger concatures.
Abstract: The observed concatemers of T7 DNA are consistent with replication schemes resulting in double-helical molecules with 3´ ended tails. Right-ended and left-ended molecules can then join to form dimers which on further replication similarly form larger concatemers.
1,409 citations
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TL;DR: The Social Contexts of Research as mentioned in this paper is a collection of articles about the social context of research in the 1970s and 1980s, edited by Saad Z. Nagi and Ronald G. Corwin. Pp. xii + 409.
Abstract: The Social Contexts of Research. Edited by Saad Z. Nagi and Ronald G. Corwin. Pp. xii + 409. (John Wiley: New York and London, August 1972.) £5.65.
1,206 citations
TL;DR: An ingenious scheme is developed in which evanescent waves are used to illuminate the object, and a magnified image is obtained using a holographic technique, and the resolution capability is determined by the wavelength of the evanescence wave.
Abstract: THE classical theory of the resolving power of optical instruments implies a limit to the observation of details in an object if these are significantly smaller than one wavelength, λ0, of the illuminating radiation. This Abee barrier is not entirely impenetrable. Lukosz1,2 has shown how an improvement by a factor of two can be made by the use of complementary spatial filters. Attempts to proceed further in this direction are soon frustrated, however, because the spatial frequencies one is seeking to transfer are such that the waves become evanescent in the direction in which one would like them to propagate. Nassenstein has developed an ingenious scheme3 in which evanescent waves are used to illuminate the object, and a magnified image is obtained using a holographic technique. The resolution capability is determined by the wavelength of the evanescent wave. This is less than λ0, but it is not easy to devise systems where it would be very much smaller.
908 citations
TL;DR: The observations underlying this hypothesis have been amply confirmed and extended and a GH-dependent plasma factor stimulates in cartilage not only the incorporation of sulphate into chondroitin sulphate, but also the incorporate of thymidine into DNA and proline into the hydroxyproline of collagen.
Abstract: THE action of growth hormone (GH) on skeletal tissue was proposed to be mediated through a secondary substance, described by the operational term “sulphation factor”1 The observations underlying this hypothesis have been amply confirmed and extended A GH-dependent plasma factor stimulates in cartilage not only the incorporation of sulphate into chondroitin sulphate, but also the incorporation of thymidine into DNA2, proline into the hydroxyproline of collagen3 and uridine into RNA4 GH has substantially no in vitro effect on cartilage metabolism
851 citations
TL;DR: Compared the pain producing activity of fatty acid hydroperoxides with that of high concentrations of acetylcholine, bradykinin, histamine and PGE1 on intradermal injection in man, the intensity of the pain induced was greater than that induced by the other agonists but for all except P GE1 the pain was transitory.
Abstract: THE importance of prostaglandins in inflammation has been emphasized by the discovery that aspirin-like anti-inflammatory drugs inhibit their synthesis1–3. The anti-inflammatory and anti-pyretic effects of this group of drugs could be explained on this basis1, but their analgesic properties could not, then, be firmly linked to inhibition of prostaglandin synthesis. This was because the only subjective effect reported on intradermal injection of prostaglandin was a sensation of warmth and a slight itching*, and on the blister base PGE2 (up to 100 µg/ml.) failed to produce pain5. Several reports now describe the pain-producing activity of prostaglandins infused i.v. and injected intramuscularly6–8 in man. Collier and Schneider have shown that PGE1 is the most powerful agent in producing writhing responses in mice9. Vane1 suggested that rabbit aorta contracting substance (RCS)10 which may be the unstable cyclic peroxide intermediate in the biosynthesis of prostaglandins11, may be involved in the production of pain in inflammation. I tried to test this hypothesis by comparing the pain producing activity of fatty acid hydroperoxides with that of high concentrations of acetylcholine, bradykinin, histamine and PGE1 on intradermal injection in man. The intensity of the pain induced by the hydroperoxides was greater than that induced by the other agonists but for all except PGE1 the pain was transitory. On testing subdermal infusions to mimic the continuous release of an endogenous mediator of pain, two important properties of E-type prostaglandins were revealed. First, they increase the pain sensitivity to chemical and mechanical stimulation. Second, their effects are cumulative and depend not only on their concentrations but also on the time of exposure. The term “pain” is used to denote the overt pain evoked chemically during the infusions; hyperalgesia is used when pain was elicited only by applying slight pressure on the infusion area. Studies were carried out in five male volunteers each of whom received a full explanation of the nature of the experiment before giving his consent. The experiments were double blind.
814 citations
TL;DR: “Tight junctions” between cells in some epithelia actually provide the main route of passive ion permeation and the degree of junctional tightness may underlie important functional differences between different epithelias.
Abstract: “Tight junctions” between cells in some epithelia actually provide the main route of passive ion permeation. The degree of junctional tightness may underlie important functional differences between different epithelia.
TL;DR: Prostaglandin biosynthesis by aspirin-like drugs has now been confirmed in several systems and one of the few anomalies was that paracetamol, which has no anti-inflammatory activity, but is analgesic and anti-pyretic12, was inactive against dog spleen synthetase.
Abstract: INHIBITION of prostaglandin biosynthesis by aspirin-like drugs1–3 has now been confirmed in several systems4–7. The theory1 that this anti-enzyme action is the basis of the clinical effects of aspirin-like drugs has recently been reviewed8–11 in detail. One of the few anomalies was that paracetamol (4-acetamidophenol) which has no anti-inflammatory activity, but is analgesic and anti-pyretic12, was inactive against dog spleen synthetase (ED50 = 100 µg ml.−1). A possible explanation for this discrepancy is that synthetase systems from different regions of the body show different sensitivities to drugs.
TL;DR: When actin molecules form “rigor complexes” with nucleotide-free myosin, tropomn binds calcium with greater affinity and in a cooperative response the remaining actin molecule not cornplexed with myOSin are “turned on” even though calcium is absent.
Abstract: When actin molecules form “rigor complexes” with nucleotide-free myosin, tropomn binds calcium with greater affinity and in a cooperative response the remaining actin molecules not cornplexed with myosin are “turned on” even though calcium is absent.
TL;DR: DPG has a two-fold effect on human deoxyhaemoglobin: it both stabilizes and slightly distorts the S form, and may therefore affect the solubility.
Abstract: DPG has a two-fold effect on human deoxyhaemoglobin. It both stabilizes and slightly distorts the S form, and may therefore affect the solubility.
TL;DR: In this article, the authors suggest that DMS is the natural sulphur compound which fills the role originally assigned to H2S; that of transferring sulphur from the seas through the air to land surfaces.
Abstract: ALL models of natural processes for the transfer of sulphur on a global scale1–4 require some volatile or gaseous sulphur compound to complete the cycle by providing a vehicle for the transfer of sulphur from the sea through the air to the land surfaces. In the past, this role has been assigned to H2S and an average atmospheric concentration of 2×10−10 by volume satisfied the mass transfer needs of the models. Attempts to detect the presence of these concentrations of H2S have always failed and, more important, the ocean surface waters are much too oxidizing to permit the existence of H2S at concentrations sufficient to sustain an atmospheric equilibrium concentration of 2×10−10 by volume. Many elements form volatile methyl derivatives; Challenger5 reported that many living systems produced dimethyl sulphide (DMS), and that prominent among them were marine algae. Here we suggest that DMS is the natural sulphur compound which fills the role originally assigned to H2S; that of transferring sulphur from the seas through the air to land surfaces.
TL;DR: Observations using electron microscopy and freeze-etching techniques show that both metabolic coupling and ionic coupling in fibroblasts are associated with the appearance of “gap” junctions.
Abstract: Observations using electron microscopy and freeze-etching techniques show that both metabolic coupling and ionic coupling in fibroblasts are associated with the appearance of “gap” junctions.
TL;DR: Transient photodichroism in the frog retina reveals that rhodopsin has a relaxation time of 20 µs, and the site rhodopin occupies in the membrane must therefore be highly fluid.
Abstract: Transient photodichroism in the frog retina reveals that rhodopsin has a relaxation time of 20 µs. The site rhodopsin occupies in the membrane must therefore be highly fluid. This suggests rhodopsin may be a diffusional carrier.
TL;DR: KNOWLEDGE of the detailed pattern of fluorescence of the normal human karyotype has enabled us to recognize, both in biopsies and in cell cultures from several Burkitt lymphomas, an extra band in one homologue of D group chromosome pair No. 14.
Abstract: KNOWLEDGE of the detailed pattern of fluorescence of the normal human karyotype, showing more than 200 bands per haploid chromosome set1, has enabled us to recognize, both in biopsies and in cell cultures from several Burkitt lymphomas, an extra band in one homologue of D group chromosome pair No. 14. The deviation was seen in all analysable cells of five out of six tumour biopsies and of seven out of nine tumour cell lines examined, representing twelve different tumours from nine male and three female patients. In three tumours both biopsies and cultures were examined, and it was found that all gave results consistent in the two types of samples. Thus, two of them had the marker band in both the biopsy and culture, the third revealed the marker band absent in both cases. The remaining tumours were investigated only in biopsies or only in culture. They were positive in eight cases, negative in one. Of the twelve tumours examined altogether, ten were positive and two negative.
TL;DR: It is shown that the structure of the matrix of cellular membranes is a bimolecular leaflet of phospholipid molecules in which the polar heads reside on the outer surfaces of the bilayer, in contact with the aqueous environment.
Abstract: IT is generally accepted that the matrix of cellular membranes is a bimolecular leaflet of phospholipid molecules in which the phospholipids are oriented so that their polar heads reside on the outer surfaces of the bilayer, in contact with the aqueous environment, the interior of the sandwich being composed of hydrophobic lipid chains1–5. To this basic structure proteins cholesterol, glycolipids and other molecules are usually inserted in such a way as to confer on the bilayer the functional properties appropriate for the particular membrane.
TL;DR: In this article, it was shown that super-radiant scattering can also be used to extract rotational energy from a rotating hole, and that a particle radiatively extracts energy from the hole at the same rate as it radiates energy to infinity; thereby it experiences zero net radiation reaction.
Abstract: Penrose1 and Christodoulou2 have shown how, in principle, rotational energy can be extracted from a black hole by orbiting and fissioning particles. Recently, Misner3 has pointed out that waves can also extract rotational energy (“superradiant scattering” in which an impinging wave is amplified as it scatters off a rotating hole). As one application of super-radiant scattering, Misner has suggested the possible existence of “floating orbits”, that is, orbits in which a particle radiatively extracts energy from the hole at the same rate as it radiates energy to infinity; thereby it experiences zero net radiation reaction.
TL;DR: In this article, the authors summarized Iranian geology and continental drift in the Middle East and suggested that plate tectonics satisfactorily explain the geological development of the Middle Eastern region.
Abstract: This article summarizes Iranian geology and continental drift in the Middle East The relation of the two suggests that plate tectonics satisfactorily explain the geological development of the Middle East
TL;DR: A clear discrepancy is reported between the product of certain cell-free reactions and authentic light chain and it is proposed that light chains are initially synthesized as a precursor of slightly higher molecular weight and subsequently converted into the authentic product.
Abstract: IMMUNOGLOBULIN light chains are synthesized in heterologous cell-free systems from reticulocytes1 and Krebs II ascites cells2 and in reconstituted homologous systems from lymph nodes3,4 and myeloma tumours5,6. Although the synthesis appeared to be essentially faithful, absolute identity with authentic light chains was not demonstrated and some small differences were observed. We report here a clear discrepancy between the product of certain cell-free reactions and authentic light chain. With the product of other cell-free reactions no such discrepancy is seen. We propose that light chains are initially synthesized as a precursor of slightly higher molecular weight and subsequently converted into the authentic product.
TL;DR: The Camp Century, Greenland, deep ice core reveals seasonal variations in the isotopic composition of the ice back to 8,300 years BP as discussed by the authors. But the complexity of the glaciological regime at Byrd Station precludes a rational choice of a time scale.
Abstract: The Camp Century, Greenland, deep ice core reveals seasonal variations in the isotopic composition of the ice back to 8,300 years BP. This is not the case for the Byrd Station, Antarctica, deep ice core. Both cores show long-term perturbations in isotopic composition reflecting climatic changes from before the beginning of the last glaciation. But the complexity of the glaciological regime at Byrd Station precludes a rational choice of a time scale. Pole-to-pole correlations of the palaeoclimatic data therefore become speculative except for the more pronounced features and general trends.
TL;DR: The existence of two distinct factors, one of which can completely replace T-cells, is reported, which is believed to be based on the heavy antigenic stimulation provided by the histocompatibility antigens carried by the B-cells.
Abstract: WE have recently shown that the immune response to sheep red blood cells (SRBC) in vitro is T-cell dependent, that is, it can be abrogated by pretreatment of the spleen cells with anti-θ serum and complement1. We further reported that reconstitution of the system can be achieved by, among other things, the addition of allogeneic thymocytes2, while syngeneic thymocytes failed to function as helper cells. Positive allogeneic effects were only obtained if the added thymocytes could recognize the remaining B-cells as foreign. One of the explanations evoked for this allogeneic effect was the participation of a potentiating factor2,3. It seemed possible that on the heavy antigenic stimulation provided by the histocompatibility antigens carried by the B-cells, added T-cells produce a soluble factor which stimulates the immune response of B-cells to unrelated antigens. We now want to report the existence of two distinct factors, one of which can completely replace T-cells.
TL;DR: An all-plastic trace element controlled isolator system has been created and it was able to demonstrate recently that tin3,4, vanadium5, and fluorine6 (K. S. and D. M., unpublished results) are essential for growth.
Abstract: To study new trace element deficiency diseases and to identify hitherto unrecognized essential trace elements, an all-plastic trace element controlled isolator system has been created1,2. It prevents access of the animals to metal, glass, rubber, dust, or caretaking personnel. Each isolator accommodates thirtytwo rats in individual plastic cages. Complete, chemically defined diets are used which are based on amino-acids in lieu of protein. The known essential elements are supplied in sufficient and balanced quantities. All ingredients are monitored for trace element contaminants. By means of this approach we have been able to demonstrate recently that tin3,4, vanadium5, and fluorine6 (K. S. and D. B. M., unpublished results) are essential for growth.
TL;DR: It is still an open question how the genetic polymorphism represented by the principal human histocompatibility system is maintained, but it may have evolved as a consequence of the necessity for cell to cell recognition during development and morphogenesis.
Abstract: It is still an open question how the genetic polymorphism represented by the principal human histocompatibility system is maintained. But it may have evolved as a consequence of the necessity for cell to cell recognition during development and morphogenesis.
TL;DR: Through modifications of the original methods used in the DNA hybridization work, techniques have been developed which make each chromosome identifiable and these observations were later made on human chromosomes.
Abstract: THE differential staining properties of the Giemsa stain were first observed by Pardue and Gall1. They were studying in situ hybridization between mouse satellite DNA and mouse chromosomes and observed that following certain pretreatment the centromeric regions of mouse chromosomes were more densely stained by Giemsa stain than other regions. The darkly stained regions were considered to consist of constitutive heterochromatin. Similar observations were later made on human chromosomes by Arrighi and Hsu2 and Gagne et al.3. Through modifications of the original methods used in the DNA hybridization work, techniques have been developed which make each chromosome identifiable4–6.
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TL;DR: Professor Yudkin discusses whether the intake of dietary sugar is linked with some diseases and if so, how to reduce it.
Abstract: Professor Yudkin discusses whether the intake of dietary sugar is linked with some diseases.
TL;DR: In this paper, simple rules for rationalizing and predicting the geometries of complex polynuclear aggregates of atoms and molecular fragments are presented, and simple rules are presented for rationalization and prediction of the geometry of these aggregates.
Abstract: Simple rules are presented for rationalizing and predicting the geometries of complex polynuclear aggregates of atoms and molecular fragments