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The Belgian physicist Joseph Plateau (1801-1883) suffered from uveitis which made him blind at the age of 42 years and which has been ascribed to a previous solar retinitis. Plateau described many visual phenomena, including the persistence of visual impressions. He invented instruments which foreshadowed the cinema.
Numerous aminoacyl-tRNA synthetase sequences have been aligned by computer and phylogenetic trees constructed from them for the two classes of these enzymes. Branching orders based on a consensus of these trees have been proposed for the two groups. Although the order of appearance can be rationalized to fit many different scenarios having to do with the genetic code, the invention of a system for translating nucleic acid sequences into polypeptide chains must have predated the existence of these proteins. In the past, a variety of schemes has been proposed for matching amino acids and tRNAs. Most of these have invoked direct recognition of one by the other, whether or not the anticodon was involved. Often ignored is the possibility of a nonprotein (presumably RNA) matchmaker for bringing the two into conjunction. If such had been the case, then the contemporary aminoacyl-tRNA synthetases could have entered the system gradually, each specific type replacing its matchmaking RNA counterpart in turn. A simple displacement scheme of this sort accommodates the existence of two different families of these enzymes, the second being introduced well before the first had undergone sufficient genetic duplications to specify the full gamut of amino acids. Such a scheme is also consistent with similar amino acids often, but not always, being the substrates of enzymes with the most similar amino acid sequences.
This study was conducted to examine the long-term outcome of 500 patients who underwent surgery for cancer of the thoracic esophagus during the past 20 years. Favorable results were obtained with postoperative adjuvant radiation and chemotherapy and there were no surgical deaths in the last 5 years. The mortality rate decreased from 17% prior to 1980 to 5% between 1981 and 1993, this being most probably attributable to the decreased incidence of suture leakage. With respect to changes in surgical techniques, during the initial years we performed intrathoracic anastomosis, after which sternal manubrium resection with anterior mediastinal esophagogastrostomy was carried out. Subsequently, we invented a technique for performing esophagogastrostomy via the posterior mediastinum. The posterior mediastinum was selected as the most physiologic route, based on measurement of tissue oxygen tension. Using blood flow determinations obtained by laser-Doppler velocimetry, we concluded that the effectiveness of thicker gastric tubes was superior to that of thin tubes. Esophagogastrostomy was performed in a shallow field in the cervical region, with the anastomosis ultimately positioned in the superior mediastinum and covered with mediastinal pleura.
In recent years, nuclear magnetic resonance spectroscopy has been enriched by a large number of new experimental techniques which, on the one hand, have opened up new areas of applications in physiological chemistry and even medicine, and on the other hand resulted in considerable progress for nmr spectroscopy as a branch of molecular spectroscopy as a branch of molecular spectroscopy as it is used in chemistry. In this context, two aspects must be emphasized: The nmr spectroscopy of rare nuclei and the invention of two-dimensional methods. Both aspects will be treated using selected examples: nmr measurements for iron-57, chromium-53, and nitrogen-15 as well as new experimental techniques like polarization transfer, J-resolved two-dimensional nmr spectra, two-dimensional shift correlations and multiquantum phenomena are discussed. Besides practical applications the basic physical principles of these techniques are briefly evaluated.
An H-shaped device was invented to facilitate placement of the distal interlocking screws during closed femoral nailing. Eleven sound cadaveric femurs were experimentally nailed before the application of the device in 15 patients with a femoral shaft fracture. In all experimental cases the insertion of the distal screws proved to be easy. In 11 of 15 patients with a femoral fracture, distal locking was achieved using the H-device. These primary results should stimulate further clinical application of the device.
Before the invention of magnetic resonance imaging (MRI), it was impossible to observe an architectural deformation of the eyelid because of its movement. The authors observed MRI films of 15 eyelids in both closed and opened positions and obtained new information on the architecture of the upper eyelid and also the mechanism of single and double eyelids, and sunken eye formation. (1) Orbital fat is transposed when the lid moves. If the fat can not return into the orbit when the lid opens, it droops and interferes with the fold formation of the lid. (2) The thickness of the eyelid skin is associated with double-eyelid formation. The skin fold is observed at the junction between thick skin with subcutaneous fat and thin skin without it. (3) We could not confirm Doxanas and Anderson's assertion that septal insertion was lower in Orientals. However, we observed pretarsally drooped or herniated orbital fat in many slit-eye Orientals. (4) There are three angles at the tarso-levato-aponeurotic line: one at the junction with transverse ligament, one at the point of septal insertion, and another at the aponeurotic terminal on the tarsus.
Comparative studies of neural mechanisms underlying the perception of natural stimulus patterns and the control of adaptive behavioral responses have revealed organizational principles that are shared by a wide spectrum of animals. Mechanisms of perception and motor control are commonly executed in a distributed network of neurons that lack 'pontifical' elements. Individual neurons even at an organizational level as high as the optic tectum may still have very general response characteristics, and the recruitment of individual neurons reveals little about the nature of the stimulus situation outside. Only the joint evaluation of messages from large populations of such neurons yields unambiguous pictures of the outside world. Stimulus variables are commonly mapped continuously within a stratum of neurons so that their variation over time can be monitored by mechanisms similar to motion detection in a retina. The ordered representation of a stimulus variable within an array of broadly tuned elements allows for a degree of stimulus resolution that by far exceeds that of individual elements in the array. Neural systems are burdened by their evolutionary history and suffer from imperfections that are overcome by a patchwork of compensations. The existence of multiple neuronal representations of sensory information and multiple circuits for the control of behavioral responses should provide the necessary freedom for evolutionary tinkering and the invention of new designs.
Realizing that scientific knowledge was not based on a simple disclosure of reality, but was rather invented and developed in accordance with our own conceptions and prejudices, it should no longer be possible to consider matters as if they existed independently of us 'out there'. Taking as examples the notions of 'memory' and 'information' we try to elucidate the relevance this perspective has with respect to neuro- and psychophysiological research.
Cytochromes c and c1 are essential components of the mitochondrial respiratory chain. In both cytochromes the heme group is covalently linked to the polypeptide chain via thioether bridges. The location of the two cytochromes is in the intermembrane space; cytochrome c is loosely attached to the surface of the inner mitochondrial membrane, whereas cytochrome c1 is firmly anchored to the inner membrane. Both cytochrome c and c1 are encoded by nuclear genes, translated on cytoplasmic ribosomes, and are transported into the mitochondria where they become covalently modified and assembled. Despite the many similarities, the import pathways of cytochrome c and c1 are drastically different. Cytochrome c1 is made as a precursor with a complex bipartite presequence. In a first step the precursor is directed across outer and inner membranes to the matrix compartment of the mitochondria where cleavage of the first part of the presequence takes place. In a following step the intermediate-size form is redirected across the inner membrane; heme addition then occurs on the surface of the inner membrane followed by the second processing reaction. The import pathway of cytochrome c is exceptional in practically all aspects, in comparison with the general import pathway into mitochondria. Cytochrome c is synthesized as apocytochrome c without any additional sequence. It is translocated selectively across the outer membrane. Addition of the heme group, catalyzed by cytochrome c heme lyase, is a requirement for transport. In summary, cytochrome c1 import appears to follow a "conservative pathway" reflecting features of cytochrome c1 sorting in prokaryotic cells. In contrast, cytochrome c has "invented" a rather unique pathway which is essentially "non-conservative."
Pulse oximetry is based on a relatively new concept, using the pulsatile variations in optical density of tissues in the red and infrared wavelengths to compute arterial oxygen saturation without need for calibration. The method was invented in 1972 by Takuo Aoyagi, a bioengineer, while he was working on an ear densitometer for recording dye dilution curves. Susumu Nakajima, a surgeon, and his associates first tested the device in patients, reporting it in 1975. A competing device was introduced and also tested and described in Japan. William New and Jack Lloyd recognized the potential importance of pulse oximetry and developed interest among anesthesiologists and others concerned with critical care in the United States. Success brought patent litigation and much competition.
There is basis for concern that applied psychophysiology, if not the field of biofeedback, is being coopted by, and merged into, a reborn "inner" model, with the return of "cognition" to preeminence in the "psych" and "neuro" disciplines. Despite currently fashionable views that such mentalistic inventions and neuro/psychological developments somehow illuminate behavior or offer simpler accounts of behavioral facts, there is little or no evidence that any such construction has ever told us anything new about behavior.
Hebrew-speaking subjects were presented with 42 pairs of Chinese characters designating antonymic concepts and were required to match them with their corresponding Hebrew words. Correct translation was significant and was related to foreign language study and academic experience. Highest success was found for the activity domain of the semantic differential and for attributes judged to afford a diagrammatic representation. Examination of the character-referent relationships suggested that translation success was due to principles of figural symbolism rather than to pictographic representation of the attributes in question. The results are seen as suggestive of the effects of figural symbolization on the invention and/or evolution of natural scripts and are discussed in terms of the manner in which the graphic medium has been fashioned to convey abstract concepts.
Although the antecedents of cardiac ultrasound can be traced back to the 1870s, it was in 1954 that Edler and Hertz published their milestone paper. M-mode echocardiography reached its peak in the early 1970s, when the fibre-optic recorder made the method clinically viable. It was not long before real-time two-dimensional imaging was developed, however, and the invention of pulsed Doppler laid the foundation of duplex scanning. In 1985, colour flow imaging gave a fresh impetus to echocardiography. In parallel with the main developments, intravascular and transoesophageal scanning have gained clinical popularity within the last decade, together with techniques for the display of three-dimensional images. Other innovations include contrast agents, pressure gradient measurement and promising methods for tissue characterisation. It seems that current techniques are safe, but this needs to be kept continuously under review.
The present study presents the case of Didymus the Blind, worthy author, philosopher and theologian of the 4th century AD. Blinded by ophthalmia at the age of four years, Didymus succeeded in achieving great learning in the philosophical and natural sciences. He began his education by using a system which was remarkably like Braille, that is reading letters engraved into the surface of wood by touch and subsequently furthering his knowledge by listening. This learning process of Didymus the Blind appears as the precursor of Louis Braille who invented the educational system of reading embossed dots by touch. Like Didymus, Braille lost his vision in infancy (at three years of age). Another parallel of Didymus' career and written works is found in the example and achievements of Helen Keller.
The developments of reconstruction mathematics, computer technology and X-ray detectors were prerequisite to the invention of computer tomography. Essential progress was made leading to the development of the currently used third and fourth generation scanners. The use of CT has greatly influenced diagnostic imaging and therapy planning. The main advantages of CT are the demonstration of the third dimension, the differentiation of very minor density differences and non-invasiveness. In spite of the high costs of CT equipment and maintenance, an overall reduction of cost was achieved by decreasing the number of diagnostic procedures and reducing the time between the beginning of illness and therapy.
The closure of big skin defects is still a problem. Autologous skin is not unlimitedly available. Different skin substitutes are invented and available. All of them are suffering one problem. They can only be used for temporary closure. Even the immunological progress can not solve the problem of skin shortage. An interesting artificial skin was designed by Burke and Yannas. They designed an artificial dermis consisting of bovine collagen and chondroitin-6-sulfate. This is a fascinating possibility for solving the skin shortage problem especially in burn cases. But even this dermis needs autologous epithelial cells to create a complete skin coverage. So till now a complete skin substitute without autologous material seems not to be available.
Since existentialism lost its influence in philosophy in the 1960s, postmodern theory has taken over criticizing basic concepts of western thought. From a postmodern point of view, the main shortcomings of existentialism is that it criticizes traditional unitarian concepts, while re-inventing new unitarian models. Against these unitarian approaches postmodernism holds that the world can only be described in terms of difference. In this article the postmodern program and its differences from existentialism are explained in reference to three concepts of western philosophy: subject, truth, and ethics. Applying these concepts, the relevance of postmodernism for medical theory is illustrated.
A first analysis of intelligence vs. biomass development in humans shows that the increase of speed to accept new inventions appears not to keep pace with exploding population size. It is suggested to assess more accurately the "collective intelligence" of the human race, an attempt probably useful for several purposes. An equation is presented and used to calculate an upper human population limit for the world suggested by the present intelligence level. The equation suggests 1.5--2.3 billion people educated to the level of industrialized nations. The equation predicts acceptance times for innovations during the early evolution of mankind in the order of 10(6) years. Such a time span seems to be in accordance with archaeological findings for the acceptance of fire as a common tool.