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At least 1,441 records · Page 80Linked to original sources
PubMed1992

Pleistocene geochronology and palaeothermometry from protein diagenesis in ostrich eggshells: implications for the evolution of modern humans.

Proteinaceous residues incorporated within the crystal structure of ostrich eggshells (OES) are retained without loss over geological time exceeding 10 million years. Degradation of the polypeptides, including hydrolysis to smaller peptide fragments and eventual release of free amino acids, decomposition, and racemization and epimerization occur at regular, predictable rates dependent on ambient temperature. The extent of isoleucine epimerization (aIle/Ile ratio) in OES follows linear first-order reversible kinetics in controlled-temperature laboratory simulations of time up to an aIle/Ile ratio in excess of 1.0. The hydrolysis of leucine also follows a predictable pattern, but deviates from first-order kinetics. A nonlinear mathematical model has been developed that adequately describes the pattern of leucine hydrolysis through a wide temperature range. Arrhenius parameters were derived from laboratory experiments combined with rate constant values found for 14C-dated OES from stratified caves in southern Africa. These parameters for isoleucine epimerization and leucine hydrolysis differ by ca. 10%, allowing the simultaneous solution of the two equations for temperature, independent of sample age. Although the uncertainty of the simultaneous temperature is relatively high (+/- 10 degrees C), it provides an effective means of identifying burned samples. If sample age is known, palaeotemperatures (the integrated thermal history experienced by an eggshell as opposed to an 'instantaneous' temperature) can be calculated with a precision of better than +/- 1 degrees C. The ages of levels at Border Cave, South Africa, from which anatomically modern human skeletal remains have been recovered, are dated by the extent of isoleucine epimerization in associated OES.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Archaeology and the population-dispersal hypothesis of modern human origins in Europe.

The transition from anatomically 'archaic' to 'modern' populations would seem to have occurred in most regions of Europe broadly between ca. 40 and 30 ka ago: much later than in most other areas of the world. The archaeological evidence supports the view that this transition was associated with the dispersal of new human populations into Europe, equipped with a new technology ('Aurignacian') and a range of radical behavioural and cultural innovations which collectively define the 'Middle-Upper Palaeolithic transition'. In several regions of Europe there is archaeological evidence for a chronological overlap between these populations and the final Neanderthal populations and, apparently, for various forms of contact, interaction and, apparently, 'acculturation' between these two populations. The fundamental behavioural adaptations implicit in the 'Upper Palaeolithic Revolution' (possibly including language) are thought to have been responsible for this rapid dispersal of human populations over the ecologically demanding environments of last-glacial Europe.

Animals↗
PubMed1996

Rhodothermus obamensis sp. nov., a modern lineage of extremely thermophilic marine bacteria.

A novel extremely thermophilic bacterium was isolated from a shallow marine hydrothermal vent environment (depth, 22 m) in Tachibana Bay, Nagasaki Prefecture, Japan. The cells of this organism were gram-negative rods. Growth occurred at temperatures between 50 and 85 degrees C (optimum temperature, 80 degrees C; doubling time at optimum temperature, 90 min), at pH 5.5 and 9.0 (optimum pH, 7.0), and in the presence of 1 and 5% NaCl (optimum NaCl concentration, 3%). The new isolate was an aerobic heterotroph which utilized the following compounds as sole energy and carbon sources: yeast extract, peptone, starch, casein, Casamino Acids, a variety of sugars, some carboxylic acids, and amino acids. As determined by a sequence analysis of the 16S rRNA, the new isolate belongs to the genus Rhodothermus and represents a modern lineage of extreme thermophiles within the domain Bacteria. On the basis of the physiological and molecular properties of the new isolate, we describe a new species, Rhodothermus obamensis. The type strain of R. obamensis is strain OKD7 (= JCM 9785).

Base Sequence↗
PubMed2003

Koch's bacillus - a look at the first isolate of Mycobacterium tuberculosis from a modern perspective.

Using molecular methods the authors have studied mycobacterial DNA taken from a 19th century victim of tuberculosis. This was the case from which Robert Koch first isolated and cultured the organism responsible for tuberculosis. The mycobacteria were preserved within five glass culture tubes as abundant bacterial colonies on slopes of a gelatinous culture medium of unknown composition. Originally presented by Koch to surgical laryngologist Walter Jobson Horne in London in 1901, the relic has, since 1983, been in the care of the Royal College of Surgeons of England. Light and electron microscopy established the presence of acid-fast mycobacteria but showed that morphological preservation was generally poor. Eleven different genomic loci were successfully amplified by PCR. This series of experiments confirmed that the organisms were indeed Mycobacterium tuberculosis and further showed that the original strain was in evolutionary terms similar to 'modern' isolates, having undergone the TB D1 deletion. Attempts to determine the genotypic group of the isolate were only partially successful, due in part to the degraded nature of the DNA and possibly also to a truncation in the katG gene, which formed part of the classification scheme. Spoligotyping resulted in amplification of DR spacers consistent with M. tuberculosis but with discrepancies between independent extracts, stressing the limitations of this typing method when applied to poorly preserved material.

Bacteriology↗
PubMed2003

Modern approach to ureteral stones.

Urolithiasis is a very common affliction of mankind. In western countries incidence is increasing steadily. An increasing proportion of patients are presenting with ureteral stones, of which renal colic most often is the first complaint and the most common reason for an emergency visit to a urologist. Proper imaging strategy is of paramount importance in the diagnosis of acute flank pain and in the subsequent therapy planning once a ureteral stone is diagnosed. Renal colic during pregnancy poses specific problems, both in imaging and therapy. Apart from the adequate treatment of renal colic, modern therapy of those ureteral calculi that will not pass spontaneously will consist of a judicious combination of ESWL (extracorporeal shock wave lithotripsy), endourology, and laparoscopy. Open surgery should only be reserved for limited and very specific indications. Although beyond the scope of this article, metaphylaxis should take an important role in the follow-up of stone patients in general.

Diagnostic Imaging↗
PubMed2000

Modern nuclear force predictions for the alpha particle

We present new calculations of the alpha particle which are based on the most modern nucleon-nucleon interactions alone and combined with the Tucson-Melbourne or the Urbana IX three-nucleon interaction. Results for the binding energies and some properties of the wave function are given. On that phenomenological level little room is left for the action of a possible four-nucleon force.

Journal Article↗
PubMed2003

Can modern nuclear Hamiltonians tolerate a bound tetraneutron?

I show that it does not seem possible to change modern nuclear Hamiltonians to bind a tetraneutron without destroying many other successful predictions of those Hamiltonians. This means that, should a recent experimental claim of a bound tetraneutron be confirmed, our understanding of nuclear forces will have to be significantly changed. I also point out some errors in previous theoretical studies of this problem.

Journal Article↗
PubMed2005

Diagnosis of weaknesses in modern error correction codes: a physics approach.

One of the main obstacles to the wider use of the modern error-correction codes is that, due to the complex behavior of their decoding algorithms, no systematic method which would allow characterization of the bit-error-rate (BER) is known. This is especially true at the weak noise where many systems operate and where coding performance is difficult to estimate because of the diminishingly small number of errors. We show how the instanton method of physics allows one to solve the problem of BER analysis in the weak noise range by recasting it as a computationally tractable minimization problem.

Algorithms↗
PubMed1999

On the geometry of a modern imaging diffractometer.

The geometry of a modern imaging diffractometer is discussed in detail. A method to find all relevant instrument parameters from the control single-crystal measurement data is proposed and the limitations of such a procedure are indicated. Optimization of the instrument parameters by the least-squares method is presented.

Journal Article↗
PubMed2002

Modern analytical ultracentrifugation in protein science: a tutorial review.

Analytical ultracentrifugation (AU) is reemerging as a versatile tool for the study of proteins. Monitoring the sedimentation of macromolecules in the centrifugal field allows their hydrodynamic and thermodynamic characterization in solution, without interaction with any matrix or surface. The combination of new instrumentation and powerful computational software for data analysis has led to major advances in the characterization of proteins and protein complexes. The pace of new advancements makes it difficult for protein scientists to gain sufficient expertise to apply modern AU to their research problems. To address this problem, this review builds from the basic concepts to advanced approaches for the characterization of protein systems, and key computational and internet resources are provided. We will first explore the characterization of proteins by sedimentation velocity (SV). Determination of sedimentation coefficients allows for the modeling of the hydrodynamic shape of proteins and protein complexes. The computational treatment of SV data to resolve sedimenting components has been achieved. Hence, SV can be very useful in the identification of the oligomeric state and the stoichiometry of heterogeneous interactions. The second major part of the review covers sedimentation equilibrium (SE) of proteins, including membrane proteins and glycoproteins. This is the method of choice for molar mass determinations and the study of self-association and heterogeneous interactions, such as protein-protein, protein-nucleic acid, and protein-small molecule binding.

Animals↗
PubMed2006

Attachment-dissociation network: some thoughts about a modern complex theory.

The paper revises the complex theory in the light of modern infant research, neurosciences and object relation theory. The author takes up Jean Knox's idea to understand complexes as analogies to the internal working models of attachment theory. The author proposes to understand complexes as dissociated sub-networks out of the network structure of the psyche; these sub-networks contain the internal working models, the characteristic affects and unconscious expectation phantasies. With this network model one can try to understand severe defensive organizations in some patients as a pathological organization of different complexes. This is illustrated by a clinical example.

Defense Mechanisms↗
PubMedDate not supplied

The implications of the Medicare Modernization Act for dual eligibles.

Medicare beneficiaries with incomes at or near the poverty level are also eligible for benefits provided by state Medicaid programs. The Medicare Modernization Act of 2003 details special provisions for these "dually eligible" individuals compared with other Medicare beneficiaries. Issues related to enrollment, benefits, and patient compliance are discussed, as well as challenges physicians face in caring for this vulnerable population.

Aged↗
PubMed2006

A tribute to Sidney Farber-- the father of modern chemotherapy.

Sidney Farber, world-renowned paediatric pathologist, made major contributions to his field but is acknowledged as the father of the modern era of chemotherapy. He recognised that folic acid stimulated leukaemic cell growth and enhanced disease progression. He hypothesised that folic acid antagonists would inhibit or arrest the proliferation of cancer cells. His landmark study, published in 1948, demonstrated that a number of folic acid antagonists, including 4-aminopteroyl-glutamic acid (aminopterin) produced temporary remissions in children with acute undifferentiated leukaemia. These observations lead to the development and use of other chemotherapeutic agents, either singly or, more effectively, in combination for treating childhood and adult malignancies. He introduced actinomycin D for the treatment of metastatic and localised Wilms tumour. Under his guidance and leadership, both the 'Jimmy Fund', one of the first comprehensive paediatric oncology treatment centres, and the Children's Cancer Research Foundation, which later became the Dana-Farber Cancer Institute, were founded.

Hematology↗
PubMed1991

Edward Martin (1859-1938). The founding father of modern clinical andrology.

Edward Martin (1858-1938) was the first surgeon to treat successfully the problem of obstructive azoospermia, a feat that he first described in 1902. He subsequently carried out a total of 11 such operations that resulted in seven patencies and three pregnancies. He also demonstrated that the epididymis was the major site of these obstructive lesions. He pointed out the need for semen analysis in diagnosis and also demonstrated that azoospermia could have two causes, namely spermatogenic failure and ductal obstruction. He also made some important observations on sperm movement. He was probably the first clinician to demonstrate surgically ejaculatory duct obstruction, vasal atrophy and congenital absence of the vas. Most important of all, he demonstrated the need for accurate diagnosis in the treatment of male infertility. An argument is put forward that Edward Martin deserves the title of the 'Founding Father of Modern Clinical Andrology'.

Epididymis↗
PubMed1987

Drug assays--the role of modern voltammetric techniques.

Modern voltammetric techniques, e.g. differential pulse polarography and voltammetry, anodic/cathodic stripping voltammetry and electrochemical detection for high performance liquid chromatography or flow injection analysis, are reviewed with respect to their basic theory, design and usage of available instrumentation and applications to drug assays in formulation and body fluid matrices.

Electrochemistry↗
PubMed1990

Modern haemophilia treatment: medical improvements and quality of life.

Adequate replacement therapy in haemophilia has been available for two decades. This has led to considerable improvements in the life expectancy and physical status of haemophilia patients. A study was conducted to investigate whether this has also led to improvements in quality of life. With this aim, information was obtained from 935 Dutch haemophiliacs by mailed questionnaires on relationships, marriage, family life and employment. Haemophilia patients were less often married than men in the general population (13% fewer) and had a lower total number of children (30% lower, 17% for those who were married). Twenty-two per cent of the patients were not employed and received an income from the disability funds. While severity of haemophilia, joint damage and age increased the risk of disability, it was noted that home treatment was associated with a 50% reduction in this risk. Remarkably, haemophilia patients did not differ from the general population in their view of the quality of their own health. The results of this study show a positive influence of modern haemophilia treatment on quality of life. At present, AIDS overshadows all optimistic feelings one may have about this field. However, the results described here demonstrate the benefits that can be achieved with adequate replacement therapy, and justify the expectation of further improvements in the near future.

Acquired Immunodeficiency Syndrome↗