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1.
Hao X 《Cell》2008,134(3):375-377
Three decades after introducing market reforms and opening up to the rest of the world, China has become a major economic power. As the country prepares to show the world its sporting might, its competitiveness in life sciences may still need a boost.  相似文献   

2.
This personal perspective records research experiences in chemistry and biology at four German universities, two before and two after World War II. The research themes came from cytophysiology of green unicellular algae, in particular their photosynthesis. The function of inorganic ions in photosynthesis and dark respiration was investigated at different degrees of specific mineral stress (deficiencies), and the kinetics of recovery followed after the addition of the missing element. Two types of recovery of photosynthesis were observed: indirect restitution via growth processes and immediate normalisation. From the latter case (K+, phosphate, Mn++) the effect of manganese was emphasized as its role in photosynthetic O2 evolution became established during our research. Other themes of our group, with some bearing on photosynthesis were: synchronization of cell growth by light-dark change and effects of blue (vs. red) light on the composition of green cells. Some experiences in connection with algal mass cultures are included. Discussion of several editorial projects shows how photosynthesis, as an orginally separated field of plant biochemistry and biophysics, became included into general cell physiology and even ecophysiology of green plants. The paper contains an appreciation of the authors' main mentor Kurt Noack (1888–1963) and of Ernst Georg Pringsheim (1881–1970), founder of experimental phycology.Written at the invitation of Govindjee.  相似文献   

3.
After 58 years in science, mostly in pharmacology, one gains perspective. Mine is that there have been important changes over this time, some good and some questionable. In this commentary, I try to reveal how I got to this stage, partially explaining my biases, and possibly helping others learn from my experiences including mistakes. Changing from seeking an M.D. to cellular biology and then to pharmacology early in my career were the best moves I made. The next best move was migration to Canada, away from the McCarthy-McCarran hysteria. Arriving at a time after the end of World War II when science in Canada was expanding was very good luck. I had an excellent opportunity to enjoy both the administration (as Chair of the first independent Department of Pharmacology at the University of Alberta) and the practice of pharmacology (as a practitioner of research on smooth muscle in health and disease). For me, the practice of research has always won over administration when a choice had to be made. Early on, I began to ask questions about educational practices and tried to evaluate them. This led me to initiate changes in laboratories and to seek nondidactic educational approaches such as problem-based learning. I also developed questions about the practice of anonymous peer review. After moving to McMaster in 1975, I was compelled to find a solution for a failed "Pharmacology Program" and eventually developed the first "Smooth Muscle Research Program". Although that was a good solution for the research component, it did not solve the educational needs. This led to the development of "therapeutic problems", which were used to help McMaster medical students educate themselves about applied pharmacology. Now these problems are being used to educate pharmacology honours and graduate students at the University of Alberta. The best part of all these activities is the colleagues and friends that I have interacted with and learned from over the years, and the realization that many of them have collaborated with me again in this volume.  相似文献   

4.
50 years thymine dimer   总被引:1,自引:0,他引:1  
Beukers R  Eker AP  Lohman PH 《DNA Repair》2008,7(3):530-543
Fifty years ago thymine dimer was discovered in the Biochemical and Biophysical Laboratory of Delft Technological University, The Netherlands, by one of the authors of this review (Beukers) as the first environmentally induced DNA lesion. It is one of the photoproducts formed between adjacent pyrimidine bases in DNA by UV irradiation, currently known as cyclobutane pyrimidine dimers (CPDs) and (6-4) photoproducts. Major lesions found in DNA after in vitro or in vivo UV irradiation are the cis-syn cyclobutane thymine dimer and the thymine-cytosine (6-4) photoproduct. Even after 50 years the study of photo-induced DNA lesions is still going on as is illustrated by the hundreds of papers published every year and the millions hits when browsing the internet for dimer-related information. Living organisms possess efficient and different mechanisms to repair detrimental lesions in their DNA. A unique mechanism to repair CPDs is reversion by either direct interaction with light of short wavelength or by enzymatic photoreactivation. Photophysical mechanisms that induce and reverse molecular bonds in biological macromolecules have been a main focus of research of the group in Delft in the middle of the last century. This review describes the break-through results of these studies which were the result of intense interactions between scientists in the fields of physics, organic chemistry and biochemistry. Philosophically, the "view" of the group in Delft was very appealing: since in nature photolesions are induced in DNA by the sun, how is it possible that repair of these lesions could be accomplished by the same energy source. Evolutionary, it is hardly possible to think of a more efficient repair mechanism.  相似文献   

5.
The purpose of this study was to determine whether there was any recovery of the Hering-Breuer inflation reflex in ponies between 2-4 wk and 3-4 yr after hilar nerve denervation (HND). Under anesthesia and before HND, airway occlusion after a 3-liter lung inflation lengthened the subsequent occluded breath by nearly 10 times the control breath duration. Between 2 wk and 3-4 yr after HND, this maneuver increased the duration of the occluded breath by only 2.5 times the control breath duration. Also under anesthesia, the airway was occluded at end expiration. This maneuver increased the duration of the subsequent inspiratory effort by 71% in hilar nerve intact ponies but by only 20-25% 2-4 wk and 3-4 yr after HND. For both tests, the pre- and post-HND differences were statistically significant (P less than 0.05), but there were no significant differences (P greater than 0.10) between 2-4 wk and 3-4 yr post-HND. In awake ponies, at rest and during mild and moderate treadmill exercise, breathing frequency was generally lower and inspiratory time was greater after relative to before HND. The inspiratory time-to-total cycle duration ratio was consistently increased by 0.10-0.15 after HND (P less than 0.05). There was no significant change in this ratio between 2-4 wk and 3-4 yr post-HND (P greater than 0.10). We conclude that the surgical procedure for HND used in this study does not permit any significant reinnervation, and there are no significant changes within the ventilatory control system to compensate for loss of hilar nerve afferents.  相似文献   

6.
Gopal  Brij  Zutshi  D. P. 《Hydrobiologia》1998,384(1-3):267-290
The paper provides an overview of the developments in hydrobiological studies in India during the past fifty years, and links them with a historical perspective of the pre-independence studies. Hydrobiological studies which were well developed in the beginning of this century, gained momentum soon after independence as all kinds of aquatic habitats were investigated for the assessment, conservation and optimum utilization of inland fishery resources of the country. However, the environmental issues which dominated since the 1972 Stockholm Conference, and growing realization of the problem of water pollution, resulted in a rapid proliferation of hydrobiological studies which tend to focus on correlation between the distribution of various organisms and degree of water pollution or the effects of various organic and inorganic pollutants. A sampling of published literature reveals that long-term, analytical and experimental studies of the whole ecosystems (natural or experimental), and studies of population interactions, biomanipulation, food chain dynamics, and energy flows are wholly lacking. The paper calls for the strengthening of field and laboratory facilities, and establishment of regional and national institutes of aquatic ecology which will be necessary for the management of both the water quality and aquatic biological resources for sustainable development.  相似文献   

7.
The long‐term regeneration of calcareous grassland after agricultural intensification is elucidated in Redhead et al. 2014 (Applied Vegetation Science 17: 408–418). The paper generates thoughts about the impact of different pre‐purchase agricultural practices. It makes the reader think about the seeming contradiction of reducing soil fertility, grazing and atmospheric deposition. And what is it that prevents some characteristic species from re‐establishing even after 150 yrs of regeneration?  相似文献   

8.
Twenty-two years after the launch of the Onchocerciasis Control Programme in West Africa (OCP), Jean-Marc Hougard and colleagues critically review the vector-control strategy adopted. They go on to identify the few hydrological basins where transmission of the infection remains difficult to control, to analyse the causes and to propose appropriate corrective measures on a case-by-case basis. Most of these measures, which are mainly based on ivermectin chemotherapy, will continue to be applied after the end of the OCP in 2002, under the control of the countries concerned.  相似文献   

9.
The author has worked in the area of solvent denaturation and stabilization, off and on, for approximately 50 years. This paper is a personal view of the progress which has been made since 1950. The topic is limited to the development of thermodynamic molecular models for the interpretation of the unfolding and stabilization of protein structures. The story starts with the work in Kauzmann's laboratory shortly after World War II and proceeds through models for multisite binding, the linear denaturation curve, the special considerations required for understanding weak solvent exchange and a new model for the balance of solvent contact interactions and excluded volume.  相似文献   

10.
The effect of human disturbance on mangrove forest may be substantially different from the effects of natural disturbances. This paper describes differences in vegetation composition and structure of five vegetation types in two mangrove areas near Darwin, Australia, 25 years after disturbance. The vegetation in clear-felled forest showed more adult Avicennia marina than in the hurricane-affected forest, and a virtual absence of A. marina juveniles and saplings. This indicates that A. marina will be replaced by other species in the canopy, showing a multi-phase vegetation development in mangrove forest after human disturbance. The mechanism of disturbance and the conditions after clearing therefore affects the vegetation composition for at least 25 years after this disturbance took place.  相似文献   

11.
A 30-year old female underwent kidney transplantation after unsuccessful 3-year dialysis for renal cortex necrosis. Immunosuppression was achieved with cyclosporin followed by azathioprine with prednisone. The patient conceived after 22 months with kidney transplantation. Mild decrease in arterial blood pressure and marked increased in glomerular filtration rate were seen during the first three months of pregnancy. Arterial blood pressure increased but insignificantly at the end of pregnancy. That time, gradual decrease in creatinine clearance was observed. An increase in serum bilirubin and alkaline phosphatase was noted. Pregnancy was terminated by cesarean section on the 38th week. Newborn was female, full-termed, viable, with body weight of 3,300 g. All examined parameters were normalized after delivery. Described case indicates that transplanted kidney functioning during pregnancy is similar to that in healthy women.  相似文献   

12.
Cytogenetic analysis performed 4-13 years after the Chernobyl accident showed an elevated frequency of acentrics, chromatid exchanges, dicentrics and rings in Chernobyl cleanup workers compared to the control group. Cytogenetic data were analyzed according to the information on exposure to radiation (the year when the cleanup workers worked at the Chernobyl station, doses rates, time elapsed since exposure to radiation, and cytogenetic examination) and some lifestyle factors. The data obtained suggested that some types of chromosome aberrations could be influenced by the action of different environmental factors or lifestyle factors. The frequency of acentrics was correlated with the age of the cleanup workers, and the increased chromatid exchange frequency was attributed to smoking. The numbers of dicentrics and rings suggested a genotoxic effect of ionizing radiation that is still present over 13 years after the exposure.  相似文献   

13.
Volz PA  Parent SL 《Microbios》1998,96(384):111-125
Four species of micro-fungi were selected for study in the National Aeronautics and Space Administration (NASA) Apollo Microbial Ecology Evaluation Device (MEED) mycology experiments. Trichophyton terrestre, Rhodotorula rubra, Saccharomyces cerevisiae and Chaetomium globosum were selected from a series of preflight test fungi for the MEED mycology studies during the 2 years prior to the actual flight (Volz, 1971a, 1972b). Conidia of T. terrestre, ascospores of C. globosum and yeast cells of R. rubra and S. cerevisiae were suspended in sterile distilled water and loaded into wet and dry cuvettes for exposure to specific space flight parameters according to the filters built into the space flight hardware (Volz, 1971b). Living cells were found in the original inocula and phenotype water storage after 27 years. Colony cells were also examined after 27 years of continuous culture.  相似文献   

14.
Since 1977, we have used a live attenuated varicella vaccine to immunize 10 children with acute leukemia. 8 patients had no adverse clinical reaction but 2 patients developed mild fever and papulovesicular rash after vaccination. All 9 tested children became seropositive after the vaccination. Also in all 3 children who were observed for more than 4 years, persistence of neutralizing antibody was detected. Most of the recipients were prevented from developing symptoms of varicella in spite of contact exposure. Two patients developed varicella when they were in severe immunosuppressive states but their symptoms were mild. None of the children developed herpes-zoster during the 6 year follow-up period. The results suggest that the varicella vaccine is effective in children with acute leukemia, and that long-term effectiveness can be expected.  相似文献   

15.
Abstract —Loberg Lake, Alaska was colonized by sea-run Gasterosteus aculeatus between 1983 and 1988, after the original stickleback population was exterminated. Annual samples from 1990 to 2001 reveal substantial evolution of lateral plate (armor) phenotypes. The 1990 sample was nearly monomorphic for the complete plate morph, which is monomorphic in local sea-run populations; the low plate morph, which is usually monomorphic in local freshwater populations, was absent. By 2001, the frequency of completes had declined to 11%, and lows had increased to 75%. The partial plate morph and two unusual intermediate plate phenotypes were generally rare, but occurrence of the intermediates was unexpected. These intermediate phenotypes rarely occur in other, presumably older, polymorphic populations. When low morphs first appeared, they averaged 6.8 plates per side, indicating that the ancestral plate number of low morphs is high, and their mean has subsequently declined. Contemporary evolution in this population indicates that threespine stickleback adapt to freshwater habitats within decades after invasion from the ocean, and thus phenotypes in most populations are adapted to current conditions.  相似文献   

16.
The aims were to determine the benefit of bilateral cochlear implantation in a 20 years old patient implanted in Croatia on hearing and speech development. The male patient, after 10 years of deafness, got cochlear implants Med-EL Combi 40+ on both sides in one-stage surgery. The etiology of his deafness was posttraumatic meningitis. Auditory capacity and speech recognition tests were performed for both ears separately and together Average hearing level on the right ear with right cochlear implant switched on started at 62 dB 1 month after the cochlear implantation and was on 55 dB after 10 years. Average hearing level on the left ear with left cochlear implant switched on started at 55 dB 1 month after the cochlear implantation and was on 32 dB after 10 years. Average hearing level on the both ears with 2 cochlear implants switched on started at 35 dB 1 month after the cochlear implantation and was on 27 dB after 10 years. Long-term functional outcomes with bilateral cochlear implantation provides advantages over unilateral implantation including improved hearing level, speech perception in noise and improved sound localization.  相似文献   

17.
Periphytic diatoms are a key primary producer in floodplain systems. In this study, we assessed the species and functional traits in the periphytic diatom community in three lentic environments directly connected to the Paraná River shortly after damming and a decade later. Samples were collected in 2001–2002 and 2010–2011 during high waters phase. Periphytic samples were obtained from Eichhornia azurea Kunth, found in the shore zone of these environments. We recorded a total of 90 diatom species. 47 taxa were exclusive during the period shortly after damming and 18 taxa were only found in 2010–2011. The analysis of the similarity, diversity, beta diversity and non-metric multidimensional scaling (NMDS) suggested that there were differences in the species and functional traits of the periphytic diatom community between the two study periods. Variations in water transparency and nutrient (including nitrogen and phosphorus forms) were the most important variables shaping diatom communities diatoms during the study periods. High and motile profiles were characteristic shortly after damming and taxa of high and low profiles predominated a decade later. High transparency, high water and nitrogen levels favored the development of high and low profile, such as Gomphonema augur var. augur, Synedra goulardii and Amphora sp., whereas taxa belonging to high-profile and motile algae (e.g., Eunotia indica, Nitzschia amphibia) were found in the opposite conditions. Species turnover was an important diversity component that was greatly influenced by limnologic differences over time, represented by environmental and temporal dissimilarities between the years. These changes reinforce the modifications that have occurred in the environmental component of the Upper Paraná River floodplain downstream of the dam from the start of its operation.  相似文献   

18.
The aim of our study is to evaluate results of treating war injuries of colon and rectum, after 10 years. During the war in Croatia, 21 wounded, with colon (19) and rectum (2) injuries, were treated in the Department of Surgery at Nova Gradiska General Hospital from August 1991 to April 1992. Bullet wounds accounted for 57% of the injuries. All patients had other associated injuries. Primary repair and proximal derivation was possible in 2 cases (9.5%), while primary resection with intraperitoneal anastomosis was performed in 3 (14.3%) patients. In 2 (9.5%) patients sustained intraperitoneal and extraperitoneal rectal penetrating injury rectum was resected and closed performing temporary sigmoidostomy. When multiple perforations or crush injury of the colon were found, in 8 (38.1%) injured persons resection of the involved segment was combined with proximal end colostomy and aboral mucous fistula. Exteriorization of injured segment of the colon and creating colostomy incorporating the injured colon as the stoma was performed in 6 (28.5%) wounded patients. Four of the wounded (19.0%) died two of them during the operative procedure due to hemorrhagic shock. One injured died after eight days due to pulmonary embolism, and one patient died after thirty days due to sepsis. Reoperation was necessary in two (9.5%) injured due to bowel obstruction four days following initial surgery because of adhesions. Three (14.3%) of the injured had wound infection, one of them died 30 days after injury due to sepsis, and two (9.5%) consequently developed ventral hernia that was operated after 4 and 5 years respectively. Four (19.0%) of the injured are still occasionally experiencing occasional abdominal pain.  相似文献   

19.
《Acta Oecologica》2001,22(5-6):277-283
Recovery after cutting and burning in two series of experimental shrubland plots dominated by Cistus laurifolius and Cistus ladanifer, respectively, was studied over 11 years. The two communities tend to recover by an autosuccession process after disturbances, with Cistus species being dominant from the first or second year. The greatest diversity is recorded in the first few years after the disturbances, with higher species richness, basically herbaceous ones, and lower dominance effect. Cover by woody species tends to increase but from the fourth year the differences are not significant. The highest herbaceous cover is after one year and the peak is more marked in the cut plots. Herbaceous species cover decreases afterwards and there are small changes in the different years but without clear trends. When all the samplings are compared by a TWINSPAN, the first division separates both communities and the  second division the initial and the final phases from each community. The separation between cut and burnt plots is only observed in the final phases.  相似文献   

20.
We studied long-lasting consequences of the low-doses irradiation on the immune system of 71 clean-up workers who participated in the emergency work after the Chernobyl Plant accident in 1986 and 25 healthy donors from Belarus. In sera of the workers the level of autoantibodies to thyroid gland antigens (thyroglobulin and microsomal fraction of thyroid gland) was increased in 48% of cases, the level of autoantibodies to lens oculis antigen was increased in 44% of cases; the level of circulating immune complexes was elevated in 55%, and the serum level of thyroglobulin in 60% of people. Immunological disorders were found without any definite clinical evidences of diseases and this allows us to consider the examined contingent as a group of risk for the development of autoimmune pathology in the future.  相似文献   

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