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101.
OBJECTIVE: To explore the possible association between intramuscular vitamin K given to neonates and the subsequent development of childhood cancer. DESIGN: Retrospective case-control study on the basis of hospital records. SETTING: The former Northern Health region of England. SUBJECTS: 685 children who were born and lived in the region and who developed cancer before their 15th birthday, and 3442 controls also born between 1960 and 1991 and matched only for date and hospital of birth. The notes of a further 701 index cases were untraceable. MAIN EXPOSURE MEASURE: Administration of intramuscular vitamin K versus no exposure to vitamin K. RESULTS: There was no association between the administration of vitamin K and the development of all childhood cancers (unadjusted odds ratio 0.89; 95% confidence interval 0.69 to 1.15) or for all acute lymphoblastic leukaemia (1.20; 0.75 to 1.92), but there was a raised odds ratio for acute lymphoblastic leukaemia developing 1-6 years after birth (1.79; 1.02 to 3.15). No such association was seen in a separate cohort-based study not dependent on case note retrieval in which the rates of acute lymphoblastic leukaemia in children born in hospital units where all babies received vitamin K were compared with those born in units where less than a third received prophylaxis. CONCLUSIONS: It is not possible, on the basis of currently published evidence, to refute the suggestion that neonatal intramuscular vitamin K administration increases the risk of early childhood leukaemia. Any association may have been masked in earlier studies that did not use controls matched for time and locality by other unidentified factors affecting the spatiotemporal variations in incidence of leukaemia. 相似文献
102.
Peat accretion and phosphorus accumulation along a eutrophication gradient in the northern Everglades 总被引:7,自引:1,他引:6
Recent rates of peat accretion (as determined by137Cs) and N, P, organic C, Ca and Na accumulation were measured along a 10 km eutrophication gradient in the northern Everglades
area of Water Conservation Area 2A (WCA 2A) that has received agricultural drainage from the Hillsboro canal for the past
25–30 yrs. Rates of peat accretion were highest at sampling locations closest to the Hillsboro canal, 1.6 km downstream, (5.67
± 0.50 mm/yr) and decreased to 2.01 ± 0.31 mm/yr at distances of 7.1 to 10.7 km downstream. Phosphorus and Na accumulation
were a function of both peat accretion and soil P and Na concentrations. The concentration and accumulation of P in peat deposited
in the past 26 years was highest near the Hillsboro canal (1478 ± 67 ug/g, 0.66 ± 0.06 g/m2/yr) and decreased to 560 ± 20 ug/g and 0.10 ± 0.02 g/m2/yr at distances of 8.8 to 10.7 km downstream. Like phosphorus, the concentration and rate of Na accumulation was highest
near the Hillsboro canal (3205 ± 1021 ug/g, 1.48 ± 0.53 g/m2/yr). Although sodium enrichment of the peat was limited to 1.6 km downstream of the Hillsboro canal, increased rates of Na
accumulation penetrated 5.2 km downstream of the Hillsboro canal, the extent of the area of enhanced peat accretion.
In contrast to P and Na, there was no difference in the concentration of soil organic C, N and Ca along the eutrophication
gradient. However, there was a gradient of organic C, N and Ca accumulation corresponding to the area of enhanced peat accretion.
The highest rates occurred 1.6 km south of the Hillsboro canal (212 ± 5 g organic C/m2/yr, 14.1 ± 0.4 g N/m2/yr, 22.1 ± 5.2 g Ca/m2/yr). Accumulation of organic C, N and Ca at distances of 7.1–10.7 km downstream averaged 87 ± 11, 6.3 ± 0.7 and 6.5 ± 0.9
g/m2/yr, respectively.
The areal extent of enhanced peat accretion and organic C, N, Ca and Na accumulation encompasses approximately 7700 ha of
the northern part of WCA 2A. The area of enhanced P accumulation is larger, covering 11,500 ha or 26% of the total area of
WCA 2A. The 11,500 ha area has functioned as a sink for P for the past 25–30 yr removing 74% (49.3 MT/yr) of the 67 MT/yr
that enters via agricultural drainage and rainfall. Moreover, P accumulation along the gradient was related to mean (1989–1990)
surface water P concentration, decreasing as surface water P decreases. These findings suggest that P accumulation is dependent
on the P concentration in the water column and that decreasing P loadings per unit area result in less P storage per unit
area. The potential longterm equilibrium of the 11,500 ha area as a sink for P is based on a mean annual loading of 67 metric
tons P/yr. Input rates exceeding this loading rate could result in an expansion of the 11,500 ha area until a new equilibrium
size is reached. 相似文献
103.
Unusual pattern of bacterial ice nucleation gene evolution 总被引:5,自引:0,他引:5
Edwards AR; Van den Bussche RA; Wichman HA; Orser CS 《Molecular biology and evolution》1994,11(6):911-920
Bacterial ice nucleation activity (INA+ phenotype) can be traced to the
product of a single gene, ina. A remarkably sparse distribution of this
phenotype within three bacterial genera indicates that the ina gene may
have followed an unusual evolutionary path. Southern blot analyses, coupled
with assays for ice-nucleating ability, revealed that within four bacterial
species an ina gene is present in some strains but absent from others.
Results of hybridization experiments using DNA fragments that flank the ina
gene suggested that the genotypic dimorphism of ina may be anomalous. A
phylogenetic analysis of 16S ribosomal RNA gene sequences from a total of
14 ina+ and ina- bacterial strains indicated that the ina+ bacteria are not
monophyletic but instead phylogenetically interspersed among ina- bacteria.
The relationships of ina+ bacteria inferred from ina sequence did not
coincide with those inferred from the 16S data. These results suggest the
possibility of horizontal transfer in the evolution of bacterial ina genes.
相似文献
104.
Improving Keszthelyis simple model the evolutionary appearance of concentration difference of enanthiomeric compounds due to their differential decomposition by -rays is investigated taking into account the racemization as well. It is shown that if the difference in the cross sections is very small then the resulting concentration difference will never exceed the statistical fluctuations, while in the case of a sufficiently large difference in the cross sections the concentration difference can overgrow the statistical fluctuations in an evolutionary reasonable period of time. The relative difference of the concentrations, however, will be generally much smaller than that of the cross sections. Therefore some other, amplifying mechanism must be postulated in order to explain the optical purity of living beings. 相似文献
105.
Extra-amniotic prostaglandin E2 (PGE2) suspended in a slow release gel (Tylose) was instilled in 35 patients prior to a planned surgical termination in an attempt to dilate the cervix, minimize cervical trauma, and reduce the possible risk of cervical trauma, and reduce the possible risk of cervical incompetence and its sequelae. Dilatation occurred in all patients to a minimum of 8 mm and 74% aborted before surgical evacuation performed 6 to 24 hours after injection. No serious side effects occurred. Extra-amniotic PGE2 in gel should be considered as a primary procedure when the cervix is obviously immature on examination. If the cervix is found to be tight and unyielding at surgical dilatation, the latter procedure should be dicontinued and PGE2 in gel injected. 相似文献
106.
Ian L. Craft Dale V. Evans Linda B. Richfield 《Prostaglandins & other lipid mediators》1979,18(1):143-152
Extra-amniotic prostaglandin E2 (PGE2) suspended in a slow release gel (Tylose) was instilled in 35 patients prior to a planned surgical termination in an attempt to dilate the cervix, minimize cervical trauma, and reduce the possible risk of cervical incompetence and its sequelae. Dilatation occurred in all patients to a minimum of 8 mm and 74% aborted before surgical evacuation performed 6 to 24 hours after injection. No serious side effects occurred. Extra-amniotic PGE2 in gel should be considered as a primary procedure when the cervix is obviously immature on examination. If the cervix is found to be tight and unyielding at surgical dilatation, the latter procedure should be discontinued and PGE2 in gel injected. 相似文献
107.
The biosynthesis of cytochrome P-450 in vitro 总被引:1,自引:0,他引:1
108.
Light absorbed by retinal photoreceptors triggers a cascade of reactions that initiate cGMP hydrolysis, cation channel closure and membrane hyperpolarization. Down-regulation of the cascade involves additional proteins that interfere with amplification along the cascade. Pinealocytes are activated by norepinephrine during the dark phase of the day/night cycle. Mature pinealocytes of the mammalian pineal express the known photoreceptor proteins that are implicated in down-regulation of the visual cascade, but the cascade components that produce cGMP hydrolysis and membrane hyperpolarization are absent. Pinealocytes accumulate cyclic AMP minimally when norepinephrine activates their beta adrenergic receptors alone, but the response is potentiated by the simultaneous activation of their alpha-1 adrenergic receptors. A model is proposed whereby phosducin, a phosphoprotein that binds the beta, gamma subunit of G-proteins, could modulate the synthesis of cyclic AMP by buffering the amount of beta, gamma G-protein subunits that are available for activating adenylate cyclase.Special issue dedicated to Dr. Frederick E. Samson. 相似文献
109.
The murine gene encoding the highly conserved Sm B protein contains a nonfunctional alternative 3' splice site. 总被引:2,自引:0,他引:2
The cDNA and partial genomic nucleotide (nt) sequences were derived for the mouse Sm B polypeptide and compared to the cDNA and genomic sequences encoding human Sm B. The deduced amino acid (aa) sequences from the mouse and human genes are identical with the exception of a single conserved aa substitution, accounting for the ability of anti-Sm antibodies to recognize the Sm polypeptides from a broad range of species. The genomic sequence of mouse B gene is similar to the human B genomic locus that extends from exon 6 to exon 7. These loci include conservation of both 3' alternative splice sites and putative branch points required to process B and B' mRNAs in human cells. However, the nt sequence downstream from the putative distal 3' splice junction and single nt flanking the 3' splice site consensus sequence, differ between mouse and human B. This results in a murine mRNA with a different predicted secondary structure around the distal 3' splice site when compared to humans. Thus, secondary structural constraints in the mRNA or changes in the exon sequence might prevent recognition of this alternative splice site to form B' mRNA in murine tissues. 相似文献
110.
Peter J. Hundt Lauren A. White Meggan E. Craft Przemyslaw G. Bajer 《Ecology and evolution》2022,12(3)
Heterogeneity in social interactions can have important consequences for the spread of information and diseases and consequently conservation and invasive species management. Common carp (Cyprinus carpio) are a highly social, ubiquitous, and invasive freshwater fish. Management strategies targeting foraging carp may be ideal because laboratory studies have suggested that carp can learn, have individual personalities, a unique diet, and often form large social groups. To examine social feeding behaviors of wild carp, we injected 344 carp with passive integrated transponder (PIT) tags and continuously monitored their feeding behaviors at multiple sites in a natural lake in Minnesota, USA. The high‐resolution, spatio‐temporal data were analyzed using a Gaussian mixture model (GMM). Based on these associations, we analyzed group size, feeding bout duration, and the heterogeneity and connectivity of carp social networks at foraging sites. Wild carp responded quickly to bait, forming aggregations most active from dusk to dawn. During the 2020 baiting period (20 days), 133 unique carp were detected 616,593 times. There was some evidence that feeding at multiple sites was constrained by basin geography, but not distance alone. GMM results suggested that feeding bouts were short, with frequent turnover of small groups. Individual foraging behavior was highly heterogeneous with Gini coefficients of 0.79 in 2020 and 0.66 in 2019. “Superfeeders”—those contributing to 80% of total cumulative detections (top 18% and top 29% of foragers in 2020 and 2019 respectively)—were more likely to be detected earlier at feeding stations, had larger body sizes, and had higher network measures of degree, weighted degree, and betweenness than non‐superfeeders. Overall, our results indicate that wild carp foraging is social, easily induced by bait, dominated by large‐bodied individuals, and potentially predictable, which suggests social behaviors could be leveraged in management of carp, one of the world''s most recognizable and invasive fish. 相似文献