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1.
A study of 10 infants in severe metabolic acidemia (pH below 7) led to the conclusion that the clinical signs—hyperventilation, coma or lethargy, peripheral vascular collapse, a significantly palpable liver, and abdominal distension—may all be directly related to the metabolic acidemia. In five of 10 infants, an initial erroneous diagnosis of congestive heart failure or pneumonia was made. Dramatic clinical improvement followed correction of the acidemia with rapid intravenous administration of sodium bicarbonate. This rapid administration of sodium bicarbonate was safe, provided hypocalcemia was recognized and treated in its early stages. In severe metabolic acidemia the measurement of blood bicarbonate alone does not reflect adequately the magnitude of the acid-base derangement and repeated measurements of hydrogen ion concentration, Pco2 and bicarbonates are needed to evaluate and treat such infants correctly. 相似文献
2.
3.
Nielsen J; Peixoto AA; Piccin A; Costa R; Kyriacou CP; Chalmers D 《Molecular biology and evolution》1994,11(6):839-853
The region of the clock gene period (per) that encodes a repetitive tract
of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran
species both within and outside the Drosophilidae. All the non-
Drosophilidae sequences in this region are short and present a remarkably
stable picture compared to the Drosophilidae, in which the region is much
larger and extremely variable, both in size and composition. The
accelerated evolution in the repetitive region of the Drosophilidae appears
to be mainly due to an expansion of two ancestral repeats, one encoding a
Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and
asparagine or threonine. In some drosophilids the expansion involves a
duplication of the pentapeptide sequence, but in Drosophila pseudoobscura
both the dipeptide and the pentapeptide repeats are present in larger
numbers. In the nondrosophilids, however, the pentapeptide sequence is
represented by one copy and the dipeptide by two copies. These observations
fulfill some of the predictions of recent theoretical models that have
simulated the evolution of repetitive sequences.
相似文献
4.
Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene 总被引:8,自引:1,他引:7
We have analyzed the conserved regions of the gene coding for the
circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria
parasite. The closest evolutionary relative of P. falciparum, the agent of
malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is
consistent with the hypothesis that P. falciparum is an ancient human
parasite, associated with humans since the divergence of the hominids from
their closest hominoid relatives. Three other human Plasmodium species are
each genetically indistinguishable from species parasitic to nonhuman
primates; that is, for the DNA sequences included in our analysis, the
differences between species are not greater than the differences between
strains of the human species. The human P. malariae is indistinguishable
from P. brasilianum, and P. vivax is indistinguishable from P. simium; P.
brasilianum and P. simium are parasitic to New World monkeys. The human P.
vivax-like is indistinguishable from P. simiovale, a parasite of Old World
macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are
evolutionarily recent human parasites, the first two at least acquired only
within the last several thousand years, and perhaps within the last few
hundred years, after the expansion of human populations in South America
following the European colonizations. We estimate the rate of evolution of
the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year.
The divergence between the P. falciparum and P. reichenowi lineages is
accordingly dated 8.9 Myr ago. The divergence between the three lineages
leading to the human parasites is very ancient, about 100 Myr old between
P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between
P. falciparum and the other two.
相似文献
5.
Madin-Darby canine kidney cells deacylate arachidonic acid from cellular phospholipid in response to 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and convert the free arachidonic acid to prostaglandins. We have used this system to characterize the acyl specificity of deacylation. Cells were labeled with either [14C]linoleic, [14C]eicosatrienoic (delta 8,11,14 or delta 5,8,11), or [14C]arachidonic acid and stimulated with 10 nM TPA. We found that TPA stimulated the deacylation of all four acids, primarily from phosphatidylethanolamine and phosphatidylcholine.l Only products from linoleic (presumably through chain elongation and desaturation), eicosatrienoic (delta 8,11,14), and arachidonic acids produced prostaglandins. Those produced from linoleic and eicosatrienoic acid (delta 8,11,14)-labeled cells were determined to be primarily of the 1-series, while arachidonic acid-labeled cells produced prostaglandins of the 2-series. Together these results indicate that the stimulated deacylation of phospholipids is not specific for arachidonic acid and that the membrane acyl composition controls the particular series of prostaglandin which is produced. 相似文献
6.
Photosynthetic enhancement studies performed at 619 nm (excitation of Systems I and II) and at 446 nm (mainly excitation of System I) revealed an 18% photosynthetic enhancement simultaneously with a 31% reduction in glycolate excretion. This observation supports the hypothesis that some glycolate may be consumed in an oxidation process associated with System I when System II is poorly excited and the supply of electrons from the water splitting process of photosynthesis is low. 相似文献
7.
The arterio--alveolar nitrogen difference (aADN2) has been associated in 27 normal adult subjects aged 20--60 years. As it may be assumed that venous and arterial PN2 are identical, we have used a sample of venous blood. There is a significant positive correlation between aADN2 and age. As the increase of aADN2 with age resembles that found in the literature for AaDO2, we concluded that the latter may be explained by increasing VA/Qc inequality within the lung. 相似文献
8.
土壤中棉花黄萎病菌SYBR Green Ⅰ荧光RT-PCR定量检测技术研究 总被引:3,自引:0,他引:3
为实现田间土壤棉花黄萎病菌的早期检测,建立了土壤中棉花黄萎病菌的SYBR Green I荧光定量PCR检测方法。以含342bp PCR扩增产物的阳性质粒为参考,构建了标准曲线,并对该曲线的特异性、敏感性、可重复性进行了评价。结果表明,该方法具有快速、特异性强、敏感度高等特点。检测范围在3.8×103-3.8×108copies/μL之间有良好的线性关系,相关系数R2为0.996,扩增效率为101.5%,灵敏度比常规PCR方法高102倍。 相似文献
9.
10.
Felix E.G. Beaudry Spencer C.H. Barrett Stephen I. Wright 《Evolution; international journal of organic evolution》2020,74(2):256-269
Empirical evidence from several animal groups suggests sex chromosomes disproportionately contribute to reproductive isolation. This effect may be enhanced when sex chromosomes are associated with turnover of sex determination systems resulting from structural rearrangements to the chromosomes. We investigated these predictions in the dioecious plant Rumex hastatulus, which is composed of populations of two different sex chromosome cytotypes caused by an X-autosome fusion. Using population genomic analyses, we investigated the demographic history of R. hastatulus and explored the contributions of ancestral and neo-sex chromosomes to population genetic divergence. Our study revealed that the cytotypes represent genetically divergent populations with evidence for historical but not contemporary gene flow between them. In agreement with classical predictions, we found that the ancestral X chromosome was disproportionately divergent compared with the rest of the genome. Excess differentiation was also observed on the Y chromosome, even when we used measures of differentiation that control for differences in effective population size. Our estimates of the timing of the origin of neo-sex chromosomes in R. hastatulus are coincident with cessation of gene flow, suggesting that the chromosomal fusion event that gave rise to the origin of the XYY cytotype may have also contributed to reproductive isolation. 相似文献