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1.
Fifteen children who had become positive for hepatitis B surface antigen (HBsAg) by perinatal transmission were traced and re-examined after a mean of 8.1 years; all had been born in England to mothers from ethnic minorities who were carriers of HBsAg. Fourteen of the children remained carriers of HBsAg; of these, more girls than boys developed antibody to hepatitis B e antigen (anti-HBe). Those children whose transaminase activities had been above normal within the first three years of life were more likely to have developed anti-HBe. The earlier production of anti-HBe suggests that girls have a more effective immune response. Increased transaminase activity early in the course of asymptomatic carriage of HBsAg may be a favourable prognostic sign. 相似文献
2.
Goats and some sheep synthesize a juvenile hemoglobin, Hb C (alpha 2 beta
C2), at birth and produce this hemoglobin exclusively during severe anemia.
Sheep that synthesize this juvenile hemoglobin are of the A haplotype.
Other sheep, belonging to a separate group, the B haplotype, do not
synthesize hemoglobin C and during anemia continue to produce their adult
hemoglobin. To understand the basis for this difference we have determined
the structural organization of the beta- globin locus of B-type sheep by
constructing and isolating overlapping genomic clones. These clones have
allowed us to establish the linkage map 5' epsilon I-epsilon II-psi beta
I-beta B-epsilon III-epsilon IV- psi beta II-beta F3' in this haplotype.
Thus, B sheep lack four genes, including the BC gene, and have only eight
genes, compared with the 12 found in the goat globin locus. The goat
beta-globin locus is as follows: 5' epsilon I-epsilon II-psi beta X-beta
C-epsilon III-epsilon IV-psi beta Z-beta A-epsilon V-epsilon VI-psi beta
Y-beta F3'. Southern blot analysis of A-type sheep reveals that these
animals have a beta- globin locus similar to that of goat, i.e., 12 globin
genes. Thus, the beta-globin locus of B-haplotype sheep resembles that of
cows and may have retained the duplicated locus of the ancestor of cows and
sheep. Alternatively, the B-sheep locus arrangement may be the result of a
deletion of a four-gene set from the triplicated locus.
相似文献
3.
4.
Patients with hyperthyroidism usually present with symptoms of hypermetabolism with or without goitre and/or eye signs. Occasionally, however, the chief complaints are not immediately suggestive of hyperthyroidism. Patients with hyperthyroidism are described who presented with such atypical manifestations as periodic muscular paralysis, myasthenia, myopathy, encephalopathy, psychosis, angina pectoris, atrial fibrillation, heart failure without underlying heart disease, skeletal demineralization, pretibial myxedema, unilateral eye signs, and pitting edema of the ankles. 相似文献
5.
AMPA receptors mediate fast, glutamatergic synaptic transmission in the central nervous system. The time-course of the associated postsynaptic current has been suggested to be determined principally by the kinetics of glutamate binding and receptor desensitization. Aniracetam and cyclothiazide are drugs capable of selectively preventing desensitization of the AMPA receptor. To investigate the relevance of desensitization to fast synaptic transmission in the cerebellum we have tested these compounds against AMPA-induced depolarizations and postsynaptic potentials using the grease-gap recording technique. Aniracetam (1 M-5 mM) and cyclothiazide (1 M-500 M) both enhanced the depolarising action of AMPA (1 M) on Purkinje cells in a concentration-dependent manner. At the highest concentrations tested, the increases over controls were approximately 600% and 800% respectively. Aniracetam also increased, in a concentration-dependent manner, the amplitude of the evoked synaptic potentials of both parallel fibre-Purkinje cell and mossy fibre-granule cell pathways, with the highest concentrations tested enhancing the potentials by approximately 60% and 75% respectively. These data suggest that, at two different synapses in the cerebellum, AMPA receptor desensitization occurs physiologically and is likely to contribute to the shape of fast synaptic currents.Abbreviations CNQX
6-cyano-7-nitroquinoxaline-2,3-dione
- NMDA
N-methyl-D-aspartate
- AMPA
-amino-3-hydroxy-5-methyl-4-isoxazole propionate
- AP5
D-2-amino-5-phosphopentanoate
- EPSP
excitatory postsynaptic potential
- EPSC
excitatory postsynaptic current
- DMSO
dimethyl sulphoxide
- NBQX
2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo(F)quinoxaline
Special issue dedicated to Dr. Robert Balázs. 相似文献
6.
Antenatal screening in the West Midlands during a three-year period identified 297 mothers who were chronic carriers of hepatitis B surface antigen (HBsAg)--a prevalence of about 1 in 850. About half of their infants had HBsAg in the cord blood, but of 122 infants followed up for over three months (mean 8.5 months) only 17 (14%) were still positive for HBsAg. Cord-blood HBsAg-positivity was evenly distributed among different ethnic groups, but the transmission rate was highest among the Chinese, and no carriers were discovered among 39 European infants. Raised serum transaminase concentrations were found in some of the carrier infants who were otherwise healthy. The results suggest that adequate follow-up of HBsAg-positive infants may be achieved by tests at 4 months and 1 year of age, and that the role of breast-feeding in mother-to-infant transmission of HBsAg is unimportant. The Chinese community may be a suitable population in which to test the effectiveness of specific immunoglobulin administration at birth in preventing the development of the HBsAg carrier state. 相似文献
7.
8.
Calcrete aquifers from the Yilgarn region of arid central Western Australia contain an assemblage of obligate groundwater invertebrate species that are each endemic to single aquifers. Fine-scale phylogeographic and population genetic analyses of three sympatric and independently derived species of amphipod (Chiltoniidae) were carried out to determine whether there were common patterns of population genetic structure or evidence for past geographic isolation of populations within a single calcrete aquifer. Genetic diversity in amphipod mitochondrial DNA (cytochrome c oxidase subunit I gene) and allozymes were examined across a 3.5 km2 region of the Sturt Meadows calcrete, which contains a grid of 115 bore holes (=wells). Stygobiont amphipods were found to have high levels of mitochondrial haplotype diversity coupled with low nucleotide diversity. Mitochondrial phylogeographic structuring was found between haplogroups for one of the chiltoniid species, which also showed population structuring for nuclear markers. Signatures of population expansion in two of the three species, match previous findings for diving beetles at the same site, indicating that the system is dynamic. We propose isolation of populations in refugia within the calcrete, followed by expansion events, as the most likely source of intraspecific genetic diversity, due to changes in water level influencing gene flow across the calcrete. 相似文献
9.
10.
Holger?J?SchünemannEmail author Brydon?JB?Grant Paola?Muti Susan?E?McCann Deepa?Kudalkar Malathi?Ram Tom?Nochajski Marcia?Russell Maurizio?Trevisan 《BMC pulmonary medicine》2002,2(1):3