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1.
The yeast Saccharomyces cerevisiae mRNA capping enzyme is composed of two subunits of alpha (52 kDa, mRNA guanylyltransferase) and beta (80 kDa, RNA 5'-triphosphatase). We have isolated the alpha subunit gene (CEG1) by immunological screening. In this report, with the aid of partial amino acid sequences of purified yeast capping enzyme, we isolated the gene, designated CET1, encoding the S. cerevisiae capping enzyme beta subunit. Amino acid sequence analysis revealed that the gene encodes for 549 amino acids with a calculated M(r) of 61,800 which is unexpectedly smaller than the size estimated by SDS-PAGE. Gene disruption experiment showed that CET1 is essential for yeast cell growth. The purified recombinant CET1 gene product, Cet1, exhibited an RNA 5'-triphosphatase activity which specifically removed the gamma-phosphate from the triphosphate-terminated RNA substrate, but not from nucleoside triphosphates, confirming the identity of the gene. Interaction between the Cet1 and the Ceg1 was also studied by the West-Western procedure using recombinant Ceg1-[32P]GMP as probe.  相似文献   

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As part of an ongoing surveillance program of antibiotic-resistant Streptococcus pneumoniae in Sofia, Bulgaria, 120 penicillin-resistant strains (PRSP) (most of them recovered from children hospitalized with pneumococcal disease) were analyzed by microbiological and molecular methods. Several unique features of this collection are of particular interest. (i) Most isolates (112 of 120) were also resistant to trimethoprim-sulfamethoxazole (SXT) (97 of 120 isolates, or 80%), and over 70% (86 of 120) of the isolates were resistant to at least three antibiotics in addition to penicillin. (ii) Close to 80% of all isolates were represented by large clusters of bacteria, each with a unique serotype, antibiotype, and chromosomal macrorestriction pattern (determined by pulsed-field gel electrophoresis), as well as unique restriction fragmentation length polymorphisms of the penicillin-binding protein genes pbp1a, pbp2x, and pbp2b. (iii) A large proportion (45 of 120, or 38%) of the strains belonged to two internationally spread epidemic clones of S. pneumoniae, the first expressing capsular type 23F and the second expressing serotype 9. (iv) A unique Bulgarian cluster composed of eight serotype 19F isolates was resistant to tetracycline, SXT, cefotaxime, and extremely high levels of penicillin and erythromycin. Nevertheless, this clone did not react with either the erm or the mef DNA probes, and thus the mechanism of macrolide resistance in this group of PRSP remains to be elucidated.  相似文献   

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OBJECTIVE: To understand the transition from breast-and bottle-feeding to solid-feeding and factors that might affect the duration of breast- and bottle-feeding. DESIGN: Cohort followed up from birth with relatively well-educated, middle-class parents. SETTING: Community sample recruited from 3 suburban newborn nurseries (a teaching hospital, community hospital, and large health maintenance organization). PARTICIPANTS: One hundred ninety-one healthy full-term infants. MEASURES: Assessment of feeding practices through the ages of complete weaning from breast- and bottle-feeding. RESULTS: More than 90% of participants breast-fed for at least 2 weeks. Infants of older mothers were weaned from the breast later than infants of younger mothers. First-born infants were weaned from the breast earlier than later-born infants. Eighty-four percent of infants bottle-fed at some time during the first year of life. More than 40% of the cohort was still receiving bottles at 24 months of age, 16% at 36 months, and 8% at 48 months. The duration of breast- and bottle-feeding was related to maternal work status; mothers who returned to work during the first 3 months postpartum weaned sooner from the breast and later from the bottle than women who returned to work after 3 months postpartum. CONCLUSIONS: The frequency of late bottle-weaning in this well-educated, middle-class cohort was unexpected and was related to the timing of the mother's return to work. The impact of prolonged bottle-feeding on later growth and adiposity deserves further investigation.  相似文献   

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Nasopharyngeal carriage of Streptococcus pneumoniae was studied in 162 healthy infants at ages 2, 4, 6, 7, 12, and 13 months and in an additional 352 healthy children at ages 12, 15, 18, 21, and 24 months. Carriage was 26%, 39%, and 62% at 2, 12, and 24 months, respectively, and the respective resistance to > or = 1 antibiotic was 11%, 19%, and 27%. The presence of an older sibling or antibiotic treatment during the month preceding the culture was associated with carriage of resistant pneumococci in infants, whereas attendance at large day care centers was associated with carriage during the second year of life. Antibiotic resistance was detected in all 7 serotypes included in the candidate pediatric conjugate vaccines and was significantly more prevalent among vaccine-type pneumococci than among non-vaccine-type pneumococci. The use of conjugate vaccines may reduce the spread of resistant pneumococci.  相似文献   

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The purpose of this study was to evaluate the molecular relatedness of clinical isolates of glycopeptide-resistant Enterococcus faecium isolates collected from hospitals in Michigan. A total of 379 isolates used in this study were all vancomycin-resistant E. faecium isolates collected from 28 hospitals and three extended-care facilities over a 6-year period from 1991 to 1996. For the 379 isolates, there were 73 pulsed-field gel electrophoresis (PFGE) strain types. Within strain types, there were as many as six restriction fragment differences. Most isolates (70%) belonged to six strain types, which were designated M1 (36%), M2 (3%), M3 (18%), M4 (6%), M10 (4%), and M11 (3%). PFGE strain M1 was cultured from 135 patients in 13 hospitals during the period 1993 to 1996. Strain type M2 was cultured from 11 patients in two hospitals during the period 1991 to 1992 and was not observed after 1992. Strain type M3 was cultured from 70 patients in 10 hospitals during the period of 1994 to 1996. Both M4 and M10 were cultured from 23 patients in three hospitals and from 15 patients in two hospitals, respectively, during 1995 to 1996. M11 was cultured from 13 patients in four hospitals during 1996. A total of 23 of 28 hospitals had evidence of clonal dissemination of some isolates. Plasmid content and hybridization analysis done on 103 isolates from one hospital and two affiliated extended-care facilities indicated that the strains contained from one to eight plasmids. Mating experiments indicated transfer of vancomycin resistance from 94 of these isolates into plasmid-free E. faecium GE-1 at transfer frequencies of <10(-9) to 10(-4). Gentamicin resistance and erythromycin resistance were cotransferred at various frequencies. A probe for the vanA gene hybridized to the plasmids of 23 isolates and to the chromosomes of 72 isolates. A probe for the vanB gene hybridized to the chromosomes of 8 isolates. The results of this study suggest inter- and intrahospital dissemination of vancomycin-resistant E. faecium strains over a 6-year period in southeastern Michigan. The majority of isolates studied belonged to the same few PFGE strains, indicating that clonal dissemination was responsible for most of the spread of resistance that occurred.  相似文献   

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BACKGROUND: The establishment of the nasopharyngeal flora was followed in Costa Rican children from birth to 1 year of age. METHODS: Nasopharyngeal cultures were obtained at 1 (n = 413), 3 (n = 393), 6 (n = 376) and 12 months (n = 356) of age from children representative of the population in the Puriscal district. Weekly cultures were obtained from a subcohort of these children (n = 101). Mother-infant diads (n = 95) and preschool children (n = 208) attending day-care centers were also studied. RESULTS: The estimated proportion of colonized children in the population differed markedly depending on the frequency of culture. Quarterly cultures showed a slow increase in carrier rates from 3.9% for Haemophilus influenzae, 3.1% for Streptococcus pneumoniae and 6.5% for Moraxella catarrhalis at 1 month of age to 10.1% carrying H. influenzae and 19.4% carrying S. pneumoniae by the end of the first year. By quarterly culture the proportion of children colonized at least once was 36% for S. pneumoniae, 26% for H. influenzae and 28% for M. catarrhalis. In contrast weekly sampling showed that 95 to 100% of the children were colonized at least once during the first year of life with H. influenzae, S. pneumoniae or M. catarrhalis. Nasopharyngeal carriage of H. influenzae, S. pneumoniae and M. catarrhalis was low in the mothers, and very few mother-infant pairs carried identical bacteria at the same time. In contrast carrier rates were high in the siblings attending day care (H. influenzae 27.9%, S. pneumoniae 39.4%, both organisms 26.6%). Infants with siblings had significantly higher bacterial carriage at all ages than infants without siblings. CONCLUSIONS: Quarterly nasopharyngeal cultures showed that Costa Rican infants acquire their nasopharyngeal flora at a rate comparable with that for infants in developed countries and that siblings are an important source of the bacteria. Weekly samplings showed that virtually all children were colonized at least once during the first year of life.  相似文献   

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The appearance and course of serum immunoglobulin E-antibodies (IgE-ab) to egg-white (EW), cow's milk (CM) and inhalants (pollen, danders and mite) were followed from birth to 12 years of age in 84 children unselected for family history of atopy. During the follow-up 36 children developed atopic symptoms and 48 children did not. IgE-ab to EW and CM reached a peak prevalence at 8 months of age--with high concentrations almost exclusively in atopics and disappeared successively during childhood. IgE-ab to inhalants appeared from 2 years of age and then in increasing frequency during childhood. Similar to the pattern of IgE-ab to EW and CM, transient low levels of IgE-ab to inhalants were commonly encountered in non-atopic children while high concentrations without tendency to decline were almost exclusively seen in atopics. High responders to EW-antigen during infancy were usually also high responders to inhalants during childhood. Clinical allergy to EW and CM and subsequent tolerance appeared early in childhood, whereas allergy to inhalants appeared later and did not disappear. The temporary low-grade IgE antibody response in non-atopic individuals to eaten and inhaled allergens is similar to the results of animal studies demonstrating a transient IgE production followed by tolerance.  相似文献   

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We recorded reaching movements from nine infants longitudinally from the onset of reaching (5th postnatal month) up to the age of 3 years. Here we analyze hand and proximal joint trajectories and examine the emerging temporal coordination between arm segments. The present investigation seeks (a) to determine when infants acquire consistent, adult-like patterns of multijoint coordination within that 3-year period, and (b) to relate their hand trajectory formation to underlying patterns of proximal joint motion (shoulder, elbow). Our results show: First, most kinematic parameters do not assume adult-like levels before the age of 2 years. At this time, 75% of the trials reveal a single peaked velocity profile of the hand. Between the 2nd and 3rd year of life, "improvements" of hand- or joint-related movement units are only marginal. Second, infant motor systems strive to obtain velocity patterns with as few force reversals as possible (uni- or bimodal) at all three limb segments. Third, the formation of a consistent interjoint synergy between shoulder and elbow motion is not achieved within the 1st year of life. Stable patterns of temporal coordination across arm segments begin to emerge at 12-15 months of age and continue to develop up to the 3rd year. In summary, the development toward adult forms of multijoint coordination in goal-directed reaching requires more time than previously assumed. Although infants reliably grasp for objects within their workspace 3-4 months after the onset of reaching, stereotypic kinematic motor patterns are not expressed before the 2nd year of life.  相似文献   

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PURPOSE: Partial seizures in early postnatal life may be catastrophic and associated with poor long-term outcome. Epilepsy surgery can alleviate partial seizures in older children and adults, but there is little experience with surgical therapy in infancy apart from hemispheric epilepsy syndromes. METHODS: We analyzed the results of cortical resection to treat medically refractory partial epilepsy in 31 children (16 boys, 15 girls) aged <3 years (mean, 18.3 months). Subjects were included only if seizure relief was the primary indication for surgery. RESULTS: Follow-up of at least 1 year (mean, 4.6 years) in 26 patients revealed that 16 were seizure-free, 4 had >90% seizure reduction, and 6 had <90% reduction. There was no significant difference in seizure outcome between hemispherectomy/multilobar resections and lobar resections or temporal versus extratemporal resection. Seizure outcome was independent of the amount of cortex removed in nonlesional patients. Only the presence of a discrete lesion on preoperative neuroimaging correlated with a favorable outcome. Family perceptions of accelerated development in seizure-free patients were not confirmed on developmental assessment. CONCLUSIONS: We conclude that cortical resection often benefits very young children with catastrophic partial seizures, but does not guarantee enhanced neurological development. The location and extent of the excised cortex may not be critical as long as the entire epileptogenic region and lesion are removed.  相似文献   

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OBJECTIVE: The purpose of this study was to determine the pattern of adjustment over time of a cohort of children with newly diagnosed diabetes compared with a cohort of peer-selected children without diabetes over the first 2 years after the diagnosis of insulin-dependent diabetes mellitus (IDDM). RESEARCH DESIGN AND METHODS: Children (n = 89 with IDDM, n = 53 without IDDM) ages 8-14 years were studied with the Children's Depression Inventory, State-Trait Anxiety Inventory for Children, Child and Adolescent Adjustment Profile, Self-Perception Profile for Children, and a general health scale. Initial data were collected within 6 weeks of the diagnosis of IDDM and at 3, 6, 12, and 24 months thereafter. RESULTS: There were no demographic differences between the two groups. Initially, children with diabetes were more depressed, more dependent, and more withdrawn than their peers. By 1 year postdiagnosis, there were no significant differences in psychosocial status between the two groups. By 2 years postdiagnosis, depression, dependency, and withdrawal were significantly higher in children with diabetes than in their peers without IDDM. Self-perceived competence remained similar between the two groups at all time points. CONCLUSIONS: After an initial period of adjustment, children with IDDM have equivalent psychosocial status to children without IDDM, but by 2 years after diagnosis, they have experienced twice the amount of depression and adjustment problems as their peers. Interventions should be aimed at this critical period between 1 and 2 years postdiagnosis.  相似文献   

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Observed 20 2-5 yr olds and their mothers while they interacted verbally in an unstructured situation. Quantitative as well as categorical aspects of the interactions were analyzed. Both types of dependent variables were found to change with the age and the language level of the children. Close mutual adaptation of both partners for the quantitative as well as the qualitative dimension were demonstrated. The correlation patterns between the types of utterances allow the abstraction of a "primitive" and an advanced cluster of language-teaching-learning behaviors. The stability and generalizability of these trends are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

16.
Protein losing enteropathy is rarely associated with Henoch-Sch?nlein purpura. Moreover, the disease association of Henoch-Sch?nlein purpura and rheumatoid arthritis is also rare. We report a case of a 46 year old patient with rheumatoid arthritis presenting with Henoch-Sch?nlein purpura associated with protein losing enteropathy.  相似文献   

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From 1969 through 1974, 25 patients under age 21 years had prosthetic cardiac vlave replacement at the Emory University Hospital. Twenty-nine valves were replaced in this group. Patients ranged in age from 2 to 21 years, with a mean of 14 years. Concomitant correction of associated cardiac lesions was required in 14 (56%). Five (21%) had had prior open valvuoplastic procedures. Operative mortality for the entire group was 12%, with an additional late mortality of 8%. There have been no early or late deaths in the last three years' experience. Best results are obtained when early correction of isolated valvular lesions is done as soon as clinical deterioration on vigorous medical management is recognized. The presence of multiple intrcardiac lesions or prior valve surgery does not preclude excellent results. Current indications for surgical correction and follow-up management are presented.  相似文献   

18.
During a surveillance program associated with the Italian clinical trial for the evaluation of new acellular pertussis vaccines, two bacterial isolates were obtained in cultures of samples from immunocompetent infants who had episodes of cough. Both clinical isolates were identified as Bordetella bronchiseptica by biochemical criteria, although both strains agglutinated with antisera specific for Bordetella parapertussis, suggesting that the strains exhibited some characteristics of both B. bronchiseptica and B. parapertussis. Both children from whom these strains were isolated exhibited an increase in serum antibody titer to pertussis toxin (PT), a protein that is produced by Bordetella pertussis but that is not thought to be produced by B. bronchiseptica. We therefore examined whether the clinical isolates were capable of producing PT. Neither strain produced PT under laboratory conditions, although both strains appeared to contain a portion of the ptx region that encodes the structural subunits of PT. In order to determine whether the ptx genes may encode functional proteins, we inserted an active promoter directly upstream of the ptx region of one of these strains. Biologically active PT was produced, suggesting that this strain contains the genetic information necessary to encode an active PT molecule. Sequence analysis of the ptx promoter region of both strains indicated that, while they shared homology with the B. bronchiseptica ATCC 4617 sequence, they contained certain sequence motifs that are characteristic of B. parapertussis and certain motifs that are characteristic of B. pertussis. Taken together, these findings suggest that variant strains of B. bronchiseptica exist and might be capable of causing significant illness in humans.  相似文献   

19.
PURPOSE: To evaluate the outcomes and ocular growth after intraocular lens (IOL) implantation in the first 2 years of life. SETTING: University-affiliated eye institute. METHODS: The medical records of consecutive children under 24 months of age who had cataract extraction with IOL implantation were reviewed. Change in axial length over time, postoperative complications, need for additional surgery, predicted versus actual postoperative refraction, and visual outcomes were recorded. Complication rates were compared with those in a similar group of age-matched patients who were left aphakic at the time of surgery. RESULTS: Twenty-two eyes of 17 patients aged 12 days to 22 months had IOL implantation. Length of follow-up ranged from 2 to 36 months (mean 14 months). Visual acuity measurement, limited to fixation-preference testing in most patients, revealed amblyopia in the operated eye in the majority of cases. Postoperative refractive error, predicted using the Holladay formula, showed a mean error in prediction of 1.5 diopters (D) (range -1.8 to 4.1 D). Serial axial lengths in 11 patients with a mean follow-up of 20 months showed no significant difference in growth in the fellow versus the operated eye. There was no significant difference in complication rates between pseudophakic patients and the age-matched aphakic group. However, in 14 of 32 aphakic eyes (44%), a notation in the chart indicated that the patient had stopped wearing glasses or contact lenses for at least 2 months. CONCLUSION: Intraocular lens implantation appeared to be a safe and effective alternative to contact lens or spectacle correction of aphakia in children younger than 2 years of age. It may aid amblyopia treatment by eliminating periods of uncorrected aphakia.  相似文献   

20.
Accommodative esotropia during the first year of life   总被引:1,自引:0,他引:1  
Two infants developed accommodative esotropia during their first six months of life. One infant, whose age at onset was 4 1/2 months, had 4.50 diopters of hyperopia. The second infant, whose age at onset was 5 months, had 3.50 diopters of hyperopia. In both infants, the eyes completely aligned with hyperopic correction. Two points are stressed. First, when the amount of hyperopia exceeds +3.00, consideration should be given to an accommodative element as the cause of the esotropia, even if the child is only 4 to 6 months old. Second, even with small angles of esotropia, an accommodative element should be considered, if there is a substantial amount of hyperopia.  相似文献   

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