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A Zaritsky

Publications and source records attributed to A Zaritsky.

At least 37 records · Page 2Linked to original sources
PubMed1999

Transcription- and translation-dependent changes in membrane dynamics in bacteria: testing the transertion model for domain formation.

Cell cycle events have been proposed to be triggered by the formation of membrane domains in the process of coupled transcription, translation and insertion ('transertion') of nascent membrane and exported proteins. Disruption of domain structure should lead to changes in membrane dynamics. Membrane viscosity of Escherichia coli and Bacillus subtilis decreased after inhibition of protein synthesis by chloramphenicol or puromycin, or of RNA initiation by rifampicin, but not after inhibition of RNA elongation by streptolydigin or amino acid starvation of a stringent strain. The decrease caused by inhibitors of protein synthesis was prevented by streptolydigin if added simultaneously, but was not reversed if added later. The drug-induced decrease in membrane viscosity is energy dependent: it did not happen in KCN-treated cells. All treatments decreasing membrane viscosity also induced nucleoid compaction and fusion. Inhibition of macromolecular synthesis without membrane perturbation caused nucleoids to expand. Changes in membrane dynamics were also displayed during a nutritional shift-down transition that causes imbalance in macromolecular syntheses. The results are consistent with the transertion model, predicting dissipation of membrane domains by termination of protein synthesis or detachment of polysomes from DNA; domain structure is conserved if the transertion process is 'frozen'.

Bacillus subtilis↗
PubMed1999

Instillation of calf lung surfactant extract (calfactant) is beneficial in pediatric acute hypoxemic respiratory failure. Members of the Mid-Atlantic Pediatric Critical Care Network.

OBJECTIVE: Prospective study of the efficacy of calf lung surfactant extract in pediatric respiratory failure. DESIGN: Multi-institutional, prospective, randomized, controlled, unblinded trial. SETTING: Eight pediatric intensive care units (ICU) of tertiary medical centers. PATIENTS: Forty-two children with acute hypoxemic respiratory failure characterized by diffuse, bilateral pulmonary infiltrates, need for ventilatory support, and an oxygenation index of >7. INTERVENTION: Instillation of intratracheal surfactant (80 mL/m2). MEASUREMENTS AND MAIN RESULTS: Ventilator parameters, arterial blood gases, and derived oxygenation and ventilation indices were recorded before and at intervals after surfactant administration. Complications and outcome measures, including mortality, duration of mechanical ventilation, and length of pediatric ICU and hospital stay, were also examined. Patients who received surfactant demonstrated rapid improvement in oxygenation and, on average, were extubated 4.2 days (32%) sooner and spent 5 fewer days (30%) in pediatric intensive care than control patients. There was no difference in mortality or overall hospital stay. Surfactant administration was associated with no serious adverse effects. CONCLUSIONS: Administration of calf lung surfactant extract, calfactant, appears to be safe and is associated with rapid improvement in oxygenation, earlier extubation, and decreased requirement for intensive care in children with acute hypoxemic respiratory failure. Further study is needed, however, before widespread use in pediatric respiratory failure can be recommended.

Adolescent↗
PubMed1999

Priorities for research in emergency medical services for children: results of a consensus conference.

OBJECTIVE: To arrive at a consensus on the priorities for future research in emergency medical services for children. METHODS: A consensus group was convened using the Rand-UCLA Consensus Process. The group took part in a 3-phase process. Round I involved reviewing a compendium of relevant research articles and answering a mailed questionnaire. Panel members were asked to prioritize topics on the basis of the 1993 Institute of Medicine Report on Emergency Medical Services for Children. Participants were asked to rate each topic based on the significance of the research, and whether the topic would (1) improve general knowledge (2), change behavior (3), improve health (4), decrease the cost of care, or (5) change public policy. A 4-point Likert scale was used. Participants were also asked if the research would require a multicenter study and if the research were feasible. Round II of the study involved a meeting of the panel, where the results of Round I were discussed and the topics were reprioritized. The topics were given a rank order and a final ranking was done in Round III. RESULTS: The panel considered a list of 32 topics; these were combined and reworded to give them more precise meaning. Several new topics were also added. Fifteen topics were given a rank order and placed within the 7 broad categories of the Institute of Medicine report. Clinical aspects of emergency care, systems organization, configuration, and operation and injury prevention were given high priority rankings. The first 5 topics were very close in point-rank order. CONCLUSION: The panel was able to develop a list of important topics for future research in emergency medical services for children that can be used by foundations, governmental agencies, and others in setting research agenda for such services.

Child↗
PubMed1999

Multiplex PCR screening to detect cry9 genes in Bacillus thuringiensis strains.

An extended PCR method was established to rapidly identify and classify Bacillus thuringiensis strains containing cry (crystal protein) genes toxic to lepidopteran, coleopteran, and dipteran pests (Ben-Dov et al., Appl. Environ. Microbiol. 63:4883-4890, 1997). To optimize identification of all reported cry genes, this methodology needs a complete PCR set of primers. In the study reported here, a set of universal (Un9) and specific primers for multiplex rapid screening for all four known genes from the cry9 group was designed. PCR analyses were performed for cry9 genes on 16 standard strains and 215 field isolates of B. thuringiensis. Among the standard strains, only B. thuringiensis subsp. aizawai HD-133, which harbors cry1 and cry2 genes, was positive with Un9 but negative to all four specific primers for cry9 genes. DNA of 22 field-collected isolates was also found to be positive with Un9. These isolates were classified into three cry9 profiles using specific primers; all of them harbor cry1 and cry2. This newly designed set of primers complements the existing PCR methodology for most currently known cry genes.

Bacillus thuringiensis↗
PubMed1999

Model for bacteriophage T4 development in Escherichia coli.

Mathematical relations for the number of mature T4 bacteriophages, both inside and after lysis of an Escherichia coli cell, as a function of time after infection by a single phage were obtained, with the following five parameters: delay time until the first T4 is completed inside the bacterium (eclipse period, nu) and its standard deviation (sigma), the rate at which the number of ripe T4 increases inside the bacterium during the rise period (alpha), and the time when the bacterium bursts (mu) and its standard deviation (beta). Burst size [B = alpha(mu - nu)], the number of phages released from an infected bacterium, is thus a dependent parameter. A least-squares program was used to derive the values of the parameters for a variety of experimental results obtained with wild-type T4 in E. coli B/r under different growth conditions and manipulations (H. Hadas, M. Einav, I. Fishov, and A. Zaritsky, Microbiology 143:179-185, 1997). A "destruction parameter" (zeta) was added to take care of the adverse effect of chloroform on phage survival. The overall agreement between the model and the experiment is quite good. The dependence of the derived parameters on growth conditions can be used to predict phage development under other experimental manipulations.

Bacteriophage T4↗
PubMed1999

[The influence of the 20 kDa protein from Bacillus thuringiensis subsp. israelensis on the cytolytic activity of CytA].

In order to understand the influence of the 20 kDa protein on the cytolytic activity of CytA protein, a set of PCR primers were designed to amplify 20 kDa protein and CytA protein genes. The genes were ligated to E. coli expression vector pUHE24 and transformed into E. coli XL1 and DH5 alpha. The clones, LZ20, LZcytA and LZ20A containing 20 kDa protein gene, cytA protein gene and 20 kDa-cytA genes were obtained respectively. The influence of the clones on the growth of E. coli cells was determined under induction of IPTG. The results showed that the growth of LZ20 cells were not affected, LZcytA cells were killed, and the growth of LZ20A cells were not affected. It was suggested that expression product of 20 kDa protein gene protected the host cells from the cytolytic effect of CytA protein. This was supported by using different host strains.

Bacillus thuringiensis↗
PubMed1999

[Preliminary study of P19 gene from Bacillus thuringiensis subsp israelensis].

The P19 gene and cyt1A gene were obtained by PCR with 9.7 kb HindIII fragment containing P19 gene and cyt1A gene from 72 MD plasmid of Bt as a template. Digested PCR products were ligated to expression vector pUHE24 and transformed into E. coli XL-1. Three clones, LZ19 harboring P19 gene, LZcyt1A harboring cyt1A gene, LZ19A harboring P19 gene and cyt1A gene, were screened. The growth cure of cloned strains were determined under IPTG induction. The result showed that pLZ19 did not affect the growth of E. coli, pLZcyt1A is typically Lethal for E. coli, Lethal initial efficiency of pLZ19A is much higher than that of pLZcyt1A. Probably, this was a result that P19 gene enhanced initial expression of cyt1A gene in E. coli.

Bacillus thuringiensis↗
PubMed1998

Effect of nebulized ipratropium on the hospitalization rates of children with asthma.

BACKGROUND: Anticholinergic medications such as ipratropium improve the pulmonary function of patients with acute exacerbations of asthma, but their effect on hospitalization rates is uncertain. METHODS: We conducted a randomized, double-blind, placebo-controlled study of 434 children (2 to 18 years old) who had acute exacerbations of moderate or severe asthma treated in the emergency department. All the children received a nebulized solution of albuterol (2.5 or 5 mg per dose, depending on body weight) every 20 minutes for three doses and then as needed. A corticosteroid (2 mg of prednisone or prednisolone per kilogram of body weight) was given orally with the second dose of albuterol. Children in the treatment group received 500 microg (2.5 ml) of ipratropium bromide with the second and third doses of albuterol; children in the control group received 2.5 ml of normal saline at these times. RESULTS: Overall, the rate of hospitalization was lower in the ipratropium group (59 of 215 children [27.4 percent]) than in the control group (80 of 219 [36.5 percent], P=0.05). For patients with moderate asthma (indicated by a peak expiratory flow rate of 50 to 70 percent of the predicted value or an asthma score of 8 to 11 on a 15-point scale), hospitalization rates were similar in the two groups (ipratropium: 8 of 79 children [10.1 percent]; control: 9 of 84 [10.7 percent]). For patients with severe asthma (defined as a peak expiratory flow rate of <50 percent of the predicted value or an asthma score of 12 to 15), the addition of ipratropium significantly reduced the need for hospitalization (51 of 136 children [37.5 percent], as compared with 71 of 135 [52.6 percent] in the control group; P=0.02). CONCLUSIONS: Among children with a severe exacerbation of asthma, the addition of ipratropium bromide to albuterol and corticosteroid therapy significantly decreases the hospitalization rate.

Adolescent↗
PubMed1998

Germination, growth, and sporulation of Bacillus thuringiensis subsp. israelensis in excreted food vacuoles of the protozoan Tetrahymena pyriformis.

Spores of Bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated in the protozoan Tetrahymena pyriformis, in which the toxin remains stable. Each T. pyriformis cell concentrates the spores and crystals in its food vacuoles, thus delivering them to mosquito larvae, which rapidly die. Vacuoles containing undigested material are later excreted from the cells. The fate of spores and toxin inside the food vacuoles was determined at various times after excretion by phase-contrast and electron microscopy as well as by viable-cell counting. Excreted food vacuoles gradually aggregated, and vegetative growth of B. thuringiensis subsp. israelensis was observed after 7 h as filaments that stemmed from the aggregates. The outgrown cells sporulated between 27 and 42 h. The spore multiplication values in this system are low compared to those obtained in carcasses of B. thuringiensis subsp. israelensis-killed larvae and pupae, but this bioencapsulation represents a new possible mode of B. thuringiensis subsp. israelensis recycling in nontarget organisms.

Animals↗
PubMed1997

Efficacy of nebulized ipratropium in severely asthmatic children.

STUDY OBJECTIVE: To determine the effect of adding the nebulized anticholinergic drug ipratropium bromide to standard therapy compared with standard therapy alone for acute severe asthma (peak expiratory flow rate [PEFR] < 50% of predicted) in children presenting to the emergency department. METHODS: Ninety children aged 6 to 18 years were randomly assigned to two groups in a prospective, double-blind, placebo-controlled study performed in the ED of an urban children's hospital. All children received nebulized albuterol solution (.15 mg/kg) every 30 minutes, and all received oral steroids with the second dose of albuterol. Children in group 1 received ipratropium bromide (500 micrograms/dose) with the first and third dose of albuterol those in group 2 received saline placebo instead of ipratropium. Pulmonary functions (PEFR and 1-second forced expiratory volume [FEV1]) and physiologic measurements were assessed every 30 minutes up to 120 minutes. By chance, the baseline values for percent of predicted PEFR and FEV1 differed between the two groups. Therefore a multivariate model accounting for both time and baseline effects was used to compare the response between groups. RESULTS: On average, and adjusting for baseline measures, children in the ipratropium group had a significantly greater improvement in percent of predicted PEFR than did children in the placebo group at 60 minutes (P = .02), 90 minutes (P = .002), and 120 minutes (P < .0001). The improvement in percent predicted FEV1 was significantly greater for children in the ipratropium group only at 120 minutes (P = .013). Nine children (20%) from the ipratropium group and 14 (31.1%) from the control group were admitted (P = .33, chi 2). There were no significant adverse effects attributable to the ipratropium, and there was no relation between ipratropium use and changes in pulse, respiratory rate, blood pressure, or oxygen saturation. CONCLUSION: We detected significant improvement in pulmonary function studies over 120 minutes in children with severe asthma who were given nebulized ipratropium combined with albuterol and oral steroids, compared with children who received the standard therapy. Further study is needed to determine whether early use of ipratropium decreases the need for hospitalization.

Adolescent↗
PubMed1997

Paediatric life support. An advisory statement by the Paediatric Life Support Working Group of the International Liaison Committee on Resuscitation.

This document reflects the deliberations of ILCOR. The epidemiology and outcome of paediatric cardiopulmonary arrest and the priorities, techniques and sequence of paediatric resuscitation assessments and interventions differ from those of adults. The working group identified areas of conflict and controversy in current paediatric basic and advanced life support guidelines, outlined solutions considered and made recommendations by consensus. The working group was surprised by the degree of conformity already existing in current guidelines advocated by the American Heart Association (AHA), the Heart and Stroke Foundation of Canada (HSFC), the European Resuscitation Council (ERC), the Australian Resuscitation Council (ARC), and the Resuscitation Council of Southern Africa (RCSA). Differences are currently based upon local and regional preferences, training networks and customs, rather than scientific controversy. Unresolved issues with potential for future universal application are highlighted. This document does not include a complete list of guidelines for which there is no perceived controversy and the algorithm/decision tree figures presented attempt to follow a common flow of assessments and interventions, in coordination with their adult counterparts. Survival following paediatric prehospital cardiopulmonary arrest occurs in only approximately 3-17% and survivors are often neurologically devastated. Most paediatric resuscitation reports have been retrospective in design and plagued with inconsistent resuscitation definitions and patient inclusion criteria. Careful and thoughtful application of uniform guidelines for reporting outcomes of advanced life support interventions using large, randomized, multicenter and multinational clinical trials are clearly needed. Paediatric advisory statements from ILCOR will, by necessity, be vibrant and evolving guidelines fostered by national and international organizations intent on improving the outcome of resuscitation for infants and children worldwide.

Adolescent↗