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Biomedical subjects

A Zaritsky

Publications and source records attributed to A Zaritsky.

At least 19 recordsLinked to original sources
PubMed1992

Sensitivity to plating of Escherichia coli cells expressing the cryA gene from Bacillus thuringiensis var. israelensis.

The gene (cytA) coding for the 27 kDa polypeptide of the Bacillus thuringiensis var. israelensis mosquito larvicidal delta-endotoxin, was cloned into a plasmid containing the T7 bacteriophage promoter. The plasmid was used to transform an Escherichia coli strain containing the T7 RNA polymerase gene 1, under the control of lacP. Loss of colony-forming ability without substantial lysis, associated with immediate inhibition of DNA synthesis, was observed after induction of transformed cells. The cytA gene product may kill E. coli cells by disrupting their chromosome replicating apparatus.

Bacillus thuringiensis↗
PubMed1992

Digestion of Bacillus thuringiensis var. israelensis spores by larvae of Aedes aegypti.

The larvicidal activity of Bacillus thuringiensis var. israelensis against mosquitoes and the blackfly is included in parasporal crystalline bodies which are produced during sporulation. Following ingestion, the crystals are solubilized in the larval midgut and induce death within a short time; the spores germinate in the dead larvae and complete a growth cycle. The fate of the spores in surviving live larvae was elucidated by using a nonlarvicidal B. thuringiensis var. israelensis mutant. When introduced as the only food source, spores of this mutant support development to the adult stage of newly hatched Aedes aegypti larvae at a rate directly related to spore concentration. The conclusion that spores of B. thuringiensis var. israelensis are digested in the larval gut was substantiated by following the incorporation of [35S]methionine-labeled spores into larval tissues.

Aedes↗
PubMed1992

Neural computing in discovering RNA interactions.

High-order RNA structures are involved in regulating many biological processes; various algorithms have been designed to predict them. Experimental methods to probe such structures and to decipher the results are tedious. Artificial intelligence and the neural network approach can support the process of discovering RNA structures. Secondary structures of RNA molecules are probed by autoradiographing gels, separating end-labeled fragments generated by base-specific RNases. This process is performed in both conditions, denaturing (for sequencing purposes) and native. The resultant autoradiograms are scanned using line-detection techniques to identify the fragments by comparing the lines with those obtained by 'alkaline ladders'. The identified paired bases are treated by either one of two methods to find the foldings which are consistent with the RNases' 'cutting' rules. One exploits the maximum independent set algorithm; the other, the planarization algorithm. They require, respectively, n and n2 processing elements, where n is the number of base pairs. The state of the system usually converges to the near-optimum solution within about 500 iteration steps, where each processing element implements the McCulloch-Pitts binary neuron. Our simulator, based on the proposed algorithm, discovered a new structure in a sequence of 38 bases, which is more stable than that formerly proposed.

Algorithms↗
PubMed1992

Length-based endotracheal tube and emergency equipment in pediatrics.

HYPOTHESIS: Pediatric endotracheal (ET) tubes can be accurately selected based on body length using a specialized emergency tape. POPULATION: Derivation set: Two hundred five children undergoing elective surgery. Validation set: Two hundred thirteen children undergoing elective surgery. Each child served as his or her own control. METHODS: Derivation phase: Two hundred twenty-one children undergoing ET intubation for elective surgery had their body length and leak pressures measured. The 205 children who had leak pressures between 10 and 40 cm H2O constituted the derivation set. The body length for a given ET tube size was derived from the interquartile range of patient lengths in this derivation set. Sizes for other resuscitative equipment items were chosen by a panel of experts using a modified Delphi technique. This information was placed by length on a color-coded tape. Validation phase: The tape was validated by using it to select ET tube size in another group of 203 children undergoing elective surgery. Criteria for acceptable fit in this group included leak pressure as above and the anesthesiologists' decision to accept the tube size or to retintubate. In the validation phase, length-based ET tube selections were compared with age-based rules: (age + 16)/4, and (age + 18)/4. RESULTS: The tape selected the appropriate ET tube size by leak pressure criterion in 77% of the cases and was within +/- 0.5 mm of the "correct" size 99% of the time. This was significantly better (P less than .005) than two widely used age-based rules, which gave the correct initial size in only 47% and 9% of these cases, and were within +/- 0.5 mm for 86% and 59%. The anesthesiologists chose to continue with the tape-sized tube rather than to reintubate in 89% of cases. CONCLUSION: A system for length-based selection of emergency equipment represents a significant adjunct to emergency physicians and paramedics who must deal with critically ill children. Length-based ET tube selection is clearly superior to age-based rules, which are difficult to remember and require accurate estimation of a patient's age.

Body Height↗
PubMed1992

Nonphysician transport of intubated pediatric patients: a system evaluation.

OBJECTIVE: To evaluate the occurrence of complications and patient deteriorations during the air and ground transportation of intubated pediatric patients, performed by a nonphysician-based team under the direction of an intensive care attending physician or fellow. DESIGN: Retrospective chart review. SETTING: A 600-bed university hospital with a 16-bed neonatal ICU and a 12-bed pediatric ICU. PATIENTS: All intubated pediatric patients (422 of 614 patients transported during the study period) transported by the dedicated neonatal/pediatric transport team from April 1988 to April 1990. MEASUREMENTS AND MAIN RESULTS: The transport records of intubated pediatric patients were abstracted. Recorded data included age, weight, gestational age, vital signs, diagnosis, interventions received, and use of paralytic agents and sedatives/analgesics. Patients were analyzed in three groups: group 1 (n = 295) included neonates; group 2 (n = 66) included patients greater than 1 month and less than 1 yr of age; and group 3 patients (n = 61) were ages greater than 1 yr. Group 1 had nine (3.1%) complications or patient deteriorations; four (1.4%) were related to the endotracheal tube. Group 2 had one (1.5%) airway complication and one deterioration. Group 3 had no complications or deteriorations. All but one of the airway complications were effectively handled by the transport team. At the referring hospital, the transport nurse or respiratory therapist intubated 62 (19.8%) patients in group 1, five (7.5%) in group 2, and three (4.9%) patients in group 3. Sixty-seven (23%), 21 (32%), and 30 (49%) patients of groups 1, 2, and 3, respectively, were paralyzed for transport. No complications were secondary to the use of paralytic agents or sedatives. CONCLUSIONS: Under proper medical guidance, well-trained nonphysician personnel can provide low-risk transport of intubated pediatric patients. Use of sedatives and paralytic drugs did not increase the risk of complications or patient deterioration.

Child↗
PubMed1992

Rate maintenance of cell division in Escherichia coli B/r: analysis of a simple nutritional shift-down.

A competitive (nonmetabolizable) inhibitor of glucose uptake, alpha-methylglucoside, was used to limit the growth of Escherichia coli. Cell division during such a nutritional shift-down was studied in batch cultures and with the "baby-machine" technique. Following a brief delay, the rate of division was maintained for 60 to 70 min in batch cultures and for an extended period in the baby machine. Decreases in cell size were due, in part, to a possible reduction in the mass per chromosome origin at the time of replication initiation and a shorter time interval between initiation and the subsequent division. These unusual findings suggest that this method for abrupt change in growth rate without modifying repression patterns is useful for studying the control of various aspects of the bacterial cell.

Cell Division↗
PubMed1991

Role of early fluid resuscitation in pediatric septic shock.

OBJECTIVE: To examine the association of the volume of fluid administered at 1 and 6 hours after presentation, with survival and the occurrence of the adult respiratory distress syndrome, cardiogenic pulmonary edema, and persistent hypovolemia during the resuscitation of children with septic shock. SETTING AND PATIENTS: All pediatric patients with septic shock presenting to the emergency department over a 6-year period and having a pulmonary artery catheter inserted by 6 hours after presentation were identified. METHODS: Patients were analyzed together and in three groups based on fluid volume in the first hour: group 1, less than 20 mL/kg; group 2, 20 to 40 mL/kg; and group 3, more than 40 mL/kg. Adult respiratory distress syndrome was diagnosed by the presence of alveolar infiltrates, hypoxemia, and a pulmonary capillary wedge pressure of 15 mm Hg or less. Cardiogenic pulmonary edema was diagnosed similarly, except the pulmonary capillary wedge pressure was greater than 15 mm Hg. Hypovolemia was diagnosed by the presence of oliguria, hypotension, and a pulmonary capillary wedge pressure of 8 mm Hg or less 6 hours after presentation. RESULTS: We identified 34 patients (median age, 13.5 months). At 1 and 6 hours, respectively, group 1 (n = 14) received 11 +/- 6 and 71 +/- 29 mL/kg (mean +/- SD) of fluid; group 2 received 32 +/- 5 and 108 +/- 54 mL/kg of fluid; and group 3 received 69 +/- 19 and 117 +/- 29 mL/kg of fluid. Survival in group 3 (eight of nine patients) was significantly better than in group 1 (six of 14 patients) or group 2 (four of 11 patients). Adult respiratory distress syndrome developed in 11 patients (32%) and cardiogenic pulmonary edema developed in five patients (15%). Having adult respiratory distress syndrome was associated with increased mortality, but adult respiratory distress syndrome was not increased in any group. Similarly, cardiogenic pulmonary edema was not associated with the fluid volume received or with decreased survival. Hypovolemia occurred in six patients in group 1 and two patients in group 2; all eight subsequently died. CONCLUSION: Rapid fluid resuscitation in excess of 40 mL/kg in the first hour following emergency department presentation was associated with improved survival, decreased occurrence of persistent hypovolemia, and no increase in the risk of cardiogenic pulmonary edema or adult respiratory distress syndrome in this group of pediatric patients with septic shock.

Adolescent↗
PubMed1991

A simulation program to display specific digestion products of predicted RNA foldings.

A parameterizable program in Pascal was developed for VAX/VMS computers to simulate the autoradiograms of gel-separated RNA fragments generated by partial cleavage of a folded RNA molecule using five specific RNases. Each screen displays the results of cleavage by either one enzyme or all five, with the RNA molecule labeled at either of its ends (5' or 3'); each run is performed with three different lengths and against a ladder containing alkaline hydrolysis products of the same RNA molecule as size markers. The program should be useful for comparing actual results with predicted functional foldings of RNA molecules.

Algorithms↗
PubMed1991

Characteristics of pediatric intermediate care units in pediatric training programs.

BACKGROUND/OBJECTIVE: To assess effective alternate care sites for the technology-dependent, but less acute critically ill child, we surveyed pediatric training programs to determine the availability and characteristics of non-neonatal pediatric intermediate care units. METHODS: A questionnaire was mailed to the program directors of all 226 United States pediatric residency programs in October 1988. Institutions were queried about pediatric residency program and hospital demographics, along with specific day-to-day management issues in an intermediate care unit. RESULTS: The intermediate care unit offers highly skilled nursing care with greater than 90% of the units primarily covered by RNs in a 1:2 or 1:3 RN/patient ratio. The technologies used in these units were similar to those technologies used in an ICU, and the average daily bed charge was 40% less than the average daily bed charge in an ICU. However, an intermediate care unit was present in only 33% of pediatric training programs and pediatric residents were not specifically trained to care for patients in these units; 37% of these units did not have daily attending physician/nurse/resident rounds, despite the complexity and degree of illness in the patients located in these units. In addition, greater than 20% of intermediate care units were predominantly staffed by RNs with degrees less than BSN. Thirteen percent of these units had a predominance of RNs with only routine experience. CONCLUSIONS: Standard levels of care and academic and financial guidelines should be established to optimize the value of pediatric intermediate care units.

Child↗
PubMed1990

The fate of Bacillus thuringiensis var. israelensis in B. thuringiensis var. israelensis-killed pupae of Aedes aegypti.

Carcasses of mosquito larvae killed by Bacillus thuringiensis var. israelensis allow its complete growth cycle (germination, vegetative growth, and sporulation), thus becoming toxic themselves to scavenging larvae. In this study, we demonstrate that the bacterium is capable of inducing death of Aedes aegypti pupae and of recycling in the resulting carcasses. B. thuringiensis var. israelensis-killed pupae were obtained by treating 40-hr-old synchronized fourth instar larvae with a low dose of spores (8000/ml). The fraction of dead pupae was reduced by higher or lower spore concentrations as well as by treating younger or older larval populations (both fourth instar): Increased proportions of dead larvae were obtained at higher concentration or by earlier treatment, whereas lower concentrations or later treatment resulted in more living pupae. Multiplication of B. thuringiensis var. israelensis is shown to occur in the carcasses of dead pupae. The number of spores in each pupal carcass followed a similar kinetic as in larval carcasses, but the final yield was about 10-fold higher, apparently reflecting the difference in dry weight between the two mosquito developmental stages (426 micrograms vs 83 micrograms, respectively). The specific larvicidal activity in a homogenized dead pupa was similar to that of B. thuringiensis var. israelensis powder, LC50 of about 600 spores/ml.

Aedes↗
PubMed1990

Deviation from homeoviscous adaptation in Escherichia coli membranes.

The process by which an organism changes the composition of its membranal fatty acids in response to growth temperature, so as to maintain optimal membrane functioning, is known as homeoviscous adaptation (HA). One expression of HA is the constancy of the fluorescence polarization (P) of the lipophilic probe 1,6-diphenyl-1,3,5-hexatriene (DPH) in membranes of cells grown at various temperatures. The P of DPH in the membranes of Escherichia coli was shown by us to be inversely proportional to bacterial growth rate on different carbon sources. This result, implying failure of HA, is now complemented by measurements of DPH lifetimes, which indicate that the dominant variables contributing to the drop in P are (a) the order parameter of the membrane, which goes down, and (b) the fluidity, which may slightly increase. These are then the changes induced by enhanced growth rate. Two additional effects, cell membrane permeability and sensitivity to thermal shock, determined by the diffusion of o-nitrophenylgalactoside (ONPG) and by exposure to 52 degrees C, respectively, are reported to increase with growth rate. We can now conclude that there is a deviation from the principle of HA in E. coli grown at various rates, brought about by controlling the growth media at constant temperatures.

Cell Membrane↗
PubMed1990

Simplified assay of amrinone in plasma by high-performance liquid chromatography.

An isocratic high-performance liquid chromatography method for the assay of plasma amrinone is described. Plasma amrinone is extracted using protein precipitation with an internal standard, separated with a reverse phase column, and detected using ultraviolet absorption. Each run is completed within 10 min. The assay can detect amrinone concentrations between 0.5 and 10.0 micrograms/ml, within the accepted therapeutic range. The assay has a within-day coefficient of variation of less than 5% and a day-to-day coefficient of variation of less than 10% in the therapeutic range of amrinone. This technique is an accurate, simple, and rapid method for the determination of amrinone concentrations in plasma.

Amrinone↗
PubMed1989

Drug therapy of cardiopulmonary resuscitation in children.

In contrast to adults, cardiopulmonary arrest in infants and children is rarely an acute, primary cardiac event. Instead, it is often the terminal event in a progressive deterioration of respiratory or circulatory function. Successful resuscitation from cardiac arrest therefore is unusual in the paediatric patient and most survivors have persistent neurological impairment. Rapid vascular access and recall of drug dosages are major obstacles in treating paediatric emergencies. This paper reviews vascular access and alternative drug delivery methods. The endotracheal and intraosseous routes provide alternative sites for drug delivery, but the optimal doses and methods of drug administration via these routes are unknown. Indeed, although great progress in cardiopulmonary resuscitation (CPR) research has been made over the past 10 years, there are only limited data on paediatric arrest mechanisms and drug treatment. In this paper, recommended dosages and mechanisms of action of drugs useful during cardiopulmonary resuscitation are reviewed, highlighting recent data which suggest that changes in current drug recommendations may be needed. To avoid delays in management, precalculated tables of drugs should be readily available in emergency departments and other care areas where paediatric cases are likely to be seen. Adrenaline (epinephrine) remains the drug of choice in a cardiac arrest, but the most effective dose may be higher than currently used. Treatment of acidosis during the arrest concentrates on restoration of ventilation and blood flow and not on bicarbonate administration. In the post-arrest setting increasing data suggest bicarbonate may not be beneficial and may actually be detrimental. Calcium and atropine also have relatively minor roles in resuscitation pharmacology. Calcium is only indicated to treat hypocalcaemia, counteract the effects of hyperkalaemia or hypermagnesaemia, or reverse calcium channel blocker toxicity. Finally, the role of isoprenaline (isoproterenol), dopamine, dobutamine and adrenaline infusions to restore or maintain cardiovascular stability post-arrest is reviewed.

Child, Preschool↗