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Biomedical subjects

A Zaritsky

Publications and source records attributed to A Zaritsky.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1990

Ammonium Excretion by an l-Methionine-dl-Sulfoximine-Resistant Mutant of the Rice Field Cyanobacterium Anabaena siamensis.

An ammonium-excreting mutant (SS1) of the rice field nitrogen-fixing cyanobacterium Anabaena siamensis was isolated after ethyl methanesulfonate mutagenesis by selection on 500 muM l-methionine-dl-sulfoximine. SS1 grew in the presence and absence of (l)-methionine-dl-sulfoximine at a rate comparable to that of the wild-type strain, with a doubling time of 5.6 h. The rate of ammonium release by SS1 depended on cell density; it peaked at the 12th hour of growth with 8.7 mumol mg of chlorophyll h (at a chlorophyll concentration of 5 mug ml) and slowed down to almost nil at the fourth day of growth. A similar pattern of release by immobilized SS1 was observed between 12 to 20 h after loading alginate beads in packed-bed reactors at the rate of 11.6 mumol mg of chlorophyll h. The rate was later reduced significantly due to the fast growth of SS1 on the substrate. Prolonged release of ammonium at the peak level was achieved only by maintaining SS1 under continuous cultivation at low chlorophyll levels (5 to 7 mug ml). Under these conditions, nitrogen fixation in the mutant was 30% higher than that in its parent and glutamine synthetase activity was less by 50%. Immunoblot analysis revealed that SS1 and its parent have similar quantities of glutamine synthetase protein under ammonium excretion conditions. In addition, a protein with a molecular weight of about 30,000 seems to have been lost, as seen by electrophoretic separation of total proteins from SS1.

Journal Article↗
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↗
PubMed1988

Steady-state dopamine clearance in critically ill infants and children.

Little is known about dopamine pharmacokinetics in pediatric patients, especially in critically ill infants and children who often receive treatment with dopamine. Arterial plasma concentrations of dopamine were measured in 27 patients who were hemodynamically stable and received dopamine for at least one hour. The dopamine levels were measured using liquid chromatography with electrochemical detection. Dopamine clearance averaged 96.2 +/- 55.4 ml/kg.min in 13 patients in the neonatal ICU, and 58.8 +/- 51 ml/kg.min in 14 patients in the pediatric ICU. Six patients had renal (BUN greater than 25 mg/dl, or creatinine greater than 1.2 mg/dl) or hepatic (liver enzymes greater than 3 times normal) dysfunction. Dopamine clearance in these patients (25.1 +/- 17.2 ml/kg.min) was substantially lower than in the other patients (p less than .01). Neither postnatal nor gestational age correlated with dopamine clearance. Substantial interindividual variation was observed in steady-state dopamine clearance in critically ill infants and children, and plasma dopamine could not be predicted accurately from the dopamine infusion rate. Because of the more than three-fold prolongation of dopamine clearances in patients with hepatic or renal dysfunction, these patients may be more likely to suffer toxic effects of dopamine at the usual drug infusion rates.

Adolescent↗
PubMed1988

Replication forks of Escherichia coli are not the preferred sites for lysogenic integration of bacteriophage Mu.

The question of whether bacteriophage Mu prefers replication forks for lysogenic integration into Escherichia coli chromosomes was tested by using two different systems. In the first, inactivation of genes was scored in synchronized cultures infected by Mu at various times. No increase in the mutation frequency of a gene was found after infection at the time of its replication. In the second, the composition of colonies formed by bacteria lysogenized by Mu was determined; the newly formed lysogens should give rise to mixed colonies (containing lysogenized as well as nonlysogenized bacteria), uniform colonies, or both, depending on the mode of integration. Both types of colonies were found, and the fraction of uniform colonies was proportional to the relative length of the unreplicated segment of an average chromosome in the culture. The results in both systems clearly preclude the possibility that a lysogenizing Mu integrates with high preference at the chromosome replication forks.

Bacteriophage mu↗
PubMed1988

Selected concepts and controversies in pediatric cardiopulmonary resuscitation.

Although more than 80 years of research in cardiac resuscitation produced many important findings and greatly enhanced our understanding of the arrest state, outcome following pediatric cardiac arrest remains poor. Resuscitation guidelines have recently been published, but they may not reflect optimal therapy. Closed-chest compression-induced cardiac output may be higher in pediatric patients, particularly infants, than that previously reported in adults. To achieve higher cardiac outputs, direct cardiac compression is important; the recommended compression location has therefore been changed based on recent data. The optimal rate of compression, however, is uncertain, so further research is needed. Alternative vascular access sites, such as the endotracheal and intraosseous route for drug administration may permit more rapid drug delivery, but data suggest that a larger epinephrine dose than currently recommended should be used. It may also be helpful to dilute the drug in normal saline before endotracheal administration. Although experimental data suggest that a pure alpha-adrenergic agonist may be beneficial in a cardiac arrest, recent data show that epinephrine remains the drug of choice. Finally, the role of sodium bicarbonate in both the arrest and postarrest setting has become controversial. Recent data suggest that bicarbonate may be detrimental and that therapy of acidosis is best directed at improving perfusion, oxygenation, and ventilation. Alternative forms of therapy for acidosis, such as THAM and dichloroacetate may prove beneficial in the postarrest setting.

Acidosis↗
PubMed1987

Endocrine manifestations of critical illness in the child.

The stress response in humans commonly includes elevations in plasma concentrations of glucocorticoids, catecholamines, glucagon, growth hormone, aldosterone, and renin, resulting in alterations in the metabolism of glucose and other energy substrates, and in increased sodium and water retention. In severe illness, triiodothyronine and sometimes thyroxine are decreased without evidence of clinical hypothyroidism. Antidiuretic hormone may be elevated in bacterial meningitis and other central nervous system disorders, as well as in acute asthma, chronic ventilator therapy, pneumothorax, atelectasis, and postoperatively. Increased ADH concentration can lead to significant hypoosmolality and hyponatremia with adverse effects on the patient. In the setting of severe intracerebral insults, ADH may be inappropriately low, resulting in diabetes insipidus. Insulin concentrations may be inappropriately low for serum glucose concentration, or insulin may have diminished receptor responsiveness in seriously stressed patients. Either situation leads to hyperglycemia. Disturbances in calcium, phosphorus, and magnesium homeostasis may occur relatively frequently in the critically ill patient in response to therapeutic interventions, or illness-induced altered metabolism. It is not always clear when an altered metabolic or hormonal state is an appropriate response to a stress, or represents decompensation of the body's mechanisms for coping with that stress. It is important, however to recognize the common responses of the organism to severe illness, and to monitor for treatable abnormalities which occur.

Aldosterone↗
PubMed1987

CPR in children.

CPR has not been well studied in children and little is known about factors predictive of outcome. We conducted a study with three goals: longitudinal determination of demographic and laboratory data characterizing pediatric arrest victims; identification of factor(s) predictive of outcome; and determination of the prevalence of ionized hypocalcemia in pediatric arrest victims. All resuscitation efforts were documented during a one-year period in a 240-bed tertiary care children's hospital. Patients were classified into two groups--respiratory arrest (RA, requiring only assisted ventilation), and cardiac arrest (CA, absence of palpable cardiac activity requiring closed-chest CPR). Collected data and laboratory tests were analyzed using a step-wise discriminant analysis to determine which factors were predictive of outcome. There were 113 arrests in 93 children; 53 were CA victims and 40 were RA victims. CA had a high in-hospital mortality (90.6%) compared to RA (32.5%). The population was young (55% less than 1 year old) and 87% had at least one chronic underlying disease. No laboratory or demographic value was significantly associated with eventual outcome. The number of doses of epinephrine in CA victims, or bicarbonate in RA victims, was associated with eventual outcome. None of 31 CA victims receiving more than two doses of epinephrine survived to discharge. Low ionized calcium concentrations (less than 3.5 mg/dL) were identified in ten patients; septic shock was present in seven, and chronic renal failure in two.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Cardiopulmonary resuscitation in children.

The management of the pulseless, nonbreathing pediatric patient continues to be a frustrating experience because mortality and morbidity are high. Improvement in outcome awaits a better understanding of the pathophysiology of organ ischemia and reperfusion injury. In the interim, early recognition and therapy of respiratory and circulatory failure are the only effective means to affect outcome. The approach to the pediatric cardiac arrest victim differs from the adult, because dysrhythmias rarely are the etiology of pediatric arrest. Instead, attention to securing the airway and provision of adequate ventilation are keys. Epinephrine is the most effective drug in this setting, and may be administered through an endotracheal tube as well as intravenously or intraosseously. The latter route provides a useful means of rapid vascular access in the pediatric victim less than 3 years of age. Sodium bicarbonate use has been discouraged and there are few indications for calcium, greatly simplifying the pharmacologic approach to the pediatric cardiac arrest patient. In those patients in whom a rhythm and pulse are restored, support of the circulation often is required. Dopamine or epinephrine are the catecholamines of choice in this setting. Ventricular arrhythmias are treated with defibrillation or cardioversion as appropriate. Infrequently, lidocaine or bretylium may be needed. Once the patient has been stabilized, further care is best delivered at a tertiary care center with a pediatric intensive care unit.

Adolescent↗