Search PubMed⌕ Search

Biomedical subjects

A Boyarsky

Publications and source records attributed to A Boyarsky.

11 recordsLinked to original sources
PubMed1993

Hemolytic anemia associated with lead poisoning from shotgun pellets and the response to Succimer treatment.

Symptomatic lead poisoning with severe hemolytic anemia was observed in a patient with retained shot gun pellets. Surgical resection of the retained pellets and the use of a newer chelating agent, Succimer (2,3-dimercaptosuccinic acid) successfully lowered blood lead level. Hemolytic anemia was associated with deficient erythrocyte pyrimidine 5'-nucleotidase, and lowering of the lead level corrected the deficiency, suggesting that the enzyme deficiency is responsible for the hemolysis associated with lead poisoning. This case illustrates that retained lead pellets from shotgun wounds can cause severe lead poisoning.

Adult↗
PubMed1991

A mathematical model describing consequences of abnormally high levels of epidermal growth factor receptor on the proliferation of neoplastic cells.

Recent laboratory and clinical data suggest that some human neoplasms exhibit unusually high levels of cell-surface receptors for epidermal growth factor, and that this abnormality is associated with rapid cellular proliferation and poor prognosis. We propose that the existence of an abnormally high number of mitogen receptors is not merely correlated with rapid proliferation but is pathophysiologically responsible for such behavior. Cells with high levels of mitogen receptors may be rendered 'hypersensitive' to mitogenic stimuli, and hence may be stimulated to divide even when ambient mitogen concentrations are at a low 'background' level, insufficient to prompt the division of cells with a normal number of receptors. To investigate this hypothesis further, we have developed a mathematical model that describes proliferative behavior of cells as a function of mitogen concentration and receptor number. The model enables us to simulate the proliferative behavior of cells with various receptor levels at various mitogen concentrations and predicts a growth advantage associated with excess mitogen receptors. Computer simulations based on the model are consistent with previously published experimental data. This work provides support for the view that overexpression of genes encoding normal growth factor receptors can contribute to the inappropriate proliferation of neoplastic cells.

Cell Division↗
PubMed1988

Analysis of cell three-dimensional locomotory vectors.

A method is presented for analysing the vectors of cells locomoting within three-dimensional collagen gels. The method detected differences in locomotory vector patterns between cells locomoting in two different gel formats. The potential of this analytical method for determining the role of the extracellular matrix in modulating cell locomotory behaviour is discussed.

Animals↗
PubMed1987

Optimal pressure waveforms for pressure-limited ventilation.

In this paper, we find the pressure waveform that minimizes the work of distending the alveoli in the lungs while achieving the desired mean airway pressure and alveolar tidal volume. The model used takes into account the compliance of the airway. The main result is a formula for the pressure waveform at the mouth as a function of time and lung parameters.

Humans↗
PubMed1987

Computerized ventilation management system for neonates.

This paper introduces a ventilation management system for neonates. Its main feature is the manner in which it incorporates the clinician's decisions and the prediction of ventilator adjustments based upon actual patient data.

Humans↗
PubMed1985

Temporary banding of the gastroesophageal junction in the critically ill neonate with esophageal atresia and tracheoesophageal fistula.

Patients with esophageal atresia and a distal tracheoesophageal fistula with associated conditions contributing to decreased pulmonary compliance present special problems in management. In the face of positive pressure ventilation, the fistula acts as a vent preventing adequate ventilatory effort from reaching the lungs. A thoracic approach to ligate or divide the fistula carries with it a high mortality rate. A technique is described whereby a silicone rubber band is applied to the gastroesophageal junction to effectively occlude the esophagus. It is designed so that is can be adjusted or removed, without operative intervention, according to the patient's clinical course and growth.

Emergencies↗
PubMed1979

Human lymphocyte migration in vitro: characterization and quantitation of locomotory parameters.

Using a time-lapse cinephotomicrographic technique, the locomotory paths taken by lymphocytes have been shown to satisfy the requirements for a continuous-time Markov chain analysis consisting of four directional states defined by the four quadrants of a Cartesian plane and state 0 in which the cells are stationary. The important parameters characterizing this path motion are the average time (waiting time) that a cell spends in each state and the state transition probabilites which, using the Markov model, allow the computation of the probability of the cells moving in a given direction. Our results show that lymphocytes moving alone on glass exhibit a random migration pattern.

Cell Movement↗
PubMed1977

Pattern prediction for moving cells.

A continuous-time Markov chain model consisting of four positional and directional states is used to predict the eventual relative positioning of two motile cell types. It is assumed that the period of observation is small in comparison with the generation time of both cell types. The method is useful in predicting developmental phenomena and is applicable to complex patterns involving more than two types of cells.

Cell Movement↗
PubMed1977

A Markov chain characterization of human neutrophil locomotion under neutral and chemotactic conditions.

The locomotion of human neutrophils is modelled by a continuous-time Markov chain model consisting of five states: state O, where the cell is stationary, and four motile states whose directions are defined by the four quadrants of a Cartesian plane. In this paper, the Markov property is verified experimentally in special cases. Further experimental evidence for the model is provided by the waiting-time distributions in each of the five states, which are well approximated by exponential distributions. Using the steady-state distribution of the Markov chain as a measure of the ultimate motion of the cells, it is possible to detect the effect of known chemotactic agents upon neutrophil locomotion. Other useful parameters describing neutrophil locomotion are presented.

Cell Movement↗
PubMed1976

The ureterovesical junction of the rabbit.

Twelve New Zealand rabbits were studied for ureterovesical reflux. Dissections revealed the intramural ureter and ureterovesical junction to follow an upward and medial course, unlike the course observed in man. This course could not be altered or distorted by dissection of the bladder base or ureter, by freeing the urether retroperitoneally, or by changing the position of the animal.

Animals↗