PubMed Health⌕ Search

Biomedical subjects

S Dubin

Publications and source records attributed to S Dubin.

At least 19 recordsLinked to original sources
PubMed1995

Measurement of wound healing by image analysis.

Chronic wound healing is a major health problem consuming more than $10 Billion/year. Noninvasive measurements of wounds are critical for evaluation of different therapies. In this paper, we present two image processing methods which can be used to compare the effects of different dressings on pig skin wounds. In the first part, the healing process is monitored by area measurements. Using thresholding the wound areas are calculated by pixel counting and corrected with perspective scaling. This technique showed good correlation with manual area measurements. In the second part, 3 D coordinates of the selected wound points are calculated using triangulation from a single colored image coordinates. Such a 3 dimensional image reconstruction from a single camera is made possible by projecting a structured light pattern onto the skin. In this study, a unique pattern consisting of colored dots is used. This color-coded pattern provides many advantages over widely used grid patterns: it is not necessary to see the whole image to recognize the points, since every dot can be identified correctly from its closest eight neighbors, eliminating occlusion problems. Our approach to structured light also mitigates the problem of motion in a subject, since all the coding information is contained in a single image.

Animals↗
PubMed1995

Non-invasive approach for body composition measurement: differential buoyancy method and correction for water loss.

The Differential Buoyancy method uses Archimedes' principle to non-invasively determine body fat percentage by measuring the subject's weight in breathable high and low densities atmospheres. We currently use both air and helium/oxygen mixtures in our experiments[1]. When the method was tested on rats, an anomaly was observed. As helium/oxygen mixture was admitted to the weighing chamber, while the atmospheric density monotonically decreased, the rat's weight first increased but then after several minutes decreased. Water loss from the rat's body was found to be the main cause of this anomaly. Therefore it was necessary to compensate for this water loss. Consistent with experimental findings the water loss was modeled as a constant rate process, and determined experimentally from weight measurements at the beginning and at the end of the experiment. Making these corrections allowed for accurate predictions of the rat's volume and body fat percentage.

Adipose Tissue↗
PubMed1994

Essential amino acid reference profile affects the evaluation of enteral feeding products.

The chemical score is a measure of the predicted metabolic usefulness of a protein in a food based on the comparison (ratio or percentage) of the concentrations of the essential amino acids (EAAs) to a "profile" assumed to reflect the true needs of the body. The score for the limiting EAA is taken to represent the value of the food. Such a chemical score is particularly useful for therapeutic diets where bioassay (such as nitrogen-balance studies) in a large number of patients may be unethical or impractical. Although a major limitation to the chemical-score method previously was scarcity and/or imprecision of data about EAA concentrations in foods, this situation has been mitigated by modern analytic methods. The validity of a chemical score is also exquisitely sensitive to the EAA profile used for comparison. Chemical scores published for a variety of enteral and parenteral feeding products implied a low (approximately 50%) protein value. These computations were based on the EAA profile of egg protein. This pattern is sufficient, in most cases, for body needs, but it may be far more than is necessary. Recently published profiles, based on measurements in human beings of actual protein and EAA requirements, point to a more realistic chemical-score computation. These profiles accommodate age and lifestyle factors and provide greater flexibility in the formulation of therapeutic diets.

Adolescent↗
PubMed1994

EKGenius: a computer-interactive electrophysiology learning tool.

EKGenius is a computer-interactive learning environment in electrocardiography for the cardiovascular specialist including those who design and evaluate monitoring equipment. It provides a comprehensive review and assessment in electrocardiographic principles, 12-lead EKG interpretation, and arrhythmia detection. The program combines a simulated examination, tutorial lessons, and practice quizzes. An authoring system facilitates implementation of an a database of 250 questions and 100 lessons. The program provides the user with his/her score at the end of the exam, and the user has the option to review incorrect responses with the associated lessons. In the quiz mode, 10 questions are selected from the bank in the category selected by the user. Immediate feedback is provided with each response, and the user has the option of receiving a hint or reviewing an associated lesson. A mode is also available to view the tutorial lessons independently.

Computer-Assisted Instruction↗
PubMed1994

Bioengineering approach to non-invasive measurement of body composition.

Measurement of body fat percentage is essential for medical care and research. The "gold standard" method for humans is underwater weighing, which is clearly inappropriate for infants, sick people and non-human animals. The corresponding criterion method for animals is comminution of the carcass followed by extraction of the fat with a volatile solvent such as ether. Our goal has been to develop a method for body composition (fat percentage) for use in animals and humans which is non-invasive and minimally intrusive, independent of variation in body conformation and fat distribution, and reasonable in cost. In one variant, our approach to this problem has been to move Archimedes' principle "on to dry land." The subject's volume is determined by measuring the differential buoyancy in comfortably breathable light (low density) and heavy atmospheres. In another, we use "structured light," in which a pattern of illumination is cast on the patient. The image is acquired using a video camera and the geometrical spatial coordinates of a large number of points on the surface of the subject are acquired. This permits the computation of the surface area and volume of the subject; which, combined with the weight, determines the fat percentage.

Adipose Tissue↗
PubMed1992

Optimal controller for intraaortic balloon pumping.

An optimal control algorithm was adapted to identify and track the optimal deflation time of the intraaortic balloon pump (IABP). Routines for handling physiologically imposed constraints were added to the algorithm which was implemented in a computer-controlled system. The system was designed to provide real time optimization for the clinical setting. The controller continuously maximizes a performance index while observing the constraints. The index is composed of clinically available hemodynamic variables which indicate changes in myocardial energy balance. Proper values for the algorithm parameters were determined and the system was tested in animal experiments. The results indicate that controlling deflation time relative to the R wave, which precedes the next ejection phase, reduces the time required for optimization when the heart rate varies.

Algorithms↗
PubMed1991

Showcase, a veterinary case authoring and presentation system.

Showcase is an instructional authoring and case presentation system for veterinary medicine. It is intended to permit instructors and students to deal with clinical case information in a dynamic and interactive way. The programs are distributed as "adware;" and, it is hoped, the case files will be freely shared and distributed.

Authorship↗
PubMed1984

Automatic calculation for the renal failure diet.

A logical scheme for algorithm for computation of the renal failure diet is presented along with its application to a programmable calculator. The program is user-interractive; the user may add or delete foods without re-entering previous data. Program outputs include water, protein, calories, carbohydrate, sodium, potassium, calcium, phosphorus, and the essential amino acids (EAA) in absolute and percentage terms. As an index of relative protein quality, the chemical score is computed on a meal-by-meal basis. Individual EAA scores are available to permit designation of the limiting EAA of a meal. A major benefit of the program is the ability to explore and document rapidly a wide variety of meal plans. Improvements in "user-friendliness" will facilitate application with patients.

Computers↗
PubMed1980

Studies on the importance of the asparagine residue in oxytocin. Synthesis and some pharmacological properties of [1-alpha-mercaptoacetic acid, 5-isoasparagine] oxytocin.

[1-Alpha-Mercaptoacetic acid, 5-isoasparagine] oxytocin was synthesized to study the effects of moving the side chain carboxamide group of the amino acid residue in position 5 of oxytocin from the beta to the alpha position. The analog has an isoasparagine residue in position 5 and the 20-membered ring size of oxytocin is maintained by substituting cysteine in position 1 of oxytocin by alpha-mercaptoacetic acid. The analog was found to possess 0.098 +/- 0.002 U/mg of uterotonic activity but no milk-ejecting, antidiuretic or rat pressor activity could be detected. The substance did not inhibit the uterotonic or milk-ejecting activity induced by oxytocin nor the antidiuretic or rat pressor responses to the USP posterior pituitary standard. These results, together with the data available in the literature, indicate that an analog of oxytocin lacking the asparagine residue in position 5 is neither an agonist nor an antagonist. The observations may mean that the asparagine residue is critically important for the interaction of oxytocin with its receptor.

Amino Acid Sequence↗
PubMed1980

A reticulated cover slip.

Preparation and use of a reticulated cover slip is described as an aid in orientation under the microscope.

Animals↗
PubMed1978

Effect of anticoagulants and glucose on refractometric estimation of protein in canine and rabbit plasma.

The effect of ethylenediaminetetraacetate (EDTA) compounds on the refractometric estimation of plasma protein concentration was attributed largely to osmotic fluid shifts, as reflected in changes in hematocrit, and to addition of total solids to the plasma. With H4EDTA, these two mechanisms were additive and caused increased plasma protein readings of significant magnitude even at recommended (1--2 mg/ml) anticoagulant concentrations. For the potassium and sodium salts, the two mechanisms were partly compensatory, which ameliorated the effect at 1--2 mg/ml concentration. At higher concentrations, such as might occur if a blood collecting tube were incompletely filled, all of the EDTA compounds caused technically significant over-estimation of plasma protein. When dextrose (d-glucose) was added in-vitro to canine blood, in amounts analogous to clinical hyperglycemia, the effect upon plasma protein estimation was minimal.

Animals↗