Search PubMed⌕ Search

Biomedical subjects

N Abramson

Publications and source records attributed to N Abramson.

At least 19 recordsLinked to original sources
PubMed1991

Risk monitoring of randomized trials in emergency medicine: experience of the Brain Resuscitation Clinical Trial II.

Risk monitoring for the Brain Resuscitation Clinical Trial II, a multicenter, placebo-controlled trial to evaluate the efficacy of the calcium-entry blocker lidoflazine in the amelioration of brain damage in comatose cardiac-arrest survivors, posed unexpected challenges. Concern arose when monitoring of adverse reactions showed an excess of dangerous cardiac arrhythmias, including rearrest, in the lidoflazine group. To ascertain the cause of this problem and determine whether it was ethical for the trial to continue, an in-depth review of data was conducted, outside experts were consulted, and additional data were collected. These efforts suggested possible causes for the problem. Existing drug administration protocols for blood pressure control were reinforced, resulting in lower subsequent arrhythmia rates. Thus, through an efficient monitoring system, an important problem was uncovered and resolved, allowing the trial to be completed without major changes.

Arrhythmias, Cardiac↗
PubMed1989

Principle of least wave change.

Fermat's principle of least time has some well-known limitations. It does not, for example, apply to diffraction gratings and holograms, because it does not include the concept of waves. The substitution of least number of waves in flight for least time of flight and the addition of a term that is a function of the grating frequency result in a generalized principle. It is easy to remember because it is based on only the number of waves minus the number of grooves, and it would be especially useful when refraction and diffraction are combined, as, for example, in some holographic optical elements.

Light↗
PubMed1988

Measurement of gingival swelling from dental casts by generation of a moiré pattern with laser light.

The aim of the study was to develop a sensitive measuring method enabling direct evaluation of gingival swelling to be made as registered on dental casts. On two separate occasions, when different degrees of severity of gingival inflammation were present in the same subject, reversible hydrocolloid impressions were taken of the mandible. The casts obtained were located successively in identical three-dimensional relationships in a field of interference fringes generated by two intersecting beams of collimated helium-neon laser light, and were photographed. The evaluation of the moiré pattern obtained directly by superimposition of the two images of the surface studied indicated that a decrease in gingival height of 0.38 mm in the direction of the camera had occurred between the two occasions. The use of a computer-based image-processing system considerably improved the visibility of the pattern. The reproducibility of the impression technique, as well as the relocation and superimposing techniques, proved satisfactory at the moiré resolution used (0.19 mm). The method has potential application in clinical experimental research, and therefore warrants further evaluation.

Adult↗
PubMed1987

Cardiopulmonary bypass after cardiac arrest and prolonged closed-chest CPR in dogs.

We studied a clinically realistic field-to-hospital scenario in dogs with four-minute ventricular fibrillation (VF) cardiac arrest followed by 30-minute standard external CPR basic life support (BLS). At the end of this 34-minute insult, cardiopulmonary bypass (CPB) was used for early defibrillation and assisted circulation for one hour (n = 10). Recovery was compared with that of control dogs (n = 10) in which standard CPR with advanced life support (ALS) for another 30 minutes was used for restoration of spontaneous circulation (ROSC). Both groups had hemodilution and heparinization; controlled blood pressure, blood gases, ventilation, and other parameters for 20 hours; and intensive care to 72 hours. During CPR-BLS of 30 minutes in both groups signs of cerebral viability returned. CPB achieved ROSC more successfully (ten of ten vs five of ten CPR-ALS controls) (P less than .02); and more rapidly, with less defibrillation energy (first countershock in eight of ten) and with less epinephrine (P less than .01). CPB improved 72-hour survival (seven of ten vs three of ten controls) (P less than .05). Between two and 24 hours, of those with ROSC, cardiac complications killed three of ten CPB dogs (after weaning), and two of five CPR-ALS dogs (NS). All seven CPB survivors to 72 hours were neurologically normal; of the three CPR-ALS survivors, one remained with severe neurologic deficit and two were neurologically normal (seven of ten CPB vs two of ten controls, P = .025). Starting CPR-BLS within four minutes of arrest can maintain cerebral viability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Effect of prophylactic antibiotics in radical head and neck surgery.

One hundred major head and neck operations performed on 77 patients were evaluated regarding the effectiveness of an aminoglycoside and cephalosporin antibiotic combination given prophylactically to prevent postoperative infection. The postoperative infection incidence was 6%, significantly lower than that reported in similar series where no antibiotics were used. The addition of the aminoglycoside did not appear to provide any additional protection compared with the use of cephalosporin alone.

Aminoglycosides↗
PubMed1976

Immune markers in adult acute leukemia.

Three cases of adult acute leukemia were examined for immunologic markers. Incubation of leukemic cells with anti-D (IgG)-coated erythrocytes was used for the identification of monocytes; sheep erythrocytes were employed for T-cells and fluorescein-conjugated anti-mixed immunoglobulins for B-cells. It was shown that IgG receptors (monocytes) were present on immature cells with predominant monocytic components; T- and B-cell markers were absent in the mono- and myelocytic leukemias.

Adult↗
PubMed1976

Short-course radiation therapy in the treatment of head and neck tumors.

A pilot study undertaken to evaluate short-course, high-increment radiation therapy. This type of treatment was tolerated well by the patients, with a surprisingly low level of acute reaction to the regimen and few late complications. Tumor regression seemed to be earlier than might be expected and involved more than 50% of the tumor in over 75% of the patients following the fourth course of treatment. Preliminary results show that long-range survival rates are at least equivalent to those obtained with the conventional longer treatment regimen. In general, this seems to be a more economical and efficient method of treatment which entails less patient discomfort than the conventional method.

Body Weight↗
PubMed1975

Fractionated dose of 35-MEV fast neutrons and hypoxic tumor cell survival curve.

The determination of the RBE for the MANTA fast neutrons produced by NRL is inprogress, with the model system using tumor cell population kinetic response patterns assayed in vitro after irradiation in vivo. Ascites tumor cells BW-5147 were irradiated with a clinically usable fast neutron beam from the NRL cyclotron, which is produced by accelrating deuterons to 35 MeV and using htem to bombard a thick berylliumtarget. The comparison of dose-effect relationships was made for doses ranging from30 to 1000 rads. The doses required for an isoeffect on BW-5147 hypoxic tumor cell survival and impairment of its reproductive capacity from fast neutron exposure were not different wheither it was given a single dose or the same dose given in three fractions separated by long recovery periods in situ. No intracellular repair of sublethal injury when the dose was given in three fractions, although the hypoxic BWp5147 tumor cells haveno effective reoxygenation or repopulation in this time interval. The RBE for the fast neutron beam is 4 relative to x rays for fractionated doses at the surviving fractionlevel of 0.6-0.7, while the RBE IS 2.5 FOR SINGLE DOSES. However, at a surviving fraction of 0.1, the RBE is 1.9 for single and 2.8 for fractionated doses. Analysis of thedaily cell population rate or mitotic delay between the two types of radiations at a similiar level of survival.

Animals↗