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Biomedical subjects

J H Goldstein

Publications and source records attributed to J H Goldstein.

At least 19 recordsLinked to original sources
PubMed1992

The reliability of adjustment in strabismus surgery.

It has been recommended that the position of the operated muscles be adjusted shortly after strabismus surgery to achieve better alignment on the first postoperative day and thereby ensure satisfactory later alignment. We compared prism cover test measurements on the first postoperative day with measurements within the first few months after surgery to determine whether day 1 measurements remained stable or whether they changed significantly, providing an inaccurate basis for adjustment. Our study found a fairly large variability in the deviation between the first and last day of the study. Eighteen percent of patients varied by 5 to 9D, and 49% differed by > 10D or more. Equally important was the finding that, had an adjustment been made, it would have made the final result worse than without adjustment. Both of these factors would seem to indicate a degree of variability that controverts the predictability of the adjustment procedure.

Adolescent↗
PubMed1989

A review of water diffusion measurement by NMR in human red blood cells.

This review of water transport measurement in normal human erythrocytes attempts to harmonize discordant results obtained under diverse study conditions with two different techniques: nuclear magnetic resonance (NMR) and radioactive tracer (THO) diffusion. Natural aggregation of red cells into rouleaux appeared to cause most of the variation among results from NMR experiments. The remainder of the discrepancy was attributed to the use of inappropriate mathematical approximations of the two-site exchange equations, differences in blood storage time, and failure to adjust NMR calculations for the nonwater protons. Differences in hematocrit, frequency-magnetic field strength, or NMR pulse technique played no apparent role in the disparity among NMR reports. When these confounding factors were removed, diffusion results obtained by NMR or by influx or bulk diffusion of radioactive tracer agreed within a relatively narrow range of values. These techniques place the mean lifetime of water inside fresh normal human erythrocytes at room temperature (20-25 degrees C) between the extremes of 9.8 and 14 ms, where the uncorrected range was previously 9.8-21.7 ms. This new range of water exchange times corresponds to a range of diffusional permeability between 3.3 and 4.7 x 10(-3) cm/s.

Body Water↗
PubMed1987

NMR investigation of hydroxyethyl starch-induced aggregation of human erythrocytes.

Aggregation of human erythrocytes at physiological hematocrit by hydroxyethyl starch (HES) was investigated with a 1H nuclear magnetic resonance method which measures the erythrocyte mean water exchange time, tau a. A relationship that takes into account the effect of the aggregate as the water-exchanging unit was used to transform tau a values into the number of cells per aggregate, n. The procedure permits the determination of the time course of aggregation as well as its initial and equilibrium status. The values of n at equilibrium range from about 2 to 4 cells over the concentration of 1 to 5% HES in isotonic saline. The aggregation of erythrocytes in the presence of HES was found to follow first-order kinetics. The feasibility of this technique for application in the study of diseased states is indicated.

Erythrocyte Aggregation↗
PubMed1987

Transverse relaxation of saline and plasma using Mn(II), HSA-EDTA-Mn, and HSA-EDTA-Gd: application to erythrocyte water exchange.

Enhancements of 1H nuclear magnetic transverse relaxation rates by Mn(II)- and Gd(III)-ethylenediaminetetraacetic acid (EDTA)-human serum albumin (HSA) complexes are compared with MnCl2 in human plasma and isotonic saline. HSA-EDTA-Mn and HSA-EDTA-Gd in saline, at physiological concentrations of HSA, afforded T2's comparable to 2 mM MnCl2 in 4% HSA saline. The above reagents are new and potentially useful relaxation agents for the measurement of H2O exchange rates in erythrocyte suspensions. The exchange rate of water across the red cell membrane was determined using these new reagents over the temperature range from 20 to 37 degrees C.

Biological Transport↗
PubMed1986

Inferior oblique advancement for "A" pattern esotropia.

The treatment of "A" pattern esotropia includes bilateral weakening of the superior oblique muscles, vertical displacement of the horizontal rectus muscles, bilateral or unilateral, and horizontal displacement of the vertical rectus muscles. The cases presented indicate that bilateral inferior oblique advancement is an effective alternative procedure for the management of large "A" pattern esotropia.

Adolescent↗
PubMed1985

Management of large-angle esotropia.

If large-angle esotropia is defined as 80 D or more, and if the surgery induces no limitation of movement or incomitance, there is an excellent likelihood that four-muscle surgery in one operation will result in a residual deviation between 15 D of convergent strabismus and 15 D of divergent strabismus.

Child↗
PubMed1984

Magnetic resonance imaging in the diagnosis of breast disease: use of transverse relaxation times.

The ability of magnetic resonance imaging (MR) to demonstrate breast carcinoma depends upon significantly different relaxation times in benign and malignant tissues. The authors conducted an in vitro study of transverse relaxation times (T2) of 393 breast tissue samples in order to establish a range of values for normal tissue, benign lesions, and carcinoma. All T2 values were multiexponential. Benign lesions were readily distinguished from both invasive and noninvasive carcinoma in samples containing fat or a mixture of fat and fibrous tissue; however, in purely fibrous samples there was some overlap of T2 values in benign and malignant tissues. Although the data acquisition and analysis requirements involved in this in vitro study exceed the capabilities of present whole-body MR imagers, the added understanding gained through efforts of this type may aid both interpretation of current images and future developments.

Adenofibroma↗
PubMed1981

Time dependence of the effect of p-chloromercuribenzoate on erythrocyte water permeability: a pulsed nuclear magnetic resonance study.

Pulsed nuclear magnetic resonance spectroscopy is employed to determine the time dependence of the change in erythrocyte water permeability following exposure to p-chloromercuribenzoate (PCMB) or p-chloromercuribenzene sulfonic acid (PCMBS). pH variation was used to examine the environment of the sulfhydryl groups reactive to these drugs. PCMB reacted with at least two sulfhydryl groups which affect water permeability. This was shown by the double exponential character of the change in erythrocyte diffusional permeability with time after PCMB addition. However, only one inhibition rate process could be distinguished following PCMBS exposure, suggesting that one site bound by PCMB is not accessible to PCMBS. This site is postulated to be located in a hydrophobic region of the membrane, whereas the site reached by both drugs is located in the normal anion permeation channel. The effect of pH on the degree of inhibition due to each component and the inhibition rates is explained in terms of its effect on solubility of the reagents in the membrane and variation of the dissociated-to-undissociated ratio of PCMB.

4-Chloromercuribenzenesulfonate↗
PubMed1979

Pulse nuclear magnetic resonance measurements of water exchange across the erythrocyte membrane employing a low Mn concentration.

A simple, precise, and rapid pulse nuclear magnetic resonance technique for measuring the rate of water exchange across the erythrocyte membrane is presented. The technique is based upon the nonlinear fit of Carr-Purcell-Meiboom-Gill (CPMG) transverse relaxation time data of blood doped with 1.7 mM MnCl2 to the general two-compartment exchange condition. Previous approaches using CPMG data required high MnCl2 concentrations (25-53 nM), shown in this work to induce systematic errors ranging from 35 to 45%. At 23 degrees C the average residence time of a water molecule inside the erythrocyte (tau a) is 21.0 +/- 0.6 ms (SE). The Arrhenius plot for water exchange is linear over the range of 3 degrees - 37 degrees C and th Arrhenius activation energy is 4.79 +/- 0.03 kcal (SE). This value does not differ significantly from the energy required for bulk water flow. Results are compared with previous determinations, and sources of systematic error in tau a and the activation energy are evaluated.

Body Water↗
PubMed1979

Tissue response to the Fadenoperation.

The Fadenoperation was performed on 24 rabbit eyes. In 8 eyes the globe and muscle were removed intact and in 16 eyes the muscle was dissected from the sclera to determine the site and degree of attachment. The greatest degree of adherence was found between the muscle and the sclera at the site of the suture, less attachment at the lateral and medial border of the muscle, less in the central area close to the suture site, and least in the central anterior area. The Fadenoperation creates adherence of the muscle to the sclera. Its clinical usefulness will, however, depend on clinical evaluation.

Animals↗
PubMed1978

Management of large angle exotropia.

Four cases of large angle exotropia secondary to third nerve palsy are presented. An effective technique involving recession of the lateral rectus and splitting and advancement of the medial rectus is presented.

Adolescent↗
PubMed1976

Vitreous fluidity in myopia.

Forth-eight eyes were examined to determine if degeneration and liquification of the vitreous could be determined by vitreous movement in subjects with myopia compared with subjects who had either emmetropia or hypermetropia. The difference in duration of vitreous movement for the myopes was significantly greater than that for nonmyopes (p less than 0.05).

Adult↗
PubMed1976

The disposition and pharmacokinetics in humans of 5-azacytidine administered intravenously as a bolus or by continuous infusion.

The disposition of 5-[4-14C]azacytidine, administered i.v. as a bolus or continuous infusion, was studied in cancer patients. After bolus, plasma 14C levels exhibited as multiphasic disappearance pattern; half-life (t1/2, beta phase) = 3.4 to 6.2 hr. Of 14C in plasma, less than 2% was associated with 5-[4-14C]azacytidine 30 min after dose. The ratios of 14C levels were: red cells/plasma, approximately 0.8; leukocytes/plasma, 1.1 to 2.3; nucleic acids/leukocytes, 0.2 to 0.43; sputum/plasma, 0.05 to 0.17. Urinary excretion (3 days) accounted for 73 to 98% of 14C, LEss than 1% in feces. The relative concentration of 5-azacytidine in plasma with continuous infusion stayed higher than with bolus; urinary excretion was similar. Fewer side effects were observed with continuous infusion than with bolus. The stability of 5-azacytidine was determined in various media at several temperatures by thin layer chromatography and nuclear magnetic resonance. At 20 degrees in Ringer's lactate (pH 6.2), the t1/2 was 94 to 100 hr. Stability increased with lowering of temperature and pH. From our data we conclude that 5-azacytidine should be given by continuous infusion rather than as a bolus.

Azacitidine↗
PubMed1975

Escalation of aggression: experimental studies.

A finding commonly obtained in research using the Buss "aggression machine" is a main effect for trail blocks, indicating an escalation in shock intensity over trails. Theoretical explanations for this effect were tested in a modified verbal operant-conditioning situation. In Experiment 1, subjects could administer any of 10 levels of positive reinforcement to a "learner" for correct verbal responses or any of 10 levels of negative reinforcement to a learner for incorrect responses. Half of the subjects were required to begin with weak, half with strong, reinforcements. Results indicated that, regardless of condition, subjects gave more intense reinforcements as the learning trails progressed. Those who administered negative reinforcements devalued the learner relative to those who administered positive reinforcements. In Experiment 2, a role-playing procedure was used in which subjects administered either positive or negative reinforcements to a learner whose performance either did or did not improve over trials. Again, in all experimental groups, subjects administered increasingly intense reinforcements over trials. The results are interpreted as supporting a disinhibition theory of anti- and prosocial behavior.

Aggression↗